NoWorries

Ok, so I'm still chasing this no-start condition. I changed the ECM, to no avail. I put a new fuse in the ECM spot and now I have a SES light(unfortunately with no codes :( ). The fuse looked good and checked good, but apparently it wasn't working??? Hmmm...

Anyways, I'm following the factory fault isolation manual, and it says to connect a test light to a disconnected injector connector, and the test light should blink when the car is turned over. My light comes on steady and stays on steady! Eeek. But what is weird is the fuel pump isn't running continuously and the car is maintaining fuel pressure. :confused: Anyways, at this point, the manual says to check the injectors for +10 ohms, and they are all at 14 ohms, except one at 16 ohms. So the injectors test good as per the check.

What I need someone to do is pull an injector connector on a TPI car and see if you have power there continously, or if it there is no power there when the car isn't cranking.

I'm going to eat dinner, then go shoot some more wires.

Thanks for any help!

Canyon

scorp508

With key "on" you'll get a hot 12v at the injector and the other side should be nothing basically as it is switched to ground in order to open the injector. Thats why it should blink twice per rotation of the engine (batch fire system).

69vetteracer

You will always have power on one side of the injector. The left bank is powered by one fuse and the right bank is powered by another. The computer only grounds the injector to open it. If you go from the connector to ground you will only get a steady light. You need a noid light (lamp with the correct resistance) to flash when turning the engine over, and it plugs into the connector so the computer can ground it. If you have @12 volts to one side of each connector then the fuses and wiring to the fuse block is ok. Next thing to do is check from the injector to the computer for an open wire. The injectors are spliced at the rear of the intake on each side. Unplug all the injectors and run continutity checks to the correct pin on the computer.
You may have received a bad computer. It happens, believe me...

SunCr

Injectors are wired in parallel. Should have steady light at both terminals with ignition on. If steady light on one and no blinking light, possibility of a short to ground on the bank with only one light. If both sides, you need to probe the driver circuit at the ECM. Each should have a light to ground with your test light. Use Chart A-3, Section 6 of your Service Manual if that's what you're relying on.

69vetteracer

Thats correct if you leave the injectors pluged in.

tjwong

There are two fuses in your fuse box, most likely called Inj 1 and Inj 2. Each of the two fuses powers up one bank of 4 injectors. To test them connect your test light to ground, probe the pink wire side of the injector connector, there should be continuous power with the ignition on.

To check if the ECM is firing them, connect your test light aligator clip to Battery (+) Positive, then probe the second wire and crank the engine over, it should blink as the ECM fires the injectors. If it does not it could mean that the ECM is not receiving a SPARK Reference pulse from the distributor. In that case pull a plug wire and check for spark.

If there is no spark then chances are the HEI module is bad or the ECM is bad. If there is spark it could be wiring problem, bad ECM or still a bad Module. Check all the fuses that supply power to the ECM as well. If its not powered up then there won't be any injector pulses as well. And check the large red wire feeding the HEI distributor, make sure that there is power at that point when ignition is on and when cranking.

Hey do you get to fly some of them helos I seen in that shop where your car was painted? Must be a fun job you got there!


[Modified by tjwong, 9:57 PM 9/21/2003]

NoWorries

Thanks for the reply. :) I got the light to blink using your method. So, I have good injector pulses, and I have spark, fuel...air...I've got everything necessary to make the car run. Even if the computer tables were screwed up, it should still at least fire for a second....

:confused: I checked the timing, but it was daytime and the light was kind of dim(in comparison to the sunlight), but it looked like it was in time. I'm going to go check TDC and set the timing to there and see if she'll light....

TJWong, I used to work on those helicopters, and flew them a few times. Now I joined the AirForce, and hopefully I'll get to fly an F-15E soon! :cool:

Thanks again for the reply.


[Modified by NoWorries, 2:02 PM 9/22/2003]

69vetteracer

Up and running yet? Maybe pumping up the JFS will work.

tjwong

well if you are sure you have fuel and you know you got spark and if its sparking at the right time then it should fire off. Check it at TDC with number one ready to fire and see where its at. Its pretty easy to do, remove number one plug, roll the engine over until you feel compression, roll it to TDC at th timing marks then check to see where the rotor is pointed in relation to where number one wire is on the cap. So are you going to give me a ride in one of them F15's? :D

NoWorries

It's stillnot running. :( I'm getting to a point that I think something serious broke. :( I'm wondering at this point if shemight have jumped time. :( The spark time was on before I pulled the distributor for a visual inspection, is there anyway the cam could be off and have that happen? Idon't know if mydad might have reset the ignition timing thinking it was the problem.

