Mtwise

88 iroc 305 tpi 5 speed

All started a month ago. Car wouldnt start. Fuel in the oil case. Drained everything out. Replaced the fuel psi regulator and all injectors.
Now when i turn key to on psi in rail builds up properly. Pump shuts off and i hear a spraying sound. Disconnect all wires to right side injectors and then pump build pressure but no spray sound. Does not matter which injector you plug in it will spray. Power to on pushing the clip on and off so it makes contact you hear the injector click open and close. Left side injectors still connected no problem no spray sound no clicking. Checked voltage 12v reaching all injectors.
Both leads of the pins will show zero ohms with one pin on car ground and will also show zero ohms with one pin on positive cable ( batt disconnected ) also with batt connected i get 12 v on either pin with other voltmeter lead to ground.

vetteoz

iTrader: (13)

I suspect that bank injector driver in the ECM is faulty.
Do the same pressure / power up test with the ECM disconnected,
if that bank doesn't pulse then you know the problem is internal to the ECM

Mtwise

Vetteoz

After talking with some mechanic buddies, thats what we came up with trying. Cant get to it till wed.

eseibel67

Internal ECM problem is a possibility. If the spray continues after the ECM is disconnected, then the black/green wire inbetween D16 at the ECM and the injector harnesses is shorted to ground somewhere.

vetteoz

iTrader: (13)

He already stated he has checked for and found no ground path on the injector control wires

RBob

iTrader: (1)

The odd thing is, is that the stock '7165 ECM only has one injector driver. It exits the ECM on two pins: D15 & D16.

So unless the left side injector fuse is blown, something else is going on. Such as possibly the terminal for the right bank pulled out of the ECM connector and is grounding on the chassis.

RBob.

Tuned Performance

iTrader: (92)

Sounds like a rip in the fpr diaphragm or stuck open injector not a wiring or ecm issue. I don't see how that could happen.

Mtwise

so here is where it stands now. ECM pulled off, no spraying sound, but also the pump did not pressurize. However no clicking sound when clipping the injector wire on and off the injector. Plug ecm back in and got the clicking of the injector.

Rbob, The ECM was a reman unit 7-7165. my buddies info showed all fire at once. Batch fire I looked up showed left and right bank. Not sure which is right, but I was getting voltage to both sides, so if the left fuse blew I would think I wouldnt get any reading off those wires? ( this is my assumption)

Tuned Performance, I just replaced the the FPR diaphragm and all the injectors, plus no matter which injector I had the wires connected it would fire, which what would the chance be that 4 out of 8 new injectors were bad and all on the same side.

Orielys has a Cardon reman that I will pick up tmmrw. Hopefully I plug in the new ECM, turn the key to on, hear the fuel pump pressurize the system for a second and then all is quiet.

vetteoz

iTrader: (13)

http://forums.corvetteforum.com/c4-t...-debunked.html

http://forums.corvetteforum.com/1568748397-post19.html

vetteoz

iTrader: (13)

Agree
but it doesn't make sense.
His testing has established a fault internal to the ECM but if it was a ground fault on one bank ;
because D15 and D16 circuits are joined to the driver it should be affecting the other bank also?

Mtwise

okay so here is where I am t today.

New ECM, did not come with eprom so took old one out and placed in new ecm, Same issue. If ecm plugged in spraying/clicking sound is there. ECM not plugged in no clicking sound.

More probing...
Lets say wires 1357 are on drivers side 2468 on pax side.
ECM unplugged - all wires unplugged from injectors - ohm meter one connected to car negative.

solid wire on all shows continuity stripped wire shows none.
If I plug any wire onto an injector ( except wire 1-explain shortly) the other 3 on that side show continuity on both wires.
Plug any injector on other side in and solid continuity stripped none

ECM plugged in - battery disconnected
Same as above except plug on opposite side will have the effect of showing conitnuity on both wires for all plugs.

now for plug 1.
solid shows continuity, stripped shows none. Plug in any plug and it shows continuity on both wires. However if #1 is the wire that is plugged in then the other wires on that side show solid continuity, stripped none. This is the same if I clip #1 to either injector 1 or 3

I am lost. Someone please point me in the right direction.

thnx

Mtwise

one question. Does the engine have to be cranking for the open signal (ground off ecm) be sent or is it possible that where the engine is currently sitting in its rotation, that is is where the injector should be firing. I have not turned the engine over at all because to remove the fuel rail I have the alternator and some other wires like the ac and maf sensors etc off.

