yzfr6i

I'm having a problem with my car running poor while it's in cold loop. If you sit idling for too long it acts like it's loading up. The Idle drops to 500 and the car chuggs like it has a huge cam. Vacuume drops to about 15 inches when it does this. Then when you pull away the car shudders and hardly wants to get out of it's own way. If you floor it it clears up and takes off like a rocket. As soon as the engine comes out of cold loop it runs perfect.

It has a 306 with stock heads and cam, GT40 intake. Your usuall bolt ons, and a powerdyne supercharger that only puts out 3lbs of boost(It came on the car). 24lb injectors with an FMU. 16 degrees of initial timing (I run the car with the spout in) 40lbs of fuel pressure (no vacuume).

I swapped out the Air Charge Temp Sensor last night and it seemed like it seemed like it fixed it, but as soon as I got up the street and hit he third stop sign it started acting up again. The old ACT looked like a fouled out plug in a two-stroke.

Any ideas would be appreciated.[/align]

89mustangfive0

try doing the diy koeo koer code check and see if theres codes. buy i had idle problems and i changed my iac and my coolant temp snesor and idle problem was fixed

yzfr6i

I just went out and looked, and noticed that the vacuume line to the EGR has been removed and blocked off. The EGR it self is still plugged into the computer. Seems like everytime I look under the hood I find something else that the previous owner didn't do right.

I'm going to remove the EGR once I make my block of plate and get the eliminator to plug in so I don't get a CEL.

89mustangfive0

sounds like dejavu i had the same problem with mine...didnt help the guy who i got it from ( close friend of my family) was on all kinds of meds from his motorcycle accident...i found alot of stuff not done right....like when put the cobra intake on the manifold gaskets were on backwards, bolts werent tight...made me thinkk lol

yzfr6i

I'm pretty sure I found and fixed the problem. I thought the heater was going on out one or both of my O2 sensors, so I bought new ones. When I went to replace them the drivers side was broken. Put in the new ones and it ran great. I have the battery disconnected now so I can re-set the idle.

Now I can tell you that the car actually ran fine in open loop (it wasn't reading the O2s). Which is why it would run fine untill I got to the end of my subdivision (which is when it would go into closed loop and start reading the cold/broken O2).

When it would start to stumble if you floored it the car would take off with no problems (it stopped reading the O2s).

It would run like crap until the heat in the exhaust got hot enough to make the sensor start to read somewhat right.

I hope this helps anyone else that is having the same issues.

50Stocker

What O2 sensors did you put in? I just got a set of Bosch #13942 (i think that's the #)to put in with my O/R H. Is this what you put in? Someone told me that the Bosch ones are crap and to go with Denso. However, I believe the Bosch's were stock on our cars.

I just went to the parts store and the clerk there said they were reading four 02 sensors, two before and two after the cats. I never looked under my car because it was always dark and I never had the time. So I just went with the ones labeled for before the cat. I hope it doesn't matter b/c it will be an O/R pipe anyways. Thanks.