Dave's Evo X Build/The Life of Dave blog

[Murlo26]

Originally Posted by asshanson

Probably not an O2 sensor if both are reading lean. Your fuel trims are maxed out on the positive side right, it can't add any more?

I would guess this is an air metering problem if your fuel pressure at the rail is good. Maybe an air leak pre-turbo but after the air sensor? Have you gone into boost? If it goes super rich under boost you may have a massive air leak somewhere, letting in extra air under vacuum and letting out air under boost.

12.5% is the max for Long term fuel trims. however you can get more added through short term fuel trim. They add, so if LTFT is 12.5 and STFT is 10 then I get 22.5...not sure on max STFT though.

I found out the lean code comes from a maxed fuel trim, so until I get that resolved it will keep popping up. I am guessing the other codes are tied to the "lean" factor as well because they are new with the pump gas map.

I am going to add 10% MAF tonight to richen it up and see what that does. If that works then its probably a combination of more MAF scaling needed and the fact E85 was still left in there.

I shouldn't have any leaks. We checked for exhaust leaks at MAP like two weeks ago on the lift, didn't see anything. Also we boost leak tested everything at the intake and found one leak that I have since fixed so that should be good. MAP did obviously have a ton of stuff off for the head work they did so I am guessing everything got replaced correctly.

[Murlo26]

Well with another 10% MAF, almost no change

Idle trims improved, they are almost spot on at 1.5%. However cruise, quickly maxed out at 12.5% and I can't even do partial throttle really without going lean, it quickly maxes out my wideband lean if I try to go more than like 10/15% throttle so something has got to be off...

I did check my fuel filter, even cleaned it off with some brake cleaner, it was pretty clean actually so the problem is else where.

I have two thoughts. One, my AFPR...are the AEM's known to have issues?

The second, my walboro 255 main pump. When my second pump kicks in (before on e85) the car goes stupid rich, like 10.0 AFR's. So it almost seems like my 255 isn't working well. Tempted to almost buy a new one as they are so cheap. I have had it for 3 years, but I am not sure how they fail.

Tomorrow night or saturday morning I will pull my assembly because I guess that could be a problem, maybe loose hose clamp, ripped hose or something strange is wrong is my only other thought.

My fuel system isn't that complicated and it seems to be only at low speeds I have the issue.

[asshanson]

If you have fuel pressure at the rail I don't see how that can be an issue. Can you log fuel pressure while you're driving? Even when my CTS-V had fuel issues, basically half the fuel was bleeding back into the tank and not even making it to the feed line, I could do an easy 30% throttle on E85 on a single Walbro 255 and never drop below 60psi. You would have to be starving almost all of the fuel for you to have part throttle lean issues. Either that or letting 100% of the fuel by the regulator back into the tank, but then you wouldn't be showing any fuel pressure.

Log fuel pressure while cruising. If you have just a gauge on the rail with a 1/8" NPT fitting, get a 6' section of hose with NPT fittings on the end and run the gauge into the car so you can read it. This is what I did to verify my fuel pressure was dropping under high throttle. If it is dropping, it could be the main pump getting very weak, or the regulator giving up and letting everything by.

[Murlo26]

Originally Posted by asshanson

If you have fuel pressure at the rail I don't see how that can be an issue. Can you log fuel pressure while you're driving? Even when my CTS-V had fuel issues, basically half the fuel was bleeding back into the tank and not even making it to the feed line, I could do an easy 30% throttle on E85 on a single Walbro 255 and never drop below 60psi. You would have to be starving almost all of the fuel for you to have part throttle lean issues. Either that or letting 100% of the fuel by the regulator back into the tank, but then you wouldn't be showing any fuel pressure.

Log fuel pressure while cruising. If you have just a gauge on the rail with a 1/8" NPT fitting, get a 6' section of hose with NPT fittings on the end and run the gauge into the car so you can read it. This is what I did to verify my fuel pressure was dropping under high throttle. If it is dropping, it could be the main pump getting very weak, or the regulator giving up and letting everything by.

I have one more thing to try, then checking fuel pressure in the car will be the next step I guess. One more tuning thing that is.

That is a good idea to run the hose into the cabin, thanks bud. Maybe I should just buy a fuel pressure gauge for inside the car..hmmm.

[asshanson]

I bought a section of plastic hose with male NPT fittings on both ends, and then a female/female adapter so I could plug in the gauge on the other end. I still have the hose, cost me about $15 to make at Fastenal. If you want, I could mail it to you, should only cost a couple bucks and save you some money (I wont be up there again until mid July). I just have to find it haha, let me know if you want it.

