Runs terrible until warmed up.
05-09-2009, 09:51 AM
#1
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Car: 88 IROC
Engine: 5.7 RamJet
Transmission: T56
Axle/Gears: Dana44 4.10
Runs terrible until warmed up.
1987 2.8L V6 w/ auto transmission.
Just recently picked it up. Engine has supposedly 129,000 on it.
When it's cold, it's difficult to start. Have to feather the gas to get the RPMs up to keep it going. It will eventually stay running and idle, but it's very erratic. trying to drive the car like this results is very low power and popping through the intake manifold. As it starts to warm up it improves gradually. If cruising it will surge.
If I let the car just sit and idle for several minutes it's no where near as bad. It's still never fully right even when all warmed up. It seems to be running extremely rich at startup, and my thought was that once it hits closed loop the O2 sensor readings allow the ECM to compensate for it somewhat.
However, it never sets any codes. It WILL set codes if I dissconnect sensors while it's running ( tried pulling the TPS and MAF and the appropriate codes were stored )
Also if I drive the car to where it's warmed up, it can sit for awhile ( tested up to an hour so far ) and then will start right up and drive ok. It has to sit for a long period of time to where it has completely cooled off before it acts up again.
I changed the CTS to a new one with no difference in the problem.
Just recently picked it up. Engine has supposedly 129,000 on it.
When it's cold, it's difficult to start. Have to feather the gas to get the RPMs up to keep it going. It will eventually stay running and idle, but it's very erratic. trying to drive the car like this results is very low power and popping through the intake manifold. As it starts to warm up it improves gradually. If cruising it will surge.
If I let the car just sit and idle for several minutes it's no where near as bad. It's still never fully right even when all warmed up. It seems to be running extremely rich at startup, and my thought was that once it hits closed loop the O2 sensor readings allow the ECM to compensate for it somewhat.
However, it never sets any codes. It WILL set codes if I dissconnect sensors while it's running ( tried pulling the TPS and MAF and the appropriate codes were stored )
Also if I drive the car to where it's warmed up, it can sit for awhile ( tested up to an hour so far ) and then will start right up and drive ok. It has to sit for a long period of time to where it has completely cooled off before it acts up again.
I changed the CTS to a new one with no difference in the problem.
05-09-2009, 04:20 PM
#2
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Car: 88 IROC
Engine: 5.7 RamJet
Transmission: T56
Axle/Gears: Dana44 4.10
Re: Runs terrible until warmed up.
update -
On initial start I let it run just a bit, pulled the #1 plug and it was wet with fuel, but otherwise just about brand new.
then I did the following-
reset the IAC
throttle position sensor was reading somewhat high at idle so I reset that as well
timing was 12* BTDC, so I put it back to the stock 10*
results - better but still not right.
On initial start I let it run just a bit, pulled the #1 plug and it was wet with fuel, but otherwise just about brand new.
then I did the following-
reset the IAC
throttle position sensor was reading somewhat high at idle so I reset that as well
timing was 12* BTDC, so I put it back to the stock 10*
results - better but still not right.
05-12-2009, 09:53 PM
#3
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Car: 88 IROC
Engine: 5.7 RamJet
Transmission: T56
Axle/Gears: Dana44 4.10
Re: Runs terrible until warmed up.
Another update.. it is VERY related to temperature. Car starts MUCH easier now, but still runs like crap and backfires badly.. when cold. This AM was on the cilly side and the car never fully warmed up on the 13 mile mostly highway ride to work.
Get out of work 9 hours later and it was mid 70s and the car drove FAR better with basically no warm up time at all. Came home, parked it and a passing thunderstorm brought cool air back through mid 50s.. went to drive it and it ran terrible again. It had sat for about 3 hours.
Can a bad IAT screw things up THAT much?
Get out of work 9 hours later and it was mid 70s and the car drove FAR better with basically no warm up time at all. Came home, parked it and a passing thunderstorm brought cool air back through mid 50s.. went to drive it and it ran terrible again. It had sat for about 3 hours.
Can a bad IAT screw things up THAT much?
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