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98 PCM died..replaced...reflashed...now speedo is way off and tranny wont shift

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Old 07-08-2006, 05:43 PM
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Default 98 PCM died..replaced...reflashed...now speedo is way off and tranny wont shift

cant figure out the deal...tested for continuity on all wires...

the car is a 98 A4 that was an M6
pcm has an A4 file in it...
had a pcm from an M6 with the A4 data in it..replaced it with a pcm from an M6
and wrote the A4 file that worked fine last night

the car wont shift into first to get going
have to manually put it in 1st and its acting like its in 3rd/4th and doesnt go into 1st at all


I also have no VCM control toforce the trany to shift...

car has a 98 2 bar file in in
Old 07-08-2006, 05:57 PM
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What does it do with a regular A4 stock tune in? Same outcome? Did you try another PCM to see if it does the same thing?
Old 07-08-2006, 05:58 PM
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yes..same problem
tried his original file in it thinking maybe it was a 2 bar issue...but the stock file does the same thing
Old 07-08-2006, 05:58 PM
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Edited my post Scott
Old 07-08-2006, 05:58 PM
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Originally Posted by soundengineer
yes..same problem
tried his original file in it thinking maybe it was a 2 bar issue...but the stock file does the same thing
His stock M6 file or a stock A4 file?
Old 07-08-2006, 06:05 PM
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stock A4 file...
his car WAS an M6...converted into an A4
his car was wired up and flashed with an A4 file....
then it was tuned with an A4 file on the PCM....
ran great..changed intake and injectors..and the pcm decided to not let up write to it..threw a p0601 which is the ROM chip...
had the file that was in the old pcm that wa in teh car and running fine last night...
wrote it to the "borrowed from another M6 car" pcm....
speedo is WAY WAY OFF and it wont shift...when we drop it into first manually it stays in 2nd...wont shift otherwise
Old 07-08-2006, 06:18 PM
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Ok, so the "borrowed from another M6 car" is the PCM that is having problems or another PCM you tried. Its been a long day here.
Old 07-08-2006, 06:19 PM
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Originally Posted by soundengineer
stock A4 file...

ran great..changed intake and injectors..and the pcm decided to not let up write to it..threw a p0601 which is the ROM chip...
Scott, I know you are a smart cookie but, essentially the car worked fine until the intake and injectors were changed n'est pas?

I know you said you checked continuity...just seems like one of those "where are my keys moments?"
Old 07-08-2006, 08:40 PM
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we tried another rewrite entire...
it seemed to take this time...
dont know why....dont know what changed....

a buddy suggested to undo the battery cables..and touch them together for like a minute(maybe to drain power or something??)..
so we humored him cause we were at the just do something else stage...
he also decided to replace his battery with a brand new optima at the same time...
then did a write entire......
it works fine now...

dont know why...if anybody has a real technical explination I'll gladly listen to it...cause I'd lik eto know why..LOL
Old 07-08-2006, 08:41 PM
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Glad we could help Scott.
Old 07-08-2006, 08:58 PM
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There are a bunch of incompatible OSs for '98 and the tune
file from one may not digest properly placed into another?

I know this was a warning I've seen, not to just stuff
somebody else's '98 tune file into your '98 PCM without
knowing you're "on the same page".
Old 07-09-2006, 01:09 AM
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Originally Posted by jimmyblue
There are a bunch of incompatible OSs for '98 and the tune
file from one may not digest properly placed into another?

I know this was a warning I've seen, not to just stuff
somebody else's '98 tune file into your '98 PCM without
knowing you're "on the same page".

That was my first guess. I'd look at the mfg date of the bad pcm vs the mfg date the borrowed pcm came from. I have ran into this issue before when hp tuners was new, but have not had an issue lately.


As far as touching the cables together, I don't know if i'd ever condone such activity If you disconnect the battery and turn the ignition on for a few seconds all power should be drained.
Old 07-10-2006, 01:43 AM
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Ok, it's my car, here's the full story with all details..

