OK f this car NO START
 

Mods: CAI, catback, TB bypass, cat EGR AIR delete, race LT's, ORY, wideband, LT4 knock module.

Things I've done since issue started: new o2's, new ECT sensor, IAC seems to work properly, douched entire throttle body, new fuel filter, new fuel pump.

Timeline of fucked events:
Spring 2011 takes a few cranks to start fine.
August 2011 return from PR car starts like poo, takes few cranks fires skips and stumbles do death unless I give it throttle at startup, car calms down and idles.

Weeks later me and Pizza tune it with tuner CATS to resolve my outrageous lean A/F mixture (now that I had a wideband) and tune my shift points and speedo for the 2.73 -> 3.42 rear swap.

The morning after the tune car won't start at all, starting fluid fires it right up. Mike fucks with some A/F tables thinking its too lean or rich on cold start. I check my IAC, IAT, and coolant temp resistances and they're all good. Changed a new ECT sensor for the hell of it, and douched the entire oily sludgy throttle body and IAC area. IAC seems to work improperly, only budges about 1/8" when key turned on. So I swap another IAC of a properly working one and does the same.

Last week I tested the fuel pressure, 20psi with key on and 35 psi when running (after a spray of starting fluid / gas.) tracked it down to a bad fuel pump, which I installed yesterday.

Now I have the proper 41psi at key on and 35psi at idle, bumped down by the regulator like its supposed to. STILL NO FUCKING COLD START!!

Its still somehow getting no fuel on startup, I'm getting spark tested that but cold cranking it shows me 41psi, and pull a spark plug and its dry. I'm going to test the voltage going to the injectors... but seriously.

WHAT THE FUCKKKK!?!??!?!



:klab:

Regulator? Or pizza fucked it up lol

Regulator has to be good its 41 psi key on and bumps down to 35psi when it starts.

like its supposed to...

injectors gummed?

Leaky injectors?

Get. Noid light. To see if injection. Is getting. Signal.

flashed STOCK TUNE still no start...

BFH?

Have you tried pulling the rail and putting it in a container and tried cycling they key to see if they are spraying? Its kinda caveman style but youll know if they are working lol I like being able to visually see things work if i can.

^^^ was my recomendation. Its clearly not tune related. And sensor/ecm related. Wiring can also do it. Burnt/shorted wires near the headers?

Was checking grounds covered? Just trying to think of anything simple and easy it might be. lol

VATS

Joe brings up a good point are your keys worn

vats i disabled and if it was vats the car would fire rev and then stall right away. it wouldnt just no start.

I would give this a shot too.

It runs good when it starts.... lol

tomorrow is going to be a decent day of more testing. i didnt bother with it much this week too much school work >.<

TPS?

When my security light just stayed on in my lt1 I got no start when I turned the key.

let me know if you want a hand tinkering on it, im not super far from you.

no melted wires near headers, re-routed them so they're away now, getting 12V key on to injectors and the injectors are pulsing when cranking (made a resistor and LED to see the flashed, quick 2 pulses at beginning then steady pulses cranking), correct fuel pressure key on engine off 41psi, getting spark, and supposedly tune is fine flashed the stock tune and it didn't do anything unless somehow the stock tune got changed. I have no way of checking for DTC's...

So car has correct fuel pressure behind injectors, voltage to injectors, steady pulsing, spark, no cooked wires, new coolant temp sensor, working IAC and IAT, and somehow it cannot figure out how to start itself cold.

Its out of my hands, bringing it to the chevy dealer down the street tomorrow. Time to get the saturn on the road.

:klab:

booo... take it to the lab ya freakin mad scientist!!! lol

I got enough lab work to be getting done lol... Time I should be putting into my school work I'm under my car trying to get it to fuggin start grrrr

no pulse getting to the injectors. cranking it over scanner reads 0 rpm. opti death?

i think if the opti was bad then it wouldnt run...would start but not run..well..?

stop trying to diagnose it and chase th ghost just replace the damn opti already....

read quick95lt1/mikev's post in this thread
http://ls1tech.com/forums/lt1-lt4-mo...-no-start.html

http://www.autozone.com/autozone/par...35554_0_45590_

http://www.summitracing.com/parts/SUM-G5241/?rtype=10

http://www.summitracing.com/parts/ACC-8136/

http://www.summitracing.com/parts/SMP-DR473/

http://www.jegs.com/i/JEGS+Performan...40461/10002/-1



I'm sure there's more, but it's a start... lol

DON'T start throwing optis at it, that will get you nothing but a headache and a lighter wallet.

o rpm but you sed you were getting spark? if you have spark and no injector pulse on ALLL of your injectors under crank. then its ecm?

^that...and from some personal expierience i would check grounds

had a truck that would not cold start with out a little starting fluid when it was cold..but once it was warm it would start... noticed a bad ground strap...replaced it then it fired up no problem

^found some stuff on that in this thread: http://www.automotivehelper.com/topic516221.htm

I checked the PCM grounds but I'm going to check others.

You think I should just go and replace the opti? That's foolish. Process to problem solving: locate issue --> fix it, dont just assume what it is (like you and many others hear LT1 issue and call out "woop must be da OPTI LOOL") and go buy a new opti and go through hell to replace it and still have the issue a lot of good that would do.

Furthermore if I do end up diagnosing a faulty opti I'll either replace it with a GM one not an auto zone junk, or dive right into an LS swap. I'm leaning towards saving $$$ replacing opti and using it to do the swap.

I have a spare opti on my shortblock btw to try...
:klab:

well where the hell is he when i need him haahaha. Why didn't he chime in on this!??

just busting bawlz ... but it sure would be funny if it is the problem.



(I also should stop the teasing b4 someone gets upset or something breaks)

camaros and firebirds dont have the tach filter that the vette has.

I thought that sounded new to me... haha I've been through like my whole service manual and never saw anything about a tach filter

just because theres no tach filter doesnt mean he shouldnt check those circuits.

the injectors are NOT getting a pulse... The other day I jerry rigged an LED and resistor to see and it blinked but must have been very low voltage. Used a real NOID and NO PULSE.

http://s3.amazonaws.com/kym-assets/e...jpg?1291495361

myth... CONFIRMED!!! My opti is toast. No pulse going from my opti to the PCM to fire the injectors.

Noid light in and scanner hooked up cranking over no injector pulse and the rpm reading stayed at 0 then randomly hit 193? Strange.. This led me to test stuff that sends signal to the injectors. Tested the ICM, good. Tried heating up the back of it imitating a hot motor with heat gun maybe the ICM was bad and only worked when it got hot. Nope. Wires from PCM, good. Grounds, good. So I got as far as suspicion that the opti wasn't giving a low res pulse or whatever the PCM needs to know to fire injectors. So I got an idea ripped the opti off my shortblock in my shed plugged that opti in grounded it and spun it by hand while cranking INJECTOR PULSEEEE! Noid lit up. So that sucks this concludes that my opti fails to send a pulse to the PCM to fire the injectors and by testing the spare opti I had seeing that it got the signal... How clearer can it get.