Hey guys, this is my first time posting and a new member, and I am absolutely stumped on this issue i am having.

I have a JDM B18C GSR swapped turbo EK hatch. I have built the engine myself with wiseco 9:1 pistons Eagle rods, eBay turbo and intercooler, hondata s300, FID 750cc injectors, stock fuel rail, AEM fuel pressure regulator, AEM 320LPH fuel pump, brand new fuel filter,AEM failsafe wideband boost gauge combo, tuned by my local tuner Forrest Luster(Fulltune) making 315hp on 14psi. I didn’t mention all the mods, but just the ones I believe are retaining to my issue.

I was driving the car hard and noticed at full boost the car was at 15.7 AFR on my boost gauge. I immediately got out of it and contacted my tuner. He said that it was probably a fuel supply related issue, so i went ahead and installed the AEM fuel regulator and replaced the fuel filter. I set my base pressure to 44psi.

After I replaced both of those the car ran much worse. At idle the car was rich, and under any sort of load the car was lean. Just going 10mph in first gear the car was completely lean according to my gauge. I went ahead and replaced the fuel pump with another AEM320 tonight.

Now the car is rich at idle(13.1) lean during light cruising(16-17) and under full boost rich(9-10).
My tuner said he will schedule a time for me to come to his shop so he can look at it. He thinks during tuning there was a fuel delivery issue and he was able to tune around it, but as it deteriorated more it was out of wack.

I am just curious what y’all think about this, and if anyone has had any similar issues to this.

Thanks guys,
Logan

 

You're on the right path - you changed something and you need to re-tune.

What kind of injector duty cycles are you seeing? What type of fuel are you running? What kind of fuel filter was the original one, and what kind did you replace it with? What is your fuel pump wiring like?

 

My duty cycle is around 70%.
I am running 93 pump gas.
I am unsure what the original fuel filter was, but i replaced it with just an autozone one.

The fuel pump was originally done by the previous owner when they swapped the engine, but the wiring looks good from what I’ve seen.

I have changed ALOT since the tune. Nothing performance oriented, but maintenance items.

New skunk2 radiator, Gates oil pump, OEM water pump, eagle squirter delete, New clutch, lightweight flywheel, and carbon synchros plus everything i mentioned i installed to combat the problem.

Thanks for the reply. I really want to get the car sorted by Feb 20th because that’s my first ever track day scheduled. I just hope my tuner can fit me in before then.

 

What map sensor you running?

 

i am running a hondata 4bar. I guess that’s something i could check. Just hook my laptop up and see if my boost gauge correlates to the map.

Thanks man

 

Hondata 4 bar should be set up as Omnipower 4 bar unless you're running an S300, then it's actually programmed as Hondata 4 bar. With key on, engine off and monitoring sensors, your MAP reading should be 0. The rich idle and wot is not uncommon with that particular pump, I've experienced this one myself when tuning a setup that changed from a walbro 255 to an AEM 320.

 

I am running s300. I will check tomorrow and see what it is doing.

That’s really interesting for that fuel pump. It sounds like a regulator issue when I really try to wrap my head around it, but I guess I’ll just need it tuned ASAP. I’m sick of always working on my car and never driving it lol

Plus like i mentioned earlier the ever looming track day that i was preparing for.

 

Could be a regulator issue as well, most likely vacuum. Check the hose for damage. I've had this one happen to me a couple times. Lol! Saw more trouble with leaner under load though than cruise but, possible.

 

The hoses are relatively new, but what can hurt in checking them right. Thanks for all the info so far. I’ll be updating the thread the more info i get.