Help with misfire code

Post by **erikv11** » 16 Nov 2011, 16:43

You can check the MAF cable for shorts by just unplugging it. The car will throw a CEL for no MAF, but also go into a default mode and run better than if there was a bad MAF connection.

However, MAF trouble would not lead to a misfire specifically in #4. Car needs a compression test now. Is #4 low, and if so how low?

draser · Post by **draser** » 16 Nov 2011, 17:45

Pulling on the MAF cable will not give you cable shorts - it may however open up the circuit by pulling out of the connector or just breaking. But you will get a fault for it either way.

Post by **JimBee** » 16 Nov 2011, 19:23

If you really get stuck on this, you might want to check out the ignition control module. I pulled one recently from a junk yard car not knowing what it was but it looked interesting and was easily accessible. According to Jimmy on this site, some years have it built into the computer. I don't recall the year of the one I pulled it from. It's a little black module that mounts under the cowl cover by the windshield wiper motor.

This writeup describes symptoms a bad one can cause: http://www.bosch.com.au/content/language1/html/2256.htm

rjaywhit · Post by **rjaywhit** » 21 Nov 2011, 07:20

Checked compression this weekend.

Cyl 1 = 180 psi
Cyl 2 = 200 psi
Cyl 3 = 185 psi
Cyl 4 = 0
Cyl 5 = 165 psi

Obviously I'm disappointed to see the reading on #4. There was a litte pressure in the guage when I released it, but not enough to show a reading on the guage. Checked it 3 times for good measure.

What's my next step?

Billc1015 · Post by **Billc1015** » 21 Nov 2011, 09:41

Sounds like it is time to pull the head to see why there is no compression.

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I am here: http://maps.google.com/maps?ll=40.334505,-75.131051

rjaywhit · Post by **rjaywhit** » 21 Nov 2011, 10:01

I'm going to see if I can rent a leak down tester from autozone to see where the problem is.

I don't think that I want to pull the head again.

Billc1015 · Post by **Billc1015** » 21 Nov 2011, 12:55

You can do that but all it is going to tell you is whether you have a problem with an intake valve, an exhaust valve, a piston, or a cracked head. Regardless of what failed, you are still going to need to pull the head to repair it. I would hate to see you waste time on an un-needed test when that time could be spent starting the tear down process.

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I am here: http://maps.google.com/maps?ll=40.334461,-75.130706

Post by **jblackburn** » 21 Nov 2011, 13:15

Seafoam it first - maybe one's just stuck open. What have you got to lose?

You can also try holding a piece of paper over the exhaust while it's running. If it sucks in when that 4th cylinder goes down, that points to a burned exhaust valve.

rjaywhit · Post by **rjaywhit** » 21 Nov 2011, 13:45

I'm not interested in rebuilding the head again.

If Seafoam doesn't help, then I'm going to get rid of it.

rjaywhit · Post by **rjaywhit** » 22 Nov 2011, 08:19

I checked the compression again on #4 last night after my Italian tune up Sunday evening. It is now reading at 20 psi instead of 0 so maybe it is getting better.

I will do another run later this week before trying Seafoam.

Help with misfire code

Re: Help with misfire code