HELP cranks but won't start
 

I have a 05 5.3 that I topped off with the FITECH Ultimate LS kit. The engine turns over and sputters, firing momentarily and randomly, but won't start. I have checked the injectors and they seem to be pulsing, there is spark, and there is plenty fuel pressure. This kit literally hit the streets last week and there isn't much tech support other than the company itself, so just trying to eliminate other possible issues before I sit on the phone with tech support for two hours tomorrow. Thanks!:read:

Do you have crank sensor signal? Let us know how you make out with that kit. I am looking to use that kit in the future.

I have a new delco sensor for the crank and cam. I know "new" doesn't mean much but I am getting an RPM reading while cranking on the controller so I assume that means it is reading the crank sensor. I checked injectors with a noid light and they all seem to be pulsing and am obviously getting some spark because it wants to backfire almost every time, making be believe it's out of time. I am not sure how to test if the fuel and spark are in sequence or not. Fuel pressure, voltage, etc are all good.

I would verify if the ECM is configured correctly for the equipped trigger wheel on the crank. There are different tooth count reluctors that get used in different ls applications.

Yes the computer is compatible for both 24 or 58 tooth wheels. The engine has a 24 tooth and I have set it to that in the computer. When I switched it to 58 just to try it, I did not get any firing. With everything I have tried, I am thinking its software

Have you checked base timing?

Does anything happen if you give it some throttle while it's cranking?

I am not sure how to check base timing other than when I installed the timing chain and sprockets you line up the sprockets via the marks on the sprockets themselves. I have opened up the TB a little while cranking but seems to want to backfire still with more air flow.

With a timing light.

Haha well yeah.... I mean I think that's self explanatory. I meant how can I verify if my injectors and coils are firing in time? If I hook a noid light to the injector plug and a timing light to the plug wire should they flash at relatively the same time?

I am wondering what your solution was? I tired to fire my fitech ultimate efi 750 hp version on my 2004 lq4 6.0 with gm performance ls3 heads and comp cam. I cant get it to start and it is back firing through the intake. I already confirmed with fitech that the coil harness are on the right way. I have swapped out cam and crank sensors with ones from a running 6.0 with no luck. I know it uses the 24 tooth crank sensor but tired it on the 58 tooth setting just for fun and still no luck. The engine has never ran before. My next move is to pull the timing cover to verify cam position is correct but the engine was built at a shop with a good reputation so I don't expect to find anything wrong there. I am out of ideas. HELP? :ripped:

Try unplugging your cam sensor and leaving it unplugged while you attempt to start it. Also make sure you have the two red 12v wires on a solid 12v source and the switched 12v wire cannot have any voltage loss during cranking or it won't start. If it starts without the cam sensor plugged in it means the sensor is failing or failed. It should run in limp mode without it plugged in. Also make sure you open up your TB blade via the set screw a couple turns, it's completely shut upon receiving the kit. If it fires at all then it is not your crank sensor or timing. The crank sensor tells it when it's on 1 and it fires and then the cam sensor pretty much immediately takes over. Make sure your sensors are black and not gray as well, gray is 58x sensor.

Also make sure you have the correct calibration. Go under initial settings and make sure it's on 24x... even if you upload the 24x calibration it defaults to 58. Make sure to send to ecu after changing each setting then go to dashboard and key off to save all settings.

Did you get yours running ? How is the fitech kit?

Thanks Joe

I actually sold mine and took a $300 loss. I got about 150 miles on it and it started stalling every time I would put the clutch in or come to a stop. I had programmed out all fuel cuts and even upped my loop rates for IAC opening and everything and they couldn't explain or find a fix for that. On top of that it was just not tuning well and they told me it was my fault because I had "too big" of a cam. I have the texas speed 224R cam which is not a huge cam. I was tired of the back and forth and waiting on hold for 40+ minutes each time only to have them tell me they would have to consult a tech. I believe they have a good product, but being that you can't plug it into a laptop and tune the thing it just wasn't for me. Seems the stock motors and forced induction don't have much of an issue with them though.

I ended up ordering a Vr Jr with multi port and 4150 TB with a factory ecu and harness. Should all be here later in the week and hitting the dyne for a tune in the next week or two.

Thanks for the review and good luck with your new setup.

I was gonna suggest cam sensor too!

Just an update. I got the fi tech ultimate ls 750 to run. Turns out my problem was the coi harness was backwards. Sounds like a simple problem but this one one of the first things we thought was wrong so we called fi tech and they told us what wires should be in what position. After confirming ours was correct with what they said we checked and e checked every singe other solution that anyone could come up with. We swapped the harness out of frustration and she lit right away. Turns out fi tech didn't know what way to install there harness. That being said so starts and runs good now but I don't have any miles on it yet. About 2 hours of ideal time logged so far. I have a few items left to button up then it will hit the highway this weeeknd. Thanks for the help

Also FYI this kit will run without the cam sensor even being pugged in. It has a built in limp home mode as where if the sensor fails the computer will give itself a false signal so it ill run good enough to get you home.

Any updates on the fitech kit?