A lotta problems (still)

[krock26]

I've recently replaced the head gasket on my car along with the VAF, ECM, ECT, TPS, ICM, ignition system besides disty, fuel pump and filter and I'm still having a lot of problems. It's throwing a code 17 and a code 8 and I know my VAF is primo. However, there was a short in the VAF harness that I fixed by running a new wire to the ECM. But it didn't fix the problem. Right now, when the engine is started for the first time that day, it will start and then die about 5 times before going into a perfect idle. I say first time that day because it won't do it unless it's been sitting overnight or all day, not just when it's cold. Once it's at that idle it will sputter and backfire and bog down, but it won't die if I open the throttle. I can however press the gas by maybe an 1/8" and it will rev to redline if I let it, anymore and it starts misfiring. Then at seemingly random times the engine will rev to 2k rpm for about 30 seconds, then down to 1.5k for 30 seconds and then back to normal, but I still can't open the throttle. I am sure that the timing belt is exactly perfect and no amount of fiddling with the distributor will fix the problem. I replaced both intake hoses because both of mine were shot and all of the intake gaskets are completely leak free. Compression is 150 psi in all cylinders cold. I just don't know what else I can do at this point.

[krock26]

Does anyone know what the correct voltage for the VAF is? I'm getting 3v with key on engine off, 1.9v at idle and .9v at WOT, all on the signal wire.

[Eaglefreek]

I don't have my Festiva service manual here at work, but I believe all Bosch VAF meters work the same. Here's some info I found regarding a Ford Tbird and I'm pretty sure it applies to our Festivas.

[Icedawg]

Sounds like you may well still have a wiring issue, or a bad VAF. But you could also have a significant vacuum leak elsewhere in the intake system, as it will give the unstable idle. A bad VAF or bad connection is more likely to simply not run the engine for more than a few seconds.

From the 1991 festiva factory manual; as a place to start on the voltages you asked about.

Code 17 is exhaust gas O2 sensor, but the engine will run if you disconnect the O2 sensor
Code 8 is Vane Air flow meter, the engine will not run if this is not working

PINPOINT TEST VAF - VANE AIRFLOW METER
Enter this test only when a Code 08 is displayed during QUICK TESTS procedure, or when directed here
from another PINPOINT TEST. To avoid unnecessary diagnostic time, check for unmetered air leaks
between VAF meter and throttle body. This test is intended to diagnose only VAF and VREF circuits.

1) Turn ignition off. Install BOB (break out box). Turn on ignition. Measure voltage between VAF and ground pins while moving vane in VAF meter.
Voltage should vary smoothly between .5-1.5 volts with door open, and 4.5-5.0 with door closed. If voltage is as specified, VAF meter
is okay; return to QUICK TESTS if sent here from there. If not sent here from QUICK TESTS, replace ECA (electronic control assembly). If voltage is not as specified, go to next step.

2) Remove connector from VAF meter. Using jumper wires, connect VREF and ground terminals on VAF connector to corresponding
terminals on VAF meter. Turn ignition on. Measure voltage between VAF terminal on VAF meter and ground terminal while moving
vane in VAF meter. Voltage should vary smoothly between .5-1.5 volts with door open, and 4.5-5.0 with door closed. If voltage is
correct, repair VAF circuit between ECA and VAF meter. If voltage is not as specified, go to next step.

3. Turn ignition off. Unplug VAF meter connector. Turn ignition on. Measure voltage between VREF and ground wires. If voltage is 4.5-
5.5 volts, replace VAF meter. If voltage is not 4.5-5.5 volts, go to PINPOINT TEST VREF.

[krock26]

Okay, I did the test and found 0.3v with the door open and 3.6 with the door closed. The VREF was exactly 5.0 volts so I guess it is the VAF. My first one was taken out of a car that I got to start and drive around at the junkyard so that surprises me. And my other one was completely dead, so I guess I'll need to get another one.

[krock26]

Update: Got my reman VAF today and no change. Still the same voltages that my last one had and the same symptoms. I checked and double checked all my wiring going to the sensor and it is just fine. Now what?

[krock26]

Does anyone have a pin out diagram for the ecm on a 90 manual?

[krock26]

I replaced the VAF sig (white) and the 12v IAT sig (grn/black) wires because they were both showing unusually high resistance and shorting to ground. Can the VAF and IAT grounds be grounded to the frame or do they have to be grounded to the ecm directly in order to correctly read the resistance? Right now they are grounded even when the ECM is unplugged but idk if that's how it's supposed to be because even with the new wires and new VAF I still have a check engine light for the VAF and IAT.

[krock26]

Nobody has anything?

[F3BZ]

ask (twice) and ye shall recieve.

[WmWatt]

Looks like "S" for sensor, "C" for controller which computer diagrams usually call "actuators". The Haynes manaul has equivalent diagrams for 3 (I think) Festiva models. A pinout diagram usually shows the physical location of the connectors on the chip or assembly. Maybe the circuit board uses the labels shown on the diagrams above?

[krock26]

IMG_0165.jpg What's going on there with the white VAF wire and the ground? Is it spliced to ground or something else?

[F3BZ]

oversight on my end. i musta been bleary @ 3am when i pulled the 90 EVTM. there are additional pages. ad these to the 2 i posted as a continuation.

















here are GROUNDS and actual location of grnds for ecm & vaf

[krock26]

Wow! These diagrams are awesome! Thanks!

[krock26]

I think my shielded VAF wire is f'd in the a since it goes from 4.9 volts one side and .8 volts on the other. And I can't use a normal wire to replace it. Anyone know where to buy shielded wire like that?