The car was originally a 6 speed car until last fall when I swapped it to a 4l60e, and I've driven it since without problems. On Saturday I put on the fast intake, NW 90mm TB, some FMS 36lb injectors, and a few weeks ago I had some 3.23's put in that I hadn't tuned for yet. I had Soundengineer come over to do the tuning part of it for me.

He got there when we first started the intake swap, and hooked up his wideband/laptop/power inverter/etc, but he turned my key on and left it on for a good 40 minutes, which meant my headlights were on and the door was open so the interior lights were on. My battery isn't the best, which he knew about before hand from when we tuned my car before and his inverter would pull so much with my car off that it'd drain my battery quickly.

So, he copied my file on to his laptop and made some changes, and uploaded the tune. We tried to start the car but it just cranked and wouldn't start. He then said he forgot to do something and made some changes and tried to do a rewrite, but this time he was getting an error on HP tuners.(I'll let him say exactly what it was saying) He then spent about 45 minutes troubleshooting why he was having a problem, and we checked my voltage on my battery and it was at 11.5, so he pulled up his car and hooked up the jumper cables. With them hooked up he tried to write again, but still no luck. After more troubleshooting, he did a scan and realized we were having the p0601 code. He said the pcm just went bad, but wasn't caused by him. He said the pcm just went bad because it was old, but up until this point we have never had a problem connecting to my pcm other than one day last fall, but that day he couldn't connect to his own car either and found out it was a bad cable on his end.

I did a search on here and seems like the p0601 code happens a lot when you lose power or have low voltage on the 98's. In this thread it talks about if the volts drop below 12 it can lock the pcm up.

https://ls1tech.com/forums/showthrea...ighlight=p0601

Also I found this thread where it happened with the 2Bar SD from HPTuners, which I think swapped to on my car.

https://ls1tech.com/forums/showthrea...ighlight=p0601

Soundengineer is saying the pcm just went bad and isn't throwing the p0601 code because of a connectivity issue or low voltage issue. I'm just not sure why the pcm would just happen to die at the exact time he tried to upload a tune to it. Anybody know if the pcm will just go bad because it's old and give a p0601 code like this, or if it's something caused by the low volts?

So we then borrowed my friends pcm from his 98 6 speed car and put it in. I then headed up to the parts store to buy a new battery since I was planning on it soon anyway. Before I got back Soundengineer put on the auto tune since my battery was charged from having the jumper cables on it. I then swapped the batteries out, we got it to idle and off we went down the road. I immediately noticed it wasn't shifting at all and that the speedometer was WAY off.(showing like 60 when doing 30) I told him it had to still have the 6 speed tune on it so we went back around the block to the house. He then reflashed it with the auto tune, and we went down the road again and still it was not shifting and speedo was way off. We then headed back to the house, and he said it could be something in my wiring for my transmission and maybe we pulled a wire loose when he swapped out the pcm's. I said it was still like it had a 6 speed tune, but he said he put the auto tune on it and it can't be the pcm/tune. So we then checked all the wires and continuity on all the wires from the tranny harness plug to the pcm plug and everything was fine. I then asked my friend who is a GM mechanic if he had any ideas and he said to pull the battery cables off the battery and put the cables together for a minute then try to retune it. We did this and then it took the auto tune, so off went went.

We tried to get the tune dialed in, but at WOT it was pinging BAD. He pulled out a degree of timing and asked me to go WOT again, but yet again it was pinging bad. He did this a few more times, and each time still could hear it pinging so he took out a few more degrees and it was still pinging. He said the afr looked fine.

I thought maybe one of the injectors was bad so I used my friends lazer heat gun to check the primaries and they were all very close to each other. We checked and it had some oil buildup in the intake, but not a whole lot, but Soundengineer said that was most likely the cause of the pinging so we temporarly capped the port on the intake and used a filter I had laying around to free air vent the crank case. We only put about 75 miles on the car with the fast intake on so I don't see it sucking in that much oil when I had my ls6 intake and no pinging for thousands of miles. Anyway, he said we then need to use carb cleaner to clean out the oil in the intake, so we went and I bought some carb cleaner and cleaned it out. We then tried a few more wot runs and still pinging, even with 10 degrees out and a 11.7 afr it was pinging bad. After that I didn't have anymore time to tune on it so we called it a night.

