To Vader & Madmax: I have switched the MAF power relay with the MAF burn-off relay, and charged the battery to 13.1VDC, and STILL have the infernal code 36 staring at me! Where might I go from here?? Found out that the car runs without the MAF burn-off relay plugged in! I guess it's called "accidental information!"

 

Bob,

The MAF burn off relay is useless while the engine is running, so the engine should run without one. Unfortunately, if the MAF hot wire doesn't get burned clean after use, you may eventually start to get lean fuel mixtures from a sluggish MAF sensor. Prety soon you'd see a code '34' with the '36'.

I recall a previous situation like yours, and the problem may be similar. The MAF burn off operates by the ECM timing the signal to the relay. The ECM senses that the engine has been turned off by the ignition input and the tach feedback from the EST circuit. After a pause, the ECM will operate the relay for about eight seconds to clean the hot wire in the sensor. The ECM senses the cleaning operation via the MAF signal input from the sensor. Because of this, all connections to the MAF, both relays, and the ECM must be clean and tight. If the MAF does not signal the expected voltage to the ECM during the cleaning (burn off) period, the error code (DTC) will set. Also, if the relay is not presenting a load to the ECM, the DTC will set.

Because of this, the possibilities are:

1. Connections from the ECM to the relays (can be verified by observing the relays);

2. Connections between the relays and teh MAF sensor;

3. Connections between the MAF sensor and ECM (although this should cause other error codes during engine operation);

4. An ECM that is getting the ignition signal reapplied to the input after the engine is turned off.

Regarding item #4, I recall this happening once before. The problem was in the auxilliary oil pressure/fuel pump circuit backfeeding power through a stuck/corroded fuel pump relay. I cannot recall who the "victim" was, but it was someone on this board about a year ago. A new oil pressure switch (sticky/sluggish) new FP relay (corroded internally) and cleaned connections solved the problem.

A symptom of this could be an exended run-on of the fuel pump after engine shut down. This could indicate very good oil pressure or a sticky/sluggish pressure switch. Another way to eliminate the problem would be to unplug the fuel pump relay. This would cause extended cranking at start up to actuate the pressure switch before the fuel pump could operate, but might help narrow down the problem.

Good luck - you've got a challenging one.

------------------
Later,
Vader
------------------
"What a Day..."
Adobe Acrobat Reader

 

Thanks, Vader. Like you said, it's "challenging!" Guess I know what I'll be doin' on my days off this week. Really lookin' forward to the Helm Shop Manual arriving. Gropin' around "in the dark" without good circuit diagrams to follow. Again, thanks for your help.

 

Vader,

Thanks dude.. you answered my question as well.


Jacob

------------------
88 GTA Notchback
A4 / 350
Stock
** New User Name**

Kill List:
95 Mustang GT
88 Mustang GT
94? Impala (real close)
97 Dodge Neon
86 Corvette
2000 Prowler
And more Civic's then I can count. Why do they even bother?