86 mpfi, can't read codes

[WoodsWagon]

With either the green test mode connectors or the white ground connectors plugged together, it won't flash the LED in the ECU.

 

It's a 86 turbo wagon, and sometimes it runs good, then it switches into a wierd default mode, where it cycles the injectors at a preset interval. You can slowly rev the motor up in neutral, but it's limited by what the injectors are putting in, so it leans out as you rev it up. There's not enough fuel being injected to move the car though. If you stall the engine, it keeps cycling the injectors as long as the key is on, so it will drown the engine in fuel if you let it.

 

The diagnostic connectors are under the dash next to the computer. There's the usual green non-locking connectors, and when I plug those in and turn the key on, it does the normal fuel pump cycling, unplug and it stops pulsing the pump. In the same bundle, there's a pair of 2 pin white locking connectors, with black wires coming out each side. There's also a pair of 9 pin square connectors, probably for some diagnostic equipment to plug in.

 

When I plug the white 2 pin connectors together, nothing happens. When they and the green connectors are together, it does the cycling of the pump. No combonation of connectors or key cycling will get the led in the ECU to flash.

 

Either I'm doing something wrong, or the ECU is screwed I'm thinking.

 

Sometimes it runs great. I just want to beat the bag out of it before I EJ swap it.

Edited April 6, 2010 by WoodsWagon

[rxleone]

With either the green test mode connectors or the white ground connectors plugged together, it won't flash the LED in the ECU.

 

It's a 86 turbo wagon, and sometimes it runs good, then it switches into a wierd default mode, where it cycles the injectors at a preset interval. You can slowly rev the motor up in neutral, but it's limited by what the injectors are putting in, so it leans out as you rev it up. There's not enough fuel being injected to move the car though. If you stall the engine, it keeps cycling the injectors as long as the key is on, so it will drown the engine in fuel if you let it.

 

The diagnostic connectors are under the dash next to the computer. There's the usual green non-locking connectors, and when I plug those in and turn the key on, it does the normal fuel pump cycling, unplug and it stops pulsing the pump. In the same bundle, there's a pair of 2 pin white locking connectors, with black wires coming out each side. There's also a pair of 4 pin square connectors, probably for some diagnostic equipment to plug in.

 

When I plug the white 2 pin connectors together, nothing happens. When they and the green connectors are together, it does the cycling of the pump. No combonation of connectors or key cycling will get the led in the ECU to flash.

 

Either I'm doing something wrong, or the ECU is screwed I'm thinking.

 

Sometimes it runs great. I just want to beat the bag out of it before I EJ swap it.

 

TBH I can't help you with the ECU, because all the EA82s I've owned were either carbed or I couldn't be fucked fixing them and sold them. But have you checked to make sure there is a bulb in the CEL holder? My sisters fiance found when he had some problems with his twin-turbo legacy that someone had just taken the CEL bulb out when things started going wrong, reset the ECU, and sold it. Could it have happened to you? Seems silly but I've had stupider things hold me back for days.

[MilesFox]

the green plugs are for setting the disty timing. leave them unplugged for the moment. the white connectors are for clearing the codes. leave both sets unplugged and run the car. the led should be functioning then.

[WoodsWagon]

I had it running today, the ECS light is on KOEO, goes out when you start the car, and comes back on 2-3 seconds after starting. This is with both plugs unplugged.

 

There is no activity on the LED while the ECS light is on and the engine is running.

 

There is one other possibly important tidbit, it's an automatic car, that I swapped a pushbutton tranny into. I left the auto shifter plugged in, so I can start it in park and neutral, turn the reverse lights on, and suchnot. I have the spedo cable plugged into the tranny, but nothing else.

 

What would prevent the LED from flashing? But still let the engine run OK sometimes, and go into a default cycle others?

[ruparts]

With either the green test mode connectors or the white ground connectors plugged together, it won't flash the LED in the ECU.

 

It's a 86 turbo wagon, and sometimes it runs good, then it switches into a wierd default mode, where it cycles the injectors at a preset interval. You can slowly rev the motor up in neutral, but it's limited by what the injectors are putting in, so it leans out as you rev it up. There's not enough fuel being injected to move the car though. If you stall the engine, it keeps cycling the injectors as long as the key is on, so it will drown the engine in fuel if you let it.

 

The diagnostic connectors are under the dash next to the computer. There's the usual green non-locking connectors, and when I plug those in and turn the key on, it does the normal fuel pump cycling, unplug and it stops pulsing the pump. In the same bundle, there's a pair of 2 pin white locking connectors, with black wires coming out each side. There's also a pair of 4 pin square connectors, probably for some diagnostic equipment to plug in.

 

When I plug the white 2 pin connectors together, nothing happens. When they and the green connectors are together, it does the cycling of the pump. No combonation of connectors or key cycling will get the led in the ECU to flash.

