Contour Enthusiasts Group Archives Forums General Troubleshooting Cold Start Misfires - Coolant temp sens. Question

Hi all -

I've been trying to remedy a problem and I'm running out of ideas...

1999 SE w/ 2.5 and MTX 85,000 miles

When the 'tour sits overnight (or for at least 10 hours during the day) the engine runs rough when first started. During initial acceleration: the motor bogs, misfires pretty serious, lurches, and RPM's are slow to increase (No CE light, though). This only happens for the first two minutes of operation, after which it runs fine...

I started with new wires and new autolite double plats - no difference Pulled the EGR off, cleaned it out, put it back with fresh gasket - no difference. Cleaned the mass air sensor - no diff. Just this morning I put a new coolant temp sensor in, and still no improvement!

Here is the harness that clips onto the back of the coolant temp sensor - does it look right to you guys?



Perhaps this is worth replacing too? I'm out of ideas here... I have a new ignition module that I could put in, but since the problem seems to be temperature dependant, I don't see how it could help... DPFE sensor?? Clogged/Dirty Injectors??? intake temp sensor? Leaking UIM/LIM gasket?? what shall i do ??? thanks in advance

- Jake

Have you ever done a UIM cleaning?
I bet doing this will smooth it right out.

I've done the UIM twice just by sucking cleaner through the two vacuum lines, but have never taken the intake manifold off. I'm really stuck on how to get rid of this problem I'm hoping that later this week when I pull the manifolds off that the existing gasket is in rough shape. Perhaps there is a small leak of unmetered air into the manifold when the engine is stone cold, but after a few minutes runtime it seals... Any thoughts? Almighty Ray???

I tried the non UIM removal and afterwards pulled my UIM. It was still covered in carbon and so were the secondaries.
I only do a full removal to clean it.
The non method is ok if your maintaining the system after a full removal and cleaning.

Have you thought about doing a Motorvac fuel system cleaning?

cool... thanks for the tip Chongo. Don't know about the motorvac treatment - what is it ??? I'm not sure my problem is in the fuel system...

If that is the coolant sensor near the waterpump, it's for the gauge, and if the gauge works, the connector is fine. You would have a check engine light if the main coolant sensor failed or was misconnected.

roger that, favorite... as soon as I pulled the sensor, I went and looked at the gauge and the temp had plummeted... still clueless here