I have HUGE valve reliefes to compensate for what would have been a too high compression ratio, so maybe the valves willbe ok if this happened. For some reason what I put the engine together I didn't go with a double roller timing chain... :(

It's the onlything I can think of that would be causing this problem with fuel and spark. :( Even a carbureator would run at this point. ;) Heck, it should be dieseling at the very least...A JFS would come in handy, 15K rpm would help. ;)

I'll keep you posted,
Canyon

P.S.Myspacebar isgoing out! :eek: :smash:

And,allyouneedto get a flight inanF-15 is signoveryour soul! :lol: :seeya

War Machine

Please correct me if I'm wrong here. I thought all the injectors had to read the same #, so if one was off, that's the bad one. Is that right?

I tested mine and they all came up 17.2 ohms.

ZylaRace

I didn't read the whole thread, but here is a tid bit:
Stock standard Bosch injector should read 16.2 Ohms
If they ohm out less than 16 Ohms, they need to be replaced. They may have a different resistance hot vs cold. This would mean some of the coils are shorting out w/ the change in temp. This would indicate a replacement is needed.

NoWorries

Since they're wired in parallel, the only thing that would cause a problem with the whole car would be a shorted injector(less than 10 ohms on a stock injector) Since my only anomally is higher than all of the others, I should still have good operation on at least 7 injectors, and the 2 ohm difference shouldn't make much of a difference, I don't think.

The factory manual says that factory injectors are good until they drop below 10 ohms. My injectors are Accel, and I'm pretty sure they're all still working. They may change resistance as temperature changes, but my car hasn't changed degrees at a noticable amount in seven months. I disconnected the fuel pump with the ECM still connected so the injectors would fire, and the fuel pressure falls in increments as the injectors pulse, so one injector isn't dumping the whole amount.

Today I pulled the valve covers and the cam is still attached to the crank at the right point. I set the timing at about 10 degrees BTC to account for altitude...and it still wouldn't start.

So I went drastic and tried to bypass the fuel injection all together and sprayed varying amounts of atomized gasoline from a spray bottle directly onto the throttle blades...and it still won't start. I did get a blip from the engine where it ran for about 1.5 seconds, but nothing notable...

My two hypothesis right now is a blown head gasket or spark plug or piston damage. I put my hand over the intake and I have a superb vacuum(I don't have a compression guage)...and there is no oil in the coolant or coolant in the oil...

I'm in the process of pulling spark plugs now looking for damage, but 3 out of 8 look good so far. Then I'm going to remove the computer advance from the distributor, just in case its pulling insane amounts of time out, or something.

I dunno, somebody help! I'm running out of ideas!

loflyin

I'm gonna go way out on a limb and in another direction, but it's a thought. Laugh if you will, but it has happened to me and to others who have written about it here. OK, here goes: check the harmonic balancer. They are made of one metal disc apparently pressed into an outer ring. These eventually separate and the ring (with the timing mark) can rotate around and around, or move just enough to throw you way out of time. Mine actually started to move forward to completely separate - looked down at it and it was 1/2 inch out of alignment! Hey, everything else checks out OK, so that's gotta be it! Yeah, that's it! :hurray:

tjwong

Did you verify timing yet? As you mentioned that it ran BEFORE you pulled the distributor. Roll the engine over, set it at the TDC timing mark, then pull the distributor cap. It should be pointed to either number 1 or number 6. If its pointed at 6 roll it over one revolution, hold your finger over the number 1 plug hole feel for compression as it comes around towards TDC, if you feel it and when you stop at TDC the rotor should be pointed at 1.

If it rolls over to 1 and u don't feel compression you may have installed the Distributor 180 out.

NoWorries

Thats a good thought and something I'm going to need to check. The dampner is only 8,000 miles old, but so is everything else on the engine, so every thing is suspect.

I'mgoing to go check the timing with the distributor flipped 180 degrees over, then I'm going to to pullall the plugs and check the compression with a borrowed guage. But first I'mgoing to look at the torsion dampner(harmonic balancer).

Here's another question...the manual says that a bad computer chip wouldn't cause a no-start, but has anyone had a bad chip, and what were the symptoms?

I need to get this thing running, it hasn't run in 7 months, if I don't fix it by Tuesday, thats liable to become 2 years 7 months. :eek:

Thanks again for the help and ideas.

loflyin

Car should start if you have the big 3 and run in the back up mode at least. Run pretty rough maybe and usually rich, but run it should. I'm sorry, but what year model again (HEI vs Opti)?

NoWorries

The car is a 1987, HEI with Accel Coil, but otherwise stock.

It finally fired tonight, I'm still not sure what made it run, I flipped the distributor 180 degrees, decided that was wrong, and flipped it back, and now it runs, albeit poorly.

Here is a new thread so that you don't have to read through this whole thread anymore to get to the new stuff: http://forums.corvetteforum.com/zerothread?id=659092

CentralCoaster

If I recall, the timing mark on the balancer should be 10 degrees ahead of the crankshaft keyway.