Hi everybody. I guess this will serve as my intro to the forum. I've been working on my own cars for years and I've had a couple of Lesabres. I like them a lot.
I'm having trouble with my 98 3.8 liter, 88k miles. Initially, I thought I had water in the gas, which still may be the case. I siphoned the gas out of the tank and did get a little water. I put in fresh gas. Still the same. I just bought the Elmscan5 and I have shop manuals coming. The scanner has told me three things. Cylinder 2 misfire 0302, then 0300 random misfires, then 0305 cylinder 5 misfires. Cylinder 5 seems to be the one that comes in most often, cylinder 2 next, and I got random misfires 1 time.
I frogged the coil packs from 3-6 to 2-5, no change. I frogged the plugs from 3 and 5, no change. I did not replace the fuel filter yet. I did not try wires yet. I did not check for spark yet.
Any feelings on this one? I wonder if there could be something in an injector?

 

Best guess is you need new spark plug wires. For some reason, they seem to be short lived on this engine.


My Ultra's have always had heat shields around the wires at the plug ends. Also, the corrogated plastic wire guards in spots. People seem to discard these, but they are there for a reason. Not 100% sure if the non-supercharged engines have them, but I think they do, and, if so, you should replace them.

 

Welcome to the forum. [img]smileys/smiley10.gif[/img]

From here there's not much else to suspect as far as ignition goes but the ignition module</span> itself. Looking only as if it is the 2-5 circuit, it exists in the coil, module area, module's coil socket..etc.

Regarding the suspects.
fuel filter would logically cause problems on all cylinders and show itself under load. The same with bad gas, fuel pump, regulator, etc. Injector should be taken care of with some additive unless its a wiring.

Two bad plugs or wires falls a bit outside the box of thinking but not impossible.

A recommended procedure in the manual is by gapping a test plug to 1/4 to 3/8 run a plug wire to it and putting a solid ground to it (not installing it) and see if it helps identify a failure on the coil packs/ module area. It loads them down and helps looking for coil jumping and such. This may help you maintain direction of troubleshooting.






Edited by: bassasasin

 

Thanks for the input, I'm hoping to be able to look at it again tonight.

I forgot to mention that I can feel the miss through the steering wheel while it's idling, but if I want to produce a DTC, I get it out on the road and hit the gas pretty hard for a while, if it doesn't fail, I slow down and hit it again. It seems to fail mostly while driving up hill or during heavy acceleration. But the DTCs are mostly on cylinder 5. It will produce a code under normal driving conditions, but it's quicker if you beat on it a little bit.

Do either you or anybody else out there know how the computer determines which cylinder is failing?

Edited by: village

 

Do either you or anybody else out there know how the computer determines which cylinder is failing?, village



</span>I found some info here[img]smileys/smiley10.gif[/img]



This research says that since the PCM controls which cylinder has fired via camshaft info and ignition pulse.

The PCM also knows the instantaneous RPM.

Those two components it can calculate which piston has misfired.



It is also probable that under load, the RPM instantaneous drop is more profound and easier sensed.

I also found that a continual misfire can ruin a catalytic converter.

Edited by: bassasasin

 

That is interesting. I never considered momentary crankshaft speed detection to form a readable and comparable waveform. Then again, much of the junk I've worked on started life with points. I'm happy to say that I'm pretty much done with points;-)

I didn't get a chance last night, and tonite isn't looking much better. We have a get-together at church tonight. I haven't received the shop manuals yet anyway, and those are bound to come in handy when it comes to fuel pressures, etc. I really like the idea of hooking a laptop to the car to get it's opinion of what's happening. That's a new thrill for me. I'm looking forward to learning how to modify the parameters in the controllers to do other things, that could be interesting. Some day I hope to transplant a modern engine into an old buggy I made many years ago, that should be a good learning experience.

Thanks for your help, I can't imagine how you found that link.

 

*Solved* It was the plug wire on cylinder 5. It was open.

Thanks very much for your help on my LeSabre. I have a 98 H series shop manual now, if you need any info, let me know. It's nice to have the reference to help with some of the procedures and breakdowns. But there is no substitute for talking with people that have experience.

Thanks again.

I wonder how hard it would be to install a 3800 in a buggy that is based on a 1978 International Scout II? Have to think about that one...

 

dont forget if nyou put a 3800 fuel injected you need wiring harness,sensors,pocm and all to make it run.

 

That's true, I would have to figure out which sensors and wires I would need. No doubt that it would be fun!