need help with engine problem

[skyyred]

I need help i dont know wats wrong with my engine..i have a 92 240sx with a red top sr20det...ive had if for a few months now and everything was perfect on it...recently as i was speeding up to get on the freeway... i gunned it in third gear and around 5500rpm the motor started bucking and making a wierd rattling sound(i didnt see any some or anything)..every time i gun it it starts to do the same thing..im guessing it might have to do with the turbo ...not sure though-the car runs fine at low speeds-it idles fine the problem starts when i gun it... i can speed up slowlydoes anyone have an idea of wat might be wrong..

[wa-chiss]

take the inlet pipe off the turbo and see if the turbine spins freely. It sounds like your motor is choking. just my $.02

[skyyred]

thanks man.....before i take it apart you think i could be my fuel filter havent had time to check it

[rotorimp]

Could be a fuel filter--did you put in a walbro fuel pump?

[skyyred]

no i havent changed the pump its stock

[rotorimp]

Sounds like it is starving for fuel--dangerous on a boosted car!

[rotorimp]

That rattling sound might have been Detonation!

[skyyred]

what do mean by detonation??ima replace my fuel filter tomorrow just in case....

[skyyred]

ohh and thanks for the help its greatly appreciated

[rotorimp]

detonation--when the motor runs too lean (the fuel is ignited by heat and compression and not by the spark plug) nasty business--breaks piston rings, ring lands, melts pistons--I would do a compression test and get a new fuel pump, fuel pressure regulator ASAP!

[wa-chiss]

I don't think it would be the filter. I mean, it just happened all of a sudden right. If so that points to 90% either mechanical, eletrical, or vacuum.

[rotorimp]

It happens under load and he has a STOCK fuel pump!

[wa-chiss]

It happens under load and he has a STOCK fuel pump!

you are correct. but thats is an electrical and/or a mechanical problem like I stated before. I just said no not the filter. To the OP, if you change the pump, make sure you get a new strainer too.

[rotorimp]

I have had cars in the shop that will mimic a bad fuel pump just because the filter is clogged. Under load the filter is not able to pass enough fuel through and will cause bucking,hesitation and stalling

[wa-chiss]

but a filter wont clog in the blink of an eye like that. Unless, there is some shrapnell in the line from the pump. The strainer takes care of any debri in the tank. The filter is not the culprit here.

[rotorimp]

It is like sucking through a straw while your pinching it--sure you'll get some drinks--but them right after that super hot Jalapeno topped nacho when you want that really big gulp--BAM you detonate because you just can't get enough. Don't think about it like chunks--filters get clogged over time with very small particles (the one's that the strainer will not catch).

Read through this thread--similar problemhttp://forums.nicoclub.com/zerothread/232888

[jaytv1019]

I know what everyone is saying here but did you check for boost leaks? You say it only happens when you floor it and it bucks?

I would like to think that even if you don't know what detonation is, you would know that sound it makes is BAD. It sounds like hundreds of BB's being thrown at your windshield. I am not master of any car/motor (yet ) but my vote goes to a boost leak. Maybe a torn coupler that doesn't leak at idle only under load?

Later,

[wa-chiss]

Don't think about it like chunks--filters get clogged over time with very small particles (the one's that the strainer will not catch).

My point exactly. The filter won't clog in the bling of an eye but over time. / argument. The filter is not the problem.

[skyyred]

i changed just the fuel filter and nothing changed the same thing happens

[rotorimp]

1. Put in a real fuel pump and get it regulated to what the sr20 needs2. Check for boost leaks.3. Check TPS

And yes--I have seen filters go tits up in a -->blink of and eye--I have been working on cars for 15+ years. Based on the description he has a fuel problem! Most likely from fuel starvation (because of the stock pump) or overly rich from a boost leak. The latter is not "AS" likely due to the noise he heard. TPS/temp sensor can aslo cause this problem--but I would check the FP first!

Modified by rotorimp at 4:24 PM 3/22/2007
Modified by rotorimp at 4:25 PM 3/22/2007

[wa-chiss]

i changed just the fuel filter and nothing changed the same thing happens

Thank you.With cars, almost anything is possible.