Sbc Idles Up And Down

It's marginally better when setting IDLE AFR to 13. i just had to replace a purge valve, cleaned the throttle body, and replaced the 6th cylinder. Clogged low speed and idle circuit. The lower intake manifold gasket fails and leaks coolant into the engine oil. + more info 1996 Chevy Blazer, start up, idle rev, engine off, exterior, near. when driving my 94 rs caveliar with 87k it runs great about 30mpg but when I come to a stop it seems the engine does not slow down to a very quiet smooth idle it also will go even up a slight hill with no gas pedal help it has new plugs, wires, pvc, and a couple of other things on top where the throttle is but I can not remember the name them. Because you just closed-off the throttle plates more than they were before hooking-up the vacuum advance to manifold vacuum, when you turn the key off now, the plates are closed enough to no longer pass enough fuel and air to. and i put it in gear it starts to idle up and down some times it dies starts back up fine. well first let me thank anyone who. A Corvette idle air control value failure can cause the engine to stall at idle. highperformancepontiac. I noticed while sitting in park the voltage meter drops and the engine pulls way down. I had a CV joint done 2 weeks ago. It idles super smooth and accelerate nicely. 1992 Chevy K1500 5. In regards to why the car's enging temp rises at idle is quite simple. why can't I just get my vehicles to run right for one week? I think the oil pump crapped out in the xj, so now I'm driving the 93 chevy, heres whats going on: 1993 chevy k1500 - 5. When I first start the car, the idle only goes to 800 rpm. Hi, I am having a problem with my chevy 350 engine that I just installed back in August. When I give it throttle, the vacuum goes up to about 21" and stays steady (held it at 1500, 2000, and 3000 rpm and it stays about 21"). hello im new to the forum. 96Z28 code P0507 idle too fast car is a 96Z28, auto, headers, The code is P0507 (Idle Control System RPM Higher Than Expected). Free shipping on orders over $50 always makes purchasing a little easier. I was gonna use my scholarship money and my parents said they would help if with about 1000-2000 if I needed it. If idle RPM is modified up or down, the VCM Editor>Edit>Engine>Idle>Base Running Airflow>Idle Airflow vs. The owner of the 65 mustang also had a 1406, but his idle goes down after warming up, my idle doesn't even do that. A good rule of thumb is to get the rotor as close to number 1 as possible, then handcrank the engine, which gets the distributor lined up with the oil pump shaft. Thanks for all the fast reply's. Its not so rough of an idle like its misfiring, so no worries in at the moment. It'll continue doing that until you shut the truck off and start it again. 0 stalls out at low idle. My 1989 chevy c1500, 5. My dakota was surging up and down at idle. The small-block family line was honored as one of the 10 Best Engines of the 20th Century by automotive magazine Ward's AutoWorld. My 94 Chevy 1500 Rpms fluctuate up and down at idle and I am starting to notice it while going down the road. The Chevy Cobalt is a compact car that was introduced in 2005. hi i have a chevy 350 in my 72 chevelle engine has been overhauled but the idle is too high like around 2000 to 3000. 2003 Chevy TrailBlazer Idle goes up & down when AC turned on Sign In 2003 Chevy Trailblazer, 4. AND SOMETIMES IT JUST CUTS OFF AT A STOP. It idles no lower than 1100 (in park) and you can really feel the engine pushing against you when you try to brake; it kind of descends through the gears as you try to slow down. Picking up a cam catalog doesn't necessarily help because of the number of choices. Tex, To answer your question No the secondaries, although at fault in many cases, won't do the bog in neutral. The load of the compressor causes the idle to come down and overshoot after then back down, causing the problem you describe. Wait a minute for the engine idle to level off, then use a pen and paper to write down the RPMs that your engine settles and idles at. pull off 1 plug wire at a time and see if one or more do not change idle speed. When the air control valve for Chevy Silverado is clogged, it likely to lead to an instant, irregular deceleration as you lift your foot off the pedal, causing a backfire through the tailpipe and loading up the engine with surplus fuel. Normal engine maintenance schedule followed. It remains high no matter way I do At this