Tuned Performance

iTrader: (92)

The ecm needs to see DRP of 400rpm or higher to enable injector pulse.

Tuned Performance

iTrader: (92)

The injectors are wired in parallel, I don't understand your question.

Mtwise

i may not have worded the question properly, but I think you answered it. Basically the engine has to be cranking for the ecm to send the signal to pulse the injector. My question was could it be possible that the engine was sitting where the injectors were supposed to fire in reference to TDC.

Based on your answer that is not possible.

Mtwise

so the question being, why do the injectors spray when key turned on with ECM plugged in, but not when ECM not plugged in. ECM replaced but eprom from previous ecm installed.

Tuned Performance

iTrader: (92)

Idk, bad icm

darbysan

FWIW, with the ECM receiving power, both banks will show 12v on one wire ( assuming both fuses are good). The ECM Fires each bank by grounding the other wire. If the injectors are staying open, then there has to be a short to ground, either in the ECM or in the wiring. Since you replaced the ECM with the same result, I would look for a short in the harness between the injectors and the ECM. Check around the headers ( that's where mine got melted and shorted!).

vetteoz

iTrader: (13)

The injectors are powered directly off the Ign , they will have power to them even if the ECM is not in the car

In post # 1 he states he has tested and has no ground fault on the injector to ECM wiring.
In post # 8 he states problem only occurs with the ECM connected

darbysan

You are correct on the injectors having 12v power from the ignition. My Bad.

He would only have power to the Fuel Pump with the ECM connected ( if he is not using the ALDL Fuel Pump trigger, which I don't think he was based upon inputs in other posts), so would only have the fuel leakage problem with the ECM connected allowing the pump to work. I agree that he stated he didn't have a ground fault, but I can't think of anything else that would cause this problem, unless he got 2 ECM's that are both faulty in the same manner.

I'll back out and let the experts provide the solution.

Mtwise

Just a quick question as I am unfamiliar with what is what in the ECM, there wouldnt be anything in the eprom from the old car commanding the grounding of the injector would there be?

Mtwise

well this morning testing some more I now lost power to the right bank. So I am looking for the inline fuse but have had zero luck finding it. Is it a fuse like the fuel pump fuse? or is it the old glass cylinder type. Also any idea where it might be. I have a bunch of connectors in around the battery but looking in each one no fuse.

Mtwise

A quick electronics question. I I have the negative cable off the battery, have the negative lead on the ohm meter connected to the negative cable so its grounding to the car and I touch the posotive side of the injector lead ( the side that shows the 12V when powered) and all injector wires off --- should that show continuity? I would think it shouldnt, but as of now my mind is a jumble trying to figure this out.
FYI it does.

RBob

iTrader: (1)

Injector fuses are in the fuse block, under the dash, left side: INJ1 & INJ2

RBob.

Mtwise

Okay, fuse was blown but possibly found the issue. Previous owner had the wire to the cig lighter jumpered off the #2 injector fuse. When disconnected the wire, and changed the fuse. No clicking. Now that wire runs by the steering wheel which i had apart just prior to this whole mess starting. Dont have time to throw it all together today, but hopeful that was the issue

Mtwise

Back together and running. Have to get a new maf for it.
I do have a question. When putting everything back together i found what looks like an extra fuel injecto wire clip on the lax side that winds up being in the area of the idle air control sensor and the throttle position sensor. Anyone have any ideas of what it is or used for? Do not remember taking it off anything and it looks dirty like it hasnt been connected in some time.

Twin_Turbo

iTrader: (25)

Cold start injector temp switch

Mtwise

Thnx. I found a pic of where it should connect. Ill look for it tmmrw

Mtwise

okay the images I saw showed the cold start temp sensor up front next to the water temp sensor. but I have nothing up there. Anyone have any other ideas where to look to see if I have a sensor? I have the wire- just looking where to plug it in