Plugs Foul Fast In FI Transplant

[steviebsf]

Hello Spider People: I cannot express how appreciative I am of the helpful members of this outstanding forum. Truly!

Brief background: Dropped an 82 FI 2L trans & complete drivetrain into a 78 (I really should post my notes about that, but not here). Replaced everything on top, fluids, hoses, filters etc. also: rebuilt distrib (new mag pickup) & new control module. New O2 sensor. Ran very well for a while considering, and then developed this little tick. I should note: it was a little boggy on acceleration at upper PRMs before.

Problem: Fouling plugs to the point of not starting in about 10 min.

Plugs are dry and black in all 4 cylinders. Clean them and it starts right up. Bosch Platinum.
I have checked for air leaks (pretty well, but not super conclusively well).
I have spark at all plugs (checked with inline tester).
Inspected cap & rotor - checked gap.
Checked cold start injector for duration and pattern.
Checked fuel pump via AFM flap: good steady flow.
checked aux air intake at the plug.
Have not checked injectors individually - no liquid in vacuum hose from fuel regulator to intake.
very small amount of oil in hose with trap.
Compression consistent (160 and 150 x 3)

What else? I am stuck. Anybody... Bueller? ... Bueller?...

Thanks in Advance - stevie b

[GeorgeT]

There is an adjustment screw on the air flow meter that will enrich or lean the mixture as needed. Access to this screw was blocked by an aluminum plug and was only to be "messed with" by trained techs with while the car was running and hooked up to smog measuring instruments. You may try removing the "plug" if it's still there and adjust the mixture that way.

[BEEK]

that mixture screw is a minor adjustment. you need to verify the fuel pressure the actual amount. and check the coolant temperature sensor resistance at the sensor itself and then again at its input to the brain. the coolant temp sensor determines the fuel mixture thru its input to the ecu.

[So Cal Mark]

two items that will cause extremely rich mixtures in an FI car are a leaking pressure regulator or a faulty temp sensor

[wizard124]

FWIW, right after I bought my '80 FI, I did a full tune up. At the time, I noticed a tear in the rubber boot of the AFM connector. I wrapped it with electrical tape to seal it.

I started the car and it ran horribly. Soot out the tailpipe, missing, etc. I re-checked and swapped plugs, wires, distributor cap. Turned out that this wrapping must have shorted or affected the connector's pins.

Try wiggling this wire bundle and/or reset that connection to see if it smooths out.
Warren

[steviebsf]

Thank you so much for all your suggestions. I will get to work and report back.

Mark, thank you for taking the time, I cannot find much on testing for a leaking pressure regulator other than to look for fuel in the attached vacuum hose (which i do not have). can you please elaborate or point me in the right direction.

much obliged - stevie b

[steviebsf]

well folks, it appears to be the temp sensor. local vendor has one. i will pop it in and let you know.

thanks again - grateful member stevie b

[BEEK]

did you check the connections, thats why i said test the sensor at the sensor and again at the brain

[steviebsf]

Hi BEEK.
I did the resistance test from the ECU as well as straight off the sensor.
I checked all the wires on the fuel injection harness before i installed it as well as going through and cleaning most electrical connections and reconnected using dielectric grease.
Thanks for your input. i'll report back

[steviebsf]

Solved! temperature sensor was bad - runs like a dream!

thank you again contributors

thank you fiatspider.com