Please Help - Getting Codes after Cam Swap

[homeslice]

'98 K2500 w/L31 & 4L80e. I just completed a cam swap, along with 24x ignition, and 0411 swap. I went with Comp Cams 08-501-8 for the cam. I upgraded the valve train with springs, offset retainers, etc as well. Blackbear provided the 24x tune for 0411.

I have it all buttoned back up, and the motor starts easy and idles pretty well - while in Open Loop. The problems I'm having is that when the engine warms up and goes into closed loop, it immediatley kicks my STFT's up to 30% for both banks 1 & 2. Bank 1 STFT comes down to about 10%, but Bank 2 STFT goes all the way to 52% and just sits there. Cylinders 1 & 7 are showing significant amount of misfires. When this happens I register codes P0300, P0357, P0706.

P0300 is randam misfire but P0357 is specific to #7 coil voltage. I swapped coil number 7 with another coil, and no change; still get P0357. P0706 is a transmission switch range code. I did NOT run the 4 extra wires for the transmission to the 0411, as I read where this is no longer needed with current software.

I'm wondering if #1) Do I need to run those 4 transmission wires to the 0411 ? #2) Does this sound like O2 sensor issues ? The O2 sensors are brand new Delco AFS93 units from rockauto. I have switched the O2 sensors from bank to bank, but still getting exact same result.

Thanks in advance.

 

[stutaeng]

Well, I don't know anything about the 24x ignition or 0411 swap, other than I know they exist...

Question: Do the fuel trims stay consistent if you rev-up your engine?

Likely not O2 sensors, but you never know. What does the upstream O2 sensor waveform look like? You can always swap them between the the left and right bank and see if the problem follows the other bank. Flip the throttle and watch for a response...spray some carb cleaner in the intake and watch for a response...

How do you hook up the grounds on this type of conversion? IIRC the LS engines have a ground on the rear of each head...your miss-fires seem to be on the same bank (bank 2.) If they are truly misfiring, then that explains the really high fuel trims on Bank 2...

 

[JeremyNH]

First thing to check is injector wiring. Aloicious made a mistake in his write up. If you do the 411 swap and follow the pinout from Lextech then it is based on the Xvan which already has the injector wire swapped. So the 2/3 and 4/7 injectors are already wired in their correct position. You only need to swap the coil assignments from the LM7 pinout. Aloicious said to do it with the injectors also but that is incorrect. The other thing to check is in the tune. I presume BBP knows what they are doing but something missing from most of the write-ups is the bank assignments for O2 sensors. Since the firing order is different you have to change the O2 sensor bank assignments to reflect this. So L31 bank 0 is Injectors A/D/F/G and bank 1 is Injectors B/C/E/H. This is different from the LS based tune. If it's working well OL but fubar CL I would suspect your bank assignments are still LS based.

With regards to the transmission range wires it is selectable in the tune but default for GM is PRNDL. If you didn't run the four wires then it needs to be disabled it in the tune. BBP would have needed to be told to do this and then they would have actually had to select a configuration that doesn't read the range switches. I did run the wires and have tried driving with both the PRNDL on and off and didn't notice a difference so whatever it does seems to be minor.

 

[homeslice]

Thanks, Jeremy. So I did receive and follow the pinout spreadsheet from Lextech regarding the 0411. For the 24x ignition, I followed Aloicious wiring instructions for the 8 coils, and I also swapped injector wires for cyl 4 & 7 and cyl 2 & 3.

I thought the 0411 spreadsheet was based on the XVan which still used the L31 engine, so same firiing order as original factory sbc. When you upgrade from there to 24x ignition, the tune switches to an Fbody LS based; which causes the firing order to change - and hence you have to switch injectors 4&7 and 2&3. But it sounds like you are saying the 0411 pinout already takes into account for an LS based tune and firiing order ?

edit - pretty funny that I ask if the 0411 (an LS pcm) takes into account an LS based tune.

 

[JeremyNH]

I think it is the firing order in the 411 that can't change not the firing order in the tune. If you compare the pinouts for the Xvan 411 to the LS 411 you will notice that the injector wires for 2/3 and 4/7 are swapped. So when you convert to the LS based tune you only need to swap the ignition control wire to match the injector wire. The ecm needs to fuel and fire 2 thinking that it is 3 and vice versa. Same for 4 and 7. It's already fueling in the right order so you only need to fix the fire order. Below is the PCM lines for the L31 and LM7 (2002 Silverado) with L31 on the left and LM7 on the right for the way it needs to be. If you compare the injector wiring to the Xvan you'll notice no change. If you swapped them then you're fueling in the wrong order. I would expect it to run poorly in OL same as CL though. But I didn't experience that because I had figured out the mistake in the write-up before hand.

You must be registered for see images attach

 

[homeslice]

interesting. It starts and idles pretty dang good in OL, and starts to miss a bit in CL. Well I'm going to swap the injector wiring back to match the Lextech spreadsheet, and will report back what the results are.

 

[homeslice]

@JeremyNH OK, so I swapped the injector wiring back to match the spreadsheet from Lextech; which also matches your above chart (left side chart). This is the only change I made and it appears to been correct move. Engine started and idled again pretty good in OL, maybe a bit better than before swapping injector wires back to match spreadsheet. It looked to me to go into CL with no misfires. Then however, STFT on both banks 1 & 2 started coming up together. They got to their maximums and just sat there. Once STFT's got above 25%, misfires started coming on; and then finally CEL started blinking. I still registered codes P0300, P0357, P0706.

I still don't have the 4 trans wires hooked up, and don't know if BB disabled this in their tune. I have a note into them asking, but my question is - Would the lack of 4 trans wires cause the P0706 code; and would that code cause the engine to go into limp mode ? And is what I'm seeing and describing Limp Mode ?

You must be registered for see images attach

 

[JeremyNH]

Can't help you too much there. I never tried to drive PRNDL without it being connected just drove with it both on and off. I wouldn't think it would matter for engine performance though. I would go back to checking the bank assignment. The LS tune expects injectors on bank 0 to be the odds A/C/E/G and on bank 1 the evens B/D/F/H. This is physically correct and unchanged. However since you are firing out of order you need to fool the ecm into thinking that cylinders 2 and 4 are in bank 0 and 3 and 7 are in bank 1 else the trims will be off. But my truck was reading misfire on first start as well due to the lope which got tuned out (both the lope and the misfire though the misfire wasn't actual but just the lope being interpreted as a misfire). Might be the same for you but worse with the more aggressive cam. Other than the CEL does it run OK? If so you may have to live with it until BBP gives you a scan tune.

 

[homeslice]

just went and drove it around the block, screenshot from that datalog. Getting misfires on cyl 2&7 only. with it in gear and moving, misfires seem to go away; until its back at rest and idling. Seems to run pretty good, and my cats are not getting hot so thats good. I'm kind of leaning toward the tune myself. lets see what BB says I guess.

You must be registered for see images attach

 

[Schurkey]

Getting misfires on cyl 2&7 only. with it in gear and moving, misfires seem to go away; until its back at rest and idling.

Misfire will cause an O2 sensor to report a "lean" condition, leading to a rich-command.

my cats are not getting hot so thats good.

The catalyst is supposed to get hot. Outlet of the catalyst should be hotter than the inlet.