After Installing New Engine, Car will not Idle with MAF

[DMC]

I just put a ka24de in my 89 f/b. After wiring everything up, it starts but stalls after a few seconds and will not rev. This is with the MAF connected. BUT if i disconnect the maf it idles fine and revs fine up to the normal 2500 rpms. Does anyone have any idea what this could be? I would appreciate any help!

Thanks David

[AZhitman]

Did you swap to a DOHC ECU?

[DMC]

Yes I swapped DOHC ecu and wiring harness. I also forgot to mention that I did try to replace the MAF and ECU both with no change in results!

[elwesso]

Youll want to check for continuity on the MAF harness from the connector to the ECU.... Then assuming you have continuity youll want to check the voltage at the ECU...

The reason its doing this is because the ECU doesnt really look at the MAF voltage during cranking, because 300 RPMs (cranking RPM) requires so little air, so once the ECU starts looking for a MAF voltage and its not getting any, it stops sending fuel thus the car dies...

I would start actually by checking the MAF voltage at the ECU, and then test for continuity... I cant remember the spec for maf voltage at different times (cranking, ignition on/engine off, idle, etc)... If you dont have the FSM, ill look for you on monday.

[DMC]

Thats a good idea, I need to look in the book and figure out what wires I need to trace. I have a chiltons manual, i will see if that has anything tommorow.

[InsanityInc]

If you've swapped the MAF and the ECU, my bet is on a bad harness.

[Ni2s4s0aSnX]

Try resetting the ECU.