[Murlo26]

Originally Posted by asshanson

I bought a section of plastic hose with male NPT fittings on both ends, and then a female/female adapter so I could plug in the gauge on the other end. I still have the hose, cost me about $15 to make at Fastenal. If you want, I could mail it to you, should only cost a couple bucks and save you some money (I wont be up there again until mid July). I just have to find it haha, let me know if you want it.

was just about to post here, see below. I don't think I will need the hose anymore, but I am not out of the woods yet

Finally some good news! Well what I consider good news lol. Sad kinda as nothing has changed but I think I know the problem (i think). Thank you to Bryan (razorlab) and Tephra as they both suggested this. Bryan gave me the MAFcalc and MAPcalc addresses and I went logging at lunch.

See the attached csv/zip if you are interested.

Basically, the MAFcalc averaged 19% higher throughout the 30min log. So in essence, if I am reading tephra's 3xMAP table threads correctly, the car was never using the MAFcalcs as they were always higher. So we could richen up the MAF scaling but it won't change anything as its just using the MAPcalc. SO essentially the car is running "speed density" in a way, the way of maxing out MAF scaling so you always look at MAPcalcs.

For those of you not familiar with the X, the X runs both speed density and a MAF based system. And from what Tephra has posted it compares both the calculated loads and takes the lower of the two.

So now that I have seen this I guess we are onto dialing in the MAP tables. I am thinking maybe we should put my ghetto ass stock intake/MAF back on and use stock MAF/injectors and their scaling and get the MAP close to that? Not sure how to dial the tables in honestly but one thing is for sure I need to add % to them. Maybe just do like a 10% across the board to start, not sure.

Stay tuned I guess.

[C3L1CA]

I must have missed it, but why are you back on stock injectors and tuning on them?

[Murlo26]

Trying to scale my MAF using stock injectors and stock injector scaling. The theory is with stock injectors, scaling and some pump gas the only thing to dial in should be the MAF scaling.

Well that is fine and dandy on a 2.0L stock compression motor but my motor the VE has changed enough to where we need to do the MAP tables to it would seem.

[Kracka]

If you want my 2-cents, which you probably don't, but... take this thing to a professional tuner!

[Halon]

Originally Posted by Kracka

If you want my 2-cents, which you probably don't, but... take this thing to a professional tuner!

+ infinity

[Murlo26]

Well after like 2 revisions, Jon from HBspeed has my MAP tables infinitely better tuned! The car drives almost stock right now. I am loving it.

So it appears that it wasn't my fuel pump at this point, we will see with a few more revisions, but the trims aren't maxed out anymore, still at 10% which is way way better.

More to come.

[turbotalon1g]

what did he do?

[Kracka]

Drenas FTW!

[Murlo26]

He modified the MAP tables which are related to the speed density portion of the tune. Also they are similar and/or based on the VE tables. I don't fully understand them myself but that was the main thing he adjusted.

[turbotalon1g]

good shit. Surprised you don't just take it to get tuned and be done.

Or maybe you and scheidesy can have a get together and knock her out one night?

[Murlo26]

There are very few people that seem to know how to correctly do the MAP tables on the X...Jon at HBspeed is one of them. I trust him and am going to let him dial it in. It's only gotten better with each revision. My trims are already within +/- 5% after 4 revisions. We moved onto higher rpm spots to further dial in the tables.

edit: Jon also has the car comfortably idling at 850rpms as opposed to 1200 I had it when I was playing with it lol. Much quieter.

[asshanson]

Glad to hear it wasn't fuel related, but makes sense based on the problems you described.

So after you dial in the MAP table, are you switching parts in one at a time, like the big intake pipe next for MAF scaling, then injectors, then E85? Hopefully if you follow a good progression you should have the car on e85 with the big injectors running like stock.

[Murlo26]

Originally Posted by asshanson

Glad to hear it wasn't fuel related, but makes sense based on the problems you described.

So after you dial in the MAP table, are you switching parts in one at a time, like the big intake pipe next for MAF scaling, then injectors, then E85? Hopefully if you follow a good progression you should have the car on e85 with the big injectors running like stock.

My Primo "big intake" is already on the car, I never switched back to the stock MAF. I am still on stock injectors because I sent my DW's in for testing/cleaning and new orings so those won't be back until mid this week.

However, the plan is to finish dialing in MAP tables and the big ass MAF on stock injectors, move to dw1300's and scale, limp ass pump gas map (no idea on power for this, going to run like wastegate boost), then e85 and power time.

I am hoping to have the car back on e85 by next week.

[simulatedwood]

Glad to hear you are getting this car dialed in finally! Proving Grounds or bust!

if bust then time to buy a v8..

Shawn

[Murlo26]

Originally Posted by simulatedwood

Glad to hear you are getting this car dialed in finally! Proving Grounds or bust!

if bust then time to buy a v8..

Shawn

Pretty much the plan