200sx Unknown Fault - Please Help Me!!
Discussion
Hi,
It's really starting to annoy me now.
I have a 92 Nissan 200sx s13 (with the stage 1 chip), which is coughing and sluttering under acceleration and is a little hesitant under normal acceleration. When it is cold it is a pig to drive smoothly, it feels as if it is going to cut out and is very juddery. Sorry about the simple terminology, it is the only way I can explain it. When it does this it seems to smell of petrol. It is also popping quite a lot.
I have replaced quite a lot. I have changed the sparks to platinum ones, changed the coil packs, cleaned the air filter, replaced the fuel filter, check the boost pipes for leaks, new cam belt and checked timing, changed the ECU with another from another car.
The exhaust does not seem to be blowing and the gaps are set correctly on the sparks.
I am running out of ideas, please help me. I don't want to spend a lot on it so I would like to know what you all think before I replace other bits on it.
I look forward to your responses.
Thanks
It's really starting to annoy me now.
I have a 92 Nissan 200sx s13 (with the stage 1 chip), which is coughing and sluttering under acceleration and is a little hesitant under normal acceleration. When it is cold it is a pig to drive smoothly, it feels as if it is going to cut out and is very juddery. Sorry about the simple terminology, it is the only way I can explain it. When it does this it seems to smell of petrol. It is also popping quite a lot.
I have replaced quite a lot. I have changed the sparks to platinum ones, changed the coil packs, cleaned the air filter, replaced the fuel filter, check the boost pipes for leaks, new cam belt and checked timing, changed the ECU with another from another car.
The exhaust does not seem to be blowing and the gaps are set correctly on the sparks.
I am running out of ideas, please help me. I don't want to spend a lot on it so I would like to know what you all think before I replace other bits on it.
I look forward to your responses.
Thanks
could be anything really.
things to check for are :
boost leaks ( which you say you've done but they can be a pig to find),
inlet manifold leaks (spray WD40 on the manifold with the engine running and the revs will flutter if there's a leak and its taking in WD40, carb cleaner works too)
plugs - take the plugs out after the engine has been running, are they coming out wet? are they heavily sooted? have you changed them recently?
timing - what is your timing set at? should be 15 deg BTDC +or- 1 degree
have you bypassed the hot start solenoid? if not do it
fuel system - check the fuel filter, if it's not been replaced in a long time, or you dont know when it was replaced give it a change, easy to do and costs buttons. Z32 ones fit and are bigger, which some claim is better.
another very viable one is the air flow meter, don't generally need to replace them, but it might be worth removing it and taking a look. as they're hotwire AFM's they can be inhibited in air flow calculation if the hotwire becomes encrusted in oily filth, which happens. this can be cleaned with carb cleaner, but i must stress be very careful when you do this as they can be quite fragile.
is there any smoke being thrown out the exhaust? if so what colour is it? boost leak will normally lead to black smoke if its severe, and reduced fuel economy (usually quite severe drop), blue smoke is normally indicative of oil burning, which can be various things, rings, valves, turbo etc, all the good stuff. if you're getting lots of blue smoke give it a compression test, could well be worn rings or a sticky valve causing the massive reduction in performance / running smoothness.
finally if you're not on the sxoc, now's the time, loads of friendly folk with lots of knowledge on there, www.sxoc.com/vbb
i'd be looking for a big boost leak, i've seen people look for days for them and not have any joy, pressure testing the pipework is easy and helps. i've even seen a turbo split in half
that was a monster of a boost leak!
the petrol smell is guarenteed to be overfuelling mate, which is what you get when you have a boost leak.
are you still running the WMIC? if so get checking for cracks in the pipework leading to it, and in the core itself.
you're basically losing air which the AFM has accounted and supplied the right amount of fuel for, therefore there's a big excess of fuel as the air leaks out which only goes out the exhaust. hence the poor fuel economy, black smoke and smell.
The AFM being fouled can also cause this, but if its come on suddenly either it's shagged or you have a boost leak. my money's on the latter, but a sticking a multimeter on the afm should tell you.
get yourself a copy of the S13 workshop manual if you haven't already, it's invaluable for this sort of stuff, and can be found at Jez Horsham's website www.h-dev.co.uk
bet your plugs are wet and sooty when you pull them out, might be worth giving them a clean with carb cleaner!
in retrospect i see i have gone through a few things which you have mentioned, but i'm too lazy to edit them out of my post!
things to check for are :
boost leaks ( which you say you've done but they can be a pig to find),
inlet manifold leaks (spray WD40 on the manifold with the engine running and the revs will flutter if there's a leak and its taking in WD40, carb cleaner works too)
plugs - take the plugs out after the engine has been running, are they coming out wet? are they heavily sooted? have you changed them recently?
timing - what is your timing set at? should be 15 deg BTDC +or- 1 degree
have you bypassed the hot start solenoid? if not do it
fuel system - check the fuel filter, if it's not been replaced in a long time, or you dont know when it was replaced give it a change, easy to do and costs buttons. Z32 ones fit and are bigger, which some claim is better.
another very viable one is the air flow meter, don't generally need to replace them, but it might be worth removing it and taking a look. as they're hotwire AFM's they can be inhibited in air flow calculation if the hotwire becomes encrusted in oily filth, which happens. this can be cleaned with carb cleaner, but i must stress be very careful when you do this as they can be quite fragile.
is there any smoke being thrown out the exhaust? if so what colour is it? boost leak will normally lead to black smoke if its severe, and reduced fuel economy (usually quite severe drop), blue smoke is normally indicative of oil burning, which can be various things, rings, valves, turbo etc, all the good stuff. if you're getting lots of blue smoke give it a compression test, could well be worn rings or a sticky valve causing the massive reduction in performance / running smoothness.
finally if you're not on the sxoc, now's the time, loads of friendly folk with lots of knowledge on there, www.sxoc.com/vbb
i'd be looking for a big boost leak, i've seen people look for days for them and not have any joy, pressure testing the pipework is easy and helps. i've even seen a turbo split in half
that was a monster of a boost leak! the petrol smell is guarenteed to be overfuelling mate, which is what you get when you have a boost leak.
are you still running the WMIC? if so get checking for cracks in the pipework leading to it, and in the core itself.
you're basically losing air which the AFM has accounted and supplied the right amount of fuel for, therefore there's a big excess of fuel as the air leaks out which only goes out the exhaust. hence the poor fuel economy, black smoke and smell.
The AFM being fouled can also cause this, but if its come on suddenly either it's shagged or you have a boost leak. my money's on the latter, but a sticking a multimeter on the afm should tell you.
get yourself a copy of the S13 workshop manual if you haven't already, it's invaluable for this sort of stuff, and can be found at Jez Horsham's website www.h-dev.co.uk
bet your plugs are wet and sooty when you pull them out, might be worth giving them a clean with carb cleaner!
in retrospect i see i have gone through a few things which you have mentioned, but i'm too lazy to edit them out of my post!
Edited by MeLLoN Stu on Saturday 15th July 02:20
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