STi V, 6,500 Miles. SSBackBox, ITG Filter.

When leaving my house in the morning on the way to work, I have noticed that in 3rd gear at about 2300 revs (30mph), if held at this speed, the engine is a little hesitant (as if it can't decide exactly what speed it should be going, the engine seems to surge and back off repeatedly, not violent but quite marked). Does not do this when warmed up.

Any ideas as to what it might be ?

Cheers

Dave.

 

Auto choke perhaps?

 

The car has a cold start routine, if you are driving when it is in this mode then the fueling is too rich and the car is hesitant. Until the engine temperature (coolant) rises sufficiently and the lambda sensor starts to work this can happen and is normal.

Bob

 

Cheers Bob.

 

I will second this, my sti v5 does exactly the same on first few miles from cold start - you can actually change down to 4th gear and it pulls more smoothly at 30 mph - odd feeling - just like a misfire or electrical problem but, as you say, disappears when warm - I also get a reluctant pull away from rest - engine nearly stalls then picks up if the throttle is eased in - only when cold and just after starting - suspect there are some strange routines in the ecu - nothing to worry about though.

cheers,

Paul W

 

Just got my new MY 99 4 days ago and already noticed something similar to this at around 2600 rpm.

Would describe it as follows :
imagine accelerating slowly (in an Impreza ?!!) but progressively uphill in traffic from some lights and just as you go through 2600 it's like you just momentarily back off the pedal slightly and then re-apply as before.

I don't think it disappears when warm - but seems more noticable under load (accelerating up hill rather than on the flat at same revs)

Only done 250 km even now, so may disappear when run-in