LS1 Cranks, but doesn't start
 

Hey everyone.

I'm finishing up a LS1 swap into my 91 Camaro.

I've got the 91 harness and LS1 harness peiced together using the instructions found through searching here and TGO.

Right now, when I turn the key forward, the fuel pump is priming. When I turn the key all the way, the starter cranks. However, I'm not getting any fuel or spark from the computer.

I've checked the positive and ground wires on the injectors and coils, both are working. The test light stays positive on them as well when cranking, so they have always on power, not something disrupted when the starter kicks on.

I had a guy with HPTuners come over last weekend and scan the car. It was throwing a 1626 code, which ammounted to VATS fuel enable. We disabled that in the Trouble code section and programed the ECM. Same effect.

Any clue as to why this is happening?

you need to turn off VATS.

under the system block, theres a dropdown (Hptuners version 2) or radio buttons (HPtuners version1)

it needs to be set to none.


right now, VATS is stopping you from starting the car.

Do you have any fuel pressure?

Good info Mr Dude, I actually dont have HPT yet, and that guy probably won't come out again, so I guess I'll have to buy it. Do you have any idiot proof instructions on how to completely disable VATS? Assuming the newest version since I'll be buying it.

Rybar, I pushed in the fuel pressure spindle on the front of the fuel rail and fuel sprayed out....havnt had time to hook up my digitial fuel pressure guage yet, but I know there is at least enough fuel to make it sputter if it would command the injectors.

Also, I dont know if this matters or not, but I did a head and cam swap on the motor while it was out....could this have anything to do with it? I read a little the other day about no start conditions and some people were suggesting to check the Cam and Crank sensors....and something about a relearn procedure.

its pretty easy.

click the system button (upper arrow in pic)
in the window that pops up, change the VATS selection to none (lower arrow in pic)

If you don't want to buy HPTuner you can build or buy a VATS simulator.

but of course that turns out to be a waste of money anyway since theres a ton of codes you need to change, and a bunch of other stuff that should be done in the PCM anyway...

for example, fuel tank pressure, Evap, fuel level, fan settings, rear O2s, cat efficiency, EGR, AIR, ect.....

Why did you assume that? I'd be happy to come out again to get your baby cranking.

Today good for you?

Looks like Edit -> System -> General -> VATS.
Set to None, correct?

It's just finding the damn thing you have to turn off that's the problem, and now that I know where it is, we can disable that in a jiffy.

(I wish HPTuners 1.7 help files would find VATS when you did a search...)

Rock on Todd, so it sounds like you know where to turn it off now. We will have to give it a go.

As for doing this today, I work overnight, so I need to catch some Zzz's.

Like I said before, Ouiji was nice enough to come out once and give it a look, unforunatly my parents only have dial up so we were unable to find any good answers on VATS.

Thanks again for helping MrDude, your a stand out guy. :D

lol, dont thank me until it starts... :jest:

It does not say but I'd guess this to be a 555 chip??

:confused:

Give me a call about your weekend plans and I'll see when I can get out there again.

Yes, a 555.

Sounds like a very similar problem my friend Paul is having... we've both got Baker modules to disable the VATS, difference being that my engine starts and his doesn't. We've tried hooking up my VATS module to his engine but makes no difference.

Hey guys, thanks for all the help so far. Todd came out again today and we disabled VATS as suggested by Mr Dude. Since I have Todd to help me out, we didnt do the simulator.

After turning off the VATS, and undoing the ECM code changes, the 1626 code is no longer. So I'm 99% sure the VATS is now disabled.

Problem is, car still doesnt fire up. We took some time to check the wiring diagrams, and using the test light. Both the injectors and coils are getting power and ground, just nothing on the signal wire. One kind of odd thing I did notice on the injectors. I put the test light on the constant, tan, wire and put the test light on...depending on which post of the battery I use, I can bridge the wire and injector starts spraying. Then when I turn on the ignition to the car, it stops spraying and to make it spray again, I have to change batter posts. Seemed kind of weird, dont know if that might show what kind of problem I have.

But in summary, VATS is disabled, the injectors and coils are getting power on the right wires, and grounds on the correct wires, but still nothing on the signal wires.

Any ideas?

I also hit the menu option Advanced -> Rewrite VIN/TunerLock/VATS just to make sure that wasn't an issue.

I also re-wrote the entire VCM with a config file from the donor car the motor & PCM came out of. (I had a copy of the BIN file from some edits I did for the previous owner a year ago.)

the next step would be to hookup a 'noid light and see if its firing the injectors.
you cant test injectors with a testlight.

Ok, I'll do that today...

Any clues on why I'm not getting spark?

Just thought of this. The only code his car ever throws anymore is:
"452 - Fuel Tank Pressure Sensor Circuit Low Voltage"

We set it in "Edit -> Engine Diagnostics -> DTC's" to SES Off and 3 - No Error Reported.

Would that have something to do with it?

first id confirm that you have power to the coils and injectors.

each bank has one wire in the harness that feeds the injector power and coil power for that bank.. double check that one.

while you're at it, i would double check all power connections. including both the ignition and constant power to the PCM itself.


if the noid light doesnt flash, crank the car while looking at it in the scanner... see if it even sees the engine turning.. if not, check the crank sensor.


theres something in there stopping you, just trace it back one logical step at a time...
my first guess now would be the power feed, since that is the only thing that kills both spark and injectors... make SURE that your chosen powersource has power WHEN CRANKING... that could be the issue right there... alot of the circuits are disconnected when you are cranking the car.



no, i have that turned off on mine too..... i dont have a fuel tank pressure sensor..

if you want, you can email me his bin (or hpt file) and i can look at it... im no expert, but i could compare it to mine... my email is MrDude_1@excite.com (theres a _ between dude and 1 that you cant see when its underlined)