87 CSX running cold, hog rich, idling low

[riceboyler]

OK, car is an 87 Shelby CSX I've had since February of this year, has a recently (35K ago) rebuilt motor with JE Pistons, Mopar Perf. LM, JoeP MBC set to 15 psi, 1G DSM BOV. About a month ago, I replaced the O2 wiring harness, as the previous one had rubbed against my power steering pulley and worn the insulation off. About 3 days after that, it got relatively cold (lows in the low-mid 20s) and the car started running richer than crap and sucking down gas like crazy. For a few weeks prior to that, the car had been running rich (you could smell it in the exhaust), but no noticeable effect on the gas mileage.

Since then, the car has been running very cold (never gets above 3 bars on the temp gauge), pig rich (according to the A/F meter and the smell, and the mpgs) and idling very low when cold.

I have replaced the coolant temp sensor as of this weekend, which didn't help the gauge at all, but the heater got much warmer. I put a can of SeaFoam in the tank and in the throttle body, but that didn't help the idle issues. Now, I question the O2 sensor and think it may be bad, but it's reading that the car is running rich constantly. It does bounce, but not at cruise, and at cruising speeds (3K RPM, part throttle) reads 8 bars on the A/F (Intellitronix) gauge. Odd thing is that if I hit boost, it moves back down to normal A/F levels until I get back out of boost.

I haven't had a chance to check fuel pressure yet, but I did pull plugs, and they were all very dark brown - black, so it's not just one injector or anything. I'm think that the FPR has gone bad, and is now throwing too much fuel in for the computer to handle.

One further note. I have an FM475 cam (came in the car) and I'm only seeing 13-15psi of vacuum at idle (when it idles correctly after it's warmed up). That's all I've ever seen at idle since I got the car, and I figured it was normal for the cam, but I'm beginning to wonder. What would normal vacuum be at idle for that cam?

Thanks in advance. This is my first post here, and I want to say a big thanks to Ken and Frank for presenting a great alternative. Hopefully the crap from the other forum will stay over there and not try to poison this place. Good luck guys, and thanks.

[cordes]

I would check your FP to see if the regulator is indeed bad.

I know that with the custom cal I have in my shadow, it guzzles the gas like there is no tomorrow when it is cold outside. I have heard that the MP cals run rich, and that they are pretty bad when cold too.

I did not have a boost/vac gauge installed in my ride when I had the FM505 in my omni, so I am not 100% sure, but I would not think that 15inhg would be too far out of line for a cam like that. Might want to double check the cam timing anyway though.

[MVaughn]

I would first check to see if any codes are in the computer by cycling the on/off switch with the key. Your o2 sensor should be bouncing around some at idle after warmup has occured. You can put a volt meter on the output wire of the o2 to make sure your other gauge is reading correctly as well. Is the rocker area making any more noise than usual. Our cars w/ the higher lift cam wear the cams out premature. Lots has been discussed about this from the past and spring pressure, lube., ect was discussed but it might be worth pulling the valve cover just to make sure the cam looks ok if you don't find any other problems first.

[riceboyler]

I hadn't thought about that, but that's a great idea (the cam check). No codes being thrown (other than the typical 12 and 55), so it's fine. I've checked the voltage and it appears to be correct (as in that it's too rich).

I'll have to take a look this weekend at fuel pressure and the cam.

[BadAssPerformance]

...One further note. I have an FM475 cam (came in the car) and I'm only seeing 13-15psi of vacuum at idle (when it idles correctly after it's warmed up). That's all I've ever seen at idle since I got the car, and I figured it was normal for the cam, but I'm beginning to wonder. What would normal vacuum be at idle for that cam? ...

13-15 sounds normal from my use of that cam, but I woud still check it.

[85chargerR/T]

Check for a leak in the fuel system I had it on my Caravan just weeping out of a rotten line 5psi drop was enough to make it act like your car is