rotarypower86

First Fuel Problem:

The car runs fine for the first 10 min. . .

Then after fully warmed up it does this:
When my car hits about 4k rpm, it cuts about 60% of the power and then from about 5K-7K rpm it cuts about 30% power.

I tested both primary injectors from the ecu(using WAYNE88N/A's method) with a multimeter when the car runs correctly and when it runs bad(most of the time). Both primaries do the same thing. The secondaries run ok. Here are the results.

(Obviously tested under open throttle, and in 3rd gear)
Running Good:
3500rpm-8.2volts
4000-7v
5000-6v*
6000-4.5v* (*est)

Running bad:
3500rpm-8.5volts
4000-11.2
4800-10.2
5000 to 7000rpm-voltage stays above 7.5

The O2 sensor is ok(I have a air/fuel ratio gauge), and the tps seems to be ok(1.1volts at idle, and 4.7v at WOT).

The only thing that I tested that didn't do what the FSM said was the BOOST SENSOR. It's supposed to be 3.5volts with ign switch on and at idle... When my car is running at idle the voltage is 1.4, and more when you accelerate.

Does anyone know what the problem could be? Maybe the boost sensor is making the injectors cut the fuel? Or maybe something else?? Please help me!

Thank you if you can help me,

Charles

rotarypower86

bump^

WAYNE88N/A

The boost sensor is only going to show 3.5v or so if the vac line is disconnected (atmospheric) at idle- did you have it off? It will show a little over 1 volt otherwise, and the 3.5 would be closer to WOT conditions while driving...Your numbers look good, if you didn't take the vac line off (you'll also get about 3.5 with key on, hose on)

Are you SURE your AFR gauge isn't showing anything funny? With those voltages on the injectors between the good/bad readings, you should have very different AFR's, at comparable rpms...

WAYNE88N/A

I would start looking at temp-related sensor inputs at the ECU, like water thermo, water temp switch, AFM intake air temp, and intake air temp...

rotarypower86

OH YES! The AFR gauge cuts all the way off from 3800-4500rpm, then comes back and is closer to the leaner side all the way to redline than it normally is. . .

rotarypower86

Ok I'll try that. I have to get off the internet and will be back on tomorrow or Wednesday. My email is rotarypower86@yahoo.com

WAYNE88N/A

Lol, you're having the same problems I am (running too lean for no apparent reason), but mine are microsecond events, and yours are long enough to actually **** you off...

Don't forget all of the other temp affected things on the car that you can't read from the ECU, like the thermowax (fast idle system) & water thermo valve (secondary throttle plates control)

rotarypower86

bump^/ yes this is so aggervating! ! !

WAYNE88N/A

Why are you bumping, lol...Have you checked out everything suggested?

rotarypower86

just to see if anyone else has anything to add. . .

How do i check those things. . .

I have to go to work now...PM me i'll get back to you tomorrow

WAYNE88N/A

Got FSM? Operational & electrical checks for everything imaginable...

This might help too (This link saves me SO much typing, lol)...

https://www.rx7club.com/2nd-generation-specific-1986-1992-17/troubleshooting-your-car-ecu-340578/

zmanss

I would definately check all previous mentioned items first, but there is a resistor box (rectangular silver thing by the washer fluid tank) that affects the voltage of injectors. I would think that if it were screwed up it would have a constant affect on the operation of your car, but who knows, you may want to check the resistance from each of the leads on that box as well. Just a thought.