code string P0108,P0234,P0238

[MMcGee]

It's an 02 LB7, I'm starting with the 108 code, I think the others are linked to it (maybe?) I have all ready changed the MAP (no joy) next the BARO. I did a search of the codes, and the 108 seamed the the one to start with. I just picked up the truck with 180K for cheep and the codes are part of the deal, fixing them?? ($$$$$ ?) This might be a Q for JK, why would someone have cut the yellow wire to the MAF and butt spliced it back together? The truck starts and idles good but seams to lack power over say 70. Any Ideas?

[More Power]

The wastegate used on the LB7 has frozen in place on rare occasion, especially in trucks that are not driven regularly and stored in humid climates. The wastegate simply rusts shut.

I would suggest unbolting the wastegate actuator, then see if the wastegate lever moves freely.

The jury rigging of the wiring is a concern. Get that handled first.

Jim

[Kennedy]

It's an 02 LB7, I'm starting with the 108 code, I think the others are linked to it (maybe?) I have all ready changed the MAP (no joy) next the BARO. I did a search of the codes, and the 108 seamed the the one to start with. I just picked up the truck with 180K for cheep and the codes are part of the deal, fixing them?? ($$$$$ ?) This might be a Q for JK, why would someone have cut the yellow wire to the MAF and butt spliced it back together? The truck starts and idles good but seams to lack power over say 70. Any Ideas?

Not sure why on the cut wire except for maybe trying to install a Finger Stick which does not exist. I know that Banks had a connection at the MAF sensor as well.

Those codes indicate a LOT of boost. Does this happen when the truck is run hard or just loafing?
FWIW the boost sensors seldom if ever fail on these. I'd suggest a boost gauge and/or watch the data stream to see what the boost is. Keep in mind it will show approx 14.x psi as atmosphere static. so you will have to do the math.

[MMcGee]

Running empty to the store (10 mi @ 70 mph) the 108 and the 234 will come up twice and the 238 once. Reno to Carson City pulling a trailer (8000 lb.) same thing. Up the street and back empty slow (50 to 60 mph), just the 108.


I'm at work this week so this weekend Ill get back at it. thanks for getting back


Mark

[MMcGee]

Checked the waste-gate, it was free. (Don't drop the wrench its a bear to fish out) Replaced the BARO and the p0108 was replaced by a P0106 (power still down) Put the old GM MAP back on, then all the old codes were gone but I had a P0101 now. Drove it, power was back up. Cleared it, the p0106 code came back up and power is down again. Any ideas? Could the EGR throttle valve be whats cutting the power? Q: No vacuum EGR valve Closed ? Q: No vacuum Throttle valve closed?

Thanks

[More Power]

Checked the waste-gate, it was free. (Don't drop the wrench its a bear to fish out) Replaced the BARO and the p0108 was replaced by a P0106 (power still down) Put the old GM MAP back on, then all the old codes were gone but I had a P0101 now. Drove it, power was back up. Cleared it, the p0106 code came back up and power is down again. Any ideas? Could the EGR throttle valve be whats cutting the power? Q: No vacuum EGR valve Closed ? Q: No vacuum Throttle valve closed?

Thanks

P0106 - Definition: Difference between barometric & boost pressure sensors is more than 30 kPa (10 kPa California) for 2 seconds.

Does this truck have the factory stock ECM programming? Do you think it's possible someone uploaded a non-stock program - who didn't know what he was doing or removed something when he sold it that the new programming needs.

I had to take my 2001 back to the dealer once when a program upload failed. The truck would still run, but there was some wierdness going on. The dealer tech just smiled when I said what happened... It was a quick in-out to get it fixed.

[MMcGee]

I was going to call wild west (the local Dealer) and see what they think. Someone has tried to fix it before me. The BARO and the MAF have been changed and are new but the sensor that was installed as the BARO clearly said MAP on it. I changed it with on i got from the dealer (BARO) and put the factory MAP back in and thats when it cleared the turbo boost problems. I'm an I&E tech by trade so Ill check it to see what type of input the ORilley one reacts to. The MAP I had got at ORilleys, Ive tried back and forth with the factory one and every time i install the ORilley one I get the P0234 and P0238. I did some research (NAPA online) and found that there is a MAP, Turbo Boost and a BARO sensor. Each with its own part number? I was under the impression that the MAP, TB were one of the same.
With the P0101 and later the P0106 would come up, (truck looses power) seams to be heat soak related. Cold just the 101, after it warmed up i would get the 106. Read the page on the MAF, (DP) found the CRC cleaner. After cleaning I drove the truck that night about 30 miles and just the P0101 comes up. It was cold and rainy. Ill try it again today and see what happens. Ill check with the dealer and see if they can check the programing?? Any other Ideas are welcome also. Thanks for the help I'm going to see if I can find a reader that can read the value of the MAF out put and see if its in range.

