its an '85 Firebird 2.8L with 137,000 miles.


The other day I was driving home from the store and noticed that the engine would cut out for a brief second intermittently. It only happened 2 or 3 times in a few miles, and that was that.

Now today on the way to work it started up again, but this time wayy more noticeable and more frequent and still intermittently. It feels like an ignition problem. It's only getting worse now, and sometimes the engine idles rough and will try and die, only to splurge back alive somehow.

Things replaced in last 15,000 miles:
Cap
Rotor
Wires

I'm not totally sure if the previous owner replaced the coil or ignition module, but for now I can rule out the above 3.

The car has been getting worse and worse gas mileage lately too, and I know I need a new oxygen sensor. The car smells like it's running rich.

I've done a search on ignition modules, and it seems these symptoms are what come up time and time again. I was just wondering if it would be a place to start by replacing the ignition module, and if anyone had any suggestions on what brands to look for?

 

Take a gander at the tach while it is doing this. Is the tach fluctuating oddly with the miss?


If so, most likely a module issue.

 

Last I looked the tach didn't fluctuate much, but I may not have been paying attention.

Also, sometimes the car needs to crank a bit more than usual to start.

 

Doesn't sound too much like a module issue (although I won't rule it out...); modules generally either work or don't, and if they're intermittent, they either work or don't, depending on their temperature. I.e., they work until the temp reaches their unhappy point, at which point they quit, until they cool down. Still, works/doesn't work.

I'd strongly suggest taking a look at the cap & rotor, especially the rotor. That's what it sounds like. Doesn't matter whether it was last replaced 115,000 miles ago, 15,000 miles ago, or 15 miles ago. Look at it.

 

I took a look at the cap and rotor and both weren't in that great of shape, especially the cap.

I replaced both, but the problem still persists.

I noticed the post that the rotor goes on had some rust/corrosion on it. I tried to clean it as best as I could before putting the new rotor on.

Could the rust be causing problems for the rotor??

 

I cleaned the post that the rotor gets put on and the problem still persists, but its REALLY intermittent.

It can happen throughout the entire RPM range from idle to whatever.

I have tested the coil with a multimeter and from the 3 tests I did it seems to check out fine. Unless the ground arcs out somewhere inconsistently??

Another thing I noticed today was when the headlights are turned on, the tach flutters a little bit.

Please, any suggestions??? I'm trying to diagnose this rather than just wasting money and throwing parts at it, but it's hard to pinpoint.

Next thing I might try is a different coil. It seems to be the only thing that won't be dead or not dead (weak spark??)

 

bump

Coil didn't change anything.

I'm suspecting the plug wires may be arcing out somewhere now?


Please anyone, any suggestions would be awesome.

 

Shop told me it was was the ECM.

Dropped 104 dollars on one.

Car still does the same exact thing.

 

How old is your alternator? It's odd that the tach would flutter with the headlights on. Sounds like you might have a low voltage problem.

 

Alternator is fairly new and charges very well.

 

Changed the TPS today, set to .54v

Car still cuts out hardcore at 3,000 rpm, it's like a rev limiter, and if the car is lucky to get past 3,500 it runs fine 3,500 and up.

Wtf is wrong with this stupid car.

 

I am running into a similar problem with my 87 Camaro with a 2.8 as well. I took the distributor cap off and noticed some carbon build up. I proceeded to file the carbon off and clean the contacts. I then cleaned up the rotor. I changed to ACDELCO spark plugs and triple checked the gaping. I replaced the ign wires. Ran a continuity test on every wire and they are not very far off from one another. The car starts and runs well but after it warms up (around 10 to 20 minutes of driving) the check engine light comes on. At that point in time it was the tps came up with an error. I then replaced the TPS. The car is still running the same way. I have also began to notice my gas mileage is definately not where it is suppose to be. Right now im getting around 175mi to 12 gallons of fuel. Ive also realized that after the car warms up i can smell gas. This leads me to think the car is running rich but the car also starts to sputter when it warms up. The check engine light also still comes on after the car warms up. Im not sure if you are running into the same problem but that is what is happening with me.

 

Hey poppn, I had an all too familiar experience - engine suddenly cutting out,
tach dropping from 2500rpm to zero INSTANTLY -then finally -SILENCE.
You guessed it - ignition module. These modules do not take heat very well
and as Sofa said they will heat up-cut out - cool off and work fine. I would replace it but be aware that some cheapies can be bad out of the box.
If you do replace it ,don't forget to put the white temp grease on the bottom side of the unit - this acts as a temp insulator. Hope this helps.


" The secret of life is honesty and fair dealing...
If you can fake that, you've got it made. "
Groucho Marx

 

thanks for all the help guys, we got it figured out.

Turns out it was the MAF along with a bad oxygen sensor