BlueDragonX

Ok, I'm having a wierd problem. I finally got my car ('91 Camaro, speed density TPI setup) put back together. The engine is rebuilt and in, she'll start and run for about two or three seconds after letting the key out of the start position, then die off. It's almost like she runs out of fuel, but my fuel pressure gauge says I've got full pressure till after the motor dies.

Keep in mind that this has been a ground up resto pretty much. A lot of the wiring I've done from scratch, so it's possible that there is a mistake someplace in the engine harness. But I can't think where. It doesn't matter if I give it gas, it still dies a bit after that. In that short time I did manage to rev the engine.

Any help is appreciated...it's been a year long project and she's finally back together, but she just won't run. Makes me sad

SpitotRs305

need more informations and lots off it to even have a remote chance of helping

DENN_SHAH

iTrader: (1)

more info would help, such as did you remove the VATS module, have you changed the MEMCAL, & have you pulled codes?

being a 91 TPI it has VATS unless you removed it from the chip.
if you did away with the VATS on the car but didn't remove it from the chip will give you about 2 seconds of run time before the ECM shuts down the injectors.

BlueDragonX

Actually I was about to make another post with everything I know up to this point.

VATS is deleted from the chip - I think. It's possible the bin I'm working off of had it unflagged and I went and flagged it back on not knowing. I'm using TunerPro and Craig Moate's programmer. On my XDF I have a flag that say "Switch 16 (VATS TCC-R 4th-NO VATS OLP) - Bit 4 - VATS" and for my bin I put in my ECU I unchecked the box next to "set". I'm under the assumption that this is correct, please correct me if I am wrong.

You mentioned deleting VATS as well as deleting it from the ECU. Is there any wiring I HAVE to have if I delete VATS from the ECU? Since I did the wiring for the ECU from scratch I pretty much ignored VATS since I had every intention of deleting it from the computer.

As for everything else, I'm having a PCV issue it seems, I'm squirting some oil out of the dipstick. I may have a bit more oil in it that I should, but aside from that my vaccum lines, PCV, and breathers are all set up like stock from what I can tell. The breather is in the passenger side valve cover and connected to the larger top openning on the throttlebody. The PCV is on the driverside cover and connected to the port on the manifold base. The lower port on the passenger side of the TB is blocked, as is the small port on the bottom of the TB. I have no emissions equipment on this car (those have been deleted from the computer as well, btw). The EGR blockoff plate is installed as well. The port on the back driverside of the plenum is connected to my brake booster. The back three smaller ports on the passenger side of the plenum are blocked, FPR, and MAP respectively.

In addition to all that, from checking my plugs I appear to be running rich. However, this could be attributed to the fact that my distributor was not quite dialed in right at first and I was flooding the engine instead of burning fuel. For injectors I am using the 24 lb/hr LT1 injectors out of a 94 'vette, the ECU has also been programmed to accept these.

I know I'm getting spark, I know I'm getting fuel pressure. I've got fuel pressure until after the fuel pump shuts off, then drops off slowly as expected. The fuel pump is wired proplery through the oil pressure switch. I can hear the pump running and I have oil pressure. My injectors are hooked up correctly, I've double checked that, and I don't have any shorts in that wiring (I wired it near enough from scratch, I would hope not).

I can't be 100% sure at the moment that one or more of my injectors are not stuck open, but it seems unlikely. I can't smell any gas fumes when it runs or after it runs for that matter. And no gas coming from the headers. That reminds me, the O2 sensor is mounted in my header flange and I have three feet of flexpipe attached to that until I can get it to an exhaust shop. But I understand that the ECU operates in open loop during start so I don't know if that is relevant or not.