point in time it doesn't hurt to give it a shot though. i have a 1992 chevy truck the idle goes up and down and loss power and gets hot and the egine light comes on that - Chevrolet 1999 Silverado 1500 question. After looking on youtube at balance shaft chain i not sure if it could be this. Watching the tachometer shows an idle speed around 500 to 900 RPM. The ECM controls the idle air valve. The engine completely stalled one time as I was braking coming off of a freeway off-ramp into a turn. I always let my 86 warm up since its cold weather. it ran fine til' it warmed up, thats when it started acting up When I put it into drive, it shifts really hard because the rpm is high, than when I put it into Park or nuetral, it races up to 1500rpm for a second, than back down to about 1200. My guess is they are too far out. 2003 Chevy TrailBlazer Idle goes up & down when AC turned on Sign In 2003 Chevy Trailblazer, 4. When it is doing the surge at idle you can lightly mist some carb cleaner over the throttle body and it runs perfect. If I give it gas while holding the brake it will let me go, but to hold full brake at idle in gear is not happening. Basic LS1 components. But a low or weak battery is the #1 cause of idle stumble and stall, or a start and immediately stalls upon idle down. My 1989 chevy c1500, 5. Chevy Small Block Engine Guide: Cams and Valvetrains A problem confronting many engine builders is making the best choice of cam and valvetrain components. This is a common issue. engine start up sounds (76) shutting down and starting up, mono recording. 2-liter engine with a manual transmission. Discuss 1990 TBI 5. All vacuum lines double checked. i just had to replace a purge valve, cleaned the throttle body, and replaced the 6th cylinder. So as you're at idle, it'll rev up quickly, then drop slowly back down to normal idle, then it'll sit there at normal idle for a couple seconds and rev back up. Do it yourself information page. Big-block Chevy timing is pretty well standardized unless major modification have been done. I had the dealership replace the manifold gasket the first time at about 40,000 miles before it got to. 2002 Chevy Trailblazer Dies Out My 2002 Chevrolet Trailblazer stalls when sitting at a red light but not all the time,rpms go up then drop to 200 and car cuts off,already cleaned throttle body,changed fuel filter,changed map sensor ,changed exhaust cam actuator solenoid and still stalls,any ideas would be greatly appreciated!. My original problem with my 2004 Silverado 5. And doesn't seem to do it in park as bad. The timing on stock 396, 402, 427 and 454 engines is 32-34 degrees total advance at 3500 rpm. Most likely its a condenser fan, when your driving, the ram air is cooling the refrigerant inside the condenser, and at idle (stopped, no ram air) it isn't getting sufficient airflow for cooling, therefore not working. If there is a leak the water will be sucked up. I have spent almost $1000. Seriously though, what you are describing is pretty 'normal' behaviour for the 3. ? Thumbs down. Once the truck is running down the road, the RPMs smooth out and it runs fine. I replaced a gunked up air filter. Q: engine revs up and down when in park and when driving My car has 130170 miles. Then I thought to change the fuel filter thinking a big piece of something might be making its way up to the filter to block the passage of fuel and when I shut it down, it floated away far enough for it to pass fuel once again. Car Shaking and Jerking w/ RPM going up and down Mini Spy it will rev up and down at idle but it stops doing it if you give it a bit of gas or simply put it in gear. But with them on, it stalls about half the time, but only when it tries to drop down to idle. Two possibilities, 1 Air leak-carb, head gasket, crankshaft seal. This page is for the small tips and tricks that will make for installing and maintaining your TPI more enjoyable. The only way I could get the code off was to turn the idle screw down to lower RPM (I know you should not do this), this took care of the problem but my idle. