Contour Enthusiasts Group Archives Forums General Troubleshooting Surging/bucking/driveability

95 Contour GL, 2.0 Zetec, auto trans, all electric accessories, 83k miles

I looked through the achives, and found a thread that addresses the issue I'm dealing with. He even posted that he found the problem, but the link is dead.

Has anyone else solved the problem of surging/bucking/intermittent miss when the engine is warmed up? It runs just fine cold, until it warms to operating temp, then it runs like crap.

I seem to have narrowed it down to a certain rpm range, seems to do it just off idle, at about 1700-2000 rpms. Acts like it's not getting enough gas, but it could also be an ignition miss.

All obvious things have been checked/replaced.

new plugs/wires
new fuel filter
new air filter
new coil pack, as I discovered no. 2 cylinder had no spark when it started this
MAF is clean as a whistle
new TPS
new ECT
replaced thermostat with 180, seems to run a little better
new O2 sensor
no discernible vac. leaks
checked wiring harness for cracks/flaking, looks good, all connnectors seem to be OK
no CEL, scantool says all sensors have good signal/readouts with good waveforms
fuel pressure is rock steady at 40, at all throttle positions
all injectors seem to be working OK
replaced ICM and PCM with pulls from local boneyard
lever position sensor on trans is lined up OK

I growled at it and threatened it with a sledgehammer, but that didn't seem to faze it one bit. I think it even snickered at me.

Although I have a duratec, I have the same problem (amoung others similar to that) and all I can say is good luck as the sledge dind't even work for mine.

My 98 Zetec did the same thing. It ended up to be the VCT. Try unplugging it and see if it makes any difference.

Fortunately, this engine does not have VCT.

If it did, it would be just one more expensive thing to go wrong on this dog.

There has to be an answer somewhere, guys, the net is crawling with this problem.

Since it runs well when cold, and craps out when it reaches operating temp, I'm wondering if there is a short in the harness somewhere, and it messes up when the ECU tries to communicate with the sensors in closed loop.

The thing that gets me, though, is we get good signals from every sensor and good waveforms when we check them. No flat spots, no drop outs, no unnecessary noise on the scope. The fuel pressure reads 40 at all speeds and 35 at idle, but I guess I still can't rule out a fuel pump.

<----- that's me after dealing with this thing


sheesh