L92 swap gremlins with alternator and VATS
10-30-2011, 11:55 AM
#1
L92 swap gremlins with alternator and VATS This swap is a strange one. Using HPtuners I disabled VATS 1+2 and turned off starter and clutch diag and it fired right up. Great right? Problem is every time I turn it off it only starts back up on 3 cyls. I have to flash the ECM again and then it starts up on all 8 again. The only strange thing Im finding when it runs on all 8 is the alternator takes a few minutes before it begins charging. Its a single wire F-body alternator so I wired it to the brown wire from the L92 harness and left the grey wire unconnected to anything. Also pin 52 yellow/black is also unconnected and Im wondering if either of these two might be part of the problem? Im starting to think the ECM does not like the low voltage from running off the battery for a few minutes and this may be the root of the problem but Im getting frustrated trying all sorts of hack fixes and figured someone here may have already ran into this issue and have a remedy. Sure would be nice if thats the case.
Anyone have any input?
Anyone have any input?
10-30-2011, 01:31 PM
#2
This swap is a strange one. Using HPtuners I disabled VATS 1+2 and turned off starter and clutch diag and it fired right up. Great right? Problem is every time I turn it off it only starts back up on 3 cyls. I have to flash the ECM again and then it starts up on all 8 again. The only strange thing Im finding when it runs on all 8 is the alternator takes a few minutes before it begins charging. Its a single wire F-body alternator so I wired it to the brown wire from the L92 harness and left the grey wire unconnected to anything. Also pin 52 yellow/black is also unconnected and Im wondering if either of these two might be part of the problem? Im starting to think the ECM does not like the low voltage from running off the battery for a few minutes and this may be the root of the problem but Im getting frustrated trying all sorts of hack fixes and figured someone here may have already ran into this issue and have a remedy. Sure would be nice if thats the case.
Anyone have any input?
Anyone have any input?
thought about wiring your alt independently from the harness?
what codes come up before you reflash the computer?
10-30-2011, 01:50 PM
#3
yellow and black should be your starter relay enable control. I dont think that has anything to do with your issue...
thought about wiring your alt independently from the harness?
what codes come up before you reflash the computer?
p0102
p0480 ( dont have the fans hooked up yet )
p0481
p1516
p2176
p1516
Trending Topics
10-30-2011, 11:32 PM
#8
Thanks I'll give it a try. I think Im going to try the hotwire resistor mod temporarily to the alt and start the tune from scratch again with my factory file and clear all the codes and whatnot and try a complete re-write and see if that makes any difference. I appreciate the info though I'll try that site as well thanks
10-31-2011, 03:05 PM
#9
I tried starting from scratch again with my factory file and ONLY clearing Vats 1+2 and the clutch/start locks and same thing. It ran great when I did the first start which I scanned and attached a couple of screen grabs of the codes it pulled but on second start it went to 3 cyl mode again. Blah
10-31-2011, 03:16 PM
#10
TECH Enthusiast
Alternators are wired differently and depending on the wiring and the PCM you need to check to see what you should have. Check the wiring diagram for your particular motor PCM and wire the alternator according to the PCM or change the PCM to how your wiring is. You may be going into a low voltage situation where it is not charging correctly.
10-31-2011, 06:01 PM
#14
No I dont have a spare one sitting around but id try it if I had it. Ive tried everything I can think of at this point. I do see a LOT of posts about these ECM's especially the early ones having grief getting VATS cleared completely off. I even found a couple threads were the HP staff fixed it for a couple of guys but Im getting zilch in response over on their forum. A local friend of mine is a very experienced tuner Im going to email him my tune to have a look at and see if something comes up. Definitely weird
10-31-2011, 06:35 PM
#15
Ufffff I found this thread
https://ls1tech.com/forums/pcm-diagn...e-manuals.html
In particular this post looks like Im in for some good times
https://ls1tech.com/forums/5175701-post4.html
https://ls1tech.com/forums/pcm-diagn...e-manuals.html
In particular this post looks like Im in for some good times
https://ls1tech.com/forums/5175701-post4.html
10-31-2011, 08:09 PM
#16
Scratch that last post that doesnt apply. Ive narrowed it down some. I dont have to reflash the ECM to get it to run on all 8 all I have to do is clear the codes ( which I didnt realize you can do while its running ) and it immediately runs on all 8. The code that its detecting now is P0650 which is SEL error so Im going to look into what that means and why it would have such a drastic impact on how it runs. Fingers crossed
10-31-2011, 09:19 PM
#17
Do you have a working check engine light? I remember having some troubles before I had one hooked up (first test fires) but I can't remember the problem beyond the PCM making a bigger deal about it than I thought was necessary.
Some in depth information for you on that code...
Some in depth information for you on that code...
10-31-2011, 09:26 PM
#19
Do you have a working check engine light? I remember having some troubles before I had one hooked up (first test fires) but I can't remember the problem beyond the PCM making a bigger deal about it than I thought was necessary.
Some in depth information for you on that code...
Some in depth information for you on that code...
10-31-2011, 10:04 PM
#20
Ha! I googled the code and found the same info I guess because I just finished ohming out each and every fuse and relay. Then in dispair I disconnected my SES light thinking mayb the wiring I had was scaring it somehow but nada. I did find one slightly burred wire when I was installing the harness in the car that I just taped for the time being as I am yanking the harness back out to tape it up super clean but I just cut and soldered that lead together even though only one small wire was cut in the braid and still same. I havent yet hooked up my cooling fan so Im going to try that just so there is nothing left but these dang 1682 and 0650 codes.
Im starting to think there is something either wrong in the harness or the ECM is eukered as this engine came out of a bad write off so who knows what happened? The harness was chopped and I stripped it down, bought a second harness and made a cherry pie one out of the two with the ECM mounted under the dash and a very hidden harness on the engine side. Done plenty of these swaps now too and made a lot of harnesses but this is my first gen IV and so far?
But I'll get this sorted one way or another
Im starting to think there is something either wrong in the harness or the ECM is eukered as this engine came out of a bad write off so who knows what happened? The harness was chopped and I stripped it down, bought a second harness and made a cherry pie one out of the two with the ECM mounted under the dash and a very hidden harness on the engine side. Done plenty of these swaps now too and made a lot of harnesses but this is my first gen IV and so far?
But I'll get this sorted one way or another