Contour Enthusiasts Group Archives Forums General Troubleshooting DMD and Check Engine Light

First off.. yes I searched.



Ok here is the story. Took the SVT Tour into the shop to have the DMD put on and it was swapped out fine and I can tell the difference with it over the stock. Problem is now I have a CEL light flashing (misfire) and this was not the case before I brought it there. Sure it could be a concidence.. but I dont think it is.

Has anyone had a CEL light thrown after they did the DMD?

Any thoughts to as what could cause the CEL light to flash? The wires and plugs look to be fine.

1999 SVT Contour - almost at 30k

Thank you in advance.

Plugs and wires look fine, but maybe one has become dislodged? I would pull them off at each end and reconnect. The guys at the shop shouldn't have touched the wires, but who knows?

If you can get the code pulled, it should tell you which cylinder the misfire is occuring in, like this: P030x. For example, if its cylinder 5, you'll get a P0305. This will at least help you narrow down the source of the misfire.

It hasn;t happened to me, but try checking your plugs and wires....Iv come to realize (if you took it to a dealer) that some mechanics like to "play" with my car and screw things up just to get you to come back and pay more.


Roz

The only thing that would come to mind is that they might have accidently (or on purpose) unplugged the crankshaft position sensor. IT's the closest electrical thing to the crank pulley area. You should see it from the top of the engine w/ a flashlight.

But, not too sure if the car would even RUN with it unplugged.

I'd check it anyway though.

-John

He said relearn the PCM and then if it comes back on to bring it in. They will charge me for the diganostic but if it turns out it is something they did they will fix it at no cost.. but if it is not something they did.. I am out the diganostic fee.

To me the car runs fine.. just that darn CEL!

I will check the wires, plugs, any sensors near the DMD area and guess go from there.

Thanks again.

Any more ideas are welcome!

The first time I ever got a CEL was the day we installed my DMD. Not really sure why. I was revving up the engine 5,500-6,000 rpm when it came on. When I got home that day I unplugged the battery for 5 minutes and let it reset. There was no CEL recurrence for about 4 months. I think it is now due to aging plugs/wires @ almost 70,000 miles.

Just got back from lunch.. the CEL blinked about 10 times and the other times it did that it went off. Seems to happen around 4k+ in RPMs. This time it stayed on. Shut the car off.. restarted it still got the CEL. Lets hope the PCM just needs to be reset.



The SVT seems to run fine though.. this is just weird.

Thanks to those that replied. It is appreciated!

This is just a wild ass guess - but I know the misfire strategy looks at the crank pulses, and it is VERY sensitive to perturbances - so much so that I've read some tranny designs are scrapped because it puts too much noise/vibes onto the crank which causes the misfire monitor to fail.

I'm not sure if it's an adaptive strategy or not, but if it is and it's accoustomed to a signal with "large" amounts of timing scatter coming from undamped harmonics, suddenly removing that scatter could throw of the monitor.

Like I said it's a guess, but reset the PCM anyway, I bet the CEL goes away and doesn't come back......

If you reset the PCM and the CEL comes back, take it to Autozone and ask them to pull the code. They'll do it for free.

EDIT: Aw crap, I just noticed you're in CA. They don't pull codes for free in CA. Sorry.

We will see what happens after the reset. I can really tell that the engine is smooth now and maybe the computer is looking for those vibrations from the old dampner.

I checked the sensor near the DMD and it is on tight. I also looked over the general area for anything that might be loose. Nothing found.

Yeah.. good ol CA and their laws. I need to go get one of those code scanner things so I can do some diagnostic work at home.. or at least know what I am in for.

Thanks people!