Replaced the UIM after it died

[kelshm]

My 97 Lesabre recently experienced the dreaded UIM failure. It was at a stoplight and I managed to get it off the road where it then wouldn't turn over due to hydrolock. After sitting for awhile it turned over fine but I didn't allow it to start. Towed it home and replaced the UIM with the Dorman replacement part along with the new tubes.

I also changed the oil, plugs, plug wires and the car runs now but runs terribly at an idle. It misses out. I have checked the plugs and they are firing. I did find that one coil pack wasn't firing and relaced it but although it is now firing, the miss isn't any better. Every plug seems to be firing when checked. The compression is equal in all cylinders. My gauge isn't accurate on the pressure (I'm hoping) and it read 110-115 in all cylinders. When you get some RPM's up, the miss goes away and the car runs like it did prior to the failure. I am getting a little bit of a "backfire" (like an older carburetor backfire but not as intense) on acceleration. I've heard this could be valves........but there is absolutely no knock....does that matter?

I have also sprayed around each injector to see if perhaps they are leaking (yes I put new o-rings on) and there was no change.

ANY ideas? I'm laid off a great job and working 2 part time jobs to survive so an engine isn't really in the realm of possibility right now. Driving my truck while the car is down is REALLY draining the wallet. $60 a week for gas as compared to $20 in the Buick.

I appreciate your help and thank you in advance!

[maxwedge]

See if you can pinpoint the possible miss by shorting out one plug at a time, when you get to one that does not change the roughness, focus on that cylinder. Wire, cracked plug, bad injector.

[kelshm]

Ok, here's the latest. I checked the fuel injectors and 2 don't make any change in the idle if unplugged. I replaced them with new injectors and nothing changed. They still don't fire.

I checked the voltage and it is the same as the working injectors. Any ideas? At least I've eliminated the plugs and wires....though they are a lot cheaper!

[maxwedge]

Get a noid lite and see if the injectors are recieving pulse.

[Mickey#1]

Which cylinders are these two injectors going to?

[BNaylor]

It could be a vacuum leak. Are you sure all the vacuum lines on the throttle body and UIM body especially the one at the back of the UIM that goes to the power brake booster and accessory vacuum are connected or in good condition.

[kelshm]

The injectors on cylinders 3 and 5 are the ones not working. I can get a noid lite tomorrow if one is available.

The vacuum lines are all ok.

I don't get much time to work on this car. I have Saturday morning and Monday morning. Not enough time in the week! lol I'm going to check these things out tomorrow and I'll let you know.

[imidazol97]

Originally Posted by kelshm

The injectors on cylinders 3 and 5 are the ones not working. I can get a noid lite tomorrow if one is available.

The vacuum lines are all ok.

I don't get much time to work on this car. I have Saturday morning and Monday morning. Not enough time in the week! lol I'm going to check these things out tomorrow and I'll let you know.

The injectors always have 12 v but it's the computer that connects the ground to "fire" each injector as required. So you might be looking at a problem in the computer's ability to ground those injectors via the circuitry.

[Mickey#1]

If the noid light checks OK then I'd try new spark plugs in 3 & 5. It doesn't take much coolant to foul out plugs. Make sure the wires for 3 & 5 are going to correct coils.

[kelshm]

Problem solved. The plug wires to 3 and 5, although new, were no good. It still isn't 100% but it's about 95% back to running good. There is a little rough idle occasionally. I'm going to drive it for a bit and see if this clears up. I doubt it will but at least I have my car back!

I disconnected the battery for about 5 minutes and still have a check engine light on. I suppose that I still need to get the scanner so I can find out what's up with that....and possibly why the occasional rough idle. By rough I mean that it will miss out....very minor miss but a miss nonetheless.

[auto trainy]

Just out of curriousity what brand of plugs and wires did you put on?