Hey guys and gals... got a 1989 Olds 98 3800... hard to describe the problem, but here it goes.. it starts up when cold and has a steady miss (perfectly timed), and it gets worse as the car runs... after a while, if you try to rev it up it coughs and sputters and fights to rev up... when the car is above operating temperature (90*C) the idle smooths out, and it runs like a normal car again.

Here are my guesses 1) Ignition Module 2) Crank Position Senor 3) ECM

What I have done so far... tested the coil across each "pole" they are laid out like this

O O 11.7Kohms

O O 11.5Kohms

O O 11.5Kohms

The readings didn't deviate from hot to cold... oh, the range may be wrong, I didn't check to see what range my "digimeter" was on... Any thoughts? Anyone want to help me with their laptop and scanner software, I'd try to make it worth while....

 

Hey Nathan! AH the dredid 3.8L. I know the engine, I do think you are on the right track though. I have come across this type of problems numerous amounts of time with the Ignition Modules. I can't see it being the crank sensor. but you may have a sicky injector also, seen that before. I will look into further on my Mitchell program and see what it says. I shall return!

 

I did find a tech bulletin on my program that tells me what I even thought would be a good route to follow. IAC motor. Try disconnecting and see if the problem continues. Does this car have a lot of milage on it? If so the IAC could very well be carbened up, not allowing it to open and close properly. Cheap place to look anyway. Let me know?

 

Hey Keiran... I'll try unplugging the IAC, but it should be clean, I got it cleaned a couple years ago, and I cleaned the TB before it went back on the road last month. The problen just started this week, it seems worse than a sticky injector.

What do you guys charge for diagnosis at NAS? I don't want to play the "lets replace everything until it is fixed" game

 

My boss charges around $60/hr. BY the sounds of you problem it shouldn't be to hard to find. Trouble is electrical stuff is a pain sometimes, which I'm sure you know. A sticky injector definetaly could cause the problem, or maybe you have a shorting injector. But you do say that it clears up after awhile right? Any funny noises to be heard? Sticky lifter or something?? If the answer is no to most of these questions. Then this could get tough. How old are your plugs any wires. Also there is a good chance that one of your coil packs are on the way out, causing a intermiten missfire here and there. Maybe you should come by the shop on Monday or Tuesday and we could book you for an apointment to have it checked out. Let me know and I can let my boss know that you may be coming in.

 

The coil packs are between 11.7 and 11.5 Kohms, and the readings don't deviate when hot or cold... I'll check the resistance of the injectors, that should tell me if any are shot... I'm leaning toward the Ignition Module or Crank Position Sensor.. cause it sounds like the timing is fubar.. When you try revving it up, it spats and putters.. wires are 2 years old, plugs are about a year old.

 

OK, here's an update... got it hot enough where it ran like a car again, LOL... drove it around a bit.. and rechecked the coils, they are reading 4Kohms higher than the cold readings, is this OK?

Checked the injector resistances, they are all +/- 0.2Ohms, hot or cold.

Checked for codes, NONE

Also added another possible problem... just found out that this engine has a cam sensor as well as the crank sensor... so that could also be the problem.

Oh, Keiran, I don't have the money to spend on a mechanic yet.. so that'll have to wait

 

I agree. It sounds like the ICM. Is yours on the front of the engine down by the starter or is at the top by the back valve cover? If it is down by the starter..ouch! Sometimes they are a real pain to work with. I would really try the wires first though, they are cheap, and for the most part easy to change. Like I said though...I do agree. It does sound like it is the module. I can look into the cost of that for you on Monday, maybe I can save you a few bucks..."maybe". I would still start with the wires first. 2 years of mostly sitting around may have caused some unusual ware in spots. It is regular maintance anyway. UP to you but it should help.

 

It's beyond wires, when I bought the car, the wires were 10 years old, and it ran fine.. I will check tonight to see if there is a light show under the hood

 

Nathan...what about the CTS? Just wondering cause it sound temp related.

 

Hmmm.... good idea Chris.. I'll check the resitance of that tomorrow.. thanx dood

 

Yes that is a good idea! Just may cause all your porbs too.

 

This will sound pretty basic and you have probably already tried it but here goes anyway.

Start car cold with the problem going on. Take the plug wires off each of the spark plugs momentarily and listen for a change in the idle.

When you find a plug that does not make the engine change you have found the cylinder that is causing the problem.

Remove that plug and look at it. Fouled? Yes replace and see if problem has gone away. Plug could be bad or could be excessive oil leaking past rings or valve guides in this cylinder. Could be problem with spark to this cylinder etc.

Not fouled but burnt. Probably fuel starvation has caused overheating in this cylinder. Bad injector? etc. etc. etc.

I have always found that narrowing the problem down to a specific cylinder or system makes diagnosis much easier.

Good luck
Ric

 

I've always been scared to touch the sparkplug wires while the car is running..

The car runs perfect when its warmed up, that is what baffles me... Last time, it was hard starting, but when it started it ran good, that time it was the ignition coils.

This time the coils are 3 or 4Kohms higher when the engine is hot and running good... is that bad coils?