shuddering at 30kmh. consult cant find any prob...

[Nl5sAN]

Hey guys i was wondering if someone has got any good ideas.


I have a 99 1.6l n15 pulsar, MT. It seems to shudder, and i can feel the car shake when doing around 30kmh, in 2nd or 3rd gear. After the car gets to 40 kmh it drives ok.
It happens almost all the time, going up hills and in slow moving traffic. only times it seems it doesnt do it is going down a hill, and if i experiment with the accelerater. Going WOT when it happens makes it less noticeable.

Other things that may be related is a surge of more power when overtaking at high speeds, like 130 or 140 kmh.

The car cant hold revs between 1000 and 1500 rpm in neutral?

And sometimes the idle rises momentarily when idling in traffic etc.


So anyway, i checked the plugs and leads, and checked earth between engine and body.

Checked rolling in neutral, no shudder.

And finally got an ecu talk the other day, but it says theres nothing wrong?
Sensors seem fine, no codes, except for the nothings wrong 55 code.
I thought it was the TPS, but it reads smoothly from .48 to 4.02 volts, which seems ok...

Could oil viscosity somehow affect the valvetrain, it has mostly 15w40.
Or maybe it has a dodgy fuel pump? the car has almost done 180 000kms
Or maybe exhaust?- it makes a whistle noise like a turbo sometimes, lol. usually around 20km in 2nd and 40 km in 3rd.

Anyway any help would be appreciated.
Cheers

[inz]

clean AFM
make sure the plugs arent black, if they are replace them

[Nl5sAN]

I logged the car when it was happening, and the AFM looked pretty steady, as in it was rising steadily. I sort of dont wana clean it coz it says not to in the book. However i might give it a shot, i got some contact cleaner made by wd40 which doesnt leave residue, but i dunno id prefer to use that crc AFM cleaner everyones been talking about.

I was having a think and talking with me mate and to be honest its got to be electrical, he reckons changing the coil maybe?
Also I checked the resistance of the TPS and it didnt seem to rise smoothly, but it could have been the multimeter, i dunno.

How safe is it cleaning the AFM, u have to replace it a few months later?
Cheers

[CoZZm0]

Cleaning the AFM with the right stuff as per instructions on the can should result in no problems to the part.

[inz]

TPS is a possibility, that would make sense as to why going WOT makes the problem go away - if it's having issues on light throttle... but why wouldn't there be a problem all the time and not just somewhere in the rev range.

cant hurt to swap the coil over and see what happens.

buy yourself a can of AFM cleaner, it'll come in handy more than once.

[Nl5sAN]

Ok i gave the AFM a clean, problem still there. The volatages seem to be correct too, which is good. The car did seem to idle a little easier between 1000 and 1500 rpm in neutral, when warming up, but when warm it wouldnt. Also when warming the revs jumped higher than normal, and did stuff they havent done b4, but seemed fine once it was warm. Ill check it out next time i start it.
Anyway i found this on here today, and my car does the same kangarooing

"i guess the only real problem i've got is the kangarooing when your trying to drive slow in first gear. basically when the throttle is just open- usually when the throttle is closing to the just open position. its a real pain in the arse driving around busy car parks. not as bad as it used to be but still not good. the missus bought the car new and its had the problem since new. nissan were less than helpful the first time i asked them about it. eventually(after bitching) they gave the car back running beaut.

at the 30000 service they tried flogging me an $80 on car injector clean. i said what for - the cars never been better. we got the car back kangarooing as before. i took it back asking for it to be sorted out. after a lot more bull from the service guy(i think he assumed i knew absolutely nothing about cars and just spewed B/S) we got it back - minimal kangarooing but sluggish as ever. i had a look and the wankers had adjusted the timing to 3 degrees before TDC."




Pretty weird.. I dunno I got a 99 sentra manual (from here) and using that and perhaps this other advice i found i will try to look into the tps a little more:

"i adjusted the TPS on my N14 ga16de months ago ......

the setting was at like 800ohm (0.8Kohm).... and always had idle problems where the engine would always idle fast ..... tho i never had any performance problems or anything like u did....

i set it to the documented setting of 500ohm and now the engine idles perfectly fine all the time .....

the way i adjusted mine was disconnecting the wiring and just adjust the sensor according to the ohm readings ....
no need of measuring by voltage drop ...thats and ass and its dangerous....well it is if ur not skilled auto electricals...

-Joseph"

One last thing though, in the manual and on a service bulletin, it talks about adjusting the closed throttle position sensor switch, but im pretty sure thats for an automatic right?
They say it should read closed when you check it with a 0.3mm feeler gauge, and read open at 0.4mm
like in the pic,

but the gap on mine is like 2mm..
but it shouldnt matter coz mines manual, right?
Cheers btw

[Nl5sAN]

Yea it actually still vibrates at WOT (shame), but it doesnt do it for as long coz its out of the vibration zone quicker (i think). Bloody gremlins. Might have to take it to nissan soon.

[Nl5sAN]

Well I went to a wreckers and tried one of their AFM's, no luck =( ...must be getting closer though.