Lastly, here's how things happen when I go to start it: I turn the key to run, ECU turns on and fuel pump runs for a few seconds. I turn the key to start, she turns over and starts near enough immediately (like any good engine should). Sounds beautiful. Then a second or two into that she dies as if fuel is cut off. I turn the key off, then back into run. ECU does not kick on fuel pump. Engine does not start, as if there's no gas. No gas comes out of the headers and I can't smell any. I get frustrated and go in the house and mope for an hour or so, then come back out and try it again. She fires up beutifully and the process repeats itself.

That's all the relevant information I can think of at the moment. I'm almost 100% certain all my wiring is good. Everything else on the car works as intended. She wants to drive, but the engine won't let her If there's anything else ya'll can think of that ya'll should know, let me know. I'm at my wits end.

btw, I was forced to buy a beater today to cope with this issue since I could otherwise go nowhere. I'm getting desparate

DBLTKE

iTrader: (1)

About a month ago i had the same problem. The car would start up, run for a few seconds, then die as if it were starved for fuel. It got progressively worse every time I tried to start it to the point where it wouldn't even run. The fuel pump ended up being the culprit. After i replaced the fuel pump and put some new gas it she started right up and hasn't had any problems since. Keep in mind that when the engine wouldn't start the fuel pump was still priming when i turned the key to "ON" but was still the problem nonetheless.

BlueDragonX

While the fuel pump COULD be the issue, I find it highly unlikely. It's relatively new and does not have all that many miles on it (well, compared to the rest of the car).

I forgot to mention, I'm not pulling any codes from the ECU, but I only have a simple code reader that blinks the SES light.

All of my hardware for the ECU I got from Craig Moates' website. MEMCAL, a few spare chips, and the programmer. I'm using TunerPro and Flash & Burn for editting and burning my bins.

BlueDragonX

So anyone else have any clue?

DENN_SHAH

iTrader: (1)

post up which ECM you have & what bin & XDF your using.

as far as i know there are 2 things for VATS in the bin file, one turns VATS off, the other turns the code for VATS off

92rs365hp

I am having the very same issues with my 91 tpi z28 except mine will start and drive for about an hour or two but if I shut it off it will turn over but wont start then it did it on the way home yesterday and would only run and drive if I kept it under 45 mph so I managed to get it to the only mechanic I trust around here with my car and he says fuel pump so I am gonna let him change it and hope like h#ll that does the trick I will keep you updated if it is you might wanna consider the pump also...by the way my pump is only 4 months old and the car has 103xxx mi.,,,,,thanks steve

BlueDragonX

It's a 730 ECM. It's been a little while since I downloaded the XDF and bin I'm using as a base, so I can't remember exactly where I got it. The file names are 8D.xdf and AXXB.BIN, though.

Steve, your problem does sound like an under-capacity fuel pump. You're actually able to drive your car. I've stated why I don't think my problem is the fuel pump, but she runs strong at idle for three seconds or so then dies. Fuel pressure does not fluctuate at all during that time.

DENN_SHAH

iTrader: (1)

i found 8D.xdf, but i couldn't find the AXXB bin, so i used AXXD.
if they are the same it looks like you have the right one to turn VATS off.

i noticed in TunerPro & AXXD that there is also, VATS Select-Bit2-b2 that is checked, i don't know what it is for, it may have something to do with VATS also.

im not sure about this, but you may be able to use the AUJP bin, it was the latest update for the 92 TPI.

im still learning about chip burning so there are a ton of things i don't know, so you may want to ask over in DYI-Prom about these things.

BlueDragonX

According to everything I read all you have to do to disable VATS in the computer is uncheck switch 16, bit 4. You need to uncheck code 46 since that's the VATS code mask, but ignoring that should not effect operation of VATS.

I don't know what release AXXB was, but I did some more reading into what bins and defs are available. It looks like the 8D XDF file I had was actually an import of the super_8dm1.ecu definition, which is the definition for the Super AUJP bin.

So instead of trying to find a stock bin and XDF that will play nicely together I went ahead and got a copy of the Super AUJP bin and the latest ECU file for it. I set my injector constant, removed VATS, and upped my idle a bit since it's a little low for my cam, imo. Since I'm back at school and both my truck and chip burner are 3 hours away I don't get to test it out, but I will next weekend.

