95 ga with severe miss...PLEASE HELP

[pontiacfreak_81]

I am trying to figure this out....my sisters 95 grand am 2.3L dohc has a severe miss, so bad that it can no longer be driven. when first started its not so bad but after just a few seconds the whole car is shaking and when trying to accelerate a knocking/rattling sound is coming from the engine. So far we have replaced the plugs, boots, icm, coil packs, coil pack housing, fuel filter. we have also pulled out and cleaned the injectors, chased vacuum lines all over and have turned up nothing and the problem still remains. No ses light, no trouble codes come up when hooked to scantool. I am completely out of ideas, any help anyone could give me would be greatly appreciated i need this car fixed and out of my garage asap...thanks all

[gmack221]

You didn't mention mileage on the car ... this may help as certain parts seem to fail at certain mileage's

I would suggest you do some diagnosis before putting more money into parts. start by doing a spark test on all 4 cylinders (this can be done with 4 old fashion spark plug wires & 1 spark tester). Even new coil housings can be bad, its a problem I ran into with autozone parts ... The next test you should try is to make sure your getting power to the injectors (the injector harness's are known for going bad or getting a broken wire in them), use a noid light ($5 any autozone or parts store). If both of these test out ok the next thing I would do is let the car run at night for 10 -15 mins, then look under the car to see if the catalitic converter is red (or pull the Oxygen sensor & see if the car runs better, or pull the exhaust off at the manifold). The last test I recomend is a compression test on all 4 cylinders ... these motors are known for head gaskets going out (& check the oil for coolant or a milky look). If the head gasket is out there is probably a reason for it (water pump bad, thermostat stuck closed ....). Last thing I can think of would be the timing chain might have jumped a tooth (usually doesn't happen until after 150,000 miles, but anything is possible).

[xeroinfinity]

Sounds like its outta time

This might be the time to consider taking it apart to investigate.

[pontiacfreak_81]

sorry about that, the car has 158,000 miles on it. the head and head gasket were replaced about 3 years ago at around 120,000 miles. I will have to try the tests you mentioned tonight and see what i come up with.

[Bassasasin]

You mean a loping miss or a random totally confused firing type run?
Could be your CRANKshaft sensor has finally died..

What did the codes say?

Get the codes read?

Does sound like timing...

[pontiacfreak_81]

its the totally confused random firing, the engine rocks back and forth violently when idling, it goes to high idle then back to down to almost dying. it turned up no codes, but it did show the iac position to be going back and forth in the direction?? i dont really know what that means, and then some spark advance something or other was all over the place as well, but my friend with the scantool didnt know what any of it really meant and i didnt either