HELP!!!- Car wants to Rev on its own at times, WTF???
06-25-2008, 09:42 AM
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HELP!!!- Car wants to Rev on its own at times, WTF??? Just got my car back after adding pushrods, rockers, 92/92 combo, fuel pump and injectors. Had it retuned and dyno'd.
For some reason the car wants to rev itself to around 1500 RPM or so in Neutral while moving. Won't happen when I fire it up. Seems to be mostly when driving or pulling up to stop. I'll put it in neutral and the RPM's will stay around that 1500 RPM mark. I've been trying to put in a high gear as I slow down to get the RPM's down low before hitting neutral. This seems to work sometimes, but not all the time. I'll throw it in neutral with the RPM's around 1000 or less, then it'll rev up to 1500 sometimes.
I don't think there is a vacuum leak because it doesn't happen all the time. Also, no SES lights or anything coming up. My initial though was the new 92mm throttle body was sticking slightly open. This could be the problem, but had my mechanic look at it and he says the TB wasn't sticking.
This has been irritating me as you could imagine. I can't give it a rev or pull up to a stop without the RPM's hanging out around 1500. It's especially annoying when driving around a parking lot.
Anyone have any thoughts on this issue??? Please, any opinions would be great.
For some reason the car wants to rev itself to around 1500 RPM or so in Neutral while moving. Won't happen when I fire it up. Seems to be mostly when driving or pulling up to stop. I'll put it in neutral and the RPM's will stay around that 1500 RPM mark. I've been trying to put in a high gear as I slow down to get the RPM's down low before hitting neutral. This seems to work sometimes, but not all the time. I'll throw it in neutral with the RPM's around 1000 or less, then it'll rev up to 1500 sometimes.
I don't think there is a vacuum leak because it doesn't happen all the time. Also, no SES lights or anything coming up. My initial though was the new 92mm throttle body was sticking slightly open. This could be the problem, but had my mechanic look at it and he says the TB wasn't sticking.
This has been irritating me as you could imagine. I can't give it a rev or pull up to a stop without the RPM's hanging out around 1500. It's especially annoying when driving around a parking lot.
Anyone have any thoughts on this issue??? Please, any opinions would be great.
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06-25-2008, 01:06 PM
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Ok, just tried recalibrating my TPS by turning key to on for 30 sec. then off. Unplugging TPS, turning key to on for 30 sec. then off. Replugging in TPS, turning key to on for 30 sec. then off. Then cranked it up. Idled around 1100 or so for a moment then began to slowly go back to normal idle range. Waited 5 min. then put A/C on full blast for anther 5 min.
Seemed to help a little, but still had some of the same issues. Especially while rolling in neutral, the RPM's don't want to drop to idle range. It is the inconsistancy that has me so confused.
Anyone?
Seemed to help a little, but still had some of the same issues. Especially while rolling in neutral, the RPM's don't want to drop to idle range. It is the inconsistancy that has me so confused.
Anyone?
06-25-2008, 01:26 PM
#9
Ok, I have your answer. Although i do not know your exact cam specs, but its due to your tune, in relation the cam.
When the car was tuned, its all in the lower RPM tables.
My car with the mods in sig is tuned pretty good and the cam is small enough not to be a pain to tweak.
In my situation I did have a 90mm TB that actually stuck, to verify if its physically sticking while the engine is running, you can physically shut the TB blade and slow down the RPMs.
When I got the new TB and the tune was freshly flashed. For the next 7-10 drive cycles, I will get an occasional RPM hang in neutral. It happened more often, then lessened, It also would do it when the engine wasnt in closed loop/operating temp.
If you have put on some siginifgant miles and have at least ran the car up to operating temp (at least 10 times) and its still doing it, the tuner needs to work on the driveability areas of the tune.
They can ball park it but unless its driven, data logged, they cant get it perfect.
When the car was tuned, its all in the lower RPM tables.
My car with the mods in sig is tuned pretty good and the cam is small enough not to be a pain to tweak.
In my situation I did have a 90mm TB that actually stuck, to verify if its physically sticking while the engine is running, you can physically shut the TB blade and slow down the RPMs.
When I got the new TB and the tune was freshly flashed. For the next 7-10 drive cycles, I will get an occasional RPM hang in neutral. It happened more often, then lessened, It also would do it when the engine wasnt in closed loop/operating temp.
If you have put on some siginifgant miles and have at least ran the car up to operating temp (at least 10 times) and its still doing it, the tuner needs to work on the driveability areas of the tune.
They can ball park it but unless its driven, data logged, they cant get it perfect.
06-25-2008, 02:01 PM
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General Cam Specs: 222/224 .566/.568 (.599/.601 w/ the 1.8's)
I have had this car tuned a handful of times already. Even had another tuner from across the street from my tuner take a look. Tune feels pretty good. I'm just not 100% sure if it is tune related or TB related.
