reving up and down makes driving hard plz hlp

[CMF_chopper_84]

hey guys im having problems with my micra

the thing is when you sart it up it sometimes starts up normal and sometimes not normal. (as in the starter motor it working hard to get the engine to start (sounds like not much fuel is being pumped through.)

the the up and down reving happens if you accelerate (driving or idleing)there will be a spot (like a flat spot)
where it would just go vraum, vraum, vraum, like just rev up and down at equal intervals of one after the other.

when i start it in the morning the car does that problem then once you drive maybe a km or 2 it will stop. then after driving for a half an hour, before i rech my destination, it will start reving up and down again.

this occours while im driving and its sooo hard and embarrasing to drive to work.

i have tried:
- fuel and injector cleaner poured through the tank.
- a LITER of meths.
- checked spark leads (all fiering)
- had the ECU inspeced by the mechaninc (and the reading was good)

i have been visiting 2 mechanics lately.

1 said that he would service the injectors first and put a new fuel filter in

then the other said he would check the pressure of stuff with a pressure gauge (make sure nothing is bloked or not functioning properly)

the first mechanic said that because i told him that i drive the car all the way to the red line that alot of crap may have gotten through and so on. and that the fuel pump may be stuffed. but he doubts that atm.

the second mechanic reckons its the fuel pump however he also doubts its that because i told him that sometimes during my trip everything will go back to normal.

both mecahics cant pin point the problem.

and so i aks all members if possible to come up with a reason or something to try to test whether or not something is causing this..
basically i need alot of help with this one.

thanks guys.. i will check up on this again later.

matt

 

[CMF_Yom]

Howdy Matt,

This sounds electrical rather than mechanical.

As for your idle problems they're probably caused by that black thing on the front of the throttle body. Its called an IACV - Idle Air Control Valve. They can get gummed up as they get older. It might need to be given a clean. I used carby cleaner to clean mine and it worked like new afterwards.

As for the erratic idle, I would start by re soldering the afm circuit board. There's a how to in the tech section of this site. Due to conditions these electronics are exposed to the solder can crack and cause intermittent shorts. Resoldering all the little points on the circuit board and the connector on the side of the body usually solves these issues.

All this is free to do so youve got nothing stopping you from giving them a go. At least once you've checked these out you'll be able to move onto other possibilities.

Cheers

 

[CMF_frank2]

matt

a fuel filter problem would only show at full throttle surely ?.
a pic of the plugs would be helpful, that vraum vraum sounds like its hunting (possible lamda fault, overfueling ?) but yom is very knowledgeable so i,m only guessing !

 

[CMF_chopper_84]

thanks guys.. im not to handy with the electrics so i will try the carby cleaner first and see how that goes. then i will talk to the people at the mechanics and tell them your advice.. it might save time, money and even help me drive to work easier now.

i will try and get a pic up ..

so you guys dont think its the fuel pump?

i only got the car recently..
and a problem i had when i first took it home was the accelerator cable jammed in one spot. that only happened a couple of times.
also before i bought it the car had an engine change.

*shrugs*

thanks guys.
i will let you know what fixes this problem

 

[CMF_frank2]

chopper 84

a pic of the spark plugs colour (kept in order) is usefull for diagnosis.
i doubt its the pump (but i could be wrong).

 

[CMF_Yom]

Your mechanics will most likely laugh at you and tell you that you're an idiot if you go to them and tell them what I've told you.

I hazard the point that 80% of mechanics don't have a clue when it comes to electronics. I'm in no way an electronic engineer but I know there's limits as to what electronics can be exposed to and nissans solution with the CG13's AFM is just crap.. They've done it most recently with the ZD30 diesels in the big Patrols - the control unit on the Bosch VP44 injection pump dies from the constant heat fluctuations it experiences being attached directly to the motor! Not good. Sometimes I wish I could slap the engineers who let the accountants determine how to build something.

My rant aside...

You're much better off seeing an auto electrician about getting the AFM electronics resoldered (or another sydney micra member who's willing to do it for a carton of their favourite amber beverage).

Cheers

 

[CMF_chopper_84]

oh yes please.. i live in campeltown. so if anyone here on this site could re solder.. either for money or beer let me know..

yeah i will try and get a pic tomorrow..

yeah these 2 mechanics i reckon are both in the 80% category of not knowing how to get the electrics fixed..
i will try an auto electrition. and get him to inspect my afm
does that stand for automatic fuel management?

-----------------------

frank2

when you say that you want a pic of the spark plugs.. would i have to take them out so you can see the actual inner bit or what?

please elaborate.

thanks guys.

 

[smidge]

Air Flow Meter...

I haven't had the need to resolder my own yet, thinking of doing it anyway just for fun

once i've made the mistakes on mine i can help fix yours if you're not in a hurry

 

[CMF_frank2]

chopper 84

if you take the plugs out and they are very sooty around the electrode it would point to overfueling.

frank

 

[CMF_justo]

I'm getting this same thing happening sometimes with White Knight, except it only happens at idle. Makes taking off a bit harder.

I found that if I re-start the car, it clears up though

The only thing I've tried so far was to clean the throttle body (to fix another problem which it did fix).

 

[CMF_chopper_84]

ok

thanks again guys for your help..

here is what i had done since then.

i had a mechanic retighten the belts for me as they both were squeeling really loudly.

then after that my engine didnt play up any more.
(though i couldnt tell if it was the belts being soo lose that was causing the problem)

i then wanted to make sure and got my injectors serviced again.

ever since the service which was aboput a week ago,
it hadn't done it ever again.

the guy said there was soo much @#%! in my fuel filter (i had that changed with the injector service) so the cars runs alot smoother now

 

[CMF_chopper_84]

oh alos..

my car takes alot of effort to start up and once it starts for the first rev a puff of black smoke comes out of the exhaust.

im thinking that driving with a blocked fuel pump or something ad stuffed the fuel pump up..
what do you guys think on that? im not sure what to think.. maybe someone knows about this symptom.

also i checked spark plugs and there was no sootyness..