Judders on full throttle, RICA?

[pzorb]

My 850 has developed a judder on full throttle. Happens in all gears. I thought it was the clutch slipping, so had that changed but the problem persists. Basically all is well as long as the turbo needle is on the gauge, but as soon as it leaves it on full boost (foot firmly on the floor) the car... like it's intermittantly lunging between full power and something holding it back.
I've recently had the wastegate adjusted, had a K&N fitted, a new clutch, the gearbox is apparently a new one, RICA 280, and I haven't done a stage 0 as yet. The car used to be fine on full throttle even with rica, so it's a bit weird - no?
I could do a stage 0 tune-up but it seems like an expensive way to track down the problem (and still might not fix it).
Could it be the ECU cutting back? Maybe because the wastegate is too generously open? I would certainly have expected the garage that adjusted the wastegate to have done it correctly...

Any help/ideas greatly appreciated as ever, you fonts of swedish know-how!

Martin

[Mrsmopp]

Sounds like you need a change of plugs to me Hun!

x

[lance]

Yeap plugs is a good start up point, im sure somthing in the point 0 service will remedy the problem!

[mraldonnelly]

Martin,

A stage 0 isn't an expensive way to track down a fault - it's essential maintenance.

OK, so some things may not be necessary but the majority of it is just general service items.

Oh, and I agree with Mrs M. The plugs are a good place to start.

Regards

Andy

[Wobbly Dave]

Everybody now - after 3

1, 2, 3

PLUGS!

[Wobbly Dave]

NGK BKR7EVX x 5

[pzorb]

Top stuff, I've got 5 BKR7EVXs coming my way around lunchtime; am I just looking to replace the leads, rotor and dizzy with OEM or should I go for something better? I think bracer said that OEM was fine [here], do people agree?

In my humble opinion, I think replacing the leads is OTT. I'll start with the plugs, then the rotor and dizzy and if still no joy then the leads - any comments?

Ta muchly!
Martin

[Murphy]

remember to fill up when you have 50 miles left aswel !

[Wobbly Dave]

If the dizzy and rotor have not been replaced then it would be good to do so. You can tell if you need the leads replacing (I replaced mine with OEM - which are just the job) if you see cracks in the plastic ends and an orange discolouration which indicates arcing. Generally if the leads are gone (they either work or don't) the misfire would be much more pronounced. Plugs, dizzy and rotor - and see how you go on.

If you have the time - take a photo and show us the state of the plug ends.

Final thing - I apologise if you already knew this - Never use the rachet to start with when putting them in, start off by hand on the end of a piece of rubber tube or a plug socket (with the rubber retainer in it) on the end of a long extention. Don't drop plugs down the hole - you might accidently shorten the gap.

[Mrsmopp]

. Plugs, dizzy and rotor - and see how you go on.

All in favour say Aiiiiiiii!!

x

[Wobbly Dave]

Feeling the Ovlvo today!

[pzorb]

Cheers dave, I'll try and grab some pictures of the plugs.
Anyone know the settings for the torque wrench to tighten them up? It's an aluminium block right?; so I'd best be cautious to not overtighten and kill the threads!

Spread that Ovlov!
Martin

[Justin]

All you genius's may have overlooked another apparent issue here.

I would get the wastegate checked too see what they have set it at first, also check the hose that goes to it hasnt come off and or split while they were doing it, either way plugs or wastegate it wont be long till there is a code displayed, there could even be one stored now, no doubt it will be 414....turbo boost regulation.

If it aint broke dont try and fix it mate.

Or it could just be the plugs lol.

[pzorb]

Justin, do you have a picture of where I should be looking for the split? I'm waiting on the dizzy cap and rotor arm - volvo wanted £58 ("yeah, you can keep that") so I'm ordering them in for teatime for £35 (still a bit dear); by then I'll know through deduction what the problem is.
As for the wastegate, it should be set at 4. It better not be the wastegate.

I see you've had your lovely saffron v70 resprayed a delicious shade of alsation
Martin

[Justin]

Lol, yes, the car looks well

Actuator should be 4.5psi.

For the actuator, have a look at this pic.


The pipe that comes off it is the one to check mostly.

[Goof]

All you genius's may have overlooked another apparent issue here.

I would get the wastegate checked too see what they have set it at first, also check the hose that goes to it hasnt come off and or split while they were doing it, either way plugs or wastegate it wont be long till there is a code displayed, there could even be one stored now, no doubt it will be 414....turbo boost regulation.

If it aint broke dont try and fix it mate.

Or it could just be the plugs lol.

I was just about to say that exact same thing!

[Redbrick]

Can't argue with anything said so far but if I could just add...

I wouldn't nail it, foot to the floor style, when its doing this until it has been resolved. An engine rebuild from bent rods costs big money, been there done that

Just exactly what has been done to your wastegate?

[pzorb]

It seems to have been about 95% fixed with new dizzy, rotor and NKG plugs. It occasionally feels a little low on max power when starting a flooring but soon gets over it and hasn't been nearly as bad as it was - the judders are gone. However, I did pull the battery while doing the job so it could just be that the ECU hasn't started throttling back yet (i did give it a healthy 70 mile run afterwards though...) I shall look into a new set of HT leads and see if that finally sorts it. The most important part is, obviously, being back on form for handing anything with an MG badge it's arse on a plate (lots of them round here for some reason, usually about a foot off my bumper - I reach for my emergency ironic fake burberry cap in the glovebox and educate lol I love that hat everyone needs one!)
The job took me 2 1/2 hours!!! Getting the airbox out was a pain in the arse, who put that 3rd screw on the dizzy cap down there?! I spent a good 20 mins trying to work around it but had to give in. Next time i should be able to do the lot in under an hour; now I know exactly what I'm doing so I don't need to triple check everything!
I took pictures of the sparks for you dave, they seemed fine to me - the dizzy was the culpret i think - i'll host the pictures when I figure out how to get my prehistoric digital camera (1998!) to work with linux (aka 'when it gives in to my filthy hacks')

As for the wastegate, during the RICA roadtest it was noted that the wastegate needed a few turns, and at the time I didn't have the time to poke around it myself so had it booked in to be done properly. It should be fine, and not the problem. Tbh i doubt my 170k old 15g has the capability to overboost! Mind you it could be newer... when the clutch came out the mechanic noted that I'd had a new box in recently (nice surprise!)

So aside from new HT plugs and assuming that the wastegate is happy, what else should I check? I asked volvo to check the codes, but it costs £37 (me:'but I just want them checked' - volvo:'that's £37' - me:'it costs you nothing to do this. nothing at all' - volvo:'when would you like to book it in?' - me:'book it in? it would take two minutes! honestly!' - volvo:blah-bl[click]) I'm betting I can buy a reader cheaper than that!
Is there something I can coat the hoses with so that after a short drive any holes would be bubbled/noticable? Anything else? I'm plastic bag free!

Thanks as ever guys you really are all stars!
Martin

[Wobbly Dave]

so long as you got the firing order ok - thats all that really matters. Surprised it took that long though, although I have done a few now.

[pzorb]

Click to make these bigger:




I think it was the dizzy cap, however spark #1 does look a bit mucky at the top... eitherway it's sorted now!!

Martin