Cannot get rid of TMA occurring when going from cruising to WOT

[GHuggins]

Well, either something found it's way into the hole or the new injectors have a problem. I would say injector. Quick compression check would say for sure.

[lynmup]

Thanks Man, I went through each injector on the VCM scanner and disabled each injector one by one, when I disabled #5 the truck ran no differently but all other cylinders changed the idle significantly. Going to pull the manifold and swap #5 and #1 and see what happens. If it moves then I'll put my old ones back in and see about a refund or a replacement injector. I was really hoping these injectors would give me the extra fuel I need to make more boost. At least I had to pull the manifold to repair it so it was not a waste of time.

[GHuggins]

I'll let you know those are a pain to tune but plenty doable. Requires an entire rework of the density and injection pressure tables. The XDI's are pretty much plug in and do some minor density clean up and go injectors. Might want to get some of those in the 60's and let her rip

[lynmup]

Bad injector! Swapped #5 to #1 and #1 is showing as misfire. Put my old ones back in and she purrs like a kitten. Unfortunately, a wire broke inside of my snow meth boost sensor connector so I repaired it but ordering a new one just in case. Hoping I can get a refund on these injectors. Not taking it apart for the 5th time so they are gonna have to suck it up and give me a refund. If they only send me a new injector then I guess I'll install them later but would rather not.

[lynmup]

I got everyting back together after two transmission rebuilts (Bad TCM). She seems to be running fine as I am tying to get it fine tuned and steetable before taking it to a reputable shop for tune (transmission waranty purposes).

Just today, I have been getting a P2635 code (Fuel pump flow insufficient). All settings are good with the new 30%+ injectors but look at the screen snip and tell me why the fuel pressure is modulating high and low so bad during normal driving. It's a new Armageddon 465 in tank pump and a new sensor I installed before the tansmission went out so I really don't think that is the issue. Could it possibly be a fuel modulator as that has not been swapped yet? Any ideas as I don't want to pull the tank again to replace the sensor or a pump.

[TriPinTaZ]

I got everyting back together after two transmission rebuilts (Bad TCM). She seems to be running fine as I am tying to get it fine tuned and steetable before taking it to a reputable shop for tune (transmission waranty purposes).

Just today, I have been getting a P2635 code (Fuel pump flow insufficient). All settings are good with the new 30%+ injectors but look at the screen snip and tell me why the fuel pressure is modulating high and low so bad during normal driving. It's a new Armageddon 465 in tank pump and a new sensor I installed before the tansmission went out so I really don't think that is the issue. Could it possibly be a fuel modulator as that has not been swapped yet? Any ideas as I don't want to pull the tank again to replace the sensor or a pump.

If you have an Aftermarket or Auxiliary low side fuel pump, you should disable that code. It's just a nuisance code once you're running more than the stock low side.

[lynmup]

Thanks for your reply but disabling will not make my fuel pressure more consistent. What is causing it to fluctuation from 27 to 74 psi?

[TriPinTaZ]

Thanks for your reply but disabling will not make my fuel pressure more consistent. What is causing it to fluctuation from 27 to 74 psi?

As long as you're not seeing the VCM Scanner "bug" where some cars report low side pressure inconsistently, then you need to adjust the tune for the aftermarket/Aux low side to keep the low side pressure more stable.

[Alvin]

Thanks for your reply but disabling will not make my fuel pressure more consistent. What is causing it to fluctuation from 27 to 74 psi?

I'll back up what he's saying.. Sometimes that code pops up with a boost a pump too.. It doesn't make too much sense cause mods to cause it to flow more cause this "low flow" code.

The FP swings might be a bug in how HPtuners scans. It's a known issue.

[lynmup]

As long as you're not seeing the VCM Scanner "bug" where some cars report low side pressure inconsistently, then you need to adjust the tune for the aftermarket/Aux low side to keep the low side pressure more stable.

I'll back up what he's saying.. Sometimes that code pops up with a boost a pump too.. It doesn't make too much sense cause mods to cause it to flow more cause this "low flow" code.

The FP swings might be a bug in how HPtuners scans. It's a known issue.

Thank you both. This code is not effecting the performance, just comes on each time I stab the throttle. How do I adjust this to make the pressure more consistent or should I just wait until the tuner gets to in on June 10th? The less he has to change the more I save!

[lynmup]

I ordered the Lingenfelter check valve to help control teh fuel pressure and turned off the error code. I'll update when installed and tested so others may find a fix for this issue.

[lynmup]

I did order the updated LT4 fuel lines and it made a difference on my data log. Pictures to show comparison to stock lines. Files are named after the part number for each line.

[lynmup]

Added the LPE check valve today and it really steadies the fuel pressure. Now when WOT, it stays fairly steady and consistend keeping the Fuel line nicely supplied.

[GHuggins]

So the bouncing pressure isn't a glitch exactly per say. Its a flow problem. Think I said that a while back on a couple, but good to know it could be either and has been confirmed by someone else.

[lynmup]

So the bouncing pressure isn't a glitch exactly per say. Its a flow problem. Think I said that a while back on a couple, but good to know it could be either and has been confirmed by someone else.

You had mentioned a check valve and I did buy one but it was an off brand and the fitment was crap, finally decided to do away with it but after realizing that the line I had with the flex hose had a check valve, all I was doing was restricting my flow even more.

This combo works and I belive the below graphs show the difference. Swapping the fuel lines increased fuel flow, the check valve is what smoothed the fluctuation. Highly recommend to anyone that is having this common fueling issue.

Before fuel line and check valve and after log. Both showing a 1 minute time interval for comparison

[GHuggins]

So the bad fluctuation is basically the valve bouncing and pressure dropping and spiking over and over again to try and keep up with the loss post valve to hpfp demand. Cool... I know all of my customers running the LPE valve have good constant pressures in the logs. I've even got a couple of customers running 2 supply lines combined with the DSX aux passing through a dual ethanol flow sensor (didn't know they made such a thing until they showed me pics) then T-ing down to the single going to hpfp. They don't have any supply issues even with the regular lt4 hpfp running +30 to +60 injectors. I know at a point the hpfp has to choke it off, but these cars are still making bad ass power with the stock hpfps at the moment. One is going the new port route when Dave gets it out, but that's to come

I'm actually surprised your engine is holding together. It is stock internals isn't it? I know those turbo's have to move some air and make some cylinder pressure on a smaller piston 5.3l. Impressive...

[lynmup]

...I'm actually surprised your engine is holding together. It is stock internals isn't it? I know those turbo's have to move some air and make some cylinder pressure on a smaller piston 5.3l. Impressive...

It is a forged LME block... it can handle what I throw at it. Fuel is my only limitation...lol.

[GHuggins]

It is a forged LME block... it can handle what I throw at it. Fuel is my only limitation...lol.

Ok, that makes more sense