'94 Camaro 3.4L Cranks but No Start

I got it all back together last night. Believe it or not, I'm really having fun with this. However, it would really be frustrating if this was my primary car.

I'll (hopefully) refill the oil and anti-freeze this afternoon and will post back with the results. I'll check the ECM resistance while filling the oil.

The SES not flashing is really bugging me. I checked online and found new ECM's for around $100 (not-programmed). What am I looking at for programming. I haven't checked online or locally yet. If I remove the ECM, can I take it somewhere locally and have a diag ran? Also, the battery is disconnected right now so the ECM should reset when I hook the battery back up. I've checked every fuse, that I know of, and none are blown.

What is the best way to check the TPS voltage without destroying the integrity of the wires (I'm thinking some sewing pins).

I plan to re-read this whole post this afternoon also to see if I missed anything you folks have said.

Thanks again, I'll post back in a few hours and let you know about the outcome.
Brad

The connector for the TPS can be back probed if you use paper clips to extend the probes. Just remember, what ever route you take to measure, don't let the two leads touch each other. Check the attachment of the TPS sensor, if there are slotted holes, then its adjustable, loosen the screws and rotate. If it is not, you may have to bend the tab. The ECM will tell you if the TPS voltage is set too high or low.

ECM in the diagnostic mode should flash out code 12, if it is an OBD I.

The ECM without the prom is called a controller, the protector for the prom. On later models, starting with 1990(?), the prom is soldered into place. One has to remove the cover and see, it might be installed into a socket rather than soldered. You want to get the SAME part number of controller as OE installed. You have to transfer the prom. Do not change the prom on a metal surface nor on a carpet. Use a piece of wood and touch both metal chassis together along with yourself. Remember static electricity? I would give the chassis to an electronic friend and watch him do it.

The good news is that I have no coolant or oil leaks. The bad news is it did not start. I didn't crank it very long, however, the engine sounded like it was becoming more serious about starting.

It's been 45 mins. since I tried to start and there is still pressure in the fuel lines, don't know how much. I'm gonna run out in a bit and pick up a fuel line pressure gauge. I probably should have done this first. Anyhow.

From what I've been able to find out it is OBD I. I was expecting the code 12 but get no SES flashes at all, the light just stays on. I'll be really careful to ground myself and eliminate any static if I dive into it (the ECM). Autozone has a OBD1 scanner for $25, however, the fellow there said I'd get the same info with the jumper. I might just buy it and give it a try, what's another $25 (what am I saying, that's about the cost of a 10 gal. batch of ale I want to brew).

From what I've read the e-prom is soldered. I'll check whats available locally with the ECM while I'm out.

Right now I don't have the air filter hooked up, but I replaced it when this whole mess started, no major clogs, just one autumn leaf.

I think the next step is to re-read Haynes manual sections about Injectors and the ECM.

Thanks again for all of the valuable comments.
Brad

Okay, picked up a fuel line pressure gauge, should have done this earlier. Hooked it up and turned the key to the on position. The fuel pump ran and the pressure went to 47 psi then started to drop and was down to 42 psi in less than a minute and kept falling.

kustomwerker wrote: "if its a leaky inj, or fpr, the fuel pressure guage will peak when you turn on the key, and then drop...if everything`s good, it should hold pressure at the rail indefinately..."

So, (this is like finding lost shoes, they are always in the last place you look) I'm gonna focus in on the injectors.

(Autozone has pre-programmed ECM's for $125 BTW).

What is the best way to find out which one(s) is/are open. I'm thinking that if I pull 1 spark plug at a time I will get a pressure drop when i remove the plug that is associated with the leaky injector. Or do I need to read the resistance of each inj. Or do I use a screwdriver and listen while someone cranks the engine (really don't want to do this). If they are all open I'm thinking ECM.

Replacing the T-chain got me over the "I've never done that" hump. I'm not at all worried about replacing injectors now.

Thanks again!
Brad

check the inj wires with a noid lite...see if you get a soft glow out of the lite...it shouldnt glow at all until you`re turning the car over...then you should get a "flash while turning over...the comp controlls a ground to the injs,so you should have power to them all, but no ground until the motor is spinning...if you have a glow, then you have a ground that shouldnt be there...that could be a comp prob, or a shorted wire, but by the ses lite thing you have going on, i`d say comp...the fpr will also bleed off, but you would only see that in 1 cyl...i believe the injectors on you8r car batch fire, so if all the plugs are wet, i`d suspect the inj`s being the leak...DO NOT check for injector pulse with an analog multimeter...you could cook the comp if it isnt already...it needs to be done with dvom hooked up correctly, led penlite tester, or noidlite...last being the cheapest...you`re gettin there bro...

Look at the injector wiring both sides. One wire will be black = power from the relay/fuse panel. Second wire is green, for one side of engine, pink for the other side. Check engine electrical schematic for sure.

The colored wire goes to the ECM and as kustom states, ECM places a low potential, and this difference in voltage opens the injector and it dispenses fuel. I would disconnect each injector and measure its coil resistance. All should be within an ohm or two against each other overall, 2-4 ohms, I think. If every plug is wet, I'd suspect the injectors are working.

Timing light flashing at the marks while cranking?
If injectors are working, I suspect ignition signal to the coils would be getting there also. The ECm takes the crank/cam sensor signal and splits it into two signals, inj & ign.

I would attempt to start with pedal to the floor, as if it were flooded.

I'm real concerned about no code 12 first and foremost. My Helms manual for my 88 Dually suggests ECM. Haynes manual suggests? Both power sources going to ECM?

Everett,

No timing light. (I'm short on diagnostic tools still)
About half the times that I've tried to start it I have been holding the pedal to the floor, haven't notice any changes in the way it cranks.
The no code 12 is really bugging me also. Haynes says to take it to a qualified dealer (Don't think that is gonna happen). Autozone said 2 day delivery on a new ECM. I think I'll go order it so it is here by Saturday (yah, it's bugging me that much).
In the mean time I'll pick up a noid lite and check the TPS, inj. resistance, and check out the crank & cam sensors.

edit: I have to put this car on hold for a few days. Something else came up that I have to take care of first. I'll check back in when I get back and before I try the things I wanted to try today.

Thank you all for the responses.
Brad

Well, I'm back with the latest updates.

Mfg'd on Feb, 1994.

New ECM installed and "flashed" per Autozone. Engine cranks but still no start. The new ECM also did not make the SES light flash. I've found a few tid-bits of info on this but nothing conclusive yet.

For my next trick I think I'll measure the compression and maybe try new crankshaft sensors (haynes doesn't give any diag to check them out).

BTW, the fuel pressure at the rail dropped from 48 to 22 psi in 75 mins. (0.34 psi/min) fairly consistantly.

Thanks again for your input.
Brad