Pulled a blown motor out a few months ago. PFC worked during this time.

Installed new motor and now the PFC won't see RPM signal so it won't fire the injectors or spark.

I borrowed a second PFC to see if my pfc was toast. It does same exact thing. Zero RPM signal when cranking.

Then installed stock ECU and it fires spark immediately.


I have ohm checked the cas wires and even swapped out both CAS sensors. Crank trigger wheel is about 1.6mm clearance from sensors.

I checked voltages on the CAS sensors at the ecu and that is the weird part.
Stock ECU = .2 to .1v on 4g/h
Both PFC's read .9v on 4G/H.

Looking at the FSM it says ign on it should see under 1v.

Any idea why it's not showing RPM,thus crank signal?

Does Pin 2B have anything to do with triggering spark? or does that only drive the tach?

 

Check all the grounds for the wiring where the ECU is, and engine grounds.
The PFC seems to be bothered more by poor or missing grounds.

Since it worked and now doesn't means you missed something.

 

I'll check tonight. There were four grounds I was aware of.

One near LIM that I connected to tranny housing. Which then connects to firewall.
Then one near coil packs which I connected to rear housing under the coil pack mount.

Then one at the ECU connected to passenger firewall
Then main starter ground connected to rear iron and then drivers fender.

 

Added a ground from water pump connecting to Rear housing/coil pack ground connecting to firewall.

I even grounded the ECU chassis in case that was an issue.

No luck. Still zero rpm signal.

The weird thing to me is the voltage readings from pins 4E/G/H/
They are showing .9v

The stock ecu shows almost no volts with key on from those pins.

 

I hate to do this, but I'm going to pull the damned EFI harness out.

It's a stripped down single turbo harness. It'll suck but I might strip of all the new wrap and pull the cas wires out and make sure they're shielded..

 

Pulled harness and checked the ground sheathing and resistance. No problem with the wires. No cross contamination.

Put it all back in car and tried it again. No CAS signal.
tested pins and here's what I get. with sensors plugged in.
4E - .9V
4G - .9v
4H -.9v

Unplugged the sensors I get
4E - 4v
4G -.9v
4H -4v

Removed PFC and installed stock ECU. Instantly get spark.
Sensors unplugged
4E -.1v -null
4G -.1v null
4H -.1v null

Plugged in I can get small bounces from .1-.8v on them. I assume from triggering the hall sensors with the probe.

Totally stumped here.
WHY is the PFC sending 4v? when the stock ecu sends nothing?

 

My next step will be shimming the sensors forward to close the gap on the trigger wheel.
The gap was about 1.6mm.

If this doesn't work then I may make new CAS signal wires. Which means I have to find the connectors for the CAS sensors. Any one know what they are? Bosch? Deutsch?
Then I'll get some Shielded Tefzel for the wire.
Pin size for the ECU side?

 

ISSUE RESOLVED!

It was the trigger wheel gap! I used two washers to push the sensors out. They are now 1.1mm away from the wheel and it fired up! Woohoo!

 

Is your harness the original or a newer one?

 

Original harness that I single turbo converted and removed all the excess wires(egr, turbo solenoids,OMP,etc).

 

There is your real problem! The original engine harness was ****!
To rebuild an engine and use the original harness is pure foolishness.

It took us a few engine rebuilds back in the late 1990s and early 2000s to realize how crappy the original harnesses were. Since then, if you do not get a new harness, we will not rebuild.
Some shops do not care, it is only money to them. If it causes problems, then redoing the work means more money for them.

At age 7 years, my engine harness was crap. Hard and cracked insulation all over, and poor connections. Replace it in 1999 with the newer materials one. It is now 14 years old and looks and feels like new. Still better than the original at 7.

Don't you people check out the complete package when rebuilding? NO!

 

^Sounds like you prefer to replace components with out checking them.
My issue was the trigger wheel to sensor clearance which has nothing to with the harness.
So buying a new harness would have been a waste of money.

I went over the entire harness and ohm tested all connections. The harness had a brittle exterior but the wires are fine.

I've rebuilt plenty of FC harnesses as well. I'm not a harness newb.

 

That is like not changing engine oil because it still is working.