Lil'John

This thread is a continuation of this thread:
https://ls1tech.com/forums/generatio...g-off-lq4.html
I confirmed that the cam chain wasn't off a tooth.

Title kind of states the issues. I'll go straight to the long version.

2004 Silverado 2500HD 6.0L LQ4 swapped into a Land Cruiser with now under 70k miles on it. It WAS running mostly fine completely stock. The stock harness was reworked. I had a valve rattle at higher RPMs so I decided on a cam swap while I fixed the valve springs: cam is a fairly mild one. It is a Tick Performance towMAX Stage 1:
https://www.tickperformance.com/tick...4-lq9-engines/
208/216 | .561"/.561" | LSA113+4

I also upgraded the valve springs to BTR #SK001S.

After a long time sitting, I tried to fire it up with a TON of misfiring. I found most of the stock injectors were stuck. I replaced them with OEM Delphi injectors with part number 25343789. This resolved a large part of the misfire issue and it was 'mostly' drivable.

It feels like a misfire, for sure backfire out tailpipe when I let off the gas, super rich running to the point a car several car lengths behind me could smell it while doing 55mph, bad lack of power, and it is throwing up a code of p0200. I've thrown a noid light on five out of eight injectors and I can barely see it flashing.

I have tried swapping PCMs with no change.

The stock harness that came with the engine has been worked many times. I just wrapped up reworking a completely stock harness. I thought that maybe some of the work I did wouldn't have made the computer happy (shorter wires, longer wires, combined power) To that end, I kept the ground as is in the stock locations on the block(three) I also kept the power circuits as original(INJ1, INJ2, MAF/PCM, o2) I also kept the routing stock except for the MAF sensor.

The cam sensor is new(AC Delco) as are the o2 sensors.

I am watching the PCM with HP Tuner VCM Scanner. I did not do the tune but I can't find who did the tune for the cam.

Currently, the long term fuel trim too often gets stuck at high negative(-18%) The MAF at idle is 0.8x lb/min at idle. The MAP is 37.x kPa. It runs at a solid 210 degree F.

If you've gotten this far, any ideas or suggestions? I'd really like to get more stuff wrapped up so I can get a little bit of snow wheeling in.

Lil'John

I'm hoping that after over two weeks of being confined that someone might have some ideas.

Anyone with some thoughts?

Old Geezer

iTrader: (3)

"and it is throwing up a code of p0200. I've thrown a noid light on five out of eight injectors and I can barely see it flashing".
P0200 is what you are seeing with the NOID lite.
IMO, you have a voltage, or ground issue within your home built harness.
Loose/bad crimp on the pins pins, bad solder joints, corrosion,poor grounds....
Have you checked the voltage, and ground integrity, on all the harness power supply points?
Have you checked the plugs at the PCM?

Darth_V8r

iTrader: (4)

If you have HPT, maybe the answer is to just adjust your tune via fuel trims.

ChopperDoc

So it was tuned after the swap? Because this sounds like a bad tune. Hard to say without the log(s) and/or tune file. Sounds like you have the capability and you wouldn’t be moving the thread here if you didn’t suspect the same. The tune probably has a lot to do with it in either case assuming this hasn’t ran correctly since the swap.

ChopperDoc

Every cam swap I’ve done so far has always been pretty rough at the beginning of the tune (first crank) and can do all kinds of crazy ****, as described, like misfire, backfire, etc. but getting the tune right, all of it goes away. And you can get some codes too. Just did the wife’s stang a few months back and it would barely run initially, and those were pretty mild cams that went in that too. They always need more air, and typically a lot less fuel. Spark needs played with too. Depending on how crazy the cam is, it can be pretty challenging just getting the car to run at first to get good data logs. Experience helps though, and adding air/reducing fuel is the first thing I do to get it stable enough to log something. Cams really mess up airmass calcs, so you’ve basically blinded your PCM and it has no idea what is going on. The computer doesn’t know your cam numbers. Just keep that in mind. It’s one of the biggest changes you can make, just saying.

Lil'John

Thank you to all who have replied so far... and my apologies for lack of a reply. It looks like my thread subscribe didn't stick
I had the issues with two separate harnesses. One that was hacked up to hell. The other is a complete stock harness that I stripped a couple of circuits out, crimped power wires together, and lengthened some of the in cab items.

On the one that was hacked to hell, I checked power at the injectors. All of them were same as battery. I will check PCM power points. The grounds in this one were hacked up and tied together.

I will check the voltage on the new minimal hack harness. The grounds are untouched and in stock location. Should I try to tap the ground holes? Or should I sand the area?

What should I be checking at the PCM plugs? When I was removing auto tranny pins, all the other pins looked in reasonable shape.

I had a 'half ***' mail tune before the swap for the stock cam. Basically trying to get a manual transmission segment to convert an auto PCM to manual tranny

I had another mail order tune done for the cam swap. I sent the cam specs with the PCM. This was a 4wd reputable tuner.

I can absolutely tune the PCM. I have HP tuner in my hands.

Lil'John

I checked power to all injectors. All were same as battery. I tried jiggling them to see if broken wire. No change on them.

I've attached the tune for the cam (trail55_cam.hpt) and a log of the latest run(miss1.hpl)

The gas is fairly fresh and was high octane from Chevron.

Any thoughts?

Lil'John

A quick update. During the latest run, the P0200 didn't pop up.

But I may have found the root of the issue.

When I replaced the injectors, I bought Delphi 25343789 which was advertised as being a supersede part from the Delphi 25317628. As it turns out, this is NOT the case. The Delphi 25343789 injectors are actually for the 8.1L.

So the question now is: Is it a simple matter of adjusting the injector data on the 4-5 tables similar to a Deka injector swap?