My cam might be pushing the limits of the stock tune anyways. I'm worried that the cam I have in it might be causing some of the problems. I need to get ahold of a vacuum gauge, really. I'm running a Comp computer compatible cam, grind CS XE262H-14. Duration is 218/224 @ 50 with a 114 LSA. Here's there spec sheet on it: http://www.compcams.com/Technical/Se...umber=12-262-4. Probably not the best choice, but I wasn't quite as sure what I was doing when I bought it, lol. But if that's the problem then I need help getting around it...

DENN_SHAH

iTrader: (1)

there are several XDF or ecu files you can use, Super_8dm2.ecu is the newer file, you can get it at the TunerPro site or over at Craig's site.
i use 8d_v03, 1227730, & Super_8dm2, they each do some things i like better than the others.
i don't know which one you use for data stream, but i really like
First Third Gen 1227730.ads which is at Craig's site, it seems to be more complete than the others i have used.
im pretty sure there are people in DYI-Prom that can help you get dailed in with that cam when you get ready.

there are some good tuning stickies over in TBI, Come in for a FREE tune by BMmonteSS is really good along some of the others there.
in BUDGET TBI BUILDUP Fast355 put together a TBI with a nice cam, Duration @ .050 - 203/210 Lift w/1.5 rocker -.446/.449 LSA 115, so you may want to read through it too.

BlueDragonX

I don't have the hardware for datalogging at the moment. It's on my list of stuff to buy, but I'll need a working laptop and that's more than I'm willing to put down cash for at the moment.

rgarcia63

This is an SD TPI motor, right?
You don't use the FPR, or the MAP? You must be providing vacuum for these devices from some other source. The third port is probably HVAC so I assume you don't use A/C, or the heater.
The FPR will run WOT pressure without vacuum at idle.
The ECM won't be able to determine air flow without vacuum to the MAP.

I'm confused, and probably the ECM as well.

Rob Wade

Agreed......with no MAP sensor working it isn't going to run.

BlueDragonX

You misinterpret. There are three ports. One is blocked, one is plugged into the FPR, one is plugged into the MAP sensor. In that order.

rgarcia63

Ok, so that's not it.
I agree with you on that it seems like the injector signal is dead after the short run, "Then a second or two into that she dies as if fuel is cut off." do you have an injector noid light? Put it on one of the injector connectors after it dies, then see if it lights during the crank, but no start condition.

BlueDragonX

I don't have a noid light, I need to get one before I go back. Not sure if anyone around here will have one, though...

rgarcia63

A digital volt ohm meter should work in place of the noid light. Set it to the correct voltage range, don't let it autorange.
When the engine is just cranking the switching of the 12v to the injectors is slow enough for the meter to show it turning on and off.
Test either of the two wires going to the ECM with all injectors disconnected. If it reads a constant 12v while cranking after the short run then the ECM isn't driving the 12v to ground to fire the injectors. When the ECM switches to ground the meter should read 0 volts.

As a last resort if you can't get good results with the DVOM use a 1156 light bulb (12v 1 amp) in place of an injector disconnect all the injectors in that bank, it should be a bright light when the ECM fires.

Something you can Investigate
Assuming the ECM isn't shutting down the injectors because of the VATS. There is one other condition where it will do it, and that is to protect itself from too high of a current drain.
The resistive parallel load across each set of 4 injectors should be no less than 4 ohms for typical 16 ohm injectors, but because not all injectors measure the same do the following:

1. Divide 12volts by the actual resistance value you measured for each injector that will give you the current drop for each injector, for 16 ohms it should be 3/4 of amp.
2. Add the current drops for each bank together.
3. Divide 12v by the total current drop for that bank, that gives the exact total resistance that you should see across that bank of injectors.