rmike06

ok so i swapped out the 5.7 with a rebuilt lq9 block and got it all in and now it wont start. it cranks, but wont fire. im not getting spark or injector pulse. i have checked all grounds and fuses. the coils are getting 12v input on the harness, but not sparking. i can also unplug and jump the pins on the coil plug and get 12v with the multimeter on the hot and grounded on any of the other pins in that connector). Also, no injector pulse when checked with a noid light. when I turn the key and try starting it the rpms are only reading like 5-6 rpm on my scanner and occasionally jump to like 25 rpm for a second and back dowm (from what i have read it should be 100 or more rpm). i have tried 3 different crank sensors all with the same issue, so its not the sensor itself. i took a volt meter and checked the power going to the crank sensor and i have 12v, but im not sure how to check the other 2 wires on going to the sensor. i think either the reluctor wheel was messed up when it was reinstalled during my rebuild, or my pcm is bad. does anyone have any ideas? what can i check?

the setup is
lq9 block that i had rebuilt from local shop
799 heads
fast 102
233-239 .600 lift tsp cam
everything is pretty much new but the cam sensor (which is plugged in and was working in the old ls1 block)

rmike06

Well today im go in to try to check the other wires going to the crank sensor. I understand that one other wire is ground and one is signal. The ground is easy enough to test, but the signal wire all I can do is run a continuity test from the ecu pin to the sensor plug to make sure the wire is in good shape. I dont think I am going to have any luck as it is getting a constant reading of 4 to 5 rpm while cranking.


Again does anyone have an suggestion? If its the reluctor wheel that's expensive and time consuming, if its the ecu the 98 ecus are super expensive. The only other thing I can even think to do is probe every ground wire coming out of the ecu and checking to make sure it has ground against the block.

With the fast 102 on the car I have no way to get to the cam sensor to vwrify anything. And pulling that intake sucks because of clearance issues. If the cam sensor is bad or has faulty wiring would is show these same issues? Its a 98 only ecu.

rmike06

i have narrowed this issue down to the ecu. i am working on getting a replacement if anyone has one. will it need to be flashed to my vin to even to run? and or can i just put a resistor in ignition wiring like i am bypassing it to make it work? again it is a 98 only ecu

LilJayV10

iTrader: (39)

How did you determine it's the PCM?

rmike06

i have triple checked all wiring. Tested for signal and continuity on the crank sensor wiring as well as every ground for the PCM. The PCM gives me crank signal even when I understand plug the sensor. If I take the sensor out of the block and plug it in and wave metal in front of it, I can't get it to give me injector pulse intermittent, but the readings on my scanner for rpm act all kinds of funny, and will get stuck at whatever number and just sit there for extended periods of time. It appears to me like it's a software or corruption issue in the PCM. But all the other sensors do give me good readings. Do you have any kind of input or other idea? I am very frustrated with this car.

rmike06

For instance, I hook everything up and try cranking it. I get a reading of 5 rpm. And it just sits at 5 rpm. Even when I stop cranking it it reads 5 rpm, then I will unplug the sensor from the harness and I still get a reading of 5 rpm til I shut the car off. Inorder to get it back to 0 rpm the car has to be turned off with key in off position or out of ignition.

RonSSNova

iTrader: (3)

I would check the signal line in the harness. You said you have the ground and the 12v. Measure the other pin with your DVM in ohms to ground with the ign off. That harness runs near the bellhousing. I had a car come into the shop that had the trans replaced. When they put it back in, those wires got between the bell housing and the block.

Also, I have a stock 98 Camaro PCM for a 4l60 trans.

Ron

rmike06

update for anyone who has this issue in the future. it was the reluctor wheel. after weeks of scratching my head i came to find out my engine builder who did the short block for me used the wrong crank/ reluctor wheel. he put in a 58t reluctor wheel when it obviously needed a 24t reluctor. now the engine is in, and im really not wanting to take it all back out and tare it all back down, so i guess i am going to use the converter box and change out my cam sprocket and timing cover to a gen iv. this really sucks. expecially because i have a fast 102 and its a bitch to pull but i have to to even be able to get to the cam sensor in the back in order to convert everything.

RonSSNova

iTrader: (3)

Shoot, I was going to ask that question too!

Good find. The converter box works fine. Much easier than yanking the engine.

rmike06

ya the only problem I have is with a fast 102 it's damn near impossible to get the intake off to get to the cam sensor. So I may try to drop the cradle to see if I can get enough room to reach back there or at least get me the room to take the intake off.

So, this block had the provision for and s cam sensor in the back. There is no way it had a 58t wheel from factory, right? Someone obviously put this crank or reluctor in it, right?engine builder denies doing any wrong doing and says that was the crank in it when i gave it to him. I did buy a used long block someone had abandoned a project on, so it is possible I guess, but very unlikely. I made sure it had the right sensors but I did not check the wheel itself.