BudRacing

iTrader: (3)

My mother's 95 olds aurora (OBDI) has an awful misfire. She took it to a mechanic and was told it needed a new fuel injection harness, which they told her was $1400--yeah right.
So her neighbor found one at a junkyard, compared them, tested all the wires with a voltmeter, and installed it only to find that it didn't change a thing.

Since I've got a week off I've decided to take a further look at it. I've replaced all the spark plugs so far which also didn't help, but I figured I'd do the cheap and easy stuff first before I get more in-depth.
Her service records say that her 4 coils (ACDelco--2 cyl per coil) have all been replaced within the last 2 years along with her ACdelco spark plug wires.
I also ran some seafoam through it last night before I changed the plugs this morning.
It starts up fine, but has a gas smell coming from the tailpipes and it has NO power--can't even back out of the inclined driveway.

The engine doesn't shake indicating a dead cylinder, but I'm not sure if it's a random misfire or not. But the engine has a very different, low pitched almost bogging type sound.
The worst plug I pulled was the frontside #2 plug--very corroded, and the rest looked OK but had some oil on them, or perhaps unburnt fuel sludge?

What, if anything, should I test next? Should I unbolt the cat converter to see if it's clogged?

Thanks for any help or suggestions.

BudRacing

iTrader: (3)

Update: Cat converter not the problem.

ghardester

New spark plug wires before you do anything else. Everyone changes the plugs and re-uses the old wires. Just the act of taking them off can ruin them. I'm not saying that is the problem, but if you want to try the next cheapest solution, make sure the wires ar new and good.

After that I would have the coils tested.

BudRacing

iTrader: (3)

If there's no arching can the wires still be bad?

Also, how/where do i test the coils. I may do that before wires.

BudRacing

iTrader: (3)

What are the chances of the valve timing being off? I noticed the DOHC's are turned by a small serpentine style belt which looks to be in good shape, but there's really no telling whether it's ever been changed after the 150k+ on this engine.

ghardester

Yes wires can be bad if you can't see arching. I have had several problems of misfire on various cars over my many years of driving, a lot of them were wires. When I had the 3800 engine in the V-6's I owned, I could count on the misfire being the wires. What engine is in the Aurora? I am unsure why so many people trust their spark plug wires but suspect everything else.

You procede as you see fit. I would hate to have you spend money on wires and that not be the problem. So it's just advice.

There is a principle of problem solving that works great on engine repair too. It's called Occam's Razor and briefly it means that all things being equal, the simplest solution is probably the correct one. And that you shouldn't introduce new variables into the situation until the simplest have been eliminated.

BudRacing

iTrader: (3)

The Aurora engine is a DOHC 4.0 V8. It was a pretty experimental engine at the time, and I think they put them in Auroras until Olds went out. It was also the same engine design used in the Indy cars at the time.
The real reason I trusted the spark plug wires was that they're ACDelco and probably have about 25k on them at most. I checked out Rockauto.com for a price on the replacement wires and the ACDelcos are 101.79. I'd like to see if I could find a high voltage tester to test out the plug wires before I throw money into them.

And the simplest solution was my original approach, but I asked my mom when exactly it happened and she said it was while she was driving and somewhat abrupt.
--She was leaving work, had gone about a mile and stopped at a light before getting on the highway. When leaving the light the car just lost power in the middle of the intersection and could barely get out of it's own way--which is it's current state.
When I think of spark plug wires going bad I think of it as more of a progressive deterioration rather than abrupt change (as long as they're not arching). So I'm still a little stumped.

lmt0705

iTrader: (7)

pull your injector wires off in sequence with the cylinders that each coil fires. what I mean is you have 4 coil packs and they fire 2 cylinders each I believe its 2/5 1/3 4/6 or something. ill bet you will find that one of those sets of injector wires you pull will make no difference in how the car runs which means replace that coil. I had the same problem on my sisters car and I traced it for a few days before I discovered thats what it was

BudRacing

iTrader: (3)

You mean spark plug wires? The fuel injector wires aren't prompted by the coils.

I'll have to give that a try.