So my 93 400 has a strange problem that I cannot figure out. When I start it, the cel light stays lit (Code 31 - Mass Air Signal) and the car idles fine for 4-10 minutes (approx.) and then it just dies. I turn it back on and it will die a few seconds later. After a couple of tries it will either continue to die, or stumble repeatedly and then eventually smooth out and run fine. When the latter happens, the cel disappears as if nothing ever happened. Swapped MAFs with redphoenix and he is still running mine with no problems and I still have the problem with his.
Any ideas?

 

Must figure this out before the temp tag expires! Any ideas appreciated.

 

Well since the MAF swap didn't work, try unplugging the MAF all together and see if that changes the symptoms at all.
Then if that doesn't give any clarity to the situation try reseting the ECU and running the car through a drive cycle to see if the issues clear up at all.

 

Forgot to mention I removed the maf and reset the ecu and it ran fine. Then I reinstalled the maf and reset it and no problems after running for 5-10 minutes. Then I tryed again the next day and back to the dieing after a few minutes of idling fine. When you say drive cycle what are you referring to?

 

bump.......

 

bumpppppppp

 

drive cycle is what the ECU requires to run non-continuous monitors that it needs information from in order to be able to map out air/fuel ratios depending on all the situations you encounter daily while driving.

 

Update...Now the car bogs when given throttle from idle at startup and beyond. Just started the manual swap today and would like to get this fixed soon to enjoy the new trans.

 

Could it be the fuel ecu going bad, located in the driver rear compartment? Anyone care to chime in?

 

hmm interesting. im pulling the same code. update us please.

 

I did the fuel pump ecu bypass by jumping the appropriate terminals, but to no avail. I am going to attempt it again, and hope that maybe I just didn't complete the circuit in my haste the first time around. If not I'll still be

 

I think this is the exact similar problem that was happening to my cousin's mom's car (1992 SC300). They replaced the MAF and same thing happens. Now they replaced the ECU. All is fine except now they are getting code 21 & 27. So, it could be the ECU (knock on wood).

 

The ECU was just replaced (funny enough) with an ECU that came off a known running car. But it may be good to test it again!

 

Could this be a fuel pump on its last leg?

 

Would that possibly throw a Mass air signal code?