Hi everybody. I have been watching here for a while and since I am currently trying to finish up a Pro Touring Firebird build with an LS427, I figured it is time to sign up and see if anyone here can help me solve my problem.

I have the GM LS427/570 engine with the 6L80 transmission connect and cruise package in my 70's Firebird. I am not a tuner, and I bought the package so I wouldn't have to get into software tuning and diagnostics etc.

I have everything connected and can start the engine on the key, but it cuts out immediately. I wondered if it was fuel pressure, but if I leave the starter engaged (accidentally) for an extra second, the engine keeps running, and will blip on the throttle, until I release the key back into the regular run position. It feels to me like the power is turning off as soon as I release the key. I have tried swapping the pink wires (Painless wiring kit with an Ididit column) but to no affect. It feels like the power sent to the unit is good when I engage the starter, but shuts off when I release the key. I have checked and double checked my grounds.

I read that it could be VATS, but why would GM program the connect and cruise package with VATS when it is supposed to be factory setup to run its a stand alone system in old vehicles, and I have no way to check or deactivate that system.

Anyone have any experience of this?

Thanks. Trev.

 

You've narrowed it down pretty good, I would agree uts either vats or losing power to the ecm. I would take the small wire off the starter so the key doesn't energize it, make sure to wrap it in tape so it can't ground out on anything. Then have someone hold the key in the start position while you energize the starter by jumping 12v to the small lug on the starter, when it starts remove the power from the starter. If it runs great like this then the ecm is losing power, or the fp ignition or injectors. If it still dies after a few secs I would lean towards vats.

I've never messed with the connect and cruise systems, but I also don't think they'd have vats on it. Thing slip through all the time tho, good luck and let us know.

 

This sounded like a great suggestion, so I rushed out to the garage to give it a try. It didn't work, but I did notice something odd. Normally when you engage the starter, the dash goes dim? But, with the ignition held in the starter position, and the starter not engaged, the ignition appears to switch everything off. Is this normal, or is it an indication of a problem in the ignition wiring?

 

Definitely interesting. So did it do the exact same where it would fire then die or what?

 

Yes, exactly the same as before.

 

Sounds like a vats issue then. You have eliminated anything only getting power when its in the crank position by keeping the switch in the crank position. Know anyone with a scanner or hptuners/efilive? Maybe go back through the instructions again, I would have guessed vats wouldn't be active with it being designed for a swap. But stranger things have happened

Really need someone competent to scan it and see what it's saying. Could easily be the maf wigging out or alot of other things.. where in the country are you located?

 

I contacted th company that made the steering column yesterday, and they walked me through some tests that did not fix the problem, but convinced them that the ignition switch was faulty, so they are sending me a new one. I should get that by the end of the week, I will let you know what happens when I install that.

Thanks for the help and suggestions. It is difficult building a whole car on your own. I am in Sarasota, Florida.

 

It sounds like you are losing power when it goes into the run position. I don't think it is vats because it would run for a few seconds in the run position before turning off. Sounds like steering company has figured out your problem of no power while in run position.

 

Changed out the ignition switch this afternoon, but no improvement. Car still will not run.

 

You gotta get somebody with a scanner to see what the ecm is saying. Not likely you got 2 bad switches, and if you're 100% sure it's wired correctly that is the next step.
edit- doesnt look very far from Sarasota to Bradenton, I know fasterproms is around there some where. He is a stock pcm wizard. Dr. Tuneemall is around there also edit2- he is in Palm Harbor he has a Facebook and Instagram. If you don't have any buddies with the capability may try to contact 1 of them.

 

Bought a code reader. There are no error codes.

Double checked my wiring. Pink 931 from Painless takes power from the Ididit ignition (also pink) wire.

Pink 920 from painless connects to GMPP pink wire.

Volt meter on pink 920 verifies that 12 volts is present at ignition run and start. Had my daughter turn the key to watch the voltmeter while turning over the engine.

Removed all 3 ground wires from the back of the engine, cleaned them with acetone and relocated them to more accessible side of engine bolts.

Ran a 10 gauge ground wire from the battery (in trunk) to the front of the car and directly connected to the ecm ground wires.

Bled a little fuel out of the Schroeder valve, then again with ignition on (pump running) to verify fuel pressure.

Ran a jump wire to the pink (920 and GMPP) to bypass ignition switch.

No change. Engine fires initially, but will not continue running.

 

The grounds from the coils packs NEED to be on the heads.. Just my limited experience..
Your primary ground cable off the battery should be connected to the engine, not through the chassis/frame.
The stock GM harness has 1 large ground to the engine and one smaller ground to chassis/body,
and has a primary hot to the starter and a smaller + to the power distribution block.
I would build some "noids" use cheap sockets and some small indicator bulbs to tap circuit to ground on the
key parts of the harness so you can see that there is power to each set of stuff that need primary (Key on) power.
Fuel pump, ECM, Injection harness, coil harness, Key on power and "starting circuit" power.

You might try a copy of Torque on a phone with a blue tooth dongle in the OBDII port.. A little log data never hurt.

 

Thanks. The connect and cruise harness has 3 ground wires. I have them connected to the cylinder heads. I also have tried connecting them directly to the battery and have additional ground wires connecting the engine to chassis which is welded through the entire car. If there was no ground connection, I can't believe that the engine would run at all. But it definitely runs for a second or so. I have checked and rechecked my wiring using a volt meter. I am confident that the quality of my wiring and connections are good. Voltage is there on ingestion and start. Everything is new, not dealing with an engine or harness pulled out of an old vehicle. I also believe that GM builds robust systems, so for the engine to be failing so consistently on a bad ground or weak connection doesn't make sense. I have probably tried to start the car 200 times now. Every single time it does the same thing. Fires up, then dies immediately. I swapped out the Ididit ignition switch, because they diagnosed that it might be faulty, but no change. Because they sent me the wrong length switch, I have spliced the original switch back in again so that I can reassemble the steering column. Something fundamental is wrong here but a code reader is not suggesting any issues. I am not sure how useful a code reader is, would it tell me if a HEGO or TPI sensor was not working? I am putting my car back on the lift to work on some other areas as I need to walk away from this issue for a while. 3 weeks trying to diagnose this is driving me up the f*****g wall.

 

I can't tell you how pleased I am to say that my engine is running. Turned out that the bend in the rubber tubing ahead of the MAF sensor was so tight it was causing a vortex and the air was not flowing through the sensor. I pulled the tube off on the advice of Jason at Gandrud Chevrolet (the company that sold me the engine & trans package) and the thing fired up immediately.

Thanks to Jason, and to everyone else that has input help and ideas. Now all I have to do is redesign my intake system.



The guilty tube bend is the one at bottom left. When I took it off for a closer look, there is a sharp molded edge on the inside of the bend where my finger is.

 

Glad you found the problem.
Maybe lose both the rubber 90 degree elbow and the straight rubber section? Weld in a alum 90 degree elbow and join the straight sections via welding. Have it welded by someone who can weld "pretty" then have it polished?
I've purchased intake stuff from intakehoses.com. They might have a 90 that's long enough that you won't have to weld the two sections together.

 

That's awesome bud, I had a similar problem with my first build with a coupler just like that except 2.5". It would almost stall when I gave it throttle because the elbow was getting sucked together and killing the airflow. That's for letting us know!