No error codes even with sensors unplugged - big backfires
 

I've searched but can't find anything specific.

I have just rebuilt and refitted an engine in a 1992 FD with stock ecu etc but I made the turbos non- seq and removed the turbo control and emission gear, leaving the solenoids plugged in so the ecu doesn't go into limp mode.

It backfires badly as soon as vac reaches 0hg but the map sensor and wiring continuity checks out. It revs as high as I want as long as I stay under 0hg.

I can't get any error codes at all, even when I try to induce them. The car is JDM so there is no engine check light, I use a test light to + in the FEN terminal and ground the TEN. When I have checked other FDs in the past the test light comes on right away until the ignition is turned on, the light then goes out for a few seconds before cycling though codes if there are any. I can't get the light to come on at all so I'm thinking it may be a wiring or ecu problem. The test light works.

Has anyone struck this before? This is the 2nd FD I haven't been able to induce codes with.

I need to find codes so I know where to look for the problem it obviously has. I won't have another ecu to try until next week.

All i can say is that your car is in limp mode (thats the exact symptoms that it wont let your boost gauge go into positive, i bet it ildes fine and you will even be able to drive it but only under light throttle but as soon as your try to gas it to much it will kick back and backfire)
Have you tried resetting the ECU, i beleive you have to disconnect the battery and hold the brake pedal for 30 seconds, then retry.

Sounds like you know exactly how to test for ECU codes, stupid question but is the test light working ok (connect it across the battery check it), sorry had to ask

if you ground the ten, and have a multimeter with continuity beep, you can draw continuity between the "self diagnosis checker code number" (1F on the us ecu) and the main relay (1B on the us ecu)

the car hould beep out the code numbers

Yes the test light works and I've tried resetting the ecu several times.

I'm guessing only a bad input sensor would send the ecu into limp mode? Surely the output solenoids etc wouldnt affect it?

How many sensors need to bad to send it into limp mode or will just one do it?

I will try and get codes the way slo described.

i got my eyes on this thread. let me know what you come with...i may try the same to solve my shit... got s series 8 similar problem... under VAC i can rev past 4k but when boost comes and over 4k shit happens... where you located AKL??

I think I've sorted it. After all that mucking around I found that a filament type test light won't flash the error codes but an LED test light or analogue multi-meter will. I guess the filament draws too much current. I broke my LED test light recently and replaced it with a filament one and that explains why I couldn't get error codes from the last car either.

The codes were for the OMP and right away I found it wasn't properly plugged in. Problem solved, no more limp mode and no codes at all. I also calibrated the TPS which made a difference.

So I've found all turbo/emission control actuators/pipes/hoses can be removed and as long as the solenoids themselves are still pluged in the ecu will operate normally. The only 2 I left plumbed up are wastgate control and the one for the carbon canister.
I also found that the output side of the ecu will send it into limp mode as well as the inputs.

S8nana I'm in TGA. Have you checked the error codes?

Finally...
 

Man that is the exact problem i got with mine execpt i have no OMP now. And it sounds like i need to put the solenoids back in or do the resistor trick under the UIM. Let me know how the non-sequential went compared to the sequential.

Ok i have done the error code reading but a get one long flash and the rest of the flashes are short and they don't stop (i lost count of flashes by 50) and these flashes don't translate to an error in the link https://www.rx7club.com/forum/showth...ht=error+codes

Any ideas?:wallbash: