Turbo 93 LT1, crank, no start out of the blue - LS1LT1 Forum : LT1, LS1, Camaro, Firebird, Trans Am, Engine Tech Forums
 
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post #1 of 10 (permalink) Old 09-29-2018, 05:21 PM Thread Starter
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Angry Turbo 93 LT1, crank, no start out of the blue

I'm going a little crazy trying to figure this out. Car will not start at all, all of a sudden

Just installed a DIY turbo system. LT1/T56 swapped third gen camaro. 78mm VS racing, I did the hotside and cold side.

New parts also include a 340lph in tank pump, and new Siemens 60lb injectors along with requisite turbo stuff.

Yesterday was the first chance to drive it with the new setup. I had a safe tune on it, and took it out for a drive just to see how it drove putting around. It did fine. A/F was about where it used to be when it was NA. I had been using a 2 bar MAP tune for the last month or two, to prove that it would work OK, and it did. Drove home parked it, no issues.

So, after driving a bit, I came back, added a different crankcase breather, made a gauge pod and installed the boost gauge, and was ready to go tuning a bit. In the midst of that, a friend dropped by so I started it for him just for fun. Started and run fine.

Then after the gauge was all installed, I try to start the car and it started for maybe 1-2 seconds and then died. After that, all she will do is crank, maybe get a little fire every once in a while. Not very often.

The odd thing is: the first time it failed to run, it did start for just a brief couple seconds before shutting down, then won't do much. Get a pop once in a while.
Used the GM service manual to check a few things.
Check engine light is on, while engine doesn't run. GM manual says this is normal.
No DTC's found per Scan9495 and also TunerProRT.
I do see an injector fault, but it has been like this ever since the motor was built, and never caused any issues. I have asked about it before, but haven't been able to identify a real issue, and so just let it be.

I happen to have a second ECM, which delivers the exact same results.

FUEL:
fuel pressure when key is on is 50psi, little high, but that's probably because of the 340lph pump in the tank and stock 5/16" return line.
Have 12 volts at the injector connectors, fuses OK. Also noted blinking test light while cranking, so that system I would say appears to be functioning. Also still think it smells like raw fuel after cranking.
Thought perhaps it was flooded somehow, but you can't floor it to clear it out, or pull the inj. fuses to clear it either. I pulled a couple plugs as well, and they weren't really wet with fuel, and no fuel poured out of the cylinder or anything.

Injectors:
Measure all on right bank, all exactly 12.3 ohms. They have about 15 minutes run time on them.
I have not yet swapped back to the Bosch DIII 32 lb units I used to run to see what that does.

SPARK:
Using the Scan9495 program, I can see that the opti appears to be giving signals to the ECM.
I checked spark at #2 with a inline spark tester, and can see some light there, so it also appears to be functioning.

Tunes: TunerProRT
I tried the old 1 bar tune with 1 bar sensor that worked well, along with a change to proper injector flow. Still nothing
Tried the old 2 bar NA tune that worked well, etc., still nothing.
Tried reducing the cranking fuel pulsewidth - no help.
Tried increasing injector flow rating to lean it out - no help.
SteveO on the GearheadEFI applied a patch to the 2 bar tune for baro update disable. But, I've tried tunes with the patch, and back to the old tune without just to see. Nothing . . .

The only thing I can think of is it's in the opti somehow. Not triggering the ECM at the proper time or something. Odd that it would just fail all at once?? Per the scan program it appears to work? I think it's an original GM opti, with about 150k on it. Up till now it's been flawless. No leaks from water pump, I don't drive this car in rain.

I'm not sure what else to try. The injectors are new in the equation, as is the fuel pump. I can't see how the pump is doing all this. If the injectors decided to all leak or something I guess that could do it? I haven't run the car long at all with the Siemens 60's, but I did drive it for at least 10-15 minutes yesterday morning. So the tune / values etc. were working. A/F wasn't way out of whack either.

I haven't been through the "Hard start" section in the GM manual yet. Guess that's next.

Sorry for the book, my sincere thanks for anyone that can help me out. I wanna hear this damn turbo just once!!!

J. Moen
91 Camaro Road Race American Iron car - The Menace
91 Camaro RS - '93 LT1/T56 swap project, 10.5:1, 224/224 @.050, 60lb Deka, home ported heads, 78mm Vs Racing, intercooled, 2 bar MAP tune on $DA3
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post #2 of 10 (permalink) Old 09-29-2018, 07:02 PM
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I just went through this last week with my LT1. It was a head scratcher because I had good fuel pressure, good air, and I had spark. It would randomly start fine and run fine. But sometimes it would stall or not start at all; it would just crank. I had to hold gas pedal to floor to try and get it to start.

