New Engine Low on Power
03-12-2013, 11:18 PM
#21
PO756 and I believe PO754 <---- not sure about that one, are the slip codes that will trigger limp mode. Clearing the codes will give you 1st and 2nd back, even leaving the car off for a while (5 min) should bring those gears back. If you don't get them back, it's not limp mode.
03-12-2013, 11:22 PM
#22
Ive cleared the codes and disconnected the battery for about 15 min and it didnt change anything. Im starting to think its a power or ground issue to the trans that is throwing the trans codes. It just doesnt seem likely that all 3 things would go bad at the same time.
03-13-2013, 09:39 AM
#23
You know, come to think of it, the last time I had an issue with something similar, I had bad injectors. Is ur MAF hooked up with the right connectors? Another words, if its a 5.3L, u aren't running it with the 4.8? Idk if that makes a difference but check it. Recheck that the injector connectors are on right and tight. Try jacking up the rear tires putting it on drive and see if it stalls that way. If it does, then it has to be the tranny. Not to mention, I know this is common sense but I have to say it, make sure ur e brake is not engaged.
03-13-2013, 11:06 AM
#25
This may be a stupid question, but does the trans/pcm need an electrical input from the shifter to know what gear its been placed into? I only ask becuase Iam using the factory 1980 camaro shifter setup. There is no PNP switch or anything, just the shifter cable. I just know the 4th gen camaros had an electical switch mounted on the shifter itself and I want to make sure this isnt why Im having this problem.
03-13-2013, 09:34 PM
#26
Well I figured it out finally, the company I bought the harness from screwed up and put the wires in wrong in the main trans connector. Luckily I had a factory harness to compare to. The wires were put in 180 degrees backwards in the connector. I had to removed them all, turn the connector 180 and reinstall them. Everything seems to work fine now. I haven't gotten into 3rd or 4th gear yet but it seems to be shifting perfectly fine. Now all I have to do is figure this misfire out....
03-15-2013, 05:06 PM
#29
So far I have; verified good fuel pressure 58-60 psi, checked the plug wires and coil. Swapped the coil/plug wire and the misfire didnt follow the coil. I used a noid light to check the inctor circuits, removed the coil sub-harness and checked all the wires for continuity/resisance, pulled the valve cover and made sure the valves were opening properly, removed the plugs (#7 is clean and shows good continuity and isnt broken internally) I fired up the engine for a few seconds and touched each header and found that cylinder 7 is the only cold one. So far everything I have looked at checks out fine. The only things I havent done is verified good coil driver circuit for cylinder 7 or checked for a physical clog in the injector. Any other ideas??
03-15-2013, 09:54 PM
#30
03-18-2013, 08:18 AM
#31
If cylinder 7 is cold, meaning it isn't firing, then the connection is either, A) not making contact, or B) a really bad connection. it may also be a really bad injector. Do u have spark out of that spark plug wire? They may also go back to the harness u purchased.
03-18-2013, 10:17 AM
#32
Read this recent thread, the owner of this harness was losing power to a whole bank of cylinders, read the thread and see what was found to be the problem, I'll bet money you have a similar problem with your #7 cylinder missing. Especially after what you found to be with the first problem that you solved with your transmission wiring.
https://ls1tech.com/forums/conversio...pic-heavy.html
https://ls1tech.com/forums/conversio...pic-heavy.html
03-18-2013, 02:27 PM
#33
Read this recent thread, the owner of this harness was losing power to a whole bank of cylinders, read the thread and see what was found to be the problem, I'll bet money you have a similar problem with your #7 cylinder missing. Especially after what you found to be with the first problem that you solved with your transmission wiring.
https://ls1tech.com/forums/conversio...pic-heavy.html
https://ls1tech.com/forums/conversio...pic-heavy.html
03-18-2013, 03:32 PM
#35
I called SSP wiring today and talked with the owner. He told me that the wiring to the coil connector is spec at 22ga (earlier harnesses used larger wire but the newer OEM stuff uses 22ga) and that there may be an issue with the 12v (pink) wire going to the coils. He admitted that in the past they had some wire with too few strands that caused this issue. Iam going to try and run a dedicated wire with 12v to see if it fixes the issue. I have to say after talking to SSP that they are very willing to help out and even offered to bench test the harness for me and replace anything that is wrong.
03-19-2013, 09:51 AM
#36
Well I went through the harness wires (power and signals to coil connector) all the connections and wires were good. Just to be sure I pulled the wires out of a GM harness that I had and ran them instead of the wires that came with the harness. Still no change, miss on cylinder 5. I switched the coil out with one I had and it seemed to not be misfiring as bad. Maybe both my coils are bad?? I dont know what the odds of that are but Im out of ideas at this point.
03-19-2013, 12:46 PM
#37
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Well I went through the harness wires (power and signals to coil connector) all the connections and wires were good. Just to be sure I pulled the wires out of a GM harness that I had and ran them instead of the wires that came with the harness. Still no change, miss on cylinder 5. I switched the coil out with one I had and it seemed to not be misfiring as bad. Maybe both my coils are bad?? I dont know what the odds of that are but Im out of ideas at this point.
