Lumpy When Cold

[Guest j_mchattie]

I've noticed a lumpy drive when at 30mph on flat ground, constant speed.

 

My brorther has the same problem. It feels like the petrol is running out.

 

The problem goes when a change in accelerator position is made. I thought it might be the throttle position sensor, but it doesnt do it when its hot!

 

Maf? I dont know.

 

Suggestions please

 

Thanks

 

(It also seems like the throttle position changes all the time while its warming up - making it difficult to match engine to gearbox speed)

[Guest j_mchattie]

Im getting the code for the IAT on my fault code reader - its on the KAM (saved) codes - not during the test.

 

Would the IAT produce the lumpyness I describe?

 

Its just a little nudge thats all, a small kick

[Guest j_mchattie]

MAF works - i think. For the same throttle input, the MAF unpluged produces 250 rpm extra compared to it plugged in. That was done at about 2,500 rpm (plugged in)

 

Is this normal?

 

I guess unplugging it adds extra fuel and so makes the revs increase - is that correct?

 

Thanks

 

p.s - still trying to find the cause of that nudge. Ive got a feeling its the EGR solenoid - it produces a tiny vacuum at idle, and not much more with revs - not sure if thats correct.