 

Either I'm doing something wrong, or the ECU is screwed I'm thinking.

 

Sometimes it runs great. I just want to beat the bag out of it before I EJ swap it.

 

Hi,

i was thinking the plugs to check the codes were black, and located right by the green ones, they are black my 87 for sure. idk if they changed later but look for a black pair.

[WoodsWagon]

So after driving it around a bit yesterday, the ECS light went out, but there is still no activity on the LED. I'm used to the SPFI computer spitting codes out easily, so I'm concerned there's a fault inside the ECU.

 

It runs good, you can spin a wheel though all of first and second accelerating on dirt, and when it builds boost it hits hard.

 

As a side note, it's unwise to drive a car with no hoodlatch aggresively. I had meant to get hoodpins, because I have an intercooler installed where the hoodlatch used to be. Oh well, the windshield was already broken and was only sitting in the body because I have to repair the rusted cowl where the windshield seals to it, and I had a spare hood. The hood folded up like a wet rag.

[soultron]

I'm not sure what I'm doing wrong either. I have the right wires disconnected ( I think), but my light just blinks at a set interval. I'm getting a CEL when it's running...

[Gloyale]

Green connectors are for "test"

 

BLACK connectors are for "read"

 

Both plugged in at the same time is Clear.

 

 

You should check all the fuses first. But then if the LED in the ECU doesn't light you have a bad ECU.

[WoodsWagon]

No black connectors on the harness anywhere near the ECU.

 

So it's gone into it's default cycle. It clicks the injectors while the key is on, and will not turn on the fuel pump relay. If you plug the green test connectors together, it slows the rate of injector clicking, but does nothing else. All fuses and fusable links are in good shape. ECU appears clean inside, no corrosion or burnt spots. Unplugging the MAF doesn't change it's behavior.

 

It will run. The residual pressure in the lines is drained into the inake by the cycling injectors. You crank the engine, it fires up, Idles around 1400, and the vacuum in the intake will suck the fuel through the injectors from the tank with the pump OFF. You can slowly rev it up over 3k before the vacuum drops enough that the volume of fuel drops off. Runs rich as hell, but I think it's hilarious that it will run with "fuel induction" rather than fuel injection. Except for the fact you can't drive the car because of it, that's not so funny. Pretty damn annoying actually.

 

Nothing seems to bring the computer back to life, wiggling connectors, unplugging stuff, removing the ECU from the car and beating it soundly, nothing helps. If I leave the car sitting for a month it will fire right up and work for a few days, then do the same thing again.

[ruparts]

No black connectors on the harness anywhere near the ECU.

 

So it's gone into it's default cycle. It clicks the injectors while the key is on, and will not turn on the fuel pump relay. If you plug the green test connectors together, it slows the rate of injector clicking, but does nothing else. All fuses and fusable links are in good shape. ECU appears clean inside, no corrosion or burnt spots. Unplugging the MAF doesn't change it's behavior.

 

It will run. The residual pressure in the lines is drained into the inake by the cycling injectors. You crank the engine, it fires up, Idles around 1400, and the vacuum in the intake will suck the fuel through the injectors from the tank with the pump OFF. You can slowly rev it up over 3k before the vacuum drops enough that the volume of fuel drops off. Runs rich as hell, but I think it's hilarious that it will run with "fuel induction" rather than fuel injection. Except for the fact you can't drive the car because of it, that's not so funny. Pretty damn annoying actually.

 

Nothing seems to bring the computer back to life, wiggling connectors, unplugging stuff, removing the ECU from the car and beating it soundly, nothing helps. If I leave the car sitting for a month it will fire right up and work for a few days, then do the same thing again.

 

Hi,

that last comment might indicate your fuel tank might have a lot of rust or some other contaminents that are partially clogging the fuel screen, and it settles while sitting for a while, but stirs up again as you use it again. i did have that problem on an xt i had, it would run down the road for a few blocks then die, restart and go a ways, then die again, idle was ok , but no speed over about 40 could be reached. my tank was full of crud in the bottom. there is a access plate for the fuel guage sender over the top of the tank, its easy to lift out the sender to look inside the tank with a flashlight to check.

i sort of don't think the fuel is being pulled through the fi system as you described, i do think if it will start and run at all the fuel pump is working, these are quiet pumps.

Edited April 16, 2010 by ruparts
mistake

[WoodsWagon]

No, the pump is definiately not on. If you ground the pin on the fuel pump relay that the computer uses to turn on the relay, the relay closes and the pump kicks on. It's not a quiet pump, I used a F-150 framerail pump and it's held to the body with zipty's.

 

Any one got a spare 85-86 MPFI turbo ECU I can borrow? They're kind of non-existant in the rusty northeast.