94 Grand AM 2.3L Quad 4 Vin3: Fouled Plugs #1&2 [Archive] - GrandAmGT.com Forum


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09-23-2006, 09:14 PM
This is day three and I have exhausted all reasoning. Searching your forum has helped me very little.

I drove my daughter's car to a battery/alternator shop after it had basically tranded her. Alternator is good and the battery has 600 CCA available but it is 6 yrs old and will be replaced after I resolve the issues. I then drove it 20 miles home.

Driving Observations:

(1) engine starts fine
(2) rough idle in park
(3) wants to stall in drive
(4) left foot braking and higher idle make car drivable but still rough with power loss
(5) hesitation and perhaps misfire through 30 mph along with very poor acceleration
(6) 40 mph to 50 mph is top speed; yet, poor drivability seems less obvious while acceleration remains almost non-existent.

Once home I found the following:

(1) cylinders 1 & 2 are carbon fouled and smell of fuel
(2) I don't believe they are oil fouled; carbon seems dry
(3) plug gap is open

Given that this is an IDI ignition system (cylinder 1 is paired to 4 as 2 is to 3, also no plug wires), I don't believe this is ignition related problem. However, I checked components for continuity, resistance and spark and found them within tolerances as well as plugs gapped correctly. I should think this would also eliminate the Crankshaft Position sensor and PCM.

Found injectors in good order, i.e., resistance good, spray pattern good. Found injector wires in good shape and noid light shows power from PCM. Paired noids also showed expected alternating injector pattern, i.e., 1-4 and 2-3.

So, I think all that is left is a mechanical issue or issues like compression. Here, I found no significant difference between cylinders; 210psi each cylinder.

I just purchased a leak-down tester but don't want to get involved with the all the steps required for testing before I exhaust other possible reasons for the fouled plugs.

Tomorrow morning I will run an OBDii scanner with an OBDi module.

Any thoughts and or direction would be appreciated.

09-24-2006, 09:57 AM

Using the Actron CP9145 OBD II Super AutoScanner and the Actron GM OBD I ALDL Cable CP9127 that I rented from Murrays Discount Auto, I found no DTCs. I did not expect to given the MIL on the dash was not on.

I did find the following:

While the engine was running, I pulled the #1 connector from it's injector. There was no change in the engine RPMs.
I found the same with the #2 injector.

Other family commitments require my attention now.

Will post again later.