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

[Murlo26]

What other fuel system mods do you have? Do you have a fuel pressure gauge? If so what's it reading at idle? If not get one (I have a setup you could borrow/have but you'd need a gauge still). Maybe there's something going on with the blaq-ops kit where it is allowing fuel pressure from pump 1 to bleed off via the wye-that feeds from pump 2 when it is off.....this is one of the reasons I've been so adamant about sticking with a single pump.

Blaqops double pumper, 2nd pump turned on by progressive boost controller
DW1300s (normally, stock injectors temporarily).
MAP AFPR kit, with fuel gauge on the rail
stock fuel rail

At idle the fuel pressure is spot on, like 43ish psi. Shane has mentioned that about the wye fitting possibly bleeding fuel off the first pump. I assumed that is why I have always had issues with high rpm stomping on the car as the 2nd pump needed time to overcome fuel coming into it from the 1st pump. When I rolled into the throttle from a low rpm I never had an issue. Shane lowered my 2nd pump turn on boost level I believe last time on the dyno which seemed to almost get rid of all this.

The thing is even with that problem, I wouldn't think I would have an issue like this where the car is always adding fuel at cruise. It almost seems like there is a flow issue somewhere or maybe a bad o2 sensor?

I think I am going to open up the jegs fuel filter and clean it out. Then prolly pull my double pumper and see what everything looks like.
The way the fuel trims, and o2 readings are wandering, Id check the engine grounds to make sure they were installed according to the Factory Service Manual. This issues sound awfully familiar to the issues seen with bad grounds on other vehicles. I know it is a long shot, but it probable given the motor has been in and out of the car several times now.

Shawn

Its not wandering though, its only trying to add fuel and its a lot worse cruising vs. idle. Idle is 5% and cruise is maxed out at 12.5% and still not adding enough. So it gets worse as the car is cruising.

[simulatedwood]

I guess my point was that, you have something in the system saying it is running lean, but it is not running lean, then you have an feedback issue to sort out. If you know the injectors are fine, and your running consistent fuel pressure numbers (has this been verified?), then I don't see how this isn't a sensor issue of some sort.

When the car I was troubleshooting had ground issues the sensor readings were all over the map (o2, MAP, and TPS), this caused a ton of CEL's, but the car ran, OK. At time the idle would die, sometimes surge, sometimes engine ran lean, etc. Spent money on a MAP and o2 sensor that didn't need to replacement, but all the signs said they were failing. As it turns out, just needed to replace the ground wires going to and from the chassis to the engine and all was right with the world, sensor readings made sense and the car ran awesome.

[Murlo26]

I guess my point was that, you have something in the system saying it is running lean, but it is not running lean, then you have an feedback issue to sort out. If you know the injectors are fine, and your running consistent fuel pressure numbers (has this been verified?), then I don't see how this isn't a sensor issue of some sort.

When the car I was troubleshooting had ground issues the sensor readings were all over the map (o2, MAP, and TPS), this caused a ton of CEL's, but the car ran, OK. At time the idle would die, sometimes surge, sometimes engine ran lean, etc. Spent money on a MAP and o2 sensor that didn't need to replacement, but all the signs said they were failing. As it turns out, just needed to replace the ground wires going to and from the chassis to the engine and all was right with the world, sensor readings made sense and the car ran awesome.

I actually am running lean right now...1-3 gears are like 17 afrs at cruise then when I get going a bit more the AFR's get to where they should be, 14-15.5 area. But the car is struggling to run a bit when its running lean lean. I am not boosting what so ever, this is just running around honda civic style too. It's hard to say whats going on.

The idle fuel pressure has been verified, once the car is in gear not sure as the fuel pressure gauge is in the engine bay. I'd need to get the car on the dyno to know.

[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.

[Murlo26]

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]

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]

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.