A little background. I replaced the original LT1 with a 396 last month and finally got 42# injectors installed Friday night. It was running and idling just fine in the driveway so I decided to go drive it for the first time on the street, and it just died at the top of my driveway. Fuel pressure is at 50#s and the opti on it now is the one off my original LT1 (the other one was new). It cranks over just fine but no bang

I've replaced the Opti, and ignition control module and it will start if I put the accelerator to the floor, but it won't continue to run.

Update: Replaced all of the ignition components, now including the coil, and cleaned all the plugs. I've reprogrammed the PCM with the same file it was running on previously and it doesn't hiccup at all while programming.

Car still does the same thing...cranks but won't start. Occasionally it will try to backfire out the front. I'm losing my patience now and don't really know what else to look for.

Looking for ideas....

Thanks

Matt

 

Valves adjusted correctly? Vacuum lines and air intake on snugly?

Those are my first two checks.

 

I'm assuming the valves are adjusted correctly, since it was actually running before it died, unless its possible I lashed them a little too tightly, but there doesn't seem t to be any excess noise from the valvetrain.

I'll check the vacuum lines tomorrow to make sure.

Thanks

Matt

 

It could be that the lifters pumped up after your first start and now are holding the valves open.

 

Typically when the engine fires when the throttle is pushed to the floor, that means you have too much fuel. The PCM will go into what's called flood mode and decrease the fuel. The first thing I suggest you do is smell the oil for hints of fuel. This is an indication you have fuel and probably too much of it. The next thing is check for spark at the coil and then a couple of plugs. Triple check the wiring is ok (no bent pins on harnesses) and that everything is connected (plug wires)to the correct spot. I don't expect crossed wires but you could have a loose or disconnected wire.

The next thing to check is the fuel pressure when the engine is shut off. See how fast it drops. This can also be an indication of leaking into the intake. If you have an aftermarket FPR, pull the hose and see if the vac line is wet. Aeromotive FPR for example suck and leak all the time. Particularly before the design change with the new diaphragm. In my opinion, the new one sucks worse since it doesn't fit on the fuel rail correctly but that's getting away from your issue, sorry.

If your still not starting, check some plugs for spark, if they are getting wet and then do a compression test or leak down test.

The last thing to try is cranking it over as you squirt fuel into the intake. If it starts up then and shuts off when you stop squirting, you have not enough or any fuel supply. Check pressure again while cranking.

 

Well, I've checked the vacuum lines, and they all seem ok.

Checked the Fuel injectors, and they aren't leaking, at least just by turning the key on. I pulled the fuel rails off the intake and turned the ign on, and none of the injectors sprayed fuel all over, although the pressure doesn't stay up very long, and drops back to 5 lbs or so fairly quickly.

I pulled one valve cover off and the valves are all functioning at least on the drivers side. Getting ready to pull the passeger side. On all but one, I can turn the pushrod by hand still (Comp R lifter, and Comp Cams 1.6RRs and hardened pushrods).

I'm also thinking of putting my stock coil and Ignition control module back on to test for good measure.

When I did try and start it, it still wanted to backfire.

I'm starting to wonder if the cam didn't jump, but I thought I would have heard that, and it would cause worse problems.

Thanks

Matt

 

So did you fire it up the first time w/ the original / stock ICM? I used an aftermarket ICM that was broke from the day I bought it. I didn't figure out what was wrong until I diagnosed everything else possible. I finally caved and bought one from GM. Car fired up like it was never broken.

 

When I first fired it up, I was using the stock ICM, stock coil but a new Opti spark. I've since changed the Opti to my old one which was working fine on my original engine.

Its odd, because I used the stock injectors, and it ran fine, changed to the 42# injectors and it ran fine while sitting in the driveway.

I may have to return this ICM and get one and a MAP sensor from GM.

 

has anyone mentioned VATS yet?

crank but no start may point to vats, security light on or off?

just a thought

 

Vats is off. I've been watching the security light and when I put power back to the battery and went to start it last night the VATS light came on the dash and stayed on, even with both keys. Finally let it sit and tried the other key and it worked fine.

Would VATS just cause the car to die while driving/running?

 

VATS could cause all your are mentioning. Is VATS programed out in your PCM or do you have the ability to program your pcm? Something like tuner by cats it is 1 mouse click. May be worth a look??
If you can download your .bin file with any number of free or demo programs and e-mail it to me i can turn off vats and e-mail it back???

 

I have LT1 edit. I'll have to look at the program tonight.

Edit: Quick Question

Would the Security light be on if VATS was prohibitting the start of the engine?

When trying to start wouldn't the VATS light be on? (its not when I'm trying to start it)

Thanks for everyone's help and responses.

Matt

 

Get it running yet?

 

I wish.....

Anyway...I programmed the PCM with a different program, not my stock one, but one of the first ones that was modified, with different injector constant. Still the same thing.

I'm starting to really think its a wiring issue now