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I've had this problem for a while now and assumed it was plugs and leads but recently established its the air/fuel ration being off.

The problem:
car is stuttering down low when hitting the go pedal. It's pretty prevalent now as sometimes the car does this until you get to 3k on the tacho.

Car seems like it's over fueling or something. Is there a way of adjusting the ratio of air/fuel? I tried disconnecting the battery to reset factory settings, checked the intake lines for splits/vac leaks, checked my plugs and leads as stated above. Nothing has fixed it!!!!!!!!!


What do I do??

As i just wrote in the your garage thread... My ideas would be either,

o2 sensor
Fuel filter
Coolant temperature sensor (fooling the car into thinking it's cold when it's not so the ECU over fuels).
Clogged up air filter
Exhaust blocked (dead cat?)

You can lean out the air fuel ratio (I've looked into a bit) but you should make sure all of these are functioning properly before you go down that path (which can be a bit dangerous)

check out my thread, I eventually replaced the engine temp sensor

If you really think it's overfuelling, then check the plug electrodes for signs.

In addition to what ben and gob stated, might be coil-packs on their way out.
Clean the contacts of you AFM/MAF plug with contact cleaner or a light spray of WD-40 and soft tooth-brush.

Are you leads of a good quality? Doesn't matter if they are new, if they are shite, then...

Perhaps it might be as simple as the plugs being gapped too wide.

My track car was doing this and I replaced plugs, leads & gave the MAF a clean. It was one of those three things that fixed it!

i'm sure all the items mentioned above to check may be the cause

though my input is are you sure its overfueling?

i always thought if the motor running and warm rev while idling and how it returns to idle shows too rich (stumble to idle) or too lean (slow return to idle)? assuming you can rev it ;)

Have you actually tested it with a recently calibrated wideband?

If so and its too rich or lean across all ranges all the time you can use an adjustable fuel pressure regulator.

Dann

nanotech wrote:...recently established its the air/fuel ration being off.

Yeah, how was this established as the NA6 typically runs rich?

Ha it does????

nanotech wrote:Ha it does????

If that's re NA6s running rich, then absoutely stock are well known for it.

Hmm, if that's correct then I'll put up what I've done to it.
Timing is set at stock, has a 2.25" full exhaust from motor with a 4-1 set of headers and mania intake. Not really much else in terms of engine stuff. timing was set at 16 but it's been reset back to stock.

nanotech wrote:Hmm, if that's correct then I'll put up what I've done to it.
Timing is set at stock, has a 2.25" full exhaust from motor with a 4-1 set of headers and mania intake. Not really much else in terms of engine stuff. timing was set at 16 but it's been reset back to stock.

An NA6 with those mods would still run rich - in terms of NA6s running rich see here:
search.php?keywords=na6+rich&terms=all&author=&sc=1&sf=all&sk=t&sd=d&sr=posts&st=0&ch=300&t=0&submit=Search

I've heard that NA6's run rich before - surely this would mean that NA6's would foul their cat's and fail emission testing in a stock configuration?

Being rich standard explains why with a bit of leaning in the cruise cells I can get so much distance on a tank! (700km odd)

Guess the richness is within tolerances - NA8 runs similarly rich.

Has anyone stuck a wideband in there and seen just how rich?