Also we were having problems with it shifting so he adjusted my shift points/line pressures throughout the night. I was having a problem with the converter wanting to lock up 2nd gear at wot, or at least it felt this way. Soundengineer said it was just trying to do a 2-3 shift then a 3-2 shift, then 2-3, then 3-2 over and over and thats why we were feeling it bog like it was, but I still disagree. He's had my shift points wrong before when he tuned it last fall, and it did that, did a 2-3 then a 3-2, and it was very jerky when this happened. Saturday night it was completely smooth and dropped from about 6000 rpms to 5000rpms, and felt EXACTLY like a converter locking.(I got a yank PT3800) He made one more change right before he left to the shift points, and I made it about a mile down the road before I lost 3rd and 4th. It will shift into 3rd, but just rev up completely. This is a completely built tranny by a very reputable shop around here who has built transmissions for me in the past without any issues and only has a few thousands miles on it. No reason my car on motor should fry this transmission with only a few thousands miles on it.

So Sunday Soundengineer came back out and we were getting a p0748 Pressure Control Solenoid Circuit Electrical code. He said we got this code once the night before, but he didn't know exactly what it meant, but we should be fine. I'm not sure if he tried to clear it or if we ever got it again the night before when tuning. He asked me to go for a drive and he logged it, and we were still slipping in 3rd even with a completely cold tranny, but I can drop it down into 2nd manually and it doesn't slip at all. He reflashed the tune, but still did it. He then said he wanted to try a few things so he had me get going in 3rd where it was slipping and he tried a few things with HP tuners.(I think he tried up'ing the line pressure, but I'll let him say for sure) I then disconnected my relay that sends power to my transmission.(relay got wired up when I did the 6 speed to auto swap last fall, we just modified the 6 speed harness to work with the auto) With no electrical power going to the transmission, it stays in 3rd or 2nd, whichever gear I leave it in like it's supposed to, but when in 3rd it was slipping. Also he cleared the p0748 code after we plugged in the relay again, and we went for a drive and as soon as I hit 3rd gear it threw the code again. I'm pretty sure my 3-4 clutch pack is fried though, but we will for sure change out the solenoid first. Anybody have any opinions on this?

As of Friday the car was running fine, no pinging on the ls6 intake and transmission wasn't slipping. Only thing I couldn't do was a wot shifting because I just installed 3.23 gears and had a 3.42 gear tune from before, but at like 70% throttle it would shift fine.

Sorry for the long post, just wanted all the details out there and see if we can maybe get some ideas on my problems. Thanks.
Old 07-10-2006, 10:36 AM
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also to be said...

car has had this tune in it since earlier this spring/summer....
we had a 2 bar SD file in there from last time as we wanted to run SD and didnt want to be on the crappy half resolution 98 VE secondary table..


I did a Read Entire.....to get the exact file off the PCM.....as I always do...

wrote a change for gears in the tune...forgot to change the injector sizing..did a write calibration only....
when it got done..we cranked it...nothing....smelled really rich to me...realized that I forgot to change injector sizing...

went back into the same file...changed the injector sizing...wrote calibration only again...still no start and I noticed P0601

I can see all the sensors..and can se changes in them..Like TPS...and IAC and can even command fans on...


we borrowed a pcm..and even tuned on the car fine after that...got most of it dialed in pretty good except for some ping which I belive is some oil getting sucked in as the only things that really chaned were injectors and intake and gears...
tried everything from 12.8 to 11.7 on AFR and nothing helped....pulled out almost 10* at WOT and it still did it...

we changed the shift point on the tune as well and lowered it 100 prm from previous tune due to some upcoming mods that will possibly need a little lower shift pont for safety...
what I noticed in the scanner is that at the 2/3 it tried to go back and forth a few times..and teh MPH seemed to match what was in the tune for the 3/2....and I could see the change in the scanner as well..

