Hesitation after an hours driving

[Willy]

Hey guys,

I've noticed a few times that my car seems to hesitate after I've been out driving it for a while (perhaps an hour). It seems to hesitate around 2500-3000rpm when I'm not fully on the throttle. Any ideas?

I've noticed that the accelerator seems kinda sticky (always has been). By that I mean that by pressing it down just a little bit (say less than quarter throttle) it will suddenly lurch forward. You can get around it by easing the throttle VERY slowly. Is this normal? It only seems to occur when the throttle is opened very slightly. Perhaps my throttle body linkages need oiling? Anyone know anything about maintaining the throttle bodies?

Actually, is there anything special these cars need doing as a regular service? (apart from the usual of changing oil, oil filter, fuel filter occasionally, cleaning air filter etc).

 

[Willy]

Actually, as an after thought I just remembered that my mate said his Bluebird Attessa was doing the same thing. It was a rainy night, so we thought it could be rain related, but last night it was dry and still did it.

 

[JohnnyGTiR]

When you say hesitation, does it continue right through the rev range or is it just at lower revs and then clears as you further accelarate ?. Also when this occurs is the car still boosting properly ?

 

[Willy]

Thanks for the quick reply.

It only does it between roughly 2500-3000rpm. Before it's on boost. It doesn't continue to do it up in the revs. Perhaps it an O2 sensor fault. Since the ECU would probably be in closed loop and I'm just putting my foot down slightly to accelerate slowly. Seems to happen out of a corner, like I've just changed down to second and then I accelerate slowly out of the corner. Doesn't just do it on corners (I think, I'll have to check).

It could also be the timing. It's set at about 19 degrees. Also, when it's in timing adjust mode the revs drop to about 500rpm. Is this normal? It idles find out of timing adjust mode.

 

[JohnnyGTiR]

When the car is in timing adjust/reset mode, according to the manual the idle speed should be 850 rpm and should increase to 925 +25/-75 rpm in normal mode. Also 19 degrees should be fine.

Mine would hesitate a little when just coming on boost but I actually found it to be a combination of heatsoak and increased inlet temps as fitting a cold air feed and intercooler water spray has helped alot and it also was worse when the weather was warmer. I would say once I fit a heat shield it should help further.

Apart from that just the usual checking of plugs, filter etc. Another thing if you haven't changed you fuel filter DO IT, Mine was filthy and made a big difference when I changed it.

Not sure about the O2 sensor causing problems, dont really know enough about it to comment. Try a fault code check just to make sure.

 

[Willy]

Hmm heat soak could definately be a cause. I have a FMIC now and a standard bonnet, so cooling for the engine wouldn't be as good. Plan on fitting CAI soon and might have a look at that fuel filter. THanks