jmoli42572

Hey guys first time posting thought you might be able to help me out. I have a 69 Camaro and just put a 2001 F-Body Ls1 in it. I have 55 lbs of fuel pressure at the rails and the fuel pump runs when the key is first turned on and while the engine is cranking.

Constant 12 volts and keyed hot to the computer are correct. The problem is the injectors and coils are not firing. I have tested the main coil connector and an individual coil connector and get 12 volts at each. I also get 12 volts at the injectors both have been testing while cranking and voltage does not cut out. I just don't think I am getting the signal to fire the coils or injectors.

I get 11 volts at the crank and cam sensors, the book I have says 10-12 volts is normal. I have done voltage drop tests on all connectors checking ground and hot sides and have not found a voltage drop anywhere. Car has numerous grounds so I don't think grounding is a problem...the grounds all looked good when tested. The computer was programmed by Painless Performance which is where the harness came from as well. At the Painless fuse block everything checks out fine with no voltage drop. VATS was supposedly turned off.

The only codes I have are P0342 and P0122 for cam shaft and TPS sensor low voltage. The TPS is supplied with 5 volts power, I haven't had a chance to check the output yet. I ordered a new crank and cam sensor but they haven't arrived yet.

From what I have read if the camshaft position sensor is bad the engine will still start? I think the computer is picking up that the engine is cranking because the fuel pump runs while cranking. The alternator and the belt are not on but I can't see how that would effect anything. Everything seems right, the O2 sensors even heat up with the key on.

Getting frustrated any help appreciated!!

rfrankb4

can you plug up a scanner to see if you are getting RPM reported while cranking?

It is probably not a VATs issue since those most of the time cut out fuel shortly after starting but I would double check it anyhow since it is easy to check.

I would also take a spark plug and have it out where I can see it spark to a header and check the injectors for ground signal with a voltmeter.

If both systems are non-functional I would suspect that the computer cannot see the revolutions properly.

LS1MCSS

iTrader: (18)

Have you checked to make sure you have 12 volts going to the coils while the engine is cranking? A common problem is people connect the 12 volt source to a wire that's hot with the key on, but when they crank the engine, that wire loses power. It would actually be an accessory wire, not a power wire.

jmoli42572

I do have 12 volts going to the coils and injectors while cranking, I grounded a spark plug and no spark, I also tried to verify spark with a timing light. All I have is a cheap code reader so I cant verify RPM. I did hook up the tach and it does flutter when the engine cranks. I think the computer is seeing some type of cranking because the fuel pump runs while the engine is cranking. Thanks for the help.

rfrankb4

This does seem odd. I would start thinking bad computer.

Who did your wiring harness?

Who programed your computer?

Do you have a wiring diagram for the computer so you can use the ohm meter at the computer to see if the computer is sending ground to any of the coils or injectors?

can you check resistance across the relevant wires to make sure they are not cut somewhere.

jmoli42572

Painless harness and had them program the computer. That is my next step is to make sure the signal is reaching the computer. I think I might try the cam and crank sensors when they arrive.

rfrankb4

Have you called Painless. For the cost of their set up they should have good support.

jmoli42572

Support is just ok, they told me to change cam sensor since it is throwing the low voltage code and to hook up o2 sensors

bmf5150

Vats???

jmoli42572

Talked to programmer that specifically worked on my PCM, he said that he completed everything I asked including removing VATS. From what I understand it should still start but only run for a couple seconds if VATS is enabled.

TS99SS147

Did the motor sit for a long time before installing? I have had a couple with stuck injectors. Did you try a set of noid lights to see if injectors were getting a signal?

jmoli42572

Motor did sit for a couple years but I took off injectors and ran injector cleaner through them with compressed air. I used a connector off an old harness and a 9 volt battery to get the injectors to open to run cleaner through them. This was done with the injectors off the engine. I can not feelthe injector clicking like they normally do when they open

Thanks

Indyjc

iTrader: (1)

I wasn't getting fuel on my first start. Seems I had the fuel and return lines backwards. Can't help on the no spark. Are you grounds good? Good luck.

jmoli42572

Had the same problem with fuel lines at the filter regulator backwards, I have a pressure gauge on the fuel rail so I know I have pressure. I checked all the grounds and there is zero resistance and no voltage drop. I just got the cam and crank sensors and installed one at a time. Replacing crank sensor yielded no change, I replace cam position sensor and it backfired twice then nothing. Still getting the same two codes coming back cam position and tips low voltage. Next step is checking harness and feeds on harness pins at computer. Still no spark or fuel injector pulse thinking computer or harness issue since I am still getting the same codes. Replacement sensors were both ac deco. Thanks

rfrankb4

My next step would be checking resistance of the wires going to the crank and cam sensor.

If they are not clipped somewhere and they are in the correct pins then I would give this a very high chance of being a bad computer.

Have you checked spark again by putting a plug up against a header and looking for spark.

rfrankb4

Which computer do you have. Is it the Painless proprietary computer?

jmoli42572

The computer is the factory F-body ECM, the engine trans and computer were a complete pull out. I double checked the spark by using a pair of jumper cables to ground the plug..no spark also checked with a timing light. I double checked the coils and injectors and there is keyed and cranking voltage to both just no trigger.

I checked resistance from the coil ground and it is fine. I am getting battery voltage everywhere I check with little to no drop all measurements are within 3/100th of a volt when comparing to battery voltage. The only difference I have is about 11 volts at the crank and cam sensor which Chilton's says is normal. I have checked the harness and can't see any obvious pinch.

I will check to make sure the pins are in the correct position and check resisitance from the connector point to the computer. Very frustrating... the last TBI small block swap I did only had one injector out of two firing and the IAC wires were wrong but it still ran...granted only four cylinders were getting fuel and it ran at 2K...but it still ran. Thanks for all the help.

Intimidator02SS

Try cranking with the TP sensor unplugged. Maybe bad/shorted TP sensor causing it to pull reference voltage down on cam sensor (might share same ref. voltage).

mantycarguy

Since the ecm provides the ground side of each coil and injector circuit You can check to see if the coil or injector are capable of firing by temporarily running a wire to the battery - and each individual coil - with the key on. Removing the wire at each coil should cause a spark to be produced at the plug. Caution, do this one coil at a time. Injectors can be tested the same way. If this does indeed produce a spark check to see if the ecm grounds are ok by doing a voltage drop on the ground side of system.

jmoli42572

It Runs!!! I finally figured it out. I went to pull the computer from behind the glove box and remembered that I had a little trouble trying to get the bolt that holds the large rectangular connector to the computer to thread. This immediately made me think that maybe there was a gap between the computer pins and the harness pins at these connectors. Each rectangular connector that plugs into the computer has a rectangular gasket to seal the connection well it turns out there were two in each connector instead of one so the contacts between the computer and harness were very poor if making contact at all. I pulled one rubber seal out of each connector and it fired right up.

My harness is laying all over the engine so I only ran it for a second..didn't want to burn a wire. I am going to clean up the wiring and see how she runs. I hope to post some pics to help people out. I modified the stock tank for an in tank Walbro pump, notched the frame for the alternator and built a custom crossmember so I hope some of my pics and troubles will help some others out. I am looking forward to being a contributing member. Thanks for all the help.