Wile E. Toyote

88 22RE
This is a truck that I'm swapping parts into/out of. It is a 88 cab with harness/ECU onto an 87 frame. The motor is out of the 87 and was carbed, but I swapped on the EFI from the 88.

I am beating my head up against a wall. Truck starts strong and runs for 2 seconds and then dies. It throws a Code 12 "No NE RPM signal after 2 seconds".
I have ohmed at the AFM (according to 4Crawler - thanks 4Crawler), and it all seems within tolerance. I have also swapped in a second AFM for good measure and no change.

I swapped in a different coil/igniter pack, no change. I have cleared the ECU codes, the code 12 comes back.

If I disconnect the plug from the igniter back to the ECU, there is no change. Also, if I disconnect the TPS there is again no change. If I try to rev it when/after starting, it seems to try to rev and then dies. The fuel pump is on and pumping (although I haven't checked pressure). If I loosen a fuel line there is a lot of pressure and fuel squirts all over.

I need help.
What does the NE circuit consist of?
Does the RPM signal go from the distributor to the ignitor and then the ECU?
Could a bad TPS cause this issue?

Any suggestions on what to check and how to test it?
I am seriously running out of ideas, and am not a pro mechanic. I don't have a spare ECU to swap in.

Any help would be greatly appreciated. Sorry for the long post, just trying to get as many details as possible.

desconhecido

Do you have the efi distributor installed?

Wile E. Toyote

Yep, I do. Left that out of my description.

bigt

is your afm unplugged or your air intake pipe not on?

Wile E. Toyote

AFM is plugged in, and the air intake pipe is on and tight. The smaller emission pipe to the resonator as well.

abecedarian

The NE signal is 'derived' from the pickup in the distributor and sent to the igniter, which then sends that signal the ECU. Since it starts, the wiring between the distributor and igniter is good, but...
... did you use the 87 igniter or the 88 igniter?
Is there any corrosion or moisture in the plugs to the igniter?

abecedarian

Next question would be:
Did you swap the fuel tank, pump and associated wiring and hoses from the 88 EFI on to the 87 carb'd chassis?

Wile E. Toyote

@abecedarian

I used the ignitor from the 88, but swapped in a different one from an '87 and the results haven't changed. Should I put the 88 one back, is there are difference?

Also, the fuel tank, pump, wires, etc. from the 88 are on. I have the high pressure hard line from the tank to the filter. I can jump the fuel pump (diagnostic plug) and I can hear it run. Also, the soft line feels as though it has plenty of pressure. The plugs from the igniter (both directions) are clean and solid. I'm in phoenix, az by the way (go steelers), so moisture isn't much of a problem.

It seems to me that the breakdown is happening somewhere between the ignitor and the ECU. What I need to know is what needs to be tested and how to test it? What could throw the code from past the igniter in the circuit? Could it be the TPS? What can I do to check the circuit at the ECU?

thanks for the suggestions everyone.

abecedarian

I would use the igniter from the vehicle which donated the ECU and wiring.
I have an 88 4Runner and there were, as far as I've cared to check...
...3 different igniter's and 2 different ECU's, ignition coils, injector types, TPS... used in 88.

The code tells you what the ECU thinks could be wrong: igniter, wiring or the ECU itself.

The TPS won't throw an ignition related code (unless the TPS makes the mixture too rich... but that'd be a different code).

Wile E. Toyote

Is there a way to check the ignitor output, and determine if it is sending the correct signal to the ecu? If I can narrow it down from there, it is either a bad wire or a bad ECU. I think the ECU should be ok, it used to run (on the old truck) and I haven't let the smoke out.

I'm trying to determine a way to trace the breakdown in the system. The igniter and dist seem to be talking, but igniter and ECU seem to not be. From what I've told you does this seem correct?

Very frustrating, I have air, fire and fuel (but only for 2 seconds). It should RUN.

Open the pod bay doors HAL.
I can't do that Dave.

4Crawler

iTrader: (3)

Try the fuel pump test jumper:
- http://www.4crawler.com/4x4/CheapTri...shtml#FuelPump

It'll force the fuel pump to run and if that helps, test the AFM:
- http://www.4crawler.com/4x4/CheapTricks/AFM/index.shtml

And the Factory Service Manual has ECU and ignitor testing information:
- http://www.4crawler.com/4x4/FSM.shtml

Wile E. Toyote

Thanks for the help. I'll try out your suggestions.