I read about coolant temperature sensor causing issues and similar symptoms. I pulled the plug in the sensor, located in water pump, and the connection was severely corroded. I replaced sensor and pigtail. I also replaced another temperature sensor on the side of the block (right side as you face engine from front of car) because the plastic was cracked. Both sensors were less than $50 bucks from autozone. I turned the key and it fired right up. Good luck.


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post #3 of 10 (permalink) Old 09-29-2018, 09:06 PM Thread Starter
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Thanks for the ideas. Mine will not run AT ALL at this point. Hasn't since yesterday afternoon when it just suddenly refused to run. At least it's consistent I guess.

When I scan the ECM with Scan9495 I can see that my sensor reports 75F, which is about right for today. I guess I'll look into it anyway, just to make sure. TPS, MAP, IAT, all look reasonable via the scan.

Just tried a known good set of 32lb injectors, known good tune from when I ran them, and just gutting an occasional sputter / cough, almost like an carb'd motor that has the dist. a couple teeth off. But of course that's not a thing with an LT1.

Also tried another ECM that I had previously tested, that produces the same results.

2 days into this, and nothing is helping. I'm about done with the dumb thing.

I guess I need to get more serious about diagnosing the opti before I just plunk down that money. And maybe I'd just do Megasquirt at that point and be done with it.

J. Moen
91 Camaro Road Race American Iron car - The Menace
91 Camaro RS - '93 LT1/T56 swap project, 10.5:1, 224/224 @.050, 60lb Deka, home ported heads, 78mm Vs Racing, intercooled, 2 bar MAP tune on $DA3
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post #4 of 10 (permalink) Old 09-29-2018, 09:10 PM
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There were days mine wouldnít start at all either. Pull pigtail off of that sensor and check for corrosion.


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post #5 of 10 (permalink) Old 09-30-2018, 08:00 AM
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If check engine light stays on with ignition on, you have a code or codes set. Try using the old paperclip trick of shorting the 2 aldl connector pins together. This will cause cel to flash codes on a 93.

Have you considered that you problem started when you installed the gauge pod? I'd see if you hooked into an ignition line or lost a ground, etc.

But finding out the code or codes is essential to fixing your problem. If you have dtc 16, 41, or 42, you will not have a running engine. Dtc 16 is opti low resolution pulse missing. 41 & 42 are icm codes.

If you want to troubleshoot the optispark, an oscilloscope is only 100% way of testing low & high resolution signals. You can buy a pc based scope on Ebay, Amazon, etc for around $70. I suggest you get one and learn how to use it.

Since you transplanted lt1 into a 3rd gen, what did you do about vats security? If you have problems there, fuel injector opening is cut off. Same if you have dtc 16, 41, or 42.

So, you know fuel pump is working , what is your fuel pressure @ key on prime? Lt1 engine should have around 43 psi @ key on prime.

Have you pulled fuel rail up, and had an assistant crank engine to see if injectors are spraying? When doing this, have catch cans under injectors. AND HAVE A FIRE EXTINGUISHER at hand. You don't want a carbeque if ignition does throw a spark.

Try these tests, give her 2 aspirin, and call be in the morning.

Last edited by cocobolo95; 11-06-2018 at 06:26 AM.
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post #6 of 10 (permalink) Old 09-30-2018, 08:12 PM Thread Starter
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Quote:
Originally Posted by cocobolo95 View Post
If check engine light stays on weith ignition on, you have a code or codes set. Try using the old paperclip trick of shorting the 2 aldl connector pins together. This will cause cel to flash codes on a 93.
Interesting . . . I'd have to check again, pretty sure the GM manual said the CEL should be on with the engine not running, because I remember I was concerned that it was staying on. I'll have to look again.

Quote:
Have you considered that you problem started when you installed the gauge pod? I'd see if you hooked into an ignition line or lost a ground, etc.

But finding out the code or codes is essential to fixing your problem. If you have dtc 16, 41, or 42, you will not have a running engine. Dtc 16 is opti low resolution pulse missing. 41 & 42 are icm codes.
It doesn't appear to be throwing any codes. Via TunerPro and also Scan9495. But ??? ALso, while cranking and looking at Scan9495 in scan mode, I can see the low res pulses and high res as well.

For the gauge, right now it's just a mechanical line to the intake. No wiring there to be problematic.

Quote:
If you want to troubleshoot the optispark, an oscilloscope is only 100% way of testing low & high resolution signals. You can buy a pc based scope on Ebay, Amazon, etc for around $70. I suggest you get one and learn how to use it.
Not a bad thought at all. Do you feel like the Scan9495 is not a reliable source for the low res pulses? Just want to know if I should or should not trust it.

Quote:
Since you transplanted lt1 into a 3rd gen, what did you do about vats security? If you have problems there, fuel injector opening is cut off. Same if you have dtc 16, 41, or 42.
Disabled VATS requirement per the tune in TunerPro. Has never been an issue. I do have injectors pulsing per the noid light.
Quote:
So, you know fuel pump is working , what is your fuel pressure @ key on prime? Lt1 engine should have around 43 psi @ key on prime.
Yep, actually have 48-50 psi while cranking.

