Wastegated Paxton tuning

I am working with Lund on updating my tune after adding a wastegate (@ 10 psig spring), upping pulley to a 3.33 (~15-17? psig without wastegate), ATI harmonic balancer, MMR OPG and CS, and offroad h-pipe.

The fuel from 3500-6000 RPM has been a challenge. Originally lund thought no tune updates would be required from my previous tune. We noticed lean/high STFT in this range so he added 15% fuel. Now, new datalog and it helped the AFR (peaks around .86 lambda instead of ~.9 before) but the STFT went way up (peaks around 1.15 now and was 1.10 before). What is interesting is that the STFT and AFR both clear up when we get close to redline because it was originally tuned at ~10 psig at redline.

To me that says its a tune issue not a mechanical fuel issue, it would be worst at high RPM (max fuel demand). Something is definitely confusing though.

Any help appreciated.

Was the gas tank full? Same fuel? I would log it send it back and see what they say. Do you have a boost a pump?

Do you have a BAP and is it working? The wastegate setup will net you about 70-80wtq midrange so you will need the fuel to feed it.

I have dual walbro 465s with a return system. BAP removed.

I ran through a full tank before re-logging just to make sure it was good E85; tested it and it was between 85-90% ethanol. The latest datalog was in 3rd gear of 2nd full tank of new e85. My original tune was all done with the same percentage ethanol from the same gas station, tested every 2nd or 3rd fill up.

I hate to argue with Lund, they are usually pretty on the ball. In their opinion I have a mechanical issue (fuel before wastegate and fuel after wastegate should be similar) but that sounds crazy to me. Anyone else been through this with wastegate setup?

Ugh, his argument is pretty valid. The fuel is based on the MAF reading. We added 15% of fuel and the system still basically cant supply enough fuel to the system to make the AFRs happy. I guess I will be figuring out why my fuel system is having issues... first place to check - fuel filter and new lines I ran...

Are both pumps wired full time or is one on a pressure switch? Are you sure both pumps are running? Lund has done that tune over 100 times so it's probably a mechanical issue.

Both are running full time. I will be checking that they are both running and cleaning the fuel filter than checking with a new gauge for fuel pressure (at fpr) at idle. Cant log fuel pressure yet but if that doesnt fix it im thinking injector issue?

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Do you have a fuel pressure gauge on your regulator? If so any way you can do a pull and record it, might have to go to a dyno. Maybe fab a line up so you can run gauge to cabin of car. Before doing that I'd verify all your vacuum lines are plumbed correctly, also check all piping for boost leaks while your at it. You could have a small split in one of your vacuum lines.

Yes, your tune adjusts fueling based on airflow through the maf. As long as it's dialed in correctly you can raise and lower boost as long as timing and octane are in check.

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fuel filter cleaned and re-datalogged, still lean. Pulled out the injectors last night and bringing them to get cleaned/flow tested today. I checked that both fuel pumps are running and both are pulling 6 amps at idle. I will probably pull the fuel pumps out and clean the sock/make sure everything looks ok.

If all of this doesnt fix it I will be buying a fuel pressure gauge I can bring into the car somehow and possibly take off the FPR and inspect further?

The FPR is boost referenced and when I pull off vacuum line it goes from 55 to ~62 psi on the gauge but it is in engine bay so not much help at WOT while driving.

I looked over all the vacuum lines one more time, cant see any issues with any vacuum lines but with the boost gauge, vacuum block, and lines to intake there are quite a few connections. You can definitely feel the difference though when I pull the vacuum line off the FPR so that makes me think there isnt any vacuum issues.

Any other ideas?? Is it possible I found the limits of something (stock fuel rail?) with my new mods??

Have you tried a boost leak check? Mainly to see if you're getting s good reference signal to the FPR under boost?

I was trying to figure out how a boost leak could cause this issue and couldn't come up with any scenarios that made sense. Lean = too much air; boost leak = reading more air = rich. With the wastegate the intercooler piping is a little different and I was questioning a few of the connections but can't justify lean - only rich. The FPR and my boost gauge pull from the same vacuum block and I searched all over it for any leaks and couldnt see any obvious leaks. On my pulls the boost climbs quickly and then I get too focused watching the road to see if it stops at 10 but I definitely hear the wastegate opening.

Long answer to say - wouldnt it be rich if I had a boost leak? I am open to this idea though; may re-install all my IC piping but it is a real b*tch.

Long update but still can't find the problem.

I talked to fore innovations and his suggestions were to double check electrical connections (maybe an intermittent connection somewhere) and if that doesnt work to try datalogging the fuel pressure.

Cleaned the injectors, disconnected and reconnected all the power and ground wiring for the fuel pumps and still no better. I tried starting the car with one pump at a time, they both come on.

At this point I guess I have to datalog the fuel pressure and confirm it is keeping pressure. If it isn't keeping pressure its pumps, if it is its stock fuel rail? What other options do I have here?

I wish I could help you more but I'm stumped. I don't think you have a fuel pump issue. Reason being as your RPMs and load increase your fuel demand will increase as well. You said it goes lean but then begins to recover up top. If it were going leaner and leaner I would say fuel pump for sure. The fact it richens back up states the fuel is there.

I know you don't want to do this but have you but the car back to it's previous configuration with no wastegate and larger pulley. If you put it back and it's fine it has to be something with the wastegate, I wish you could log the boost in it's current state so we can see what it's doing. Do you have a log you can post?

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TTUhouston said:

I was trying to figure out how a boost leak could cause this issue and couldn't come up with any scenarios that made sense. Lean = too much air; boost leak = reading more air = rich. With the wastegate the intercooler piping is a little different and I was questioning a few of the connections but can't justify lean - only rich. The FPR and my boost gauge pull from the same vacuum block and I searched all over it for any leaks and couldnt see any obvious leaks. On my pulls the boost climbs quickly and then I get too focused watching the road to see if it stops at 10 but I definitely hear the wastegate opening.

Long answer to say - wouldnt it be rich if I had a boost leak? I am open to this idea though; may re-install all my IC piping but it is a real b*tch.

Click to expand...

Did you perform an actual boost leak check or just a visual check?

how can I send you my latest log Riddick? email? pm me

gt347- I did not perform a boost leak yet but looked back at boost piping. Everything looks ok. Boost leak would be rich not lean.

You should be able to upload it on here. If not email me at [email protected]

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TTUhouston said:

gt347- I did not perform a boost leak yet but looked back at boost piping. Everything looks ok. Boost leak would be rich not lean.

Click to expand...

Not true in all situations. And again, you cant do a visual boost leak check... smh

Will upload datalog when i get home from zoo with my son. The afrs recover to .80 but the stfts are still like 1.15 at high rpms.



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Gt347- i talked with midnight performance about helping me diagnose this. He has done a smoke test for me in the past but isnt available until this coming friday. If i havent found a fuel issue by then i will check for boost leaks but honestly i cant come up with a single example where a boost leak makes sense. Before the maf it would just read less air, after maf it would be rich.

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here is a recent log, trying to get the first log uploaded but it may be too big.