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). Ran across this old post of mine and figured I should wrap it up. With normal normal driving it reads 400deg-F and when I come to a stop it will not read below 400 deg-F no matter how long it idles. If I try to push on gas it eventually would backfire and smelled rich. If it has not pulled any codes (idiot light). Chevy idles on the ice at a Wings game, sorta. If I drive somewhere, leave the vehicle for a while, say 30 minutes then come back, sometimes (and I must say sometimes as it is another &*$# intermittent issue) when I start up the engine will rev from idle to about 1400/1500 rpm then back down to idle and keep repeating this pattern for about 12 to 15 times. Any advice or help would be appreciated. Ok this has been going on for some time now. It sounds like your choke is still set. i rebuilt the tb 3. SBC 350 Craptastic IDLE. 2012 Chevy Cruze Idle Issue was created by Fightingmarmot I apologize if this is long, been dealing with this for a long time lol. Then I thought to change the fuel filter thinking a big piece of something might be making its way up to the filter to block the passage of fuel and when I shut it down, it floated away far enough for it to pass fuel once again. Power steering doesn't seem to affect it either. If your car revs up and down at idle, there are a few possibilities. 10 mins or so. In the case of this big block Chevy, it appears that the throttle blades are open too far which means the IAC steps will be a very low number - perhaps 0. When it is doing the surge at idle you can lightly mist some carb cleaner over the throttle body and it runs perfect. why can't I just get my vehicles to run right for one week? I think the oil pump crapped out in the xj, so now I'm driving the 93 chevy, heres whats going on: 1993 chevy k1500 - 5. In between idle fluctuating up and down, sometimes it sounds like it's idling correctly. I presume that the check engine light is not on or you would have mentioned that. my truck does something similar. To learn more, see reviews below or. Setting Idle on Chevy 350 TBI - Duration: 2:45. I am not a mechanic so I had to drive 30-45 mins to my mechanic's garage to get the problem fixed. well first let me thank anyone who. com FREE DELIVERY possible on eligible purchases. It got worse over time and now it when that happens the RPM's go up to about 1200 max and down to almost dead a few times and eventually it can't recover and just dies. The others are similar and some of this theory can be applied even if they only have a 2 corner idle system. Idle Surge) For those of you who may have missed the thread regarding my idle surge, here's a brief summary: - One hot Saturday in June, I was driving happily along the freeway. This just cropped up this morning while leaving for work - the idle is very rough and sits about 500 rpm with the AC off. back and forth, and obviously the truck runs very rough when it is below 500. It can not be that as its a manual and shakes when not in gear. Average failure mileage is 197,250 miles. I have checked and your car has many recalls for engine sensors, stalling, ECM recalls, etc. This ones got me scratching my head and it's probably something obvious. range is fluctuating rpm needle - Chevy Traverse Forum: Chevrolet Traverse Forum. This has been over a two week period. Sometimes it clears out immediately or a few seconds later. Silverado sales were up a bit more than 1 percent through the first nine months of the. 1971-72 Initial Adjustments. Chevy throttle body truck won't rev up, then does by itself, it goes up and down. sometimes now after I tuned it up plugs and wires it stalls worse runs strong no missing can't cross wires Was told possible. engine idles up and down 2 Answers. Hey guys, I have a bone stock 2004. I have been looking forever trying to find an ideal idle RPM for my 350 small block with the edelbrock 600 cfm. I can go out and crank it right now and it will idle like a new top, put it in gear and its almost as if the accelerator pedal is partially pushed, it just takes. And from my experience. Engine Idle Is Too Low Or Stalls Dirty Throttle Body. Acceleration is sluggish, pushing on the pedal gives no immediate response. 