Contour Enthusiasts Group Archives Forums General Troubleshooting Low RPM Stumbling, Especially on Cold Mornings

One obvious possibility is a vacuum leak, either from a damaged or old tube/hose or the intake gaskets. If you've done work on the car recently, check those plastic elbows on top of your UIM, they get damaged/cracked sometimes. Also, just below the TB there is a vac hose that plugs into the UIM, that one is missed by me sometimes & doesn't get hooked up as snugly as it should.

code 542 is fuel pump circuit...what that indicates, I have no idea as my book indicates further testing with a break out box ( take to stealership ) I would go with the plug wires for sure. And according to your codes a fault in the O2 sensor system. Too lean, and too rich is a good sign the O2 needs replacing. Upper intake gaskets are prone to leak, and not that hard or costly to replace...then you could also do a complete check of all your vacume lines alot easier as well.

I had this problem on one of my 95 V6 Contours. As routine maintenance I performed the following:

Replaced IAT, ECT, wires, plugs, cam and crank sensor, TSS, fuel filter, fuel pump.

R&R upper and lower intakes.

Almost every morning when starting the car and first put it in gear, the engine would almost die out and then idle would come back up to normal. After that it would be fine for that day. Next morning same event would occur again.

Also replaced idle control selonoid or switch also on the throttle body.

Also replaced vacuum bundle....thinking about this now....it could have been the irmc vacuum diaphram........

I never did get this problem corrected before I sold it.

Bob

Rereading your first post, I'd replace the irmc vacuum diaphram. It may be leaking a bit. Also check vacuum lines. With it being a 95 you should replace them. There is the main bundle and there is also one line sold separately from the budle that leads to the fuel pressure regulator - I'd replace them all.

Oh Yes, 542 circuit is rather an ambiguous code...in my opinion......hard to isolate exactly..... I had the same until I began the maintenance parts replacement.

You could be running rich when you first start and drive the car if the vacuum diaphram is leaking. Secondaries are open with no vacuum. when you start the car, vacuum is applied via irmc diagphram and the secondaries are pulled shut...of course if you have a vacuum leak they could stay partially or fully open....

Bob