Jerky Performance

[Steveh24]

My Volvo S60 T5 has had jerky performance for several weeks now, the problem happens every time I accelerate and the turbo kicks in I can feel the car hesitating and jerking as the revs increase making it difficult to accelerate smoothly or to attain max revs.

I'm not sure if its fuel or an electric problem, but it has only just been serviced and had new air filter, oil filter, fuel filter and plugs.

I took it to my local Volvo dealer last Mon and they ran a complete VIDA Investigation and found nothing wrong, my own mechanic couldn't see anything wrong, but the problem only happens when on the road.


Does anyone have any ideas as to what the problem can be.

Steveh24

[t5_monkey]

Guess here but maybe a faulty knock sensor causing retardation?

[p fandango]

Guess here but maybe a faulty knock sensor causing retardation?

i''d of thought a knock sensor would of thrown up a fault code. Are all the hoses ok, no air leaks?

[princepugh]

I'd go hoses, clamps and TCV for starters. Looks like I just smoothed out some jerkiness on mine after cleaning up the wastegate/ actuator rod joint, although I'm now overboosting.. doh!

[Steveh24]

As I mentioned in my question the car had a thorough computer check by Volvo and it came up clean so no electrical components or sensors are faulty

I was perhaps thinking induction or an air leak, but someone did mention the throttle body and the disk inside not being clean or something like that.

What would be the problem if the turbo was failing.

Steve

[Liddo]

Dont know whether its the same, but my S70 T5 did that when i booted it, and it turned out to be a broken elbow joint going to the actuator...or something like that. DONT keep your foot hard down when its stuttering, as you may cause some damage

If its the same, its the cars way of protecting itself from overboost.

Im may be wrong, but its worth a look

[Steveh24]

Ok, I've just fixed it .... I think

I took out all the plugs and removed the grease that my mechanic had smothered all over the rubber boot caps, I forgot to mention previously that my car has the RICA Mod, so bhp ia around 310, which makes the problem I had far more noticeable.

Anyway just took it for a test run and now it goes really well, no more jerking when accelerating hard, it will quickly accelerate from stand still to 140 mph, didnt want to risk pushing much further as you never know when plod is around lol

Thanks for all the suggestions to fix it.

Steveh24

[T5frankie]

maybe just crap petrol mine does it if i dont use super

[Steveh24]

Problem not solved.

When I accelerate and the turbo kicks in boy is it unhappy, it hesitates, then goes, then hesitates then goes and even cruising at low revs in a high gear is lumpy, so took it to my local Volvo dealer and one of their machanics drove it while I sat in the passenger seat.

He gave it some welly down a dual carriageway and it did its stop go routine nicely, he immediately ruled out an electrical problem as it was still smooth and not missing and because it's lumpy when the turbo isnt in use his guess is an air leak somewhere, possibly the pipe at the bottom of the wastegate pipe caused by not removing that pipe and pushing it to one side when changing the plugs.

Thinking of letting Volvo do a leak test of the whole induction system, I'm sure it will be worth the £45 and that they will find a leak

[princepugh]

Do you mean the large diameter rube hose that the charge pipe connects to at the back of the engine next to the turbo? There's a whole load of plumbing around that area connecting to the vac tree and TCV etc. but moving the charge pipe around would most likely just affect the big rubber hose coming off the turbo. If they can do you a comprehensive leak test for £45 then I'd go for it as vac leaks can be a nightmare to detect.

[Steveh24]

The pipe I'm referring to is the large black pipe that runs over the top of the spark plug cover down the back of the engine, it connects to another pipe which is secured with a jubilee clip, its that pipe which could be leaking and is caused by not removing the large pipe that runs over spark plug cover when replacing the plugs as my mechanic simply forced it to one side to remove the plug.

If I dont find any damage to the pipe, then it will have to be a leak test.

[princepugh]

Yup, I know what you mean, have to admit I usually just remove the torx bolts at the front of the charge pipe and nudge it to one side when I'm doing the plugs.

If you've got the time, it might be worth taking the cross-stay and charge pipe off and having a really good look at the plubming at the bottom on the air-intake near the firewall. including the TCV pipes.

Another well known Volvo forum has an article which talks about detecting air leaks using a cooker style firelighter (vac/pressure leaks will pull/push the flame) - I'm in no way recommending you do this but you could read the article.

