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Tech / General EngineIs your car making a strange sound or won't start? Thinking of adding power with a new combination? Need other technical information or engine specific advice? Don't see another board for your problem? Post it here!
I looked through other threads for about a half hour and didn't see anyone with this problem.
I set my TPS to .54V, then set my IAC. It idles fine at about 800RPM. When I shut the card down and restart it, it runs up to 1800 RPM and then comes back down after a few seconds to 1000 RPM. Drop it in gear the idle drops to about 600 RPM and then you can feel the IAC take over and the engine is trying to accelerate. If I put it in Neutral or Park the idle immediately goes up to 1800 RPM then after a few seconds comes back down to 1000 RPM. It seams that by shutting the car off it's reseting something and it doesn't like idling at below 1000 RPM so the IAC is trying to compensate. If you try to drive the car it is constantly pushing you down the road not to mention hard on the brakes.
Yes, no vacuum leaks. After I set the IAC, I start the car up again and it runs great, no idle problems at all until I turn the car off and restart again. From that point on it's always running high.
I have the manual as well. I have checked every vacuum leak possible. My car idles at 100-1200rpm in park or neutral but is fine in drive.
Out of diagnostic aids the only things I have not checked is AC clutch loads (My AC has been deleted years ago), and AIR management system. How do I check these? Never checked injectors either but it drives fine. High idle is very very irritating though.
I have an 89 Camaro 5.0 tbi with a very high idle. I changed all the vacuum lines, replaced tps, replaced aic, put all new gaskets on tbi. Still running high idle about 1600! I've seen a ton of videos on how to adjust the tps but mine cannot adjust, it does not move like the other tps' that I've seen. My engine is a vin type E. Please help!
I have an 86 Iroc with a 305 tpi and I’m having the same issue, when I first start the car it idles fine in Park, then drops in drive, but after I’ve gone for a drive and put it back in park it will idle at 1500rpm, similarly if I put the car in neutral it won’t drop the rpm will raise to 1500. I’ve replaced the vacuum lines, checked for intake gasket leaks, tps iac and maf have been replaced and set as well. Please help
What is the readout from the coolant temp sensor (CTS)? Not the gauge on the dash - the sensor for the computer. The computer may be using a high idle because it thinks the engine is colder than it actually is. If you don't want to troubleshoot with Visa, you are going to need to acquire the equipment to read live data from the ECM. You can test the CTS for resistance and compare to a chart but that still doesn't tell you what the ECM is seeing on the other end of the harness, etc. And it could be something else entirely. That's just a shot in the dark.
What is the readout from the coolant temp sensor (CTS)? Not the gauge on the dash - the sensor for the computer. The computer may be using a high idle because it thinks the engine is colder than it actually is. If you don't want to troubleshoot with Visa, you are going to need to acquire the equipment to read live data from the ECM. You can test the CTS for resistance and compare to a chart but that still doesn't tell you what the ECM is seeing on the other end of the harness, etc. And it could be something else entirely. That's just a shot in the dark.
GD
I'm having a similar problem nobody can seem to figure out. Car idles high until it warms up. When connected to Tuner Pro it read the coolant temp at 80 degrees upon first start up which would have been about right since the car was parked in the garage during the summer. The ECM's target RPM is 800 but it still idles at 1500 for a bit then drops to 1250 until the engine is good and warm, then it idles normally. It always seems to really kick down to the proper RPM when it's in gear sitting at a stop sign or red light. You can literally feel the AIC close to drop the idle. The car runs so damn good with the annoying exception of this...Been two years and I can't figure it out. No vacuum leaks, TPS, AIC, all that stuff has been adjusted and triple checked... Driving me nuts..
I'm having a similar problem nobody can seem to figure out. Car idles high until it warms up. When connected to Tuner Pro it read the coolant temp at 80 degrees upon first start up which would have been about right since the car was parked in the garage during the summer. The ECM's target RPM is 800 but it still idles at 1500 for a bit then drops to 1250 until the engine is good and warm, then it idles normally. It always seems to really kick down to the proper RPM when it's in gear sitting at a stop sign or red light. You can literally feel the AIC close to drop the idle. The car runs so damn good with the annoying exception of this...Been two years and I can't figure it out. No vacuum leaks, TPS, AIC, all that stuff has been adjusted and triple checked... Driving me nuts..
