fuel injector control???

[Todds93SHO]

SHO's been down for over a week now and I really could use some help. I don't have any codes because the were erased when I disconnected the battery.

CPS is good so I think. (tach moves when trying to start)
New Fuel pump and filter. There is proper pressure at the manifold.
I have verified spark on the #2 cylinder.
I have verified that the timing marks line up on the crank and cams.
New O2 sensors.

My question is...
What controls the fuel injectors? Can I check this externally or do I have to remove the intake manifold to do so.

I can get the car to fire on starting fluid so it leads me to believe its the fuel at the very end of the manifold. I have posted previously with this problem and I'm up to this point, need some help.

Thanks,
Todd

 

[sdpatt]

The electronic engine control (EEC) is entirely responsible for the timing and duration of opening of the fuel injectors.

 

[projectSHO89]

I recall a few months back someone here had the exact same symtom. Turns out the time belt was installed using the wrong index mark. His problem started after maintenance service though.

Steve

 

[pjtoledo]

Todds93SHO:
SHO's been down for over a week now and I really could use some help. I don't have any codes because the were erased when I disconnected the battery.

CPS is good so I think. (tach moves when trying to start)
New Fuel pump and filter. There is proper pressure at the manifold.
I have verified spark on the #2 cylinder.
I have verified that the timing marks line up on the crank and cams.
New O2 sensors.

My question is...
What controls the fuel injectors? Can I check this externally or do I have to remove the intake manifold to do so.

I can get the car to fire on starting fluid so it leads me to believe its the fuel at the very end of the manifold. I have posted previously with this problem and I'm up to this point, need some help.

Thanks,
Todd

Verified spark on #2 ???? Why did you check the middle cylinder in the back? When you say there is pressure in the manifold, how much? The SHO needs at least 18-20 to run at all, but a meer 15 pounds of pressure will spray fuel all over the place if you push the schrader valve down. The PCM fires the injectors. You can use a "poor mans stethoscope" by placing a long screwdriver against an injector, and your ear. Should be able to hear the tick sound as it fires. If you use an electrical test meter, the injectors should always show voltage, one wire (red?)is a constant 12v, the other will have short pulses to near 0v. You may not be able to see them with a meter, I have used an Ocilloscope to view the pulses. By the way, PCM and EEC are both the computer, different years call it one or the other.

Perry Toledo,Ohio

<small>[ August 20, 2002, 09:40 PM: Message edited by: pjtoledo ]</small>

 

[Todds93SHO]

While at AutoZone tonight trying to exchange the fuel pressure gage I purchased which was junk (the part that presses the needle inside the valve was bent so wouldn't work) I saw that they had these things you can plug in place of an injector to see if it is getting the right signal, I guess it has a light that comes on when the injector is suppossed to pulse. They all seem to be for GM injectors.
Does anybody know if one of these will work with our injectors?
Also, AZ didn't have another fuel pressure gage in stock so I'll be looking elsewhere tomorrow.

No way to check the EEC or PCM I'm guessing? I'd have to see what model I have ('93 ATX) from the part itself on the firewall and go from there. Try and find one from the Junk Yard.

If I brought it to a mechanic could they plug into their computer and test the EEC?

I have a feeling it's going to the shop but the mechanic is pretty backed up at the moment so I should have some time to look into things.

Thanks,
Todd

 

[Todds93SHO]

When I said I checked spark on the #2 I did so on the front plug furthest to the left facing the engine from the front of the car. I thought that was #2, but whatever one that is, that's the one I verified spark at.

I also pulled that plug just after trying to start the car and the plug was dry, not that means anything, just thought I'd throw it up here for good measure.

 

[luigisho]

Todd just a FYI on the pcm. You can use any SHO pcm that comes from an ATX car. So exact model # isn't critical.

 

[sdpatt]

Todd, for future reference, the cylinder order on the SHO V6 is as follows.

Engine
Firewall
1-2-3
-------
4-5-6
Radiator

Coil Pack
Firewall
5 | 1
6 | 2
4 | 3
Radiator

You wouldn't be able to unplug a fuel injector's local connector without taking off the intake manifold. That is probably more effort than needed to figure this problem out.

Was anything done to the car's electrical system that could have fried the PCM? Battery hooked up backwards? New stereo installed?

Scott

 

[Todds93SHO]

Thanks for the Diagram sdpatt, that made it alot more clear. I checked spark at the #4 cylinder.