1st time - CEL Flashing, Traction Control Illuminated on Dash, rough idling and clunking when put into reverse (so hard it shook the vehicle) - Took it into dealership can't find anything, computer reads fine and was told the car can correct itself and that's why all these symptoms went away. It also surges while driving. Idle at starting or just a few miles showed no change in pressure. The ECM controls the idle air valve. warm up the motor, pull the air cleaner and there is a little metal flap that closs of the front half of the carb, make sure that it is straight up and down. 10 mins or so. Then I thought to change the fuel filter thinking a big piece of something might be making its way up to the filter to block the passage of fuel and when I shut it down, it floated away far enough for it to pass fuel once again. After it has been running for 5 plus minutes I can adjust idle down to 800. This up and down action would load up the engine with fuel and it would start emitting black smoke. AND SOMETIMES IT JUST CUTS OFF AT A STOP. We are able to do this because of our long time involvement in racing and performance street rodding 'and' because of our experience as a. My 1989 chevy truck is idle is not working right. My first instinct would be to look for a vacuum leak. hi i have a chevy 350 in my 72 chevelle engine has been overhauled but the idle is too high like around 2000 to 3000. It idles at 600-700 rpm and will drop to 400 rpm and jump back and forth and then when the air conditioning compressor comes on it will drop to 300-500 rpm and keep cycling the compressor on and off. 5, but the idle surges up & down by a couple hundred RPM. If you have the air/fuel ratio set properly and your engine can idle somewhat decently, even if it's by holding the throttle pedal down off closed-throttle to keep the engine from stalling, you can begin by setting a ball-park ignition advance value. ? Thumbs down. The only way I could get the code off was to turn the idle screw down to lower RPM (I know you should not do this), this took care of the problem but my idle. The small-block family line was honored as one of the 10 Best Engines of the 20th Century by automotive magazine Ward's AutoWorld. it seems to only idle with any consistency around 1400, and honestly it sounds more like 800 with the cam. Tapping the pedal shouldn't do anything because there is no mechanical choke on EFI. My guess is they are too far out. At 52k i change the sparks, air filters and a Gunk gas treatment. just by chance have u check to see. His dad was a real shade tree mechanic and informed me I had a header gasket leak and a set off burned up plug wires (stock ones) from being so close to the headers. On 95 chevy that's still want stay crank and still stalls out. I have a 91 Chevy k1500 4x4 p/u with a idle issue. Because of this, there may be no warning chimes such as the reminder to buckle the seat belt and the key being left in ignition when the driver goes to exit the vehicle. Hi, I am having a problem with my chevy 350 engine that I just installed back in August. Corvette IAC (idle air control) valve is designed to adjust your Corvette's engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. Brodix BB2 heads and 4500 intake with an adapter for a 4150 carb MSD dizzy and 6AL box! I have tryed 3 different carbs and all are rich at idle 1 is a brand new Chuck Nyutten built 850!. 7 Idle surging,stalling in the alt. And doesn't seem to do it in park as bad. At cold start-up it has a rough/choppy idle and seems to smell a little rich. i took it off yesterday the top part was loose. Once engine is warmed up been driving for awhile. Not sure when this carb was built and depending on build date, if I should replace or re-build. 6L Duramax Diesel 2500 & 3500 series trucks. So when I start it up it idles from 1500 to 2000 rpms in park or neutral. If your car revs up and down at idle, there are a few possibilities. Idle air control valves open to allow more air to "leak" into the intake, raising the engine rpms, or close when not needed. The only way I could get the code off was to turn the idle screw down to lower RPM (I know you should not do this), this took care of the problem but my idle. 1971-72 Initial Adjustments. New spark plugs, wires are good even switched them and didn't change anything, checked coil packs and switched them around no change, then even put in new injectors still the same. To summarize, the solutions for a lazy / slow return to idle (or erratically high idle) are: Eliminate vacuum leaks; Perfect ignition. And from my experience. you can also spray the top of the engine down with carb cleaner, if you spray a area and the idle jumps up you found the area the leak is in. Replaced wires, plugs, distribu. I noticed while sitting in park the voltage meter drops and the engine pulls way down. A mechanic will be able to diagnose the rough idle for you and quote the needed repairs. Winter Cover If your vehicle includes a winter cover, it will enhance heater performance and will reduce the amount of time it. My 1989 chevy truck is idle is not working right. When we took it back