Finished!! Forged piston block, Custom valve head (flowbenched)

[Ondonti]

How do I try to deal with this injector grounding problem?

[Una]

Each injector gets power feed from the ASD, they all share this power feed. The computer, depending on the year, will fire them in banks/batches, or one at a time by suppying the ground. If you have a SBEC car, they're fired independantly, if it's SMEC, then they are fired in groups.. Not sure if the V6 fires groups of 2 or 3.. Either way, if it's SMEC, one of those splices where multiple injector ground leads are joined may have lost it's factory issued electrical tape. If that happend all that has to happen is to have the open splice touch or rub up against ground and that injector is not only going full tilt, but because they're low impedance, you're also running a very real risk of burning out the injector.
Another thing that could have happend is the harness leading to the injectors or even under the intake could have gotten pinched.. Like something got bolted onto the engine with the harness in between that thing and the block or other metal surface. Pinch hard enough and you run through the plastic sheething and boom, grounded lead holding the injector on..
Unplug all of your injectors. Pull the plug off the computer (14pin on the SMEC) and check with a digital meter on ohms to see if you have ground on any of the injector wires.
I do this sort of electrical troubleshooting for a living..

[Ondonti]

It is Sbec sequencial.


The actual harness is very open to the air and there are no "pinches" There might be some wire damage somewhere.

I Dont have an ohmmeter though
The electronics are absolutly killing me killing me.

If you know about the sequencial sbec could you specifically explain this problem in those terms?

I believe I can follow the wires back to the ECU pretty easy since there isnt anything covering the wires.
BTW, thanks you guys for the ideas. Im all out.

[Una]

Ok.. Simple question first.. Is it possible the SBEC is bad/has gone bad? Do you have another to swap in? Having a meter is sooo important towards solving your problem..
Anyways, yes, I just converted my '88 Horizon turbo from SMEC to SBEC.. Did it on my lunch break.. heh.. I had to build my own injector harness and run 4 wires from the injectors back to the computer.. Pretty much like I said, you have one power wire going to all 6 injectors, this comes from the ASD. Then one wire from each injector runs back to the computer, the computer provides ground down each wire when it wants that injector to fire. The longer the computer leaves this ground signal on, the more fuel the engine gets.. Are all 6 of your plugs getting soaked with gas? Or just a specific few? That will help you figure out what wires to trace back..
A meter would also be able to help you troubleshoot the map signal.. If the map were not getting a good ground, or were just bad, the computer could think your at 14+psi of boost while cranking! Hell, leave the map unplugged while your troubleshooting this, and the computer will just default to fail safes for the time being.
Same deal with the TPS.. If it's not getting a ground, or not getting a good ground, the computer could think you're at WOT, and not give you any gas at all (flood clearing mode..). A meter is PRICELESS in troubleshooting this stuff.

Quote:

Originally Posted by Ondonti It is Sbec sequencial. The actual harness is very open to the air and there are no "pinches" There might be some wire damage somewhere. I Dont have an ohmmeter though The electronics are absolutly killing me killing me. If you know about the sequencial sbec could you specifically explain this problem in those terms? I believe I can follow the wires back to the ECU pretty easy since there isnt anything covering the wires. BTW, thanks you guys for the ideas. Im all out.

[Ondonti]

I have 2 sbecs..one auto one manual, both work on my spirit.

Last time I had the front 3 plugs (# 2, 4, 6) wet. plugs 1 3 5 were black.

I will try the MAP and TPS unplugging.

[Ondonti]

For kicks I swapped the engine harnesses and nothing was wrong with the harness that was on the duster.

[Una]

Ok.. Did you try the map trick?

[NA2ndgen]

I am really learning a lot form this thread. For one thing the MAP and TPS trick is really helpful. It never occurred to me that the computer would default to optimal settings like that. Of course it would though. Good to know. I also love Una's tutorial on socketing the SBEC/SMEC. I just wish I knew what to do with it after I did it.

Good luck Ondonti. Fortunately you have lots of great help.

[Una]

Yeah, working on that tutorial next.. It turns out to be much more involved and is taking me forever to produce. It'll get done tho..

[NA2ndgen]

How we all long for the day.


[on edit]

Seriously?! Are you really?!

I can hardly wait!

Please pleeeeeaase burn a chip for us NA folks too.

thankyouthankyouthankyouthankyou

You ROCK Una.

[Ondonti]

Haven't tried the TPS trick yet. I didnt want to make a lot of noise today. duster has no exhaust.

[Ondonti]

I am going up to Salt lake city tomorrow and grab all the wiring harnesses from a v6 duster tomorrow..

I am getting very pissed off at this car. The stress of failure is killing me.

[c2xejk]

Quote:

Originally Posted by NA2ndgen I am really learning a lot form this thread. For one thing the MAP and TPS trick is really helpful. It never occurred to me that the computer would default to optimal settings like that. Of course it would though. Good to know.

The computer does not default to "optimal" settings. It defaults to "safe" settings. It can't see the MAP, so it sets fueling rediculously rich to avoid damaging the engine...

As for not having an Digital Multi-Meter (aka DMM), go BUY one!!! They start at $10. No excuse to not have one. Especially if you are thinking of spending a bunch of $$$ getting another harness... Random parts swapping is an expensive way to debug a problem. You need to understand what is going on.

I think Brent (correct me if I am wrong) was planning on using injectors that were 2x the size of stock! If so, I would go back to stock or close to stock...

I agree with getting the setup as close to stock as possible (baseline) then introducing new components....

[NA2ndgen]

Quote:

Originally Posted by c2xejk The computer does not default to "optimal" settings. It defaults to "safe" settings. It can't see the MAP, so it sets fueling rediculously rich to avoid damaging the engine...

Poor choice of words on my part. I meant default setting. I shouldn't post late at night when I am tired.

btw

What do you think of article about "high velocity intake porting" LINK.

[Una]

It does set fueling a bit rich without a map, but it's better than it would be running if the map were hooked up and telling the computer that you were at 14psi (or I guess 0psi/no vacuum on an N/A motor).. It'll be close enough to fire up and run..