I haven't done anything to the car before it died. It was running great the past few months then 2 weeks ago, right after filling the tank with gas it lost a whole bunch of power one day and eventually died, hasn't started since. I emptied the "suspect" fuel but it looked fine, put it into the lawnmower and Jeep and they are alright so I'm thinking it may have been a coincidence or something got in there and bypassed the old fuel filter, but how could it **** all 6 injectors?

Nothing electrical has been touched except replacing the fuel pump and both 02 sensors after it died.

I'm going to attempt to pull the manifold off tonight and check the injectors for pulse. I have the procedure for removing the manifold for the 60k so i'll follow that and try just removing the front side of the manifold.

 

[pjtoledo]

Todds93SHO:
Thanks for the Diagram sdpatt, that made it alot more clear. I checked spark at the #4 cylinder.

I haven't done anything to the car before it died. It was running great the past few months then 2 weeks ago, right after filling the tank with gas it lost a whole bunch of power one day and eventually died, hasn't started since. I emptied the "suspect" fuel but it looked fine, put it into the lawnmower and Jeep and they are alright so I'm thinking it may have been a coincidence or something got in there and bypassed the old fuel filter, but how could it **** all 6 injectors?

Nothing electrical has been touched except replacing the fuel pump and both 02 sensors after it died.

I'm going to attempt to pull the manifold off tonight and check the injectors for pulse. I have the procedure for removing the manifold for the 60k so i'll follow that and try just removing the front side of the manifold.

Most of us pull the entire manifold. I would first find out exactly how much fuel pressure you have. Power is supplied to all 6 injectors via a common red wire. The computer fires each one individually, that means all 6 circuits would have to fry at the same time to completely **** the engine. Try pulling the connector off the idle air control valve, that red wire gets its power from the same splice that feeds the injectors. You should see approx 12 volts on that red wire. If its dead, so are the injectors. The CCRM outputs 12v on pin 24 that goes to splice # S157,,,thats the power on the red wire. So start on pin 24, red wire on the CCRM, thats where the power for the fuel injectors comes from. Sorry about rambling on, I'm reading the EVTM manual for a 95 as I type this.

Perry Toledo,Ohio

 

[Todds93SHO]

Thanks Perry,
Unfortunately I didn't get a chance to tear into this tonight, too busy, too tired. What you said about the constant 12V source makes sense, that will help alot when I trouble shoot this Thursday night.

I'm pretty sure that Chilton's I've got has a wiring diagram in it, I'll go by what you said but see if I can follow it in the diagram as I go about testing stuff.

Thanks,
Todd

 

[Todds93SHO]

I checked the power to the injectors.
Red wire has steady voltage, 11.55V probably should be more but I've tried starting the car so many times w/o luck that I should charge the battery.
I probed one of the non-red injector wires and it had the same constant voltage as the red with the engine not running.
I tried cranking the engine over to see if I could see pulsing on the second wire but all i could see is the voltage drop to about 7.5-8V and flutter around there. I'm guessing that's just from a voltage drop while running the starter, but maybe it was the digital multimeter trying to stay at 11.55 and dropping with a pulse but having a slow reaction.

So I still don't know if the injectors are w/o a pulse or the injectors are all clogged.

Unfortunately I don't have the time to rip the intake off so I guess I'm going to have to call a mechanic tomorrow. THis is going to **** me, I don't trust anybody with my car.

 

[Todds93SHO]

Screw it, I'm not giving up yet. It's only been 2 weeks.

 

[BeatDaSHO]

check for plugged cats. u said that ur car was running really poorly for 2 weeks so that could have been the cause of it. and now they are totally clogged so it can't start. try inspecting the cats.

Greg

 

[luigisho]

Todd anyone nearby to swap pcm's with? It beats buying one if it isn't needed and would eliminate another possibility.

 

[stevetatro]

Todd,

You want me to send you my spare PCM from my '93 ATX? It's a H3Z1 (have a D4U1 installed now).

Let me know. Just PayPal me a couple of $$$ for shipping.

 

[Todds93SHO]

Thanks guys...
I did some checking last night and there was a ECU for sale on Ebay from a local guy. I'm looking into that or possibly another one.
I hope to tear the manifold off tonight and do some more investigating though.

I haven't looked into plugged cats yet, I'll check that too, but it only ran bad for a day and a half before it died. I"m pretty sure it's a fuel problem.