RB20DET S13 Chewing through gas/feeling underpowered

[rbmiklary]

Hey guys,

Wondering if anybody can point me in the right direction or knows something I don't, will give the mod list first just to give everyone a frame of reference. Motor is for the most part stock except for the following.

RB20DET 92 S13
-Wiring Specialists Swap harness complete engine trans
-CXracing front mount intercooler kit (I know)
-walbro 255 (or so I'm told from previous owner, but I believe him)
-AEM Adjustable Fuel Pressure Regulator
- z32 maf (thinking what could be my problem)
- hks sport exhaust
- amperformance downpipe (awesome, probably only swap downpipe that clears the steering shaft)
- pop filter (random autozone one, mine was beat had no choice)
- NGK BCPR6ES's

Now with the exception of the fuel pump the rest was installed by yours truly, car seems good but feels like it has a slight missfire midway. Also feels like it should be faster, lacking pick up. I should mention when changing plugs recently noticed that cylinder one was far cleaner in comparison to the remaining five cylinders. All seemed covered black soot showing my rich condition but not so much in cyl 1. Black soot on the back bumper as well.

Now I have fuel pressure set to factory 43 lbs, stock turbo factory psi, stock injectors. Stock computer. Was thinking the rich condition could be caused by the Z32 maf for obvious reasons, and I have a apexi neo kicking around and a wideband o2 w/gauge that I could mount up but was curious if anyone ran into something similar, or had any thoughts as to what I could be missing.

Thanks,

[2.5T_/<ouki]

Have you checked your timing? Done a compression test? What are your spark plugs gapped to?

If the RB20 ECU is anything like the RB25 ECU that's probably your problem. I know my RB25 eats gas like no other. I am only able to get about 200 miles to a full tank in my S14. Also, i was under the impression that in order to use a Z32 ECU you would need some type of tune? I am in the process of installing my AFC-neo and AEM Uego so hopefully i see some better numbers also.

[rbmiklary]

Thanks for the input should have mentioned that I did all the duh stuff first, vacuums leaks boost leak timing all checked (the correct way), .8 on gap, 15 degrees as factory, compression test was not done but I have a snap on cylinder cam which is handy, cylinders looked clean and I'm sure would check out if I did a test probably will do one for shits and giggles.

Sounds like you and me are kinda in the same boat, that mileage can't be right.

[2.5T_/<ouki]

Thanks for the input should have mentioned that I did all the duh stuff first, vacuums leaks boost leak timing all checked (the correct way), .8 on gap, 15 degrees as factory, compression test was not done but I have a snap on cylinder cam which is handy, cylinders looked clean and I'm sure would check out if I did a test probably will do one for shits and giggles.

Sounds like you and me are kinda in the same boat, that mileage can't be right.

Oh that mileage is correct. It's SUPER horrible as the RB25 ECU makes the engine run PIG RICH.

Does it not need a tune to compensate for the z32 AFM?

[Jtuned_andy]

i dont know how you are running a z32 maf without a chipped ecu

[Redsunz916]

Sounds like a Maf issue either its bad, wired in wrong, or not tuned for it... Id check those first.

[Redsunz916]

U can't just put a z32 Maf on without a tune or ur safc to set it. It is definitely differant then the stock Rb one

[fliprayzin240sx]

Z32 MAF is not plug and play...put the stock MAF back on.

[2.5T_/<ouki]

Plug in that AFC-neo then you will be able to use the Z32 MAF. Without that or a tune it will not work.

[rbmiklary]

Thank you everybody for your input, checked again cause I have heard and can see why the Z32 MAF would like not work just plug and play. Turns out my MAF is a N60 22680-16V00 For a 1990-92 Infiniti M30 or 89-94 Maxima, now I can vouch for this thing actually working on the car no tune or ECU, however it is like you guys said probably causing my problem. Will see if I can hunt down a RB20 MAF Pigtail. That might be tough.

IMG_0944[1] | Flickr - Photo Sharing! (http://www.flickr.com/photos/88066507@N08/8341609549/in/photostream)

IMG_0945[1] | Flickr - Photo Sharing! (http://www.flickr.com/photos/88066507@N08/8342666672/in/photostream/)
And buy a factory RB20 MAF, probably from Raw as I can't find a US cross reference that I can use. May be able to use the NEO to get things right, but I rather get this thing to stock form first before I start any serious modification.

[rbmiklary]

All the more confused, wondering if anyone on here can confirm for me what the factory MAF sensor is? Cause I keep seeing that the N60 should work fine, that the one the car came with is a J60, but that I can also use a E60? Just want to be sure of what I should be buying.

[fliprayzin240sx]

Go search if RB25 and RB20 uses the same MAF. If they're the same, i got an RB25 MAF I dont need.