the next day after he has lost 3/4 we met up again and I tried just to command more pressure using VCM controls to see if we could figure out what was up...

when we got the p0748 the night before I cleared it and it didnt come back...
usualy you clear it to see if it comes back to diagnose a real problem or not...
it stayed away the night before while we were tuning and I was there...may have come back after I left while they were taking the car back home...I just know when we tried to drive it the next morning I saw the p0748 code again

hopefully thats just the solenoid going bad.......
teh car has had the same tranny parameters in it since winter...other than some shift point changes...and I know the car has had several different stalls in it...started with a pt4400...went to an ss3800??(I know he hated that thing..LOL) and now its a pt3800

Last edited by soundengineer; 07-10-2006 at 10:42 AM.
Old 07-10-2006, 10:45 AM
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:shrug: one more reason to hate 98's
Old 07-10-2006, 10:46 AM
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fwiw I've tuned many cars with voltage @11.5-11.9v and havent had any problems...thought it isnt recommended some cars just dont see a ton of volts when sitting there...so 11.5 isnt unusual meaning I doubt that was the problem.
Old 07-10-2006, 10:52 AM
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My own personal car sits at 11.7/11.8 most of the time....
hundreds of writes now on it....no issues with voltage....
when I did the read it showed 11.6.... when I did teh calibration write it showed 11.8...
I dont know why but I dont always trust the little volt meter in the scanner..LOL

also....teh car cranked fine...the first time I did the write calibration...so I know it wasnt an issue with the battery being low....didnt even struggle...

we sat there for probably 40 minutes..but the key wasnt on the entire time..and our cars have a 10 minute power off feature...so it wouldnt have killed anything from sitting with the doors open...
Old 07-10-2006, 12:21 PM
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I've flashed as low as 10.5 volts with no issue. Can't say i'd trust a 98 pcm to do the same. With so may irratic things going on I wouldn't be surprised if there was a grounding/wiring issue going on with the harness.
Old 07-10-2006, 01:15 PM
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when we had soem issues with the tranny/speedo we checked continuity on a bunch of wires going down to the tranny...so we know it wasnt an issue there...dont know about the rest...

also we had some issues with connecting to read/write to his pcm before I had a USB version of HPT...but I thought it was a bad cable cause I had some issues on my car too...replaced teh cabel and everything seemed fine...but I do remember havingsome issues till another time after I replaced the cable....
and I remember saying that my USB version was going to show up so we waited a week till it did and then went back at it...
this was all back when USB was newly released back in the spring...
issues listed in posts above are new as of a few days ago

Last edited by soundengineer; 07-10-2006 at 01:26 PM.
Old 07-10-2006, 03:00 PM
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Originally Posted by soundengineer
My own personal car sits at 11.7/11.8 most of the time....
hundreds of writes now on it....no issues with voltage....
when I did the read it showed 11.6.... when I did teh calibration write it showed 11.8...
I dont know why but I dont always trust the little volt meter in the scanner..LOL

also....teh car cranked fine...the first time I did the write calibration...so I know it wasnt an issue with the battery being low....didnt even struggle...

we sat there for probably 40 minutes..but the key wasnt on the entire time..and our cars have a 10 minute power off feature...so it wouldnt have killed anything from sitting with the doors open...
Also when we tried to start it the first time it didn't get fuel or anything. Even with the bigger injectors it should've fired and then died, but it didn't. Also didn't we later start it on the old tune from last fall with stock injectors?

Originally Posted by soundengineer
also we had some issues with connecting to read/write to his pcm before I had a USB version of HPT...but I thought it was a bad cable cause I had some issues on my car too...replaced teh cabel and everything seemed fine...but I do remember havingsome issues till another time after I replaced the cable....
and I remember saying that my USB version was going to show up so we waited a week till it did and then went back at it...
this was all back when USB was newly released back in the spring...
issues listed in posts above are new as of a few days ago
No, the ONLY time we had troubles connecting before is the one day when you couldn't connect to your own car, and you ended up replacing the cable. The time before that we didn't have a problem, and the time after that we didn't have a problem.



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