When you are in warmup under open loop the target idle RPM is not used. That is only used when in closed loop idle and once it reaches a specified minimum coolant temp. Prior to that it's going to use something like an IAC steps vs. Coolant Temp table or some such. You'll have to check your BIN for warmup idle settings. It is NOT the warm target idle setting. And yes when you drop it in gear the idle will change because of the load from the torque converter, etc.
When you are in warmup under open loop the target idle RPM is not used. That is only used when in closed loop idle and once it reaches a specified minimum coolant temp. Prior to that it's going to use something like an IAC steps vs. Coolant Temp table or some such. You'll have to check your BIN for warmup idle settings. It is NOT the warm target idle setting. And yes when you drop it in gear the idle will change because of the load from the torque converter, etc.
GD
I'm no expert but the car is not in open loop for 10+ minutes is it? When it does kick down in gear it's idling at 1000 or so then magically drops to 600. It's really weird.
Here is what the eco should be doing based off coolant temp. I’m wondering if a heated o2 might help you. I’m really confused why your car does this. Closed loop will happen with the engine temp is 77.45f and the o2 is at 500 to 600 degrees f.
Last edited by Tuned Performance; Oct 22, 2018 at 05:40 PM.
Here is what the eco should be doing based off coolant temp. I’m wondering if a heated o2 might help you. I’m really confused why your car does this. Closed loop will happen with the engine temp is 77.45f and the o2 is at 500 to 600 degrees f.
Could be running rich and the O2 is taking a long tims to get up to temp. Have you monitored open/closed loop status?
Here is what the eco should be doing based off coolant temp. I’m wondering if a heated o2 might help you. I’m really confused why your car does this. Closed loop will happen with the engine temp is 77.45f and the o2 is at 500 to 600 degrees f.
An 02 sensor with a heater in it. AKA - "Three-wire O2". You wire it up with switched power and ground in addition to the signal lead and it heats up faster.
I think it might take 10-15 min to get the o2 active. This is a issue with headers which I forget it you have them or not.
it might speed up your issue from happening I’m really out of ideas.
I think it might take 10-15 min to get the o2 active. This is a issue with headers which I forget it you have them or not.
it might speed up your issue from happening I’m really out of ideas.
That's about exactly the time it takes to kick down. After work I have been starting the car then going downstairs to change. By the time I get back out to the car it is idling better. I am running stock manifolds but this sounds like it's worth a shot.
Yeah I doubt that's going to fix it. I DO have headers and a stock single wire sensor and mine does not act like that. I have the exact same car but I'm running '89 $6E modified BIN for CSI delete, and 24 lb Bosch III's.
89 BIN's that don't use the CSI have much better programming - if you haven't done that I would upgrade the microcode before I wired in a heated O2. Not that it's going to hurt anything and yes it would warm up faster but I don't see it solving this problem.
Yeah I doubt that's going to fix it. I DO have headers and a stock single wire sensor and mine does not act like that. I have the exact same car but I'm running '89 $6E modified BIN for CSI delete, and 24 lb Bosch III's.
89 BIN's that don't use the CSI have much better programming - if you haven't done that I would upgrade the microcode before I wired in a heated O2. Not that it's going to hurt anything and yes it would warm up faster but I don't see it solving this problem.
GD
Tuned Performance burned a chip for me and I believe it's an 89 program. He could verify that though...I hate throwing parts at a car but I'm willing to try anything to solve this problem...
when I had a TPI my throttle body shaft was worn out creating a vacuum leak with symptoms very similar to these. occassionally would idle at around 1500 causing it to pull while i was at a stop light, if I blipped the throttle it would go back to its correct idle.
Tuned Performance burned a chip for me and I believe it's an 89 program. He could verify that though...I hate throwing parts at a car but I'm willing to try anything to solve this problem...
He’s running $6e , The issue was there with $32 mask as well. He has also tried another ecm and still no luck.
Last edited by Tuned Performance; Oct 23, 2018 at 06:10 PM.
im not sure the csi would make a high idle. The timer switch is ran off power from the starter solenoid wire so cold start fuel is not for a very long time seconds I think based on cranking and the engine temp. Warm I think the switch is open.
True - probably not related. Maybe he should consider a smoke test of the induction system? A vacuum leak could cause idling issues for sure. The system would learn around it to a degree. Has he checked his BLM's? Has he checked how long till it goes into closed loop?
