Hesitation/judder between 2200-2700 rpm

[-bobda-]

Right, as has been discussed here, I'm experiencing a judder between 2200 and 2700rpm (roughly). It occurs on light throttle and is most noticeable at motorway speeds (70-80 mph).

It feels like the car slows down, then speeds up again slightly and sometimes it judders in waves, which always occurs at about 2500rpm. It still does it when the cruise control is engaged, but not as badly. This is probably due to the ECU counteracting the loss in power by adding more fuel and 'smoothing out' the problem.

It's done nearly 70k miles and has recently had a new turbo fitted (old one went blew a seal and dumped oil out of the exhaust) and the garage who changed the turbo nd fitted a new exhaust, said that they had fitted a new EGR valve, but I'm not 100% sure if this was done. It has also had a custom remap, but this was fine before the turbo went pop.

I've tried cleaning off the MAF, which didn't seem to cure it, but the hesitation feels like a MAF fault, as if it is telling the ECU that there is more air getting in than actually is and less fuel is consequently injected.

Any other suggestions?

Hey there. Ive got a 1997 S40 2.0i and ive got a hesitation when the engine's cold. Its almost as if the car has a slight misfire. If you give the car more revs i seems to go through it. Once the car has warmed up the car seems to drive fine. The garage had the computer wired up to it and they couldn't find any problems. The car had a service recently so it's not the spark plugs or leads. Someone suggested it could be a faulty coolant temperature sensor. If you find out what your problem is id like to find out how you cured it. Many thanks Chris

Do you think the fault might be to do with the turbo going from overboost to low boost repeatedly, causing a judder feel? Does it feel like that do you think? Possibly when they fitted the turbo they did not set the wastegate link correctly... seems weird that the problem has occurred since then (so it is not the same problems as before, but has come since all the big work?) So I was trying to think if they messed it up somehow.

Pete

[-bobda-]

Originally Posted by peteS40

Do you think the fault might be to do with the turbo going from overboost to low boost repeatedly, causing a judder feel? Does it feel like that do you think? Possibly when they fitted the turbo they did not set the wastegate link correctly... seems weird that the problem has occurred since then (so it is not the same problems as before, but has come since all the big work?) So I was trying to think if they messed it up somehow.

Pete

It could be, especially since it only happens at a particular rpm and in all gears. I'm not sure if it only happens when the engine is warm and therefore off-choke. I'll have to give that a go and see what happens.
Is it easy to adjust the wastegate link myself or am I best to get a garage to have a look?

I also think it is slightly down on power and up on fuel consumption as well, especially when accelerating. I used to get no less than 15mpg on the instant readout, even when pressing on, but I saw 11 today and I wasn't even using full throttle.

Originally Posted by peteS40

Do you think the fault might be to do with the turbo going from overboost to low boost repeatedly, causing a judder feel? Does it feel like that do you think? Possibly when they fitted the turbo they did not set the wastegate link correctly... seems weird that the problem has occurred since then (so it is not the same problems as before, but has come since all the big work?) So I was trying to think if they messed it up somehow.

Pete

Your comments are interesting Pete because I have a '98 2.0T auto at 98K that does exactly what you are describing – begins to judder and looses power momentarily at motorway speeds or during heavy acceleration and then sorts itself out after while. Sometimes it also does it when stationary in a queue at a junction. If I put it into neutral the juddering stops.

Because it doesn't happen all the time, for example within 10 miles of a Volvo service centre, it is difficult to explain to a mechanic

Further, I recently had the engine turbo return pipe seal and gasket changed, perhaps this might be why?

Originally Posted by Abradders

Further, I recently had the engine turbo return pipe seal and gasket changed, perhaps this might be why?

Probably not, but why did you have those changed? Was oil leaking round the o-ring gasket on the engine end of the pipe?

Pete

Yes that was exactly the reason for the replacement.

Have just driven home on A roads so no more than 50mph or so. Pulled up to drop my passenger off and then when I pulled away the car starting juddering again. Hasn't done it for about sevene days or so.

It didn't do it until I had theabove done and alsoEngine RPM sensor changed Fault code EFI 131 and the throttle housing cleaned. I have also had intermittant DSA fault light problems but it goes out after ten minutes of driving or so.

Very annoying

Originally Posted by cpiddy7

Hey there. Ive got a 1997 S40 2.0i and ive got a hesitation when the engine's cold. Its almost as if the car has a slight misfire. If you give the car more revs i seems to go through it. Once the car has warmed up the car seems to drive fine. The garage had the computer wired up to it and they couldn't find any problems. The car had a service recently so it's not the spark plugs or leads. Someone suggested it could be a faulty coolant temperature sensor. If you find out what your problem is id like to find out how you cured it. Many thanks Chris

From what you have told us, I would say that your problem is something different, for a start your car is not turbocharged and not a diesel, and your problem only happens when car is cold. It could be worth you changing the coolant sensor, it is quite simple and cheap. Your symptoms could be explained by the ECU believing the engine is warmer than it is. A pity the garage didn't run a real time analysis of the engine temperature as told to the ECU, that might have given more clues. Does it idle a bit duff when cold as well?

Pete

Check the plugs and re-adjust the gaps on them as incorrect gaps will cause hessitation. Check coolant sensor also security of plug leads etc.

Charlotte

[-bobda-]

Originally Posted by charlotte001

Check the plugs and re-adjust the gaps on them as incorrect gaps will cause hessitation. Check coolant sensor also security of plug leads etc.

Charlotte

I'm not sure if your reply was to me or cpiddy, but I don't have any spark plugs!

I'll check the coolant sensor, but I don't think it's that, it's more of a fuel/air delivery issue I think.