Hesitation/judder between 2200-2700 rpm

[-bobda-]

Right.

I'm going to have a look at this on Sunday. I've convinced myself that the wastegate is what is at fault.
On changing gear, the turbo loses all it's pressure, so the car lurches when I engage the clutch.

I've also read (on the Honest John forum) of a problem with overboosting in a Citroen HDi engine which is caused by a problem with the wastegate, or wastegate actuator.

I'll see if I can have a quick read of a Haynes for the Renault DCi engine which might help me out a bit. Just hope I don't get chucked out of Halfords for using it as a library!

I might tighten mine up one notch tomorrow if a) I get brakes done and b) it doesn't rain as much as they forecast.... If I do, and I remember, I will photo it.

... I don't know why, maybe to be fair ECU still learning, but my car is now seeming down on power again (although nothing like before). It's making all the right noises, but full boost just doesn't quite seem to be there. All hoses on ok (hey, it was ME who fitted the turbo, what do you expect ) and those exhaust nuts are alright - well I checked all of them apart from "the one which is really hard to get to". Anyway the heating/cooling of exhaust probably seizes them pretty quickly and they are all locknuts.

But at least the car is still going and idling ok so will be alright for my trip up North on saturday, and if it is just a bit down on power well that is just tough. Anyway I "debadged" it so no-one can tell it is a T4 it might just be a 1.8 with a spoiler.

Re. your turbo, for more of an understanding of how simple a wastegate is, have a look at my photos section in the forum here: http://www.volvoclub.org.uk/photopos...php?ppuser=568 I have some piccys of the wastegate and my turbo off the car to show people what the fault was that I was getting. I have photos of parts off the car, but no photos of the car itself!! (Hint: it looks a lot like a phase 1 T4 in dark metallic blue!)

Re. Halfords, well these days they tend to seal all the books in polythene coz you weren't the first one to think of sneaking in for a quick read!!!!

Pete

[-bobda-]

Cheers for the pics. All I need to do now is find my wastegate and check the adjustment on it!

So, according to the theory you came up with then you would need to lengthen the rod a little try 1 or 2 turns no more.

The theory is that it overboosts causing the air bypass to open and loses boost then it overboosts again etc. too readily.

The theory goes that the reason it overboosts like this is because the wastegate is not opening enough, quick enough. The wastegate constantly paritially opens and closes to control how much exhaust is diverted around the turbine. This means the turbine doesn't go too fast which would generate too high a boost pressure.

So if you lengthen the link rod the it will mean for a given setting as told by the ECU then the wastegate will open more.

The "boost control valve" operates the wastegate arm using air under control of the ECU via the "boost control solenoid valve" and this is another possibility which could be faulty.

If you have a diagnostics package, you may be able to monitor the opening of this solenoid valve thingy which corresponds to %age opening of wastegate.

With my VOL-FCR there is a live data readout which gives you %age opening of the wastegate (or what the ECU thinks it is). Figures aren't particularly useful but if the trend of change of %age opening corresponds to what you are doing with your right foot then it makes sense and you can hopefully tell if the solenoid valve is ok or not (or it might be able to indicate something else is knackered, like the MAF if that's what you have or the MAP - whatever the ECU uses to work out the pressure).

VOL-FCR though doesn't seem to have a "log" feature so if you have this SW either take someone else with you or get good at reading the screen and the road at the same time

However, note that your car may be too new for VOL-FCR to handle.

The other day I tried it in my other S40, a phase 2, to get a comparison.

While idling, the software informed me the battery voltage was 0.11V, the engine temperature was -48 degrees and I was currently travelling at 2,432mph.



Pete

Today I adjusted mine up one turn, did seem a bit better. I did take some photos for ya of the procedure, BTW locknut was 10mm not 9mm spanner which makes more sense. I'll put those photos on my volvo gallery later (same place as the other ones of the wastegate).

Pete

[-bobda-]

Cheers Pete.
I'll definitely have a go over the weekend.

I'm concerned though, that adjusting it incorrectly could have an adverse effect on the turbo.

How am I to know what adjustment I need to make to it?

Originally Posted by -bobda-

Cheers Pete.
I'll definitely have a go over the weekend.

I'm concerned though, that adjusting it incorrectly could have an adverse effect on the turbo.

How am I to know what adjustment I need to make to it?

I didn't get round to adding those pictures last night, I'll try and do so later today.

The only way I can see in which you could break the turbo is if the air bypass valve is not working which would cause the turbine to stall. A turbo is actually a very simple bit of kit. The wastegate would still be able to open by adjusting the link, just more or less than currently. Anyway we were talking about you lengthing the rod in which case it wouldn't be a problem for potential damage at all as wastegate just opens more often.

The only way you could break it in doing the work is if you turned the link rod which could damage the boost control valve that's why I always hold that with some pliers while turning the adjustable part of the arm.

Pete

Right, finally I've put 5 photos and detailed instructions of the procedure on my volvo gallery (follow the link above). Unfortunately they seem to appear in reverse order in the gallery because I loaded the first one first if you see what I mean, anyway easy to figure out the order.

Pete

[-bobda-]

Hokay! Here goes...

Had a fiddle today (with the car!) and found that the wastegate is built into the Garrett turbo on my engine, with the actuator on top.

The arm was a bit awkward to get to, but I managed it and loosened off the locknut.

The adjustment was huge, and I was only expecting two turns to be available. Had to mark off the original point and I first tried with two turns anti-clockwise, which made the arm tighter.
finger tightened the locknut and went for a drive. I didn't get the judder, but on the return leg, I noticed a distinct lack of power at low-end and when I got home, I found that the rod had come away from the locknut and the arm was free, probably meaning that the wastgeatre is wide open.

Tightened it up (ouch...turbos get hot) to about what I thought the tension was when I began and hoped for the best. Went for a drive and I didn't get any judder, although I'll have to drive it for a couple of days to see if it has gone completely. The engine characteristics don't seem to have altered, maybe a slightly lower reach of the power band, but that's about it.

I'll monitor it this week and I'm away in Africa for three weeks from Saturday so I can have a play with it when I get back to see if I can fine tune it slightly.

I reckon I need to have the tension just on tight, with no play before the tension is taken up.
Not 100% sure if that's right, but It'll have to do for now.

If it judders this week, you can be sure that I'll have 'fiddling' top of my list for when I get back...

So for now...cheers Pete, I owe you a pint.

Well you say that, but actually sounds like (virtual ) pint not deserved because actually yours must be completely different with garrett turbo (why oh why didn't I remember that since we were discussing it previously when you had turbo problems!) and mine having the mitsubishi turbo so the procedure must've been somewhat different!!

But anyway, sounds like the theory was sound and it seems to have made a difference so lets hope this has sorted it all out!

Pete