#1 on the other bank. These plugs are the first set I installed before I installed the engine.
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.
I did the same thing, plugs even looked the same. I swore up and down it wasn’t a fuel delivery issue as well and tossed parts at it. At this point what do you have to loose?
The white crusty stuff has me wondering. also have you tried running that uphill grade with the reg vacuum unplugged ?
Neighbor was having some driveability issues with his avalanche. Hp tuners has a live reading tool, not sure if your scanner has this, but we could pinpoint the exact spot of his intake manifold leak by watching the O2 sensors and stft's while spraying starting fluid. How were you checking while spraying?
It just doesn’t make sense unless I bought bad gas at some point however I still ran about 50 plus gallons of gas through this engine. Also remember I had fouled plugs on bank 2, why would bad gas foul one bank and not both.
6 and 8 weren’t as crusty. I’m going to make a run with the new fuel filter and I’ll try it without vacuum. I have the fuel pressure gauge under a wiper so I can monitor it on the road.
I can monitor the short and long fuel trims live along with the rest of the sensors. I was simply spraying carb fluid and listening for an rpm change.
No difference with the new filter and vacuum on and off.
I’m starting to wonder if the pump is failing. I have another EP381 that I carry as trail spare.
Idling vacuum connected
Vacuum disconnected
I’m starting to wonder if the pump is failing. I have another EP381 that I carry as trail spare.
Idling vacuum connected
Vacuum disconnected
Fuel pump didn’t make a difference. Just made a a few trips up and down the hill and the pressure is right at 50-51 at idle and it jumps to 60sh under load.
The damn thing actually runs pretty good down low and has no problem barking tires.
The damn thing actually runs pretty good down low and has no problem barking tires.
50-51 is a tad below spec. Larry and I have both found with the adjustable regulator to turn them up 62-63 idling.
It sounded like the adjustable one wasn’t working. Unfortunately it’s taken me a couple before getting one that works. But having low fuel pressure is going to drive the lean fuel trim numbers. Put basically if the pressure is light the amount of fuel delivered per squirt is going to be less than expected vs at a higher pressure. The exam will compensate to a certain point by increasing the injector duty cycle to get more fuel that way. But that only goes so far. Which is why I thinks the increased pressure helps.
I know on mine it’s noticeable if it’s running at 55 or lower. Like extremely down on power. So lacking I’d have to downshift to maintain speed
It sounded like the adjustable one wasn’t working. Unfortunately it’s taken me a couple before getting one that works. But having low fuel pressure is going to drive the lean fuel trim numbers. Put basically if the pressure is light the amount of fuel delivered per squirt is going to be less than expected vs at a higher pressure. The exam will compensate to a certain point by increasing the injector duty cycle to get more fuel that way. But that only goes so far. Which is why I thinks the increased pressure helps.
I know on mine it’s noticeable if it’s running at 55 or lower. Like extremely down on power. So lacking I’d have to downshift to maintain speed
Last night I found the same FPR on the L29 manifold sitting on the shelf so maybe I’ll try that one, it’s also adjustable. The brand new AC Delco (PN 217-3299) is not adjustable and it was at 50 psi at idle.
Installed the FPR from the 454 and turned the screw about a 1/4 turn and it went to 56 at idle with vacuum connected. Took it for a drive, no difference and it’s back at 51-52 at idle.
Haven’t looked but is that what the 8.1 crowed is running for a fuel pump?
EP381
Both banks are reading very similar and have been for a while now therefore I've been digging deeper into the possibility the MAF isn't happy or maybe the MAP. While the truck is stationary the MAF values seem to be in range at 0.02-0.08 lb/s however I didn't monitor those values under load to see if they changed. The MAP was at 3.9-4.3 psi at idle and that's also in range from what I've read.
If I had a stock intake I would certainly try that to eliminate the possibility of the aftermarket piping, couplers and filter causing some sort of issue.
Map at 4psi? Shouldn’t it be under vacuum?
I know changing the intake design causes havoc with the Maf on the gen v swaps I’ve messed with. I had to hack my way through the Maf scaling on hp tuners to get Deon’s blazer to not have negative timing at idle. It’s crazy on these virtual torque tuned engines. I know your 8.1 isn’t, but the Maf scaling could definitely be an issue
You definitely want the maf in a straight section of pipe for sure. Immediately behind a bend disrupts the value.
I don’t remember what values mine runs at though.
I don’t remember what values mine runs at though.
It says psi on the handheld and I found the acceptable range noted online as 20-48 kPa. (2.9-6.9 psi). If it's the MAF, I have two of them doing the same thing.
the piping looks like this however I ditched the 45 bend for a piece of straight pipe about 10" long right after the filter.
Ok, so basically atmospheric pressure minus
Only thing I know about the MAF is that it should be at least 10" away from the throttle body but it looks like you have that covered.
What is it reading for coolant temp and intake air temp? If it's moving LTFT, that usually indicates that it's at normal operating temperature, but if the temp was wrong, it would skew the fuel.
Also, you can unplug (or disable in HP Tuners) either the MAF or the MAP and the engine will run. You could even run long-term on MAP only (speed density), but you've have to tune it, as the factory table is pretty rough, like a limp mode. Anyway, it's useful for troubleshooting. IIRC, the IAT is built into the MAF on these, so those two effects are kind of confounded by unplugging.
Also, you can unplug (or disable in HP Tuners) either the MAF or the MAP and the engine will run. You could even run long-term on MAP only (speed density), but you've have to tune it, as the factory table is pretty rough, like a limp mode. Anyway, it's useful for troubleshooting. IIRC, the IAT is built into the MAF on these, so those two effects are kind of confounded by unplugging.
