Question about my performance!!

[SRBURG13]

Hey all. I've been a floater on here for a little while now, and finally have a question for the keeners!:D

Here is the specs first:

'91 240sx HatchbackRedtop SR20DETApexi Silvia FMIC with 2.5inch pipingBlitz Dual SBC Boost controller3inch downpipeApexi N1 3inch Single Tip ExhaustTurboSmart SS BOVand all that clutch flywheel stuff. But that doesn't pertain to my question.Stock fuel pump and other fuel setup stuff.

Right when I left the shop after the swap, the car was running PRIME! After about 20km (I'm in Canada) the car started to spudder in the low RPM's. When the car reved higher, it cleared up and drove smoothly through the gears when I pinned it.

Example: I'm driving 60KMPH in 4th gear (which is pretty low RPM), and I floor the pedal. The engine just sputters away. I can hear the turbo spooling up good, but the car isn't accelerating anywhere unless I pump the pedal a little. Then after about 4000rpm, it clears up nicely.

Any ideas?????

I guy somewhere else told me that it might be that I need a Walbro 255 fuel pump or something like that. We don't think that it is a headgasket problem cause we checked the majority of the symptoms of that.

What could be wrong.

[DonDonati88]

get the fuel pump upgraded

[SRBURG13]

Yeah, that is being ordered soon. Do you think that this would solve the problem all together?

[bp2ooo]

yea, i could see a lack of fuel causing problems similar to what your having. Fuel pump upgrade is a must on an sr. Good luck.

[SRBURG13]

Thanks. Is it also neccessary to have the injectors upgraded? Or the fuel regulator or filter?

[bp2ooo]

i would put a 300 z fuel filter in. I wouldn't worry about upgrading sr injectors till you want above 14psi, and your turbo can handle it.

[SRBURG13]

Thx

[BuudWeizErr]

It's not getting louder when it starts spooling at low rpms is it? If that's the case, you have about 6 hours of work ahead of you. You have to take the whole exhaust manifold off.

I highly doubt this is a fuel problem, unless it's vaccum related. Is your FPR hooked up correctly? You would be having problems at high boost/high RPM if it was fuel related. Actually, it could be if your BOV is leaking. This could be a million things. Your MAFS could be on it's way out.

Honestly, I don't think it's vaccum, or MAFS, or BOV. Because, unless you have been messing around with your vaccum or FPR after you drove it the first time, you wouldn't be having these problems now. I'm curious to see if it's your turbo gasket. Thats what happened to me.

[SRBURG13]

Yeah, I just had the turbo and manifold off. And the gasket was replaced. It was having this problem before and after the changed gasket. MAF? Hmmm, thats a possibility. I'll replace the pump and see if there are ANY improvements whatsoever.

[Cyberkreig]

interesting problem. My take would be that it is not fuel, fuel would get worse as the RPM goes up. I would think that a boost leak or exhaust leak would get worse as you got into boost.(??) As for the MAF, the car will idle beautifuly with no maf at all. It bothers me that it gets fixed right about the spool up mark, that is confusing. -- But my first instinct was electrical. If your altinator isnt working up to prime it wont make enough juice at idle, but would provide more spark at higher RPM. Again, i dont KNOW, but it seems to me that MAF, BOV or gasget would get worse when in boost...

[SRdS14]

it could be a number of things...injectors, fuel pump, intercooler piping, or even plugs/wires...

[SRBURG13]

Here are a few other points to think about:

A friend of mine turbocharged his Nissan NX, and said that he had the EXACT same problem. He said that he just reduced the gap on the spark plugs and the problem was gone. I've been told that that is not a good thing to do if I already have the plugs at the proper gapping.

Also, when I drive the car before it can even get a chance to warm up, the problem is gone. It doesn't seem to come until the car warms up, and the warmer the engine, the worse it gets.

I'm thinking that it might also be a leak in the intercooler piping as well.

Also, idleing is slightly rough.

Finally I can get some pointers. No one up here in Edmonton knows anything about this engine. Thanks guys.

[nismojason]

As for the MAF, the car will idle beautifuly with no maf at all.

I thought that a car wouldn't even start if it didn't have a MAF hooked up. If i'm wrong could someone please enlighten me...Thanks

[Cyberkreig]

that is exactly what i though too, till i did it.

[SRBURG13]

I was thinking long and hard about it, and I think that it is an intercooler leak somewhere. A leak would lead to no boost right? Well, when it is doing the spuddering thing, the boost gauge reads a totally low boost number, but you can hear the turbo spool nicely. No, the sound does not get really loud or progressively louder. I've had a few exhaust leaks too and that was definetly noticable. I've also had the turbo come loose from the manifold, so I don't think that it is the turbo gasket cause that is anonyingly loud. If its not the MAF or electrical problem, it is either the little theory about the spark plugs, or a leak in the intercooler piping somewhere. Unfortunately I can't drive the car anywhere around here right now because of the damn snow. In march or April I'll have it out to take it for its runs.

PEACE

[SRdS14]

i tried to change the MAF on my car to the z32, but my car ran like s h i t, but i guess it has somethin to do with the jim wolf ecu...it sputters and won't accellerate hard etc etc. it might be the maf...don't ever cross that out man. thats kinda like my intercooler piping incident.~Scott

[I H8 UR DSM]

yes the ecu has to be tuned to run the z32 mafs....DUUUUUUHHHHHHHHHH : )