I have a 1998 Z24 with the 2.4L Twin Cam engine and almost 200K miles on it. It runs on 2 cylinders (1 & 2) and the other 2 (3 & 4) are not working. The exhaust header is cold to the touch on those two. I recently changed the plugs and boots. When this problem first happened I changed the ignition coil for those 2 cylinders stupidly figuring that must be bad since I didn't see a spark when engine was cranked over. I then found fuel was being dumped in large amounts in cylinder 3, so I changed the number 3 injector. After this the problem still exists and is still only running on 2 cylinders.

Hopefully someone has some insight into my problem or maybe has seen this before. This has been a great car to me, I put 130K miles on it and haven't done anything more to it than changing oil and break pads before this.

Test for spark on cylinder 3 and then on cylinder 4. If there's no spark, compression is not a factor and I would test/replace the Ignition Control Module (ICM):

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AutoZone may be able to test your old ICM for free.

Those aren't paired cylinders. I would check engine vacuum and compression as well. You may have a bad head gasket.

If your not losing coolant, the gasket may be failed between cylinders three and four.

What is your experience with this type of diag?

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Originally Posted by CaptainRich

Those aren't paired cylinders. I would check engine vacuum and compression as well. You may have a bad head gasket.

If your not loosing coolant, the gasket may be failed between cylinders three and four.

What is your experience with this type of diag?

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I haven't checked the compression.

It had been losing coolant, but not a great amount, just having to top it off every thousand miles or so. It was so minmal I hadn't looked into where it had been going yet.

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Originally Posted by txgreasemonkey

Replace the Ignition Control Module:

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I had been wondering if this could be the problem, but I didn't want to throw another part at it that may not help it. Have you seen the Ignition Control Module create similar problems to what I am having?

Tx-gm may well be right but there are other things to check, too. You've got a lot of miles on this old workhorse.

I've seen that be a problem, but I'd want to be sure before I let go my hard earned money buying more spare parts.

Unless you've got no problem spending money or an unlimited access to used parts, I'd suggest you be the technician here and do the diag first, replace the parts you need. You're doing good, so far!

Good luck and let us know.

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Originally Posted by txgreasemonkey

Test for spark on cylinder 3 and then on cylinder 4. If there's no spark, compression is not a factor and I would test/replace the Ignition Control Module (ICM):

While we find your parts, please enter your ZIP Code at PartsAmerica.com

AutoZone may be able to test your old ICM for free.

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I just called the local Auto Zone and yes they can test the ICM. I will take that off the car tonight and hopefully get that tested tomorrow.

Did you test for spark on cylinder 3 and then on cylinder 4? If there's no spark, compression is not a factor.

It isn't sparking, which was why I thought it originally must have been the coil.

Be sure and test all under-dash and under-hood fuses with a test light or multimeter. Here's how:

https://www.askmehelpdesk.com/cars-t...tml#post252145

If all of the fuses are okay, I would focus on the Ignition Control Module and ensuring the spark plug wires are in good shape and not shorting out. First, try cleaning the connectors you see in the picture below:

While we find your parts, please enter your ZIP Code at PartsAmerica.com

To me, it's looking more and more like it has to be the ICM.

I took the ICM to Auto Zone and it tested to be good. I will have to try some other tests this weekend.

The number 3 cylinder is spraying too much gas. I replaced the fuel injector thinking the seal was blown causing it to dump too much gas, but that wasn't the problem. When cranking it over to check for spark, gas is shooting up through the spark plug hole and ending up with a pool of gas sitting on top of the piston.

What sensor or computer is it that tells the injector when to spray?

The Oxygen Sensor controls the duration of spray.

Is there a way to test to see if the oxygen sensor is good? I guess I could test the voltage going to the injector to see if the injector is being told to spray constantly.

I was just reading on Auto Zone's website that when it is cold, it runs in Open Loop which is controlled by the PCM and bypass the Oxygen Sensor.

This might help:

https://www.askmehelpdesk.com/cars-t...tml#post223376

I doubt any oxygen sensor is really any good after 200,000 miles.

The oxygen sensor is a relatively cheap piece to replace. In the information on Auto Zone it says it may have 2 sensors 1 before and 1 heated one after the cat.

Yes, that's very common and there are DTCs for each. You may want to check for codes.

Do you know what code an O2 sensor would throw?