hazard2k

iTrader: (10)

So heres the basics, I swapped a 99 LQ4 into my 85 monte carlo ss. I modified the stock harness myself, and the only thing I've done tune wise is eliminate the VATS and do a 'write entire' with HP Tuners.

When trying to fire it up for the first time the other day, it started up almost instantly and I let it run for ~5 seconds or so until I saw that I had oil pressure, and then I turned it off because I didn't have any coolant in her yet.

Directly after that I decided I wanted a video of it starting up so I whipped out the phone and started recording, however the car won't start now. (Warning, the car buzzer is kind of loud at the beginning).

If I let it sit for a couple hours I can get it to do that again, but then it just cranks and cranks without any hint of trying to fire up.

Things I've checked:

• I have 58psi fuel pressure at the rail
• I have injector pulses with a noid light attached
• I have manually grounded the injectors and have heard them clicking
• Spark is good on all plugs
• Flashed the PCM again to ensure VATS was turned off
• Valve cover taken off and watched the valves moving while cranking

Where do I go next? It seems very weird to me that it fired up and ran fine the very first time, and now I can't get anything to happen.

B52bombardier1

Will it start on a little starting fluid shot through the throttle body? I don't recommend this stuff as a crutch to start an engine because its tough on the cylinder wall oil film. But it is a very good diagnostic tool.

Rick

hazard2k

iTrader: (10)

Good suggestion. I did try that actually with no different results.

mytmouz

iTrader: (2)

How long has the engine sat? I installed mine, and it did that. The ethanol gas had sat in the injector rails for a bit, and the resulting gunk clogged the injectors after a few seconds run time. I checked and chased everything for a while before I found it...

hazard2k

iTrader: (10)

The engine was sitting for around 2 years or so, but the intake/rails were off. I suppose the injectors themselves could be gunked up though. Maybe my next step will be to throw them in the ultrasonic cleaner for a bit to see if I can get them cleaned up.

hazard2k

iTrader: (10)

So updates, I cleaned the injectors and even swapped in a different set I had and still nothing. I can't even get it to fire up on starting fluid.

I hooked up my fuel injector noid light and also the spark tester on the same cylinder and found them to be firing almost at the same time. This seems very weird to me. I'll see if I can record a video of that tonight. Is it possible that the spark is firing at the wrong time? What controls that? Crank sensor, or cam sensor?

ElQueFør

I wish I could help more. But I will mention this as far as testing injectors. I built a flow bench which is an awesome tool for that. But what I have also done is pop the fuel rails out of the intake, and hit them individually with 12v and observe what they are doing. Found a few problem injectors this way before I built my flow bench.

Definitely sounds like a spark issue at this point though.

JoeNova

Pull the plugs and check them.

rpturbo

iTrader: (47)

What was the status of the fuel system of said car? Did you just pump a bunch of garbage into the injectors when you did a initial startup?

hazard2k

iTrader: (10)

The fuel system is all new braided - 6an line and fittings. I'm running a new billet fuel rail and the injectors only have 20k miles on them. I flushed the lines before doing final hookups as well so I don't think it's a dirty fuel issue at this point. The fact that I can't start it on starting fluid tells me that I have a spark issue of some sort. My spark tester shows I have strong spark on all the cylinders though so I'm at a loss.

hazard2k

iTrader: (10)

Just as an update/resolution to this.. After beating my head against the wall I finally did a compression test and found all of the cylinders very low (60-80 psi). I pulled the timing cover and found that somehow I had put on the new timing set a couple teeth off. I still have no idea how I managed that. I've put on dozens of them before. After fixing that, the motor fired right up and idles great. Good thing it was still the stock cam in there as it probably would have had some interference if not. Moral of the story is don't trust anyones work, not even your own!