I actually had this issue at times before any major mods (only CAI and cat-back). The RPM's would "lazily" return to idle. This went away after I added the heads/cam/headers. Then I put on the 92/92, pushrods, rockers, and injectors. Now it got worse than it ever was in the past. I never had the RPM's go to idle, then slowly climb to around 1500 or so, like it will do now. Seems to go back to idle when I fully stop after a few seconds. Just very annoying and irritating pulling up to red light and having the engine reving at 1500 RPM. Plus car is loud and a gas eater, so any unnecessary engine rev is costing me $$$. Not my biggest worry, but with gas prices where they are at, every MPG helps.
I have had this car tuned a handful of times already. Even had another tuner from across the street from my tuner take a look. Tune feels pretty good. I'm just not 100% sure if it is tune related or TB related.
I actually had this issue at times before any major mods (only CAI and cat-back). The RPM's would "lazily" return to idle. This went away after I added the heads/cam/headers. Then I put on the 92/92, pushrods, rockers, and injectors. Now it got worse than it ever was in the past. I never had the RPM's go to idle, then slowly climb to around 1500 or so, like it will do now. Seems to go back to idle when I fully stop after a few seconds. Just very annoying and irritating pulling up to red light and having the engine reving at 1500 RPM. Plus car is loud and a gas eater, so any unnecessary engine rev is costing me $$$. Not my biggest worry, but with gas prices where they are at, every MPG helps.
06-25-2008, 02:45 PM
#11
For some reason the car wants to rev itself to around 1500 RPM or so in Neutral while moving. Won't happen when I fire it up. Seems to be mostly when driving or pulling up to stop. I'll put it in neutral and the RPM's will stay around that 1500 RPM mark. I've been trying to put in a high gear as I slow down to get the RPM's down low before hitting neutral. This seems to work sometimes, but not all the time. I'll throw it in neutral with the RPM's around 1000 or less, then it'll rev up to 1500 sometimes.
I don't think there is a vacuum leak because it doesn't happen all the time. Also, no SES lights or anything coming up. My initial though was the new 92mm throttle body was sticking slightly open. This could be the problem, but had my mechanic look at it and he says the TB wasn't sticking.
This has been irritating me as you could imagine. I can't give it a rev or pull up to a stop without the RPM's hanging out around 1500. It's especially annoying when driving around a parking lot.
Anyone have any thoughts on this issue??? Please, any opinions would be great.
I don't think there is a vacuum leak because it doesn't happen all the time. Also, no SES lights or anything coming up. My initial though was the new 92mm throttle body was sticking slightly open. This could be the problem, but had my mechanic look at it and he says the TB wasn't sticking.
This has been irritating me as you could imagine. I can't give it a rev or pull up to a stop without the RPM's hanging out around 1500. It's especially annoying when driving around a parking lot.
Anyone have any thoughts on this issue??? Please, any opinions would be great.
Mine does the exact same thing
If I totally back off the gas and hold OD i can maintain over 30mph Tough on the damn brakes too
06-25-2008, 03:17 PM
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Is there anyway to tell if my TB is getting stuck slightly open? Or slightly opening up?
This is such a pain in the ***. I'm going to the mechanic/tuner after work and I'll see if we can't resolve this issue.
This is such a pain in the ***. I'm going to the mechanic/tuner after work and I'll see if we can't resolve this issue.
06-25-2008, 04:11 PM
#14
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It is likely in the tune. There are several tables related throttle that are bypassed as soon as you get below a certain speed (max speed and throttle position for idle). A sure sign of this is idle "hangs" until you come to s stop and then drops. Have the tuner check those tables and you should be good to go.
06-26-2008, 07:59 AM
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^^^I am in South FL (Boca area).
DaddySS: That is exactly what happens. Idle hangs until I come to a complete stop.
Went to my mechanic/tuner after work yesterday. Had him drive it. He says it could be a little strong on the idle saver properties in the tune. Told me to drive the car for the weekend and see if the car "learns" the new tune better. I'll humor him, even though I'm pretty sure no "learning" will take place.
DaddySS: That is exactly what happens. Idle hangs until I come to a complete stop.
Went to my mechanic/tuner after work yesterday. Had him drive it. He says it could be a little strong on the idle saver properties in the tune. Told me to drive the car for the weekend and see if the car "learns" the new tune better. I'll humor him, even though I'm pretty sure no "learning" will take place.
06-26-2008, 08:28 AM
#19
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There some interdependencies so it depends:
Throttle Cracker
Throttle follower
Decay rates for both
Idle Learn
Base timing in P/N
Desired Airflow in gear
Post over in the PCM diag and tuning section for more help - there are guys there that are pretty sharp.
Throttle Cracker
Throttle follower
Decay rates for both
Idle Learn
Base timing in P/N
Desired Airflow in gear
Post over in the PCM diag and tuning section for more help - there are guys there that are pretty sharp.