stalling, bucking Q45 :(

[guadofreak]

Ok it's finally gotten to where I KNOW there is a problem.

1994 Q45, 153K, transmission service has been done fluid level good, MAF has been cleaned. Knock sensors need replacing.

Sometimes in the mornings the car starts and dies immediately, sometimes twice then is fine.

While driving when downshifts car bucks like it is missing badly sometimes at part throttle.

When in traffic at a stop light occasionally dies then starts up again?! I do notice movement from the transmission when the car dies at stoplights and I am in gear.

Could all of the problems be caused my transmission issues? Or is there more to it?

Knock sensors will eventually get done when I have time, Fuel pump is still within normal life from last replacement, transmission and motor run AWSOME at times shifts perfectly etc...other times badly.

Any ideas???

[vicQ45]

im kinda new to this, but have you ohmed the injectors? mine all ohmed at 13.4-13.8 so either some electrical component was on or there all barely in spec, but they all run fine so i've got my fingers crossed as my transmission is on its way out and im ordering a new fuel pump.

[Jesda]

The part where you said its bucking makes me immediately suspect the MAF.

http://nicoclub.com/zerothread?id=82862

[96Qowner]

Yeah, this is identical to the trouble I was having last year. The same. The car would die for no reason on the freeway and restart itself. It died a couple times decelerating on exits, and would happily restart right away. It would buck and miss on acceleration, for no good reason. It would ALWAYS recover and run fine.

I'd take your MAF out again and give it another good cleaning. Mine needs it every couple thousand miles now. I was talking to Dennis about it when I was there. It was causing me serious bucking problems again, after only 1200 miles since the last cleaning. Got it cleaned at T3 again and it ran fine all the way home. The suspicion is that the MAF is failing, and that a cleaning just gives it a little more life.

Should be easy to isolate with a cleaning. It'll either be trouble free for a few weeks, or it won't help at all. (Incidentally, I think that electrical parts cleaner is the latest recommendation.)

Wish I knew if the used MAFs on ebay are worth buying - a heck of a lot less than a new one.

[DominickJ30]

Another culprit could be your TPS, if you have acess to an osciliscope then I would check it out.

[Jesda]

http://www.car-part.com/ -- Used MAFs can be had for $30 and up. 90-94 are the same. 95-96 have a different connector.

[guadofreak]

I shall clean the MAF and update everyone! <fingers crossed>

[DAEDALUS]

An intermittent problem is most likely not related to a dirty MAF element. So common that it almost goes without saying--check the connector first, and get the connection solid. Wiggle it and see if it affects the idle when the car's acting up.

[DominickJ30]

An intermittent problem is most likely not related to a dirty MAF element. So common that it almost goes without saying--check the connector first, and get the connection solid. Wiggle it and see if it affects the idle when the car's acting up.

Ahh the infamous wiggle test. A good diagnostic tool.

[guadofreak]

I have been noticing the infiniti's heavily rely on the wiggle testing.

[texasoil]

If your MAF is getting diry fast--it is because the 'burn-off' cycle is not working--usually because the connections are cruddy. You should NEVER have to clean the MAF. It is extremely delicate and easily destroyed with a hard blast of solvent or air. Sand hitting it is falta (like from a 'pop charger' or leaky air inlet box/filter. They NEVER fail if OEM filter and box are kept tight.

[guadofreak]

cleaned and wiggles, NISSAN air filter still new and good seal before the MAF.

Still having the issues. Any other ideas? I heard something about he crank angle sensor needs a wiggle? Or should I replace it? I did get a code once from the car that was teh crank angle sensor... :-/

[DAEDALUS]

Wiggle it first. No CAS--car wants to dance but can't find a rythm.

[guadofreak]

WOW, sorry about my grammar. I am so used to auto correct on word! So you are saying to wiggle the crank angle sensor first and then replace possibly?

[DAEDALUS]

Wiggle the connector. If necessary, remove, clean and replace. Make sure it has a good electrical contact.

[guadofreak]

I will go ahead and remove clean all connections and report back with findings.