I installed a Walbro 255 a few days ago and just got around to tuning my car today, and I'm having some issues getting my AFR's to lean out in the upper RPM range (5500+). I'm relatively new to EcuFlash, but not necessarily tuning and haven't experienced an issue like this with only a fuel pump change. Relevant mods are: evo 9 turbo, ETS LICP, Walbro 255, Buschur TBE, Megan o2, Hallman MBC @18 psi, and an Amsoil air filter, and obviously EcuFlash and EvoScan to tune w/ AEM wideband.

After the fuel pump install, the car was obviously running rich so I took it out tonight to do some tuning. After taking quite a bit of fuel out, I still couldn't get the AFR's leaner than 10:1 from about 5500 to 7500. There's also a really strange lean spot around 4000 that I can't get rid of. I've added as much fuel as possible and it's still dipping into the 12's. It's just really strange because before the fuel pump, the fuel map was very smooth and the AFR's weren't all over the place. I'm also using the MapTracer function in EvoScan so I'm relatively certain I'm adjusting the correct cells.

At this point, the AFR's are mid to high 11's to about 5700, where they drop off to mid to low 10's. I'm also not getting any knock.

As you can see by my fuel table, there's something weird going on. Do I need to scale the injectors or adjust anything to compensate for the increased fuel pressure? Here's a screenshot of the current map.. you can see at 6000, quite a bit of fuel has been subtracted and it still doesn't want to get out of the 10's.



And one of the initial map before the fuel pump.



Any help or insight would be appreciated, as I have a time trial event out at our local race track on Saturday and want to make sure my tune is safe for the 20 min sessions.

Thanks

 

your most recent edited map is definitely not a safe way to be editing the map.. that must be with using map tracer.. definitely not the proper way. check to see where your fuel trim mid is and go from there.. if it takes till 13's or more to get it to lean out the fuel trims are off.

 

That's why I stopped trying to adjust the table. I just didn't think changing the fuel pump would throw off the injector scaling. And PM replied.

 

mm... what are your trims at?

 

sounds like a faulty install, perhaps a pump gasket gives you a fuel leak and it only increases with fuel pressure.

 

I haven't checked trims, I will do that today after work.

Wouldn't this cause a lean condition under increased fuel pressure?

 

thing is, switching from oem pump to walbro rarely does any significant changes like the one you describe to trims/afr ratios. that's why i thought of a faulty install.

 

it can if the old filter was clogged to hell.. the new filter would make it run really rich.

 

We got it back to stock. And its running great. It is where its supposed to be now except its a little lean on spool up and causes 1-2 counts of knock. Other than that she is knock free.

We did get one log that was 5-6 counts on spool up but it was just one time.

I would attach a log file but It won't load?

Basically its stock on 21 psi. It will be fine until we can get some tephra on there and log some accurate load lol

 

i'd either try it with another walbro or checked a fuel pressure, you need a pressure gauge to do that. to me your problem is likely to be mechanical or perhaps wiring, but not ecu's.

 

You know what.. I think this was exactly it. I just looked at the stock fuel pump sock and it had dirt/hair/other **** all in it, it was probably clogged as hell. And it makes sense because my car wasn't running very rich stock, compared to what I've seen with other evos.

And about tuning with maptracer like I did, I completely agree. I wasn't going to leave the map like that, but I couldn't get the car to lean out up top and started adjusting the cells it was hitting to see if I could get the AFR's in the 11's. This is still obviously the wrong approach, but I was running out of time and getting desperate to find the issue.

Yeah, it's running ridiculously rich but I think we'll be able to get it figured out from here. Thanks again for your help Derrick. And thanks to everyone for the input, sometimes all it takes is some other thoughts to trigger the issue!