[Kennedy]

Since you are getting the DTC's at low load/low boost there's something electrical. Sounds like you may have gotten it, but now the P0101. This can be a nuisance code on some late model trucks. Check for clean MAF sensor as well and induction leaks pre turbo.

Intake is still stock?

FWIW wastegate operation can be tested with compressed air from rubber tipped blowgun to the diaphragm canister. Regulate psi down for safety.

P238 is something we'd see when we maxed out our boost sensors at over 30 psi. Sounds like you may have had the wrong sensor in the wrong spot or an improper replacement that only read 1 bar or something like that.

OE sensors only is my recommendation.

[MMcGee]

OE sensors is my pick as well unless its Sunday and your miles from home. The intake is stock and seams to be in good shape, even checked the plastic box to no-where for cracks. (6.6 on top) I have checked the WG actuator with the compressor, it works. I ordered an OE MAF sensor from the dealer, it will be a couple days before it gets hear. Thanks for the ideas.

[Kennedy]

In my experience the MAF sensors seldom fail. Also MAF codes are fairly uncommon on the older trucks. Now the LBZ and LMM is a different story. They are very sensitive to P0101 codes.

Does this truck have an EGR system on it or is it a FE9 Federal emissions truck?

[MMcGee]

It has an EGR system, the truck is exempt from smog checks hear. I could fab up a blocker plate or something but what to do with the sensors and solenoids?

[Kennedy]

It has an EGR system, the truck is exempt from smog checks hear. I could fab up a blocker plate or something but what to do with the sensors and solenoids?

That explains the P0101 then. If it's a CA truck it has or had a cat. Tamper with the exhaust and the MAF varies and sets a DTC. This is something I quite commonly take care of in ECM programming. No need for plates or removal, but you could probably stand to ditch the vacuum pump and go to a std belt once programmed.

[MMcGee]

It has the stock exhaust cat included. Looks almost as clean as the day it left the factory. programming, I would need to send you the computer??

[DmaxMaverick]

It has the stock exhaust cat included. Looks almost as clean as the day it left the factory. programming, I would need to send you the computer??

I recommend sourcing a core PCM, and have that programmed (or Kennedy may sell you one). If you have the OEM PCM programmed, it costs a fortune to have the dealer restore the original calibration (most often, they require a new PCM before they'll do it), if it becomes necessary. It WILL be necessary if the truck is ever registered in CA (or any state requiring OEM smog) again.

Also, DO NOT try to cut out the cat. You will ruin the pipe and the cat, as that section on the 2002 and 2003 CA trucks is stamped (2004 LB7 CA models are of modern " welded pipe" design). You can replace the entire forward pipe with any 2001 CA, or any Federal LB7 pipe. The flange will fit, as will the hangers. A "new" OEM pipe is less than $200, and even less if used, but the cat is nearly a grand to replace, if ever needed.

[Kennedy]

Not that we have to pass in this case, but

We've had pretty good luck with CA emissions passing provided the visual stuff was still there. In some cases the "puff" on snap acceleration has been a bit above limits depending on the condition of the rest of the vehicle.

Keeping the original ECM is always the absolute safest bet, but not entirely necessary.

[Kennedy]

I believe from my observations years back that the EGR equipped trucks idled at approx. 34 g/s MAF and the Fed trucks were 40-44 g/s. This might be a fair starting point for your diagnosis.

[Kennedy]

Almost forgot: governed engine speed

Apparently some test for this as well and if it is increased...

[DmaxMaverick]

California emission tests, so far, are purely visual. No gas or opacity sampling. The OEM equipment must be in place, the SES lamp must not be on, it must not smoke excessively, and the instrumentation parameters must within spec. Some smoke is allowed, but it must clear up when the throttle is ramped. I know of a few who have their redline increased, and it's never been mentioned as an issue. Gutted and "mocked" cats are fairly common. They don't read the instrumentation or engine parameter values with the computer, but anything that may trigger the MIL will cause a fail. I have a couple glow plugs failed, so the SES is on occasionally. I just clear it a block from the smog station. Since the engine is already at operating temp, it isn't a problem when I get there.

[Kennedy]

I've had a couple over the years that claimed to have failed due to excess RPM and opacity. Not sure what state it was.

On edit: looks like AZ may be the culprit

[MMcGee]

The p0101 code was caused by the yellow wire from the MAF. It had been cut down by the ECM and spliced into. This truck did have some sort of tuner in it at one time. I took the truck to the Dealer and had the ECM reprogrammed (cost: 1 hr shop time) and now all the smoke is gone. The truck is running good but it still has a code coming up a P0106. It doesn't matter if you go 100 miles or just down the street, about every second or third time you start it and head down the road the light comes on after its been cleared.