Spec S Running problem. Getting worse!

[-BigDave-]

So it started with a hesitation when I pressed the accelerator. Then it progressed to having a rough idle when warmed up. The idle was fine when cold but its now a bit rough when cold as well. The main problem now is that when I have the throttle just open to try and cruise along in whatever gear, the car starts to sputter and run like shit. The car revs up ok (seems to be down on power though) but just as I try to hold the revs at a certain point it all goes to shit. When the car is stationary and out of gear, and the throttle is opened, the same happens; it revs fine but can't hold the revs in any one place without starting to sputter and stutter like crazy. At first I thought it was the AFM because when the car was idling rough if I plugged out the AFM it idled ok when warm. Tired cleaning it several times and then replacing it.

I've replaced the following:

Spark plugs
Lambda/O2 sensor
Air Flow Meter/Mass Air Flow Sensor. Did this twice with 2 seperate 2nd hand units that I was assured were both in good working order.
Cleaned the throttle body and intake plenum down with throttle body cleaner
Replaced the fuel filter under the bonnet

I've also inspected the spark plug cables and they're fine. The distributor seems to be ok as well, little bit of corrosion but nothing major as far as I can see.

Should i try cleaning the injectors with a fuel additive?
Does it sound like a fueling issue or air flow issue?

And finally: WHAT THE FUCK IS WRONG WITH MY CAR!? Because i'm fit to throw a brick through the window at this stage!

Any help appreciated!

[shtones]

Mightnt be any use but we had a problem in our bmw that she was spluttering when started up and wouldnt hold revs or idle, found out was a hole on the air intake hose/pipe patched it up with silage tape ran perfect straight after!

[-BigDave-]

Checked all intake piping and she's sealed right. Thanks anyway.
Thinking it might be worn throttle body or throttle position sensor. Gonna go get it plugged in tomorrow see if any codes come up.

[hi_im_fil]

I'd try the throttle position sensor. Try run it with it unplugged. It should still idle ok without it,

[-BigDave-]

Unplugged that and it idled bad as well. Dropping down and nearly cutting out like. Took it for a spin with it plugged out and no change.

[Duck Drift]

Check fuel pressure? Tank pump maybe

[andy t]

check inlet mani gasket

[P Hooks]

same thing happened my spec R once but doesnt sound as bad as yours is. Mine had a cracked vacuum pipe leading into he back of the inlet manifold, it might be worth a look. :cool:

[-BigDave-]

Thanks for the suggestions. I haven't checked the mani gasket so I'll inspect that next. Thinking it might be coolant temp sensor but I'm not spending another penny on parts until I get her plugged in for diagnostics. Guessing and buying parts is not working for me ha!

[1jsoarer]

Thanks for the suggestions. I haven't checked the mani gasket so I'll inspect that next. Thinking it might be coolant temp sensor but I'm not spending another penny on parts until I get her plugged in for diagnostics. Guessing and buying parts is not working for me ha!
Are ya sure the ht leads arent fucked, they could be earthing out somewhere. Stick a new set on it!

[willie 180sx]

try the loom going into the coils packs,one of the wires could be cracked or broken,leave the car running and just mess around with the loom to see if it makes any difference

[paddyb01]

try the loom going into the coils packs,one of the wires could be cracked or broken,leave the car running and just mess around with the loom to see if it makes any difference

Its a spec s