Lean idle/ slow to come down.
04-21-2014, 11:01 AM
#1
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Lean idle/ slow to come down. Car in question:
1997 camaro z28 6 speed
70k miles
- k/n cold air intake
-58mm bbk throttle body (thinking this is my problem)
- LE p/p intake
-LE 2 head package
- comp cam 268xfi hr-13 grind
- racetronix 37lb injectors
- 1.6 roller rockers
- comp lifters
- pacesetter lts, ory, magnaflow
- all emissions removed
- efi connection 24x ls1 computer/ ignition system
- lc1 wideband installed,
I do have hp tuners as well
Dyno sheet , after dyno tune. I thought the numbers were a touch low
Cam specs
The problem I'm having is as told by the tuner," it's like the IAC cannot supply enough air to feed the motor in certain conditions. It's demanding
More air but not getting it"
The car for the most part runs without issue. The problem I'm having is after coming off throttle, the idle will dip down below commanded idle for 10-15 seconds. During this period the wideband appears to go rich then leans right out when the idle starts stumbling . Sometimes it hangs up around 12-1300 rpm and you can usually watch the iac counts come slowly down when scanning. Usually when completely stopped it will come down to commanded idle.
It was much much worse before the tune, but is still annoying to deal with. It's really the only issue with drive ability. The tuner is saying it's the car, I don't have enough knowledge in tuning to really tell for sure. I don't doubt any of the work he did, just don't have all the money in the world to find out .
I've had it stall before after coming off throttle from a hard romp.
The bbk throttle body has been modified to match the original. The iac passage hole is drilled through and a piece had been fitted at the back to prevent plenum air and iac air mixing. What a mistake that throttle body was.
Logging yesterday, at temperature idle, the car is registering 0% throttle,
Iac counts around 40 and as far as I know the blades are only
Hair cracked open. I'm going to try and reset that tonight to make sure.
As far as I can tell there are no vacuum leaks, checked last night. I will be taking her for a rip with the fuel guage on the windshield to confirm proper pressure . Doesn't appear to have any exhaust leaks . I do however have a slightly slower o2 sensor on one side . Would that be enough to cause these idle issues ?
Just looking for some direction before paying the dyno shop $150/ hour to do what I could possibly do.
1997 camaro z28 6 speed
70k miles
- k/n cold air intake
-58mm bbk throttle body (thinking this is my problem)
- LE p/p intake
-LE 2 head package
- comp cam 268xfi hr-13 grind
- racetronix 37lb injectors
- 1.6 roller rockers
- comp lifters
- pacesetter lts, ory, magnaflow
- all emissions removed
- efi connection 24x ls1 computer/ ignition system
- lc1 wideband installed,
I do have hp tuners as well
Dyno sheet , after dyno tune. I thought the numbers were a touch low
Cam specs
The problem I'm having is as told by the tuner," it's like the IAC cannot supply enough air to feed the motor in certain conditions. It's demanding
More air but not getting it"
The car for the most part runs without issue. The problem I'm having is after coming off throttle, the idle will dip down below commanded idle for 10-15 seconds. During this period the wideband appears to go rich then leans right out when the idle starts stumbling . Sometimes it hangs up around 12-1300 rpm and you can usually watch the iac counts come slowly down when scanning. Usually when completely stopped it will come down to commanded idle.
It was much much worse before the tune, but is still annoying to deal with. It's really the only issue with drive ability. The tuner is saying it's the car, I don't have enough knowledge in tuning to really tell for sure. I don't doubt any of the work he did, just don't have all the money in the world to find out .
I've had it stall before after coming off throttle from a hard romp.
The bbk throttle body has been modified to match the original. The iac passage hole is drilled through and a piece had been fitted at the back to prevent plenum air and iac air mixing. What a mistake that throttle body was.
Logging yesterday, at temperature idle, the car is registering 0% throttle,
Iac counts around 40 and as far as I know the blades are only
Hair cracked open. I'm going to try and reset that tonight to make sure.
As far as I can tell there are no vacuum leaks, checked last night. I will be taking her for a rip with the fuel guage on the windshield to confirm proper pressure . Doesn't appear to have any exhaust leaks . I do however have a slightly slower o2 sensor on one side . Would that be enough to cause these idle issues ?
Just looking for some direction before paying the dyno shop $150/ hour to do what I could possibly do.
Last edited by 97lt1camaro; 04-21-2014 at 11:06 AM.
04-28-2014, 05:46 PM
#3
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Nobody ???!?
- replaced the o2 sensors and the iac. Reset as per shboxs website instructions.
Doesn't seem to be lean anymore but revs up to around 1400-1500 rpm when first fired up. Seems to go down after driving a bit.
Still stumped
- replaced the o2 sensors and the iac. Reset as per shboxs website instructions.
Doesn't seem to be lean anymore but revs up to around 1400-1500 rpm when first fired up. Seems to go down after driving a bit.
Still stumped
04-28-2014, 08:44 PM
#4
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Im not seeing that my rpm guage is a fair bit off, so disregard the high idle portion when firing up.
Here is a 5 minute log of it warming it up from a cold start and a few revs. It stumbles until it warms up when revving. Iac counts are considerably higher then before so i may reset that.
Here is a 5 minute log of it warming it up from a cold start and a few revs. It stumbles until it warms up when revving. Iac counts are considerably higher then before so i may reset that.
04-28-2014, 10:22 PM
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I wish I could help, But I havent done any tuning as of yet. Somebody on here should be able to help you, dont know why they havent chimed in yet. just now figuring out tunerpro for OBD1 myself.