Car runs like POO! Help!

[Whistler]

I have a Kirban FPR with no vacuum port. No aftermarket chip, BTM, or PMS. I'm just tuning it as best I can until I can get a custom dyno tune. It did die when I came to a stop (In the CVS parking lot) and had trouble starting back up and idling. I left it sit at CVS for a few hours until I could get a ride back and get it. Later that night, I went back to get it and it still wouldn't idle without dying so it had to be towed back to my house.

Today, it started and idled GREAT for about 3 or 4 minutes then the idle got real rough and it died. The idle seems to smooth out after the car sits for a few hours. I removed my driver side spark plugs and they were very dark. I noticed when I backed my timing down to 10* it idled worse than when it was at 12*-14*. I'd bump the timing back up but I don't want to without a way of pulling some out under boost.

[fanglemeister]

The car starts and idles first in open loop mode and then switches to closed loop mode which is controlled by the O2 sensors. Sounds like your O2s are hosed, time to replace them. Make sure you clear out the eec computer's memory after you replace them.

If you are running pig rich under open loop, you can start to kill them within a few hundred miles.

[Whistler]

I had to take my O2 sensors out when I installed my headers and they looked pretty black and nasty. I'll try replacing them and see if that solves my problem. I seem to be pulling plenty of vacuum so I'm not so sure it's a vacuum leak.

Could bad O2 sensors cause the 'check engine' light to come on? I've noticed that when cruising below 2000 rpm's the check engine light will come on until rpm's increase. I'm crossing my fingers....

Come to think of it, if I'm ordering some O2 sensors, why not order a F150 pulley as well :D

[fanglemeister]

Whistler, how did you make out with the new O2 sensors?

[Whistler]

The sensors are on their way. I'm just waiting for 'Brown' to drop them off. The anticipation is killing me. I really hope my problem is with the O2 sensors.

While I've been waiting, I took off the front sway bar and removed that metal hunk of crap by the rearend. Saved a little bit of weight :)

Hopefully, Brown will show up tomorrow and I can give an update on things.

[fanglemeister]

Originally posted by Whistler
While I've been waiting, I took off the front sway bar and removed that metal hunk of crap by the rearend. Saved a little bit of weight :)

That hunk of iron is actually tuned to the rear gear ratio; once you swap to a different ratio it is virtually useless, except for use as a traction aid.:D

[Orion_134]

I have the exact same problem on my truck. When I let off the gas it surges and if I depress the clutch the revs will drop all the way to zero. Sometimes it will catch itself, not often. It idles eratically and also does it sporatically, sometimes it'll do it, sometimes not. I have looked over my vacuum's 37.5 times and even took the intake manifold off to check the gaskets. It will not hold a steady rpm, such as trying to spool up to launch, the rpms will jump all around. The MAF has been clocked to where it sort of fixed it, not totally. Where should the plug position be on it? Does it matter if the MAF get's hot? The TPS checked fine as well as the IAC. If the O2's go bad, it should throw a code and it hasn't...but it does smell very rich upon startup and in general with gas mileage out the window. And could the lack of a bypass be causing all these problems?!?! Please help before I drive this truck into a tree!

Jesse