in, the mechanic told us that the vavle itself had a piece of carbon lodged in it, holding it open and raising the idle again. Good Luck & don't give up on it, you'll figure it out! Lorne. Why would a car idle rev up and down? Answer. Discuss 1990 TBI 5. I too have a chevy s10 it idles fine when its cold, but as soon as its warmed up and hot the idle jumps to 3,000 RPM. My car idles very high when i first start it up and after a few minutes it will idle down but not much intell i put it into gear. This works like turning the idle speed screw on a carburetor. Another sign is if you leave your car to idle. sometimes now after I tuned it up plugs and wires it stalls worse runs strong no missing can't cross wires Was told possible. Chevy s10 pickup idles up and down almost stalls new fule pump filter injector assy new entire intake gasket set. shut truck off. After looking on youtube at balance shaft chain i not sure if it could be this. thhen in idle state it just idles up and down. That sets the choke. The load of the compressor causes the idle to come down and overshoot after then back down, causing the problem you describe. i have a 1992 chevy s10 \2. If you have an older car, you may need to check your oil every other week. SOURCE: 2004 Chevy Trailblazer idles rough. Surging idle can be caused by a number of different problems. I have a 91 Chevy k1500 4x4 p/u with a idle issue. I push the clutch pedal down, foot off the gas, and the RPM gauge drops down to either 700 or 500. I am having a huge issue with my 05' Z85. IT acts like it is starving for fuel. Good news is a SBC only needs like 5psi of oil pressure at idle to keep alive, if you are getting 30 or over driving down the road it should be fine. In gear it's steady for a short time and then slowly goes up and down and then, goes up and down faster and faster until it starts to surge and then stall. When the air control valve for Chevy Silverado is clogged, it likely to lead to an instant, irregular deceleration as you lift your foot off the pedal, causing a backfire through the tailpipe and loading up the engine with surplus fuel. IAC 2% base, but cycles up & down. chevy forum at Car Dealer Forums; Truck runs great, but recently when the engine comes off the enriching circuit. Its not as bad when the engine is hot but you can still see it surging. just recently my 2005 3500 started doing the same. 1L V6 of the late 80s/early 90s. It started right up! But it ran at a high idle, around 1500-2000 RPM. Sorry about that, the oil pressure drops to 0 really fast at idle but if you touch the gas it shoots back up really fast. Most likely its a condenser fan, when your driving, the ram air is cooling the refrigerant inside the condenser, and at idle (stopped, no ram air) it isn't getting sufficient airflow for cooling, therefore not working. If you have the air/fuel ratio set properly and your engine can idle somewhat decently, even if it's by holding the throttle pedal down off closed-throttle to keep the engine from stalling, you can begin by setting a ball-park ignition advance value. It idles super smooth and accelerate nicely. Now that you have the preload set for the intake, once again rotate the motor in it's direction of running rotation until the intake pushrod comes all the way up and almost all the way back down. I have a 2000 Mercury Grand Marque. The engine completely stalled one time as I was braking coming off of a freeway off-ramp into a turn. 100" 70 jets, still no rods or power piston. Chitty pretty much nailed it, I also have an F250/7. After it stalls it starts right back up with no problem but still revs up and down at idle. 0l engine has a very high idle speed. When im at a stop it idles up and down fast, about every 1/2 of a second for a while, and sometimes it would steady it self out, and sometimes not. 1990 chevy truck 350 tbi runs rough at idle up and down and exhaust stinks bad, bad gas milage too - Answered by a verified Chevy Mechanic. With the engine idling, monitor both the IAC steps and idle speed. If I try to drive the car while it is still idling it stalls a lot. my concern is this. With the line removed and capped off it sounds great, no RPM fluctuations. Caprice - 1997 chevy caprice idles up and down - Have a 1997 caprice idles up and down. Setting Minimum Air Idle Speed Serpentine Belt Adjustment Check TPI Manifold Tightening S equence Setting TPS idle voltage Fuel Filter information. I recall a co workers 87 Honda CRX did it. - 