This may be long, but I'll try and keep it short. Ok, so I was hoping to get my engine fired for the first time with the new setup (Ramjet) this weekend, everything is ready to go as far as starting-wise...or so I thought. So I went to start it, just cranks, no fire, so I pull a plug and make sure it's getting spark. Yes, put the plug back in, double check that the dist. isn't 180* out, its in right, timing should be good. Try again, nothing. Try some other stuff, yadayada, so I pull the 'D' plug on the ECM and jumper D9 and D3 to ground to make sure the injectors are working. They are clicking, so I plug it back in to the ECM and crank again and it fires once, try again nothing....long story short, my injectors are not firing. Now what could be wrong, I've verified all sensors (well, the important ones at least) are working correctly via TunerPro's datalogging feature. I have VATS turned off, and am using Craig Moates' Emulator. Now I had some ideas before (thought I had wired in the distributor wrong and had my hopes up, but after pulling the ignition module and verifying the GBRE goes to the proper wires and ECM pins respectfully, ruled that out). So anyhow, I've checked most everything and just cannot seem to figure out what is going on.

Ok now for the (hopefully) good news. I was on the way home today and was thinking about the way I had the emulator 'chip' plugged into the adapter. I'm wondering if I don't have it in backwards. But, would the datalogging still show sensor values with the chip in wrong? I noticed that I no longer had the 'check engine light' on when the key was turned on now also. Please, any ideas or thoughts? I'd like to have some ideas for things to check when I go home this weekend. I wanna get this thing running so bad!! Any question, please feel free to ask me.

 

Also, when datalogging and trying to start, under 'Fuel Trim/Mixture', the 'Injector Base Pulse Width' shows 0 mSec, I thought that this would at least show what it is supposed to be pulsing the injectors even on startup. Or am I wrong there?
Desired Idle speed shows as like 3160rpms with a 160 step count for the IAC. Would it show this with no chip in, or oriented wrongly? NV Ratio shows as 255RPM/MPH. When cranking, engine speed shows 0RPM. Can't remember what PROM ID shows, that may help, sorry. Trying to give everyone a picture of what is going on here. So....chip in wrong, faulty ECM (injector drivers), something else or what.

As always, all help is appreciated!

 

No one has any ideas at all?

 

There is several things you can try. I would first narrow it down a little.

Spray some fuel into the plenum and see if it runs for at least a short time. This would verify that spark and timing is OK.

Use a NOID light or some such in place of an injector and verify that indeed they are not firing. Use same light to verify that the hot side of the injector harness is indeed hot. There are two fuses for the inejctors, so check both sides of the injector harness.

Ignition modules can be bad where they fire the coil but don't supply the proper signal to the ECM. Without that the injectors won't fire. Check if scan tool shows RPM while running on plenum induced fuel. Also double check that VATS is off in the bin (option bit set to zero).

The SES light not coming on is bad, maybe just burned out? The fact that you get scan data is good. This means the code is running.

Verify the grounding is good. Battery minus to block (heavy gauge), battery minus to fender, ECM grounds to back of head(s),
ground strap(s) engine to firewall.

RBob.

 

It will fire on the fuel sprayed by manually (grounding computer side) firing the injectors. I do not need a noid light to know that the injectors are not firing, I can assure you they are not.

Spark is verified to be getting to the plugs.

VATS is turned off in the code.

I built my own harness using the existing engine wiring. Everything has been verified to be working except the injectors. I have verified the grounds and power wires to the ECM via an Ohmmeter.

I am going to replace the adapter/emu with the original calpack this weekend and see if the check engine light comes on, I know for sure that it was before I put in the adapter and emu (VATS code set it off). What worries me is that it doesn't even come on when you flip the key on, which it normally did before.

Yes, I get data by the datalogging in TunerPro, that's why I was thinking that the code was running too (implying that the chip is in correctly, right?)

