s14 sr loss of power in higher rpm

[cutter]

I have a 98 240sx and a 98 notchtop sr with vtc. the car pulls nice until around 4500-5000 rpm then it feels like it hits a wall. I have 550 cc injectors and z32 maf and i have an "NA" tuned ecu for it. I have had lots of experience with red tops but none with s14 sr. It is idling around 13.1 afr and under full boost it is around 10-1 afr. it is super rich.

does this sound like a vtc problem, injector problem or ecu problem? also can i put chips from a tuned s13 ecu into the s14 ecu?

[Portuguese Bend]

It's hard to tell from the AFR numbers you're quoting without a dyno graph. Too lean & too rich will give less power. It could be the VTC like you're thinking.

[codyace]

Vacuum leak? Timing correct? Troublshooting between the two is going to be the same...

[cutter]

yes i have checked the cas, tps, base timing set to 15* everything is set correctly. vacuum is right at .6 bar or what ever it is. I am thinking it is this tune. i have tried to search for the way to test the vtc but the search engine just brings up a bunch of bs.

[StryfeS13]

Does your SR have a rubber intake tube? Is the spring in it?

If it has no spring inside of it, it will collapse and cause your problem

[RACETUNE]

I have a 98 240sx and a 98 notchtop sr with vtc. the car pulls nice until around 4500-5000 rpm then it feels like it hits a wall. I have 550 cc injectors and z32 maf and i have an "NA" tuned ecu for it. I have had lots of experience with red tops but none with s14 sr. It is idling around 13.1 afr and under full boost it is around 10-1 afr. it is super rich.

does this sound like a vtc problem, injector problem or ecu problem? also can i put chips from a tuned s13 ecu into the s14 ecu?


What is your fuel pressure when this is happening. If your fuel pressure is good, most likely its your maf. And this is all assuming wiring, mechanical, all modifications are on point.

No it is not your VTC, injector or ECU.

-Frank








***If you have an issue with your vehicle and every Shop and/or Specialist you have tried failed, and you just want someone that will do it once and right the first time. Or you need a Dyno Tuner with many years of Racecar tuning experience. Hit me up.

[mewantkouki]

Knock sensor, my car had the same problem. We thought my VTC gear was messed up, when it really wasn't.

[cutter]

I have already tried a maf. I will check the fuel pressure and the knock sensor in the next couple of days.

[jr_ss]

Check your turbo inlet if youre running the stock rubber tube. Could be sucking it closed.

[cutter]

I have a metal intake.

[StryfeS13]

Does it hit a wall at the same exact rpm range, every single time?

If so, might be knock sensor

[BCaston240sx]

Did u ever figure it out i am having the same problem

[cutter]

The intake cam was 2 teeth off.