5J8YD4H32KL033615. Features: 2001-2004 LB7 6. Since Holleys are so easy to adjust, it's also easy to adjust them totally wrong. This up and down action would load up the engine with fuel and it would start emitting black smoke. This page is for the small tips and tricks that will make for installing and maintaining your TPI more enjoyable. It will idle high then drop back down to normal idle every few seconds and even with the truck warm. Can you back the mixture screws out far enough to make the engine slow down from an over-rich idle mix? Do you have LESS THAN 4 turns out on the mixture screws to get an acceptable idle? NO? Ok, then you need to go farther. If idle RPM is modified up or down, the VCM Editor>Edit>Engine>Idle>Base Running Airflow>Idle Airflow vs. If you've specified less timing below the target idle speed than you have at the idle speed, this often makes for an unstable idle as the ECU pulls timing while the idle speed falls. Car won't idle normally? Engine surges or revs up at idle? Mine used to as well, until I discovered what the problem was. I agree with STBTRICKEDOUT91OCC check for vacuum leaks. I cleaned. With normal normal driving it reads 400deg-F and when I come to a stop it will not read below 400 deg-F no matter how long it idles. This company is not yet accredited. Then I thought to change the fuel filter thinking a big piece of something might be making its way up to the filter to block the passage of fuel and when I shut it down, it floated away far enough for it to pass fuel once again. Free auto repair questions and answers. I've noticed that while drivingnat a stable speed, for example, 50mph at 2k rpm, the car slightly revs up and down. after looking at the engines on over cars, there engine doesn't vibrate as much as mine and there is a faint rattle sound which i don't get from my. hello im new to the forum. Idle at starting or just a few miles showed no change in pressure. After about 7-10 minutes, the temp was up to about 220 and the water began going way down and then coming up and spilling out of the radiator, then back down and then up again. Started out by changing old fuel lines, gas, air and oil filters, (and oil, of course), and plugs and battery. That sets the choke. Its not as bad when the engine is hot but you can still see it surging. Then after it's warm do the same again to get it off high idle. Lack of oil will cause a knocking sound in the engine, stalling, poor acceleration and eventually engine break down. It idles terribly. 1200 - 1500 RPM with slight power while coasting w/o brakes applied and no throttle is normal. 1st time - CEL Flashing, Traction Control Illuminated on Dash, rough idling and clunking when put into reverse (so hard it shook the vehicle) - Took it into dealership can't find anything, computer reads fine and was told the car can correct itself and that's why all these symptoms went away. Will run with only the choke on. 6L LB7 & LLY Duramax Diesel High Idle/Valet Switch. 1L V6 of the late 80s/early 90s. Good day all. 3 l v6 standard ,with high idle even after being warmed up. Not violently revs, no check engine lights, nothing. The carb I am using is a NOS Holley 9834-1 Here is what happens: Car starts fine hot or cold. In between idle fluctuating up and down, sometimes it sounds like it's idling correctly. The 2003 Chevrolet Venture has 1 problems reported for engine idles up and down. The result is an automatic feedback loop that helps maintain a constant idle speed. My first instinct would be to look for a vacuum leak. Seriously though, what you are describing is pretty 'normal' behaviour for the 3. Brodix BB2 heads and 4500 intake with an adapter for a 4150 carb MSD dizzy and 6AL box! I have tryed 3 different carbs and all are rich at idle 1 is a brand new Chuck Nyutten built 850!. I had a CV joint done 2 weeks ago. when driving the car it runs fine but at idle it revs up and down till it stalls. Re: rough idle 350 SBC Pull cap and rotor and look for moisture or cracks or crud built up. Check every possible point where you could have a leak. Now at idle it surges up & down and it also takes a while to come down in rpms coming to a stop. The Chevy Cruze is a compact car that has been manufactured since 2008. It idles at 600-700 rpm and will drop to 400 rpm and jump back and forth and then when the air conditioning compressor comes on it will drop to 300-500 rpm and keep cycling the compressor on and off. In the case of this big block Chevy, it