I'm down to two possiblities, but of course there may be others I am not realizing. One, the ECM is somehow faulty, which I am doubting. Is it possible that someone could have burnt out the internal injector drivers? Or two, the ignition module is not sending the right signal to the ECM, which is the way I am leaning now. Let me expand on this a little and say that I am using the origninal LG4 module, which is a Wells DR140 I think. I originally tried the one that came with the Ramjet setup for which I have no part number. I cannot see how these things can be that much different. For a 1992 Corvette, it shows a different part number, and a wayy higher price. What module SHOULD I be using? Or does it matter. All of these 4/2 pin modules I have seen are marked the same with G(round) B(ypass) R(eference) E(ST), and P N for the pickup coil, and the output to the coil. What difference could there be internally? Do different modules send different signals to different ECM's?

 

Yes, it is possible the injector driver is bad. There is only one for all eight injectors, so that will prevent them from firing. See if the scan tool shows RPM once the engine lights off (do the gas in plenum thing). If it shows RPM then the ECM sees the distributor reference pulses.

A SES blink at key-on is important. This is something I always check for while doing the PROM dance. In your case it may be a wiring problem, bad ECM, or a burned out bulb.

The difference between a Corvette ignition module and the others is the order of the pins on the connector going to the ECM. They are reversed between the two. As long as you went by the molded in letters no problem. This is the 4-pin connector.

I am going to check some data logs later to see if they show a PW with key-on, engine off.

RBob.

 

Thanks RBob, I appreciate your help. Hopefully we can get this sorted out soon.

I'll have to try the spraying fuel into the intake and seeing if the ECM is getting a reference pulse. I would have thought it may show up even from cranking it over, but maybe not.

I don't see how the SES bulb could have burnt out between switching the PROM like that, but maybe I clipped a wire or something, I'll have to check on that.

I am 100% sure that the ignition module is wired in right. This past weekend, I pulled it to check it out and thought I had wired it in backwards but it turned out that it was indeed right.

 

Hmmm, looking at a $8D data log now, not much is active until engine running has commenced. Key-on, engine-off there is: MAP, CTS, MAT, O2, INT, BLM, PumpVolts, maybe TPS%.

Don't see RPM, AFR, PW (all zero).

The MAP actually shows the pump down as the engine is cranked.

RBob.

 

My 88' uses the 1227165 ECM and doesn't have VATS.
When I installed an Xtronics romulator I disabled the VATS on the 89' ARAP bin I uploaded to the romulator for my 388 TPI stroker . It cranks and fires up as should yours.

Try this:
Apply 12volts to the ALDL diagnostic connector's "G" Terminal (lower left hand pin,) to power the fuel pump, you may hear a relay or two energizing, but if the pump doesn't run, that combined with the fact that the "SES" doesn't light with the key on is a sure sign that the ECM is dead.
FYI
Edit Correction: Let me correct myself. when I said "try this" the pump not running was with the ECM out, not dead.
You don't need to spray fuel into the TB just pour some in through the PCV vacuum hose.

The ECM doesn't control spark until the rpm reaches a set point, so the distributor has to provide spark for the motor to fire up. If you put fuel in the intake and it fires up and then dies (because as you said the scanner reports a zero injector pulse width) doesn't mean the ECM is functioning.

The ECM has 2 drivers with 4 injectors per driver, so whatever the cause it's affecting both drivers.

Please keep us posted specially if my info is wrong.

 

Thank you for the replies RBob and rgarcia.

The pump and relay are working. Flip the key on, pump primes as should for two seconds, and when I am cranking the pump stays running (which boggles me because if the ECM knows to run the pump why does it not know to fire the injectors, I would think it would use the distributor reference pulse to deteremine both of those things, injectors firing and fuel pump constantly running). The ECM is for sure not totally dead, as like I said, it will prime the pump via the relay I wired in, and I am getting some sensor info via datalogging with TunerPro.

I realize that just because the engine may run on fuel spraying into the intake that it does not necessarily imply that the ECM works, as it should run (albeit horribly) on the base spark timing. I think the idea was to get it 'running' to the point where the ECM would show an RPMs value via datalogging to see if the distributor was sending (or the ECM was receiving) a reference pulse.

You are correct, whatever it is it is affecting both drivers. Neither bank are firing or it would definitely fire (and probablyl run) if either one were working.

