Ok... I'm reaching out to the 92-up crowd for some tech advice. First off, I'm not a complete idiot but am kinda lazy so I'll ask first...lol!

Anyone here ever have any issues with the service ASR light? Here's my dilemma....

Earlier today I was driving around with my ASR OFF because...why not? Then about 30 minutes into my drive I noticed that the Service ASR and Service ABS were illuminated on my DIC. So, when I got to where I was going, I shut the car off for about 4 minutes. Turned it back on and no lights. Drove fine till I got to where I was going. Car sat for like 6 hours till it was time to go home. Drove fine for first 20 minutes. Then, while giving her the strong right foot, I took it up to about 5200, just before the upshift and it began to break up (like serious miss from ignition) and the Service ASR light came on. Now, if I got on it hard again, it would begin to buck and the tach went to zero even though it was running. Couldn't push it past about 3k before it would start to break up again.

I have not pulled the ASR codes yet. Last time I had run ability issues with the service ASR LIGHT on, it ended up being the TPS which makes sense but what's killing me is why the tach doesn't read. That didn't happen the first time when the TPS went bad.

I've done some reading and when I can, will initiate some testing. But I figured I'd ask my brethren for some possible solutions.

ICM, TPS, Ignition Coil replaced about 4K miles ago last year before I found out the Opti took a crap. Opti is new as is plugs/wires.

1992, 6 speed.

 

Have you pulled codes yet? It could be an ECM issue especially if problems come and go randomly.

 

If the tach went to zero, my first suspicion is the sensor inside the optispark. Here is a thread where the full troubleshooting procedures were discussed in detail for this.

 

Ok so here goes. Cold start, tach working to lights on DIC. Warms up, tach shuts down, service ASR light comes on. Run codes. H62 shows in module 9. "Tach signal lost" is description. So, next question, what components are in line for the Tach? I know the distributor (in my case opti) for sure but is it only that which sends signal to ECM then the ECM distributes out to all other sensors?

 

Next test will be to run until the bucking starts and see if any codes appear. The CES light never came on when this first happened.

 

be sure to check all your grounds, this will cause a bunch of different problems.

 

Are they all located in the same area or spread all over?

 

It's really not "boggling". The high RPM miss, breaking up...symptoms or clues. The tach going to zero...pretty much proof that your distributor is done.

Just just went though similar, if the exactly the same symptoms on my '92. It was the distributor. Thread HERE.


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I have yet to get a 16 or 36 code and I just replaced the damn thing about 2K miles ago.... I sure hope it isn't.

 

opti does not always set a code.

 

In the thread that I linked, mine died on me probably 6-7 times before I replaced it. Never set a code, but I could watch on the scan tool, both signals go to "0".

 

So the tach gets the signal directly from the Opti? No involvement from the ICM, TPS or ECM?

 

The Opti is the origin for the "now-now-now-now..." that provides the ECM an reference signal, so it can calculate when to:
*Fire the injectors
*create a spark
*run the tach

....among other things. The ICM has nothing to do w/the tach...nor does the TPS.

The fact that you're losing tach signal...AND the engine dies at the same time....that is a pretty strong indicator that your distributor isn't providing a reference signal. I could the the harness from the distributor to the ECM...but I'd bet it's not.

 

So the engine can still run with no tach signal as mine does, yes?

 

You seem to be losing the tach reading while the engine is bucking correct? If so, thats when youre losing the tach reference. Intermittently. Your tach doesnt always show 0 right?? Only when the engine is missing and bucking...

 

When it first happened, lost tach while bucking but now there's only tach at first start up. Then as it runs, it shuts off, the SERVICE ASR light illuminates but the car still runs. When you give it gas to higher RPM that's when it bucks but the car runs with the tach at 0.

 

You need a scan tool to confirm, but my guess is that you're losing your high res signal entirely and it's running on the low res signal only.


What you really need to do, is some diagnosis.


.

 

You're not going to believe this...

Grey plug on the coil worked itself loose... This was my issue! Set code H16 and because of the loss of tach signal, set the SERVICE ASR light and code H62 in the 9.0 section. Plugged it back in, all is as it should be!

 

Awesome.... glad you got it figured out. Sometimes KISS is the best beginning!