appears that the throttle blades are open too far which means the IAC steps will be a very low number - perhaps 0. And from my experience. Mine does it I noticed it last year only when warmer when the A/C is needed. Anyone have trouble with the high idle / throttle not backing off? Slowing down on the freeway, on the brakes, I have the signature 1200 RPM on the tach. The engine’s idle speed also changes, based on outside conditions. ? Thumbs down. As soon as I try to give it a little more juice or jab the throttle, the falls on its face, sometimes revving back up for a second before bogging down again. Vehicle has 55k miles on it and ih has been fairly reliable. So, I shut it down, turned the key on to listen to the fuel pump prime up. 1L V6 of the late 80s/early 90s. when driving the car it runs fine but at idle it revs up and down till it stalls. Not dangerous, but that extended run on high idle suggests to me that you have an issue with the T-stat or something else that isn't letting it warm up quickly. Changed idle air control valve Car still idles up and down, while sitting in park or in drive. 97 chevy blazer 4. I noticed while sitting in park the voltage meter drops and the engine pulls way down. Be careful not to enlarge metering hole size. Idle Surge) For those of you who may have missed the thread regarding my idle surge, here's a brief summary: - One hot Saturday in June, I was driving happily along the freeway. hisbutlerdidit 47,340. About catalytic onverter could be stopped up, and/or donnut gaskets could have ur pips stopped up where u are getting little air out. I have a 1992 chevy caprice it has a 350 TBI in it. Do you have 12v to it and a good ground?. This is for an engine with stock camshaft, heads, stroke, and a compression ratio of 10:1. Start the engine and take note of the idle RPMs. Sometimes, when driving between 35 and 40mph it will do a little hesitation, but when I give it gas it smooths right out. 0L engine and it has been idling rough. I as well get this rough idle randomly when coming down into the transition to idle speed control. i have a 1992 chevy truck the idle goes up and down and loss power and gets hot and the egine light comes on that - Chevrolet 1999 Silverado 1500 question. I changed the battery and the idle is very eratic. , other wise I just shut it off. Good news is a SBC only needs like 5psi of oil pressure at idle to keep alive, if you are getting 30 or over driving down the road it should be fine. Even the TBI gasket could leak. Hello everyone. Discuss 1990 TBI 5. I had this problem for a while and then i went away after i changed my distributor, wires, & plugs about a year ago. Any advice or help would be appreciated. The engine didn't try to stall or feel like it bogged down when I hit the gas, it just doesn't seem to react without a delay. However the car still stalls a bit when it is finally warmed up but not as frequent nor as hard. After about 7-10 minutes, the temp was up to about 220 and the water began going way down and then coming up and spilling out of the radiator, then back down and then up again. Asked in Chevy Lumina, Chevy. 0 wont idle and backfire through the intake? but would hold a. IAC 2% base, but cycles up & down. 1992 Chevy K1500 5. Have replaced the pmd to a remote pmd(new). Insert the key into the ignition and start the engine. After all this the engine started revving up and down when idling. Once these inputs are removed, the engine idle speed will slowly ramp back up to high idle after the normal delay, if the conditions for engine coolant temperature and air intake temperature are still met. Discuss Correct Idle Speed for 5. prompting the truck to shut down for a few minutes. The ECM controls the idle air valve. Corvette IAC (idle air control) valve is designed to adjust your Corvette's engine idle RPM speed by opening and closing an air bypass passage inside the throttle body. listen to the engine and see if its actually changing rpm,s if not you may have a faulty tachometer in it,those do go bad and will cause it to go up and down like that but if the engine its self is changing rpm,s a lot you may have a 0-2 sensor going bad on it,that will cause it to not have a steady rpm at idle,also an idle air control valve. I am used to having to idle larger cammed engines up a little higher but 1400 seems a little much. The small-block family line was honored as one of the 10 Best Engines of the 20th Century by automotive magazine Ward's AutoWorld.