Personally, I think that the drivers are faulty. It is the only logical explanation I can think of. I picked up another ECM from eBay yesterday so I can at least try another one and possibly spare me some headache. For what I paid for it, it is probably worth my time to at least try it as I have to drive 2 hours there and back just to work on the car. (Oh the things we do for our cars )

Just a quick question before I go, I would like to verify that I am unchecking the correct bit at the correct address in the bin. All of the ECUs I have tried all point to the byte at 'start address 16' (ala TunerPro). Now, different bins I have tried have different bits checked. For example, the AXCN bin has bits 4 (VATS correct?) and bit 1 checked whereas the AUJP bin only has bit 4 checked. Do these other bits matter? I have unchecked bit 4 and that is the bin I have uploaded to the emulator currently.

Sorry so long, trying to be thorough.

 

I had the exact same symptoms, (I can't say about the scanner because I didn't have one.) No SES light, it would fire with a shot of fuel. I replaced the ECM, end of story. Even though the ECM was dead it still provided a electrical path for the fuel pump relay, but wasn't producing an injector pulse. While you have the ECM out turn the key to "RUN" and see if the fuel still runs (mine cranks, but the pump won't run.) Let me correct myself. when I said "try this" the pump not running was with the ECM out, not dead.

I was driving 60 miles round trip to my mom's bi-weekly, building this 388 was slow and painfull

ala TunerPro; I use TunerCat so I can't help with the bit thang.

 

Just as somewhat of a conclusion to this thread, I got the car running finally after hours and hours of piddling around checking wires, rechecking and re-rechecking.....phew....anyhow, I've come to the conclusion that the ECM wasn't recieving a signal (reference) from the distributor. I had wired up the Fuel Pump Voltage wire to the ecm from the pump relay and, while cranking, watched 'fuel pump voltage' in TunerPRO RT datalogging. When the key is first on, you could hear the pump and see the voltage at the relay I had it wired to. While cranking, the fuel pump would not run, hence no reference signal. Anyhow, somehow I got it fired and ran it for a while, shut it off and went in to eat dinner, came back out and no-start again. I swapped the brand new GM distributor for my old one and voila', it fired first start again.

Soo... in conclusion, no reference pulse = no starty.
Arrgghhh, the agravation.

 

That's a It's running!

RBob.

 

Great work 87',
Not to keep the thread open, but just to keep things straight in my mind.
LG4 module = old distributor.
RamJet Setup = New distributor.
So what do you think was actually faulty in the distributor, the timing core, pick-up coil, or the ignition module?
I assume the timing core, pick-up coil can be ruled out since it did produce a spark.
It was the ignition module in the new GM distributor that was faulty, or intermittent since it did run at least once, right?
Ruling out the wiring which you did. Then, Spark, but no distributor reference signal = faulty ignition module, correct?

I thought you had ruled out the ignition module when you posted the following, (that's why I leaned toward the ECM being bad):
I don't see why the LG4 module didn't work with the new distributor, sure would like to know why they're incompatable.

In the shuffle do you think you might have ended up with the one that had the faulty electronic pulse switch to the ECM?

 

Not completely familiar with all components of the HEI distributors. Heres what I did. Car wasn't running on the brand new dizzy that came with the setup so I pulled the whole thing, took it apart and swapped over the shaft/gear to my 'old' dist. that was known to work when I put the car away (which ran on the LG4 setup). This included the Wells ignition module which was in it. So, old dist/pickup-coil and module with new shaft and gear. When I go home this weekend, we'll see if it wants to fire again. If not, I'm gonna just go get a new module 'cause I don't know what else it could be, there's not that many parts to the thing.

What is the timing core? The magnetic 'star' on the shaft? If so, it is fine, visually, and actually feels like it has a stronger magnet than my old one, but I don't know how true that is. That's just from me spinning the shafts of both of them, the newer one felt like it 'grabbed' a little more when the stars passed the tabs.

edit: After re-reading what you just wrote, I noticed some potential for misunderstanding in what I wrote. Just to clarify, I've tried both modules, old and new. I had it running on the new one, albeit inconsistently and eventually not at all, and I just swapped back to the old one and it ran again.

I am just guessing here. What would cause inconsistency besides a module? I would think if the p/u coil works, it will work all the time, and so would this timing core you talk of.