V6 Air flow metter
Okay chaps and chapesses heres little problem I hope someone can help me with. I have a 1990 XR4x4 2.9 V6 NON cat. Past it's MOT 3 weeks ago.
It's a little lumpy on tick over but passed emmisions on MOT, Co 0.65% HCC 73PPM so very low. Here's the problem, once driving the car is
fine EXCEPT between 40-46mph where it's a bit jerky, like it's mis firing. Car goes like stink when floored, has new plugs, HT leads, dizzy
cap and rotor arm. I have set the tappets but did notice that one side was worn and still rattles a bit. Could it be then worn rocker shaft that is
causing the mis fire? seems at bit strange how it only does it at a certain engine speed. All help welcome.
Andy.
If it's got a vane type air flow meter (think they did from memory) it could be that. They used to wear away the track at points where they often sat like idle and light load steady running. Tappets too tight is more likely to be a problem than slightly noisey.
If it's the Bosch vane or flap type like Adithorp mentions then I had an almost identical issue when I bought my 944.
There is an air bypass adjustment on the sensor which effectively enriches/leans the mixture across the board. I added about 1/2 turn richer and it
now runs perfectly at light load when cruising. Before is was stuttering but was fine at WOT just like you mention.
JC
Will have a look at that as it is burning lean going by the emissions read out.
quote:
Originally posted by SeaBass
If it's the Bosch vane or flap type like Adithorp mentions then I had an almost identical issue when I bought my 944.
There is an air bypass adjustment on the sensor which effectively enriches/leans the mixture across the board. I added about 1/2 turn richer and it now runs perfectly at light load when cruising. Before is was stuttering but was fine at WOT just like you mention.
JC
Those engines suffer from inlet manifold gasket creep then they have an air leak that may effect emissions.
Steve
quote:
Can't find the bypass, which sensor should I be looking at?
quote:
Originally posted by Chippy
quote:
Can't find the bypass, which sensor should I be looking at?
[img]
V6 Air flow metter [/img]
From memory the adjusting screw is in the bottom of the Air Inlet Vane Do Da, will see if I can find a picture of one and stick it on this post. I had one of these engines in my special untill I changed for the BOA. Cheers Ray
Edit to add picture. You should adjust the front AFM first and only adjust the rear one if you run out of adjustment on the front one. HTH Ray
[Edited on 13-5-11 by Chippy]
Hi mate, Oh! yes does a lot more than affect tick over, it will affect the fueling across the whole range. Cheers Ray