[Steveh24]

Yes I'm going to have to remove the cross stay or you can't get to the back of the engine very well and it looks tricky enough as it is, I will be so glad when this is fixed

My Volvo dealer said that the best equipment for detecting leaks is a smoke compressor in which they jam the smoke under high pressure into the induction system and just look to see if it comes out anywhere ... simples !!

Unfortunately this is an expensive piece of equipment that most workshops dont have and they will be using the good old listening with your ears technique after filling the induction system with compressed air.

[Turkish]

Try replacing the BCV, it helped when mine had similar symptons to yours and did not show in the Volvo diags.

Also look at the ignition coils these can be faulty and normally do not show as a fault on the Diags.

[Steveh24]

Try replacing the BCV, it helped when mine had similar symptons to yours and did not show in the Volvo diags.

Also look at the ignition coils these can be faulty and normally do not show as a fault on the Diags.

What is a BCV ??

I did wonder about the coil packs, but according to the Volvo mechanic who took my car out for a test drive, he didn't think the car was missing, just hesitating, so he ruled out anything electrical.

With the hot weather the car was worse today and when you put you accelerate away it hesitates and the n as the revs build to 3500rpm it feel very lumpy and when the turbo kicks in it starts to go then pulls back then goes again etc etc etc, needless to say it never reaches max boost or revs.

I was really getting p!ssed off with it, so booked it back into Volvo for a leak test and they will recheck the codes FOC, but like last time I'm not expecting them to find any.

I can't believe that such a major problem can take so long to find.

[Steveh24]

Try replacing the BCV, it helped when mine had similar symptons to yours and did not show in the Volvo diags.

Also look at the ignition coils these can be faulty and normally do not show as a fault on the Diags.

Did you mean the TCV if so I'm not sure how this can cause the problem I've got as the car is lumpy from the off and is playing up long before the turbo kicks in, it just gets worse when the turbo does kick in

However I don't really know what the TCV does and maybe it is being used even at low revs when the turbo is idle.

If anyone would like to explain to me how and what the TCV does I would appreciate it.

[princepugh]

The Turbo Control Valve does pretty much what it says on the tin, i.e. it controls the level of boost the turbo produces. It is basically a solenoid controlled by the ECU which is fed by a pressure hose from the compressor side of the turbo - the solenoid basically pulses this pressure through to the wastegate actuator, allowing the wastegate to open, thereby stopping the turbo spinning like a nutter and popping your engine. The solenoid also bleeds pressure back into the intake tract, thats why you can see three hoses going to it.

It's supposed to fail in an open mode, i.e. just passes pressure to the wastegate actuator so it fails 'safe' but they tend to get lazy and cause weird boost effects.

You're still best to check for vac leaks first IMO, then you can start thinking about the TCV and wastegate/actuator.

HTH

[steveo82]

What is a BCV ??

I did wonder about the coil packs, but according to the Volvo mechanic who took my car out for a test drive, he didn't think the car was missing, just hesitating, so he ruled out anything electrical.

With the hot weather the car was worse today and when you put you accelerate away it hesitates and the n as the revs build to 3500rpm it feel very lumpy and when the turbo kicks in it starts to go then pulls back then goes again etc etc etc, needless to say it never reaches max boost or revs.

I was really getting p!ssed off with it, so booked it back into Volvo for a leak test and they will recheck the codes FOC, but like last time I'm not expecting them to find any.

I can't believe that such a major problem can take so long to find.

i have this problem on my V70 T5, but when im at say, 4k, the bugger misfires big time making the EML flash hence coil pack checks might be wise as in checking insulator boots and that they are tightened down correctly.

As mine is bringing up codes for multiple misfire / cyls 2+4 misfire so it maybe something other than actual coil failure but related to them, seen as they have recently been fiddled with!!

[Steveh24]

I wish my car was misfiring as it would have been picked up during the VIDA Investigation, but even when it's pulling its still firing nicely on all cylinders.

Can a faulty TCV or wastegare/actuator cause problems at low revs when the turbo is not being used

[princepugh]

I'd say if you've got symptoms from tickover upwards then it's less likely to be the TCV, however, depending on the state of tune you're running, you could be pushing positive boost around 2000 rpm and from then on in, the TCV will be instrumental in controlling the wastegate/boost.