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Leeboy · Jul 19, 2009, 04:35 PM

Last night our cavalier overheated due to a faulty fan relay... It started bogging down , that's when we noticed it was very hot... Trying to limp it another block or so to a safe parking area, It kind of made a light bang/backfire and just shot off. Tried starting it a few times... Not even a sputter. Plugs look good, lotsa fuel getting there, So we pulled the plugs and checked for spark on 2 of them. Nothing... So, we replaced the 2 coil packs, and module and still no spark. We are getting power to the module because I tested it and both sides of it light the test light. So, the juice is getting to the coil/packs module but not past it to the leads/plugs... Also, we popped the valve cover and turned it over and all rockers/valves are moving... Any ideas on what we could try?

Leeboy · Jul 20, 2009, 07:48 AM

What about a camshaft or crank sensor, could that not allow spark up the spark plug leads? A fuse maybe?

TxGreaseMonkey · Jul 20, 2009, 08:21 AM

You've done a lot of good things, already. Be sure to test all under dash and under hood fuses with a test light or multimeter:

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

After that, I would check the Crankshaft Position Sensor.

Leeboy · Jul 20, 2009, 08:29 AM

Sounds like a plan... Now, does the 95 Cavalier have a Cam or crankshaft sensor? On Google, some people say one or the other or both... The thing we pulled out had one little bolt on it and it a brass looking magnetized tube... (but we didn't know how to test it so we put it back in)

TxGreaseMonkey · Jul 20, 2009, 08:34 AM

Here's what it looks like and costs:

AutoZone.com | Vehicle Selection | Year

You'd have to read up on how to test the one you have. Because of their location, they are prone to fail.

Leeboy · Jul 20, 2009, 08:50 AM

Thanks TX, I forgot to mention, I did a compression test with all the plugs out and in order starting at #1, I had 150, 90,90,90

TxGreaseMonkey · Jul 20, 2009, 08:57 AM

That's your problem! Absolute readings are low and variability of the readings is too high. Looks like you'll be doing some rebuilding.

Leeboy · Jul 20, 2009, 09:04 AM

YIKES! But, wouldn't there be somewhat of a spark or sputter? I mean, there is still some compression... ( I'm just hoping)

TxGreaseMonkey · Jul 20, 2009, 09:10 AM

From here, it's not a pretty picture. Even if you had spark, the compression is so poor that I'm not sure it would run. Did the car overheat? I see from your write-up it did. The aluminum head has likely warped and you'll have to have it machined, valves checked, and new head gasket installed. That little extra driving pushed it over the edge. Sometimes, for safety, you have no choice.

Leeboy · Jul 23, 2009, 07:32 PM

Hey Tex... Is there any way to test for spark.. I took 1,3 and grounded them and didn't get nothing... Also, is there anyway to bypass the crank sensor temporary to see if it sparks or fires up..?

TxGreaseMonkey · Jul 24, 2009, 06:17 AM

Just the standard way to test for spark. Don't know anything about how to bypass the CKP to get plugs to spark.

Leeboy · Oct 1, 2009, 08:08 PM

Well... Guess what! It was the crank sensor... put a new one in and VROOOM! Thanks guys!