Sr20 bogging

[Roguewolf240]

Did the swap myself a while ago, but have not been able to get it running right

Just drove it to get some gas nearby because of the hurricane.

Any idea why a car would "choke" around 4.5k rpms?
In other words, it felt like I could go past it but I didn't like the hesitation so I didn't. But it didn't limit me

History: last time I tried driving it it actually limitted me to 4k.


Have replaced plugs, fuel filter, tested maf( no affect, wiring?), have no affect when you unplug maf, has oil psi, spools like it should, no cel, replaced o2 sensor, have played with timing, but still bogs,

has a z32 maf and a tuned ecu i got from a friend.

[SleepR 240sx]

Is the tuned ECU set up exactly for your setup? If not that could definitely be contributing or be the whole problem. Vaccuum leak comes to mind as another possibility. Check all your piping and lines.

[Roguewolf240]

Yeah I haven't checked for a leak yet but I'm thinking that could be it because when I was drivig it today I noticed that it also hesitates when its about to hit boost. but then it gets past it when I go into boost..

Also, as far as the ecu I'm only not sure about whether its for stock or bigger injectors. Would it cause the car to behave this way if it were trying to use larger injectors?

[240srhatch]

Would it cause the car to behave this way if it were trying to use larger injectors?

Yea, if the computer is tuned for larger injectors and you still have the stock injectors installed then the computer is making your motor run extreemely lean. This is happening because the ecu is cutting down the output of the injectors thinking that they are larger than stock.

[spartanmisfit]

I'm having similar issues with my redtop. Mine's been happening though and I havn't put in a new ecu or anyhting at all but spark plugs and octane booster.

[uthemofo]

get a stock maf, and a ecu that you KNOW is stock and running perfect. Get back to basics, eliminate what could potentially be wrong, like the ecu or maf for example. A stock sr should run perfect unless there is a leak or something you messed up on. Make her stock and see what happens.

[DataXUnknown]

Did you change your fuel pump when you did the swap? My SR feels like your description a bit too...it used to run nice and fast, but now around 3-4k rpm it doesn't pull that hard at all. I'm still getting boost and everything, so I've narrowed it down to my fuel pump. I heard you are supposed to change it when you swap to SR and I never have.

I will let you know how that goes and if it fixes mine, maybe could be your problem as well.

[Roguewolf240]

Yeah, changed the pump to the Walbro 255.
Still haven't been abe to diagnose, but most of my frriends are teling me fuel. I also heard that I should've upgraded the fpr along with the pump.. is there any vaididity to that?