Got a slight problem, wondering if anyone can suggest any ideas what it might be?

It's a UK impreza Turbo 2000 saloon by the way (X-reg).

The car starts fine, idles fine and if you drive it quick it's also perfectly fine. It has a hiccup around 2500 - 3000 rpm when driving low-medium speed. An example would be if I were going up a slight hill and I was taking it steady increasing my speed, as I put into 3rd and just gently ease onto the throttle it makes it's way up past 2000rpm but then as it gets to about 3000 it sort of gets stuck and starts mis-firing. I can either floor it and after about a second or so it kicks back into life and throws me back into my seat.
It just means I can't drive the car gently at the moment, I either have to be pretty hard on the throttle or off the throttle.

I was thinking of changing the plugs just to see what happened, although I get a feeling it might be related to when the turbo/boost kicks in??
Saying that, I have no mechanical inclination whatsoever...

If anyone has any ideas what to try it'd be appreciated.

 

When you're cruising at around 65 to 70, does the car hesitate and then as you accelerate it drives fine? My 00 MY UK Classic did this, its common in 99 and 00MY cars. Changing to 97 or higher RON cured it for me. Does the car idle okay and run fine otherwise? Have you checked for fault codes? Search under MAF for another possible fault. Theres plenty of posts on here, search under misfire, hesitating and have a read Best of luck. Bob

 

check the pipes on the intercooler are ok used to have this prob when the plastic pipe cracked under the intercooler when i floored as the boost was coming on fast it didnt make it run daft, but slow accelerating it did the same must be coz at low speed the pressure is low and with it leeaking its not holding it.

 

Yep, say I'm doing about 55 in 5th on the motorway, and just slightly ease on the throttle to maintain speed, it runs really rough and jerks you back and forth in your seat almost, and I have to drop to fourth and keep it around 4000 rpm. Yep, in hard acceleration, idle, and everything else it runs completely fine. Tried a few diff fuels e.g normal / V Power etc but doesn't seem to make much difference. Thanks, Andy.

 

I second what ant said. I had a bolt missing on the intercooler plastic pipe, did exactly what you say. When the boost is low, it can't overcome the leak, causing fueling problems, but can as the boost increases.

Mit

 

Will have a look round the intercooler later then, cheers chaps.

 

Hi everyone,

I just bought a similar car, 2000 turbo, and it has the same symptoms and teh CEL came on - no signs on test drive. I'm having it looked at, at the weekend and i'll post what i find out.

 

nox sensor for the CEL and a new MAF and plugs for the hesitation?

 

Before spending a fortune on parts, try a search on hesitation /holding back or similar terms. It was common on MY 99 and 00 cars

 

the place i took to said it was a knock sensor, not a nox sensor, the fault came up on the diagnostic check. Once the work is done i'll post the outcome.