So I found this thread that exactly describes the symptoms that I am experiencing.

https://www.rx7club.com/3rd-generati.../#post10449484

One reply in the thread says that the voltage regulator went bad, causing a voltage spike, which fried one of his secondary injectors. When parameters are reached for secondaries to come online, the computer pulls all fuel because it knows one of the secondary injectors is bad.

I am inclined to go this route as I have fixed quite a few other electrical issues with this car, maybe a result of a bad voltage regulator.

Thoughts?!

 

Can you try reposting the link. It's not working (for me...)

 

Not sure why, here is the address. Post 22 raised my eyebrow.

https://www.rx7club.com/3rd-generati...0-rpms-819951/

 

Has the alternator been changed? You could throw a multimeter on it and rev to simulate driving (alternator doesn't care if car is moving) to see if the voltage is spiking.

I am guessing that by frying the injectors it means open circuit in the coil from overload. I did this in my FC once by using the wrong impedance injectors and got terrible break up above 5k rpm.

If you don't want to pull the UIM you could measure by pulling the connector off the ecu and check injector ohms through the wiring harness by wire color using the wiring diagrams.

 

Has not been changed that I am aware of. I plan on doing both the alternator test as well as testing impedance via ECU plug when I get the car back. The owner picked it up to have it inspected recently.

 

Has anyone found the issue. RGORDON is having my exact problem, i think it has to do with my odometre. Whenever its blank it does this. When its present im in boost all day long. I resoldered some capacitors and that temp fixed the odometre before it went out again.

 

Mugen,
Have you been under the UIM lately doing anything? I do not have the car any longer, but I suspect there was an issue with the secondary injectors. Either, one had come unplugged (IAT sensor was unplugged, makes me think the last person in there didn't plug everything up tight), or a voltage spike from a bad alternator/voltage regulator fried a secondary injector. It is strange to me that it happens when your odometer goes out. Maybe the voltage is too high intermittently, and takes out a secondary injector and your odometer?

Let us know what you find out.

 

This car has electrical demons usually because of bad ground points or a bad battery.

Battery may test fine but it could have intermittent hidden issues on the inside when hot or otherwise.

Triple check/replace the battery and both positive and negative wires going to it. Also check the engine ground wires and alt. Make sure all the wires are clean and in good shape. The OEM battery harness if original should probably be replaced unless the car was always garaged and well cared for etc.... and the same goes for the engine harness.

I firmly believe the CPU#2 issues, cluster issues etc... are related to bad electrical current killing the capacitors but those issues can clearly cause all kinds of other problems with fuel pump, injectors etc.....

Even if the car has 100k or less miles both engine and battery harnesses could be nasty.

Good luck

PS Also alarms, big stereos, fancy HLs etc.... should be avoided IMO unless you are very good with electronics.

 

LMFAO you hit the nail on the head with this line. RGORDON, I haven't been under the UIM at all since I got the car. Haven't had the need to. Today i gave my speed cluster a very very mild punch directly where the needle is mounted and poof the odometre comes back on. Like clock work boosting my way cleanly through the RPMS. That limp mode cut out this is such a stupid mechanism. All i use my odometre for is gauging maintenance intervals. smh.....Before attach THIS particular problem to the odometre i was seconds away from tearing my entire vaccum system apart.

 

Something is off here. I had odometer problems (since solved by resoldering EVERYTHING on the board after trying to replace capacitors). My performance was never affeceted by the odometer, the only problem i had was cruise control being disabled.

 

I only resoldered one capacitor, im literally taking both odo and cpu2 apart as im typing to resolder as much as i have replacement components for. Question for you though, are you running any other ecu besides stock??

 

I had a stock ECU and went to Power FC after my odometer fix.

You will also need to re-flow solder with a good flux to try and eliminate any cold solder joints that may be hindering otherwise good components. I had that problem with the ODO display chip, which was NLA. Reflowed the solder and all was good. Now getting to it was another problem.

 

I had no joy in my soldering adventures ...was starting to get to the point where i was doing more damage than good. On the bright side it still turns on every now and again. Doing the same thing religiously. No odo no power. Odo mo power. Except now i just have to drive for a good little bit before it does it. Especially annoying on the high. Poor engine, my rpms love that 2500 marker too. Im going to take a look at all my ground points for the car. Problem is im probably not going to find much even after that. When i first got the car the sensor on the cat grounded out a bunch of electronics in my car while driving... Still haven't replaced it but its tucked away and heavily taped off. Digressing the reason i asked about the ECU is because i heard or read dont remember that the PFC ECU and other prolly don't recognise limp mode so the car never sees it i guess. But if you did it after you fixed your ODO i guess i can't deduce that from this then.

 

Here are some shots. So right now the speedometer goes up to around 60 and sticks there, and the digits on the odometer don't work, but the backlight does as well as everything else in the cluster. The 6.3v capacitor was the one that seemed bad before changing them.

 

wrong thread edited

 

edited, wrong thread.