Engine stumble/hesitate at high revs

[ReeceZ]

Hi guys,

I'm new here, i drive a 94' S13 200SX with the CA motor.

I've been experiencing this problem for a while where the car noticeably stumbles/hesitates at high revs. It happens in 2nd, 3rd and sometimes 4th gear. If i accelarated gradually, it's fine, but happens when i floor it through out. I thought its fueling so I fitted a Walbro 255lph. But that didn't seem to work. The stock turbo has been pushed up to 0.9 bar boost, also have a 2.5" exhaust system, blow off valve, and IC but its mounted just in front of the radiator (which i'm gona change soon). I'm gona put in stand alone management soon. Do you guys think that this will sort it out or is there something else i could do?

Thanks

[sjbsuperman1425]

sounds like a boost leak..

[Ca_Silvia]

Just put your standalone in and go from there. If your a few weeks away frm that, check fuel pressure, clean MAF, Check spark plugs (lean or rich).

What heat range of plug do you have?

[ReeceZ]

I'm not sure what the heat range is, I have NGK plugs in there, the stock ones which i replaced 3 months ago when this problem started.

[ReeceZ]

Wouldn't it be happnening all the time if it was a boost leak and not just when i'm flooring it. Could an exhaust leak cause it?

[ca18detgabby]

Wouldn't it be happnening all the time if it was a boost leak and not just when i'm flooring it. Could an exhaust leak cause it?

a leak should be omni present. should be checking fuel pressure and if you have a wideband what the A/F is.

I would also check to make sure the 02 sensor is up to spec.

[ReeceZ]

Don't have a wideband. B4 i forget, I have the stock turbo in there that's been pushed to 0.9bar boost. Could it be that the internal wastegate can't handle it?

[boost_boy]

Don't have a wideband. B4 i forget, I have the stock turbo in there that's been pushed to 0.9bar boost. Could it be that the internal wastegate can't handle it?

Turn the boost down and see how it acts.

Dee

[ReeceZ]

Don't have the money to buy an electronic boost controller. can u turn down boost with a manual boost controller

[Ca_Silvia]

Wait so stock everything your at .9 bar?

I say check for boost leaks if thats the case.

[KEMP]

Yes