LB7 falling on its face

[Askaggs417]

Just picked up an 02 3500 ca emissions…for the time being. Drove it 1800 miles home ran ok all the way. Threw a p0101 a few times. Idles fine. Falls on its face uphill. Decent power on bottom end. Nothing on top.

Injector balance rate between -.7 and +1
Command time on each injector was .4-.5ms
Fuel rate at 8mm3
IAT was 141(it’s 110 degrees outside right now)
MAF was reading 17g/s at idle whether the egr was commanded on or off.

Did a boost leak test. Found a leak coming from the egr valve at the arrow in the picture. Pulled the valve off tried to clean it. Tested the vacuum line and it closed the valve fine. Mounted it back up and still leaks. Not buying a new egr valve.

Has a janky K&n CAI. There’s gasket maker on the MAF. The surface that the MAF mates to is all jacked up and not flat. O ring on the MAF isn’t doing anything.

Trying to figure out if I have a bad MAF. Don’t want to buy a delco if the current MAF is fine and the shotty intake and egr are throwing it off?

What should I do first?

Delete the egr? I don’t have to worry about emissions.

Or

Throw a new intake on it?

I want the MAF to be the last thing I replace as it’s only a few years old according to service records.

 

[2004LB7]

Replace the intake with stock if you can. Otherwise use a paper non oiled filter. Those oiled filters contaminate the MAF and cause all sorts of issues. Try cleaning the MAF and see if it helps

EGR blocker plates and federal OS or tune

 

[Askaggs417]

Replace the intake with stock if you can. Otherwise use a paper non oiled filter. Those oiled filters contaminate the MAF and cause all sorts of issues. Try cleaning the MAF and see if it helps

EGR blocker plates and federal OS or tune

Called up K&n and was able to order just the tube, adapter plate and MAF gasket. Going to try that out first to see if I get any different MAF readings. I cleaned the MAF before I hooked up to a scanner. I’ll look for a dry filter to swap out with.

Don’t want to do the blocker plate and deal with a blown out up pipe in the future. I’m piecing together a y bridge kit now. Anything wrong with installing the wherli 3” y bridge and intercooler piping? Going to leave the CA heads in, not trying to make this thing fast. Just a good reliable boat and bike hauler that’s comfortable on long trips.

 

[Ron Nielson]

MAF was reading 17g/s at idle whether the egr was commanded on or off.

That's really low. If you hadn't said that the EGR was closed after cleaning, I would have said that the EGR was open. I've seen posts with about 23-24 when EGR open, but none that low. If the stock intake piping where the MAF sits has been replaced with larger diameter piping, that might be the problem. That would cause a low MAF reading, which would cause the ECM to underfuel the engine.

 

[Lennydmaxguy]

Be a lot cheaper to pick up a used federal Y bridge since you aren't looking for big power. Just my .02

 

[Askaggs417]

That's really low. If you hadn't said that the EGR was closed after cleaning, I would have said that the EGR was open. I've seen posts with about 23-24 when EGR open, but none that low. If the stock intake piping where the MAF sits has been replaced with larger diameter piping, that might be the problem. That would cause a low MAF reading, which would cause the ECM to underfuel the engine.

Well, I wouldn’t say it was closed. After I cleaned it I charged the pipes again and the valve was still pissing out air. I put my regulator to 25 psi and the valve leaked all the air out of the system in about 8 seconds. As far as I know the K&n intake on it is roughly the same size. Figured I would have come across that problem on the forums if the K&N cold air intakes did that to everyone’s truck. Also egr was reading 0% on the scanner the entire time. Just gonna get rid of the entire thing I guess. The freakin valve is $200 from duralast. Almost 400 from GM. I’m just confused about the boost leak. Is the air just leaking from the system before it gets to the manifold? Not enough pull from the turbo causing the intake to bring in a small amount of air?

 

[Askaggs417]

Be a lot cheaper to pick up a used federal Y bridge since you aren't looking for big power. Just my .02

You ain’t wrong, but the pipes are powder coated! I’m still tossing the idea around. I found a fed y bridge on eBay. I’ll sleep on it for a day or two. I inherited the truck so I’m not out of pocket as it sits.