Quote:
Have you pulled fuel rail up, and had an assistant crank engine to see if injectors are spraying? When doing this, have catch cans under injectors. AND HAVE A FIRE EXTINGUISHER at hand. You don't want a carbeque if ignition does throw a spark.
This I have not done, but I'd be tempted to try.

After reading a bit last night, I decided that my spark tester is maybe not so good. So bought one of the adjustable get type testers today, and found that it does have some spark, but it would not jump more than 1/4" or so on the tester (in place if spark plug). I now consider this to be a "no spark" condition per the manual. The GM service manual clued me in a bit when they said their tester needed 25kV to fire. My crappy bulb tester wasn't capable of showing the strength of the spark very well.

Also found that when I attached the tester to the coil itself, it would jump about 1/2" with nice blue spark. Hmmm. Opti it seems.

So went through several test per the GM manual, found the coil to be OK, the ICM appears to be OK, connectors , grounds, etc OK. ECM is pulsing the ICM OK. Pulled the opti this afternoon, and found the contacts to be somewhat corroded inside etc..

So I guess a new cap and rotor is in order. I don't believe the Opti is dead as far as sensing goes. I'll clean this one, and try the spark test again just to see, but I'm guessing that's it.

Darn harbor freight spark tester bit me. Lot of chasing for nothing.

J. Moen
91 Camaro Road Race American Iron car - The Menace
91 Camaro RS - '93 LT1/T56 swap project, 10.5:1, 224/224 @.050, 60lb Deka, home ported heads, 78mm Vs Racing, intercooled, 2 bar MAP tune on $DA3
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post #7 of 10 (permalink) Old 10-01-2018, 06:27 AM
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Using scan9495 to check opti low & high res pulses is like using a multimeter set to ac volts to check signals. Both will let you know a signal is present. But neither will let you know if signal is the proper square wave. A scope is only tool that will show the actual wave form.


Couple of years ago, my 90 3.1 v-6 car quit running. I tested the 30 hertz fuel enable signal with my multimeter set to measure frequency. I based my outcome on the fact that a 30 hertz signal was present. But fuel injectors would not open.

When I got smart and switched to oscilloscope to look at fuel enable signal, found signal waveform to be all messed up. Even though a 30 hertz signal was present, ecm was not accepting fuel enable signal as being valid because of misshapen waveform. Changing theft deterrent module (TDM) solved problem.

CEL should come on & stay on when key turned on. But once engine starts cel shuts off. Forgot your engine is not starting. BUT dtc 16, 41 & 42 are among the silent codes that don't light the cel.

If you go to GM 93 manual and read complete dtc 16 info, you will find that for either dtc 16, low res pulse missing, or dtc 36, high res pulse missing, that other pulse must be present for code to set. If dtc 16 sets, high res pulse must be present. For dtc 36 to set, low res pulse must be present.

So if both low & high res pulses are absent, no code will set. Another reason to have a scope for testing.
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post #8 of 10 (permalink) Old 10-02-2018, 09:56 AM
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Quote:
Originally Posted by Jeremy Moen View Post
Then after the gauge was all installed, I try to start the car and it started for maybe 1-2 seconds and then died. After that, all she will do is crank, maybe get a little fire every once in a while. Not very often.
was one of the new gauges oil pressure?
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post #9 of 10 (permalink) Old 10-07-2018, 08:40 AM Thread Starter
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Quote:
Originally Posted by BALLSS View Post
was one of the new gauges oil pressure?
No, just boost.

But, success was had. I put a new MSD cap and rotor on there, and a 8226 drop in coil for good measure, and the ignition seems to be up to par. Kinda strange it would just not start before I had other telltale symptoms of failing ignition. Oh well. It's fixed.

I have some tune issues with the barometric reading update but at least the car is running / driving.

Lesson in all this: don't ignore the basics even when it seems like it just couldn't be that (spark in this case).
Second lesson: crappy bulb style spark testers really are not worth anything. They don't tell the energy in the spark very well. It can give a false positive. I got the adjustable Lisle unit from Advance and it works great.

Thanks all for reading and throwing ideas out there.

J. Moen
91 Camaro Road Race American Iron car - The Menace
91 Camaro RS - '93 LT1/T56 swap project, 10.5:1, 224/224 @.050, 60lb Deka, home ported heads, 78mm Vs Racing, intercooled, 2 bar MAP tune on $DA3
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post #10 of 10 (permalink) Old 11-05-2018, 08:01 PM
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Vats issues? My 93 z28 is having vats issues. Its a nightmare. I'm not sure if that's your problem but its pretty common
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