ok, so my maf reading is 23g/sec with the car not running. what's up with that?

 

Off the top of my head I'd say either the MAF or the ECM has goen bye-bye on you. However, some scan tools do odd things when the engine is not running. I'd scan it again with the engine running and see if it's giving more "sane" readings. Usually at idle (engine warned up, 700 RPMs) you'll be reading around 5gm/sec.

 

I'd say you have the makings of a very powerfull engine. 23g/sec and the engine is not even running.

 

well its not the maf because it reads that whether its plugged in or not. i can try the ecm because i have a spare, but i suspect wiring

 

Verify the ECM grounds are intact.

Inspect the MAf power and burn off relay (expecially burn off) for connector and wiring corrosion, carbon in the relay case, and possibly moisture on the relay (internal to the case).

Put away your scanner for now and use a calibrated DVM for diagnosis. The DVM won't lie or presume.

 

so how do you test to see if the relays are bad

 

ok, so i've determined that the maf power relay is not getting juice when the car is switched on. correct me if i'm wrong but i believe it should be. upon looking at the wiring diagrams, the circuit seems to be tied in with the oil pressure switch and the fuel pump relay as well. can someone explain the logic behind this? i'm wondering if either of those could be causing this problem. bear in mind this is a new engine install and i'm wondering if something is either not connected or broke during the install. the fuel pump is working and i've checked to see that the oil pressure switch is hooked up and i've verified that all the grounds are intact. can i have some input here?

 

guess not. oh well, doesnt matter anyway. it all just suddenly started working. kills me when you have a heinous problem that somehow all of a sudden fixes itself. but dont look a gift horse...

don't mind me, i'm just babbling to myself here.

 

Sorry for the slow reply.

If it occurs again, here are some things to check:

1. The MAF Burnoff relay should have a constant 12VDC supply (battery voltage) on both the 'E' terminal and 'C' terminal (via the orange wire).
2. The 'B' terminal should switch to ground through the ECM output transistor within 20 seconds of the engine shutting off and the oil pressure switch opening. The ECM awaits the loss of power on its 'B2' terminal (Fuel Pump Voltage) before it can initiate the burn off cycle.
3. When the ECM commands a burn off cycle, the relay should close, and 12VDC is switched to both the 'D' terminal on the MAF Sensor itself, and the 'D' terminal on the MAF Power relay.
4. Power is routed through the N.C. contacts of the MAF Power relay to the MAF Sensor to enable the MAF Sensor electronics package. This is critical, since the MAF Sensor must report a signal back to the ECM to prove a good burn off cycle. This is also why a failing MAF Power relay can cause a MAF Burnoff error.
5. Upon receiving all these signals, the MAF Sensor hot wire is heated to full incandescence, and the MAF Sensor reads the hot wire current at full. This causes the MAF Sensor to report a full, 5VDC saturated (non-duty-cycling) signal to the ECM.
6. Upon receipt of this signal, the ECM registers a complete MAF burn off cycle, ungrounds the 'B' terminal of the MAF Burnoff relay, and is satisfied.

NOTE: Any interruption of the cycle will cause an error, and subsequent error code. This includes marginal relay contacts, poor connections and grounds at any point, and intermittent operation of the auxilliary oil pressure switch, since any voltage from the oil pressure switch will indicate to the ECM that the engine is not shut down, effectively terminating the cycle.



Other things to check:

1. The MAF Power relay should have a constant 12VDC supply (battery voltage) on the 'A' terminal (via the orange wire).
2. There should be a 12VDC supply whenever the ignition is ON at the 'B' terminal (via the blk/pnk wire).
3. The 'E' terminal should have a good ground at all times through the blk/wht wire.
4. Both the normally closed and normally open contacts of the relay (from terminals 'E' to 'A' for N.O., and 'D' to 'A' for N.C.) must be operation and reliable (see above).

Hope that helps.

 

beautiful explanation, vader. thanks.