20 replies to this topic

[jimbob]

When coming onto boost recently I've noticed a little intermittent judder which happens occassionally but not always @ 2,500rpm - most noticeable in pulling from low down in 4th. Any ideas appreciated peeps Two little things I can think of: - I did recently run the fuel tank down to fumes then filled her up to the brim with Optimax again? - Car stood out in a shower over the weekend (but has the ingress plate)

Edited by jimbob, 20 June 2006 - 11:41 AM.

[Big G]

Probably your Air Massflow Meter (AMM) I'm on my fourth in under 6k on my VXR. See my thread running at the minute titled "Preventing AMM Failure" When it goes it feels like you momentarily hit a rev limiter. It seems to do it at fairly random times

[johnaachen]

Sounds like what I had (surprise surprise ) and it was water in the spark plugs.....this was before I had had the ingress pack fitted though...... Check them and see....most likely culprit is plug #4...on driver end of engine

[P11 COV]

Had a mis fire problem recently which was cured by taking the dIS pack out and sprying some WD 40 in. It seems this was due to me washing the car! I do have the water ingress kit fitted. All the way to and from Le mans it felt juddery and mis firing occasionally until it finally went to 3 clynders a few miles from home and the engine light came on. After taking DIS pack out and Spark plugs and using lots of WD 40 it is fine again now.

[jimbob]

No water in the pack area. Most deffo only happenning when the car is boosting. What is /where is the AMM and what are the symptops of failure? Says...the total technophobe

[johnaachen]

The AMM is the Air Mass Meter... it tells the ECU how much air (and its temperature) is going into the engine. It then uses this information to work out when and how much fuel to inject and when the spark fires. If the AMM was faulty I would have thought that you would get a poor idle and generally bad engine running. This "intermittent judder" does sound to me like the plugs....maybe a bad connection? Did you look at the the plugs themselves? They may be corroded? If you rev the engine when the vehicle is stationary does it do it? If not, then its probably booast/load related and then a poorly firing spark plug is then more likely to be the problem. the more I think about it and stop rambling and type as I think it reminds me of when my car did this....the first time it got properly wet.....plugs definitely.....well about as definitely as ENgland are to get much further....(hopefully not!) HTH

[P11 COV]

No water in the pack area.

Says...the total technophobe

It really does sound just like mine was last weekend. Water in the pack area is not visible. Just take it out and give a it a good spray of WD40 and maybe take the plugs out aswell.

It hadn't rained for a week and it had done 800miles in 30 degrees heat but it was deffo damp that was the problem.

[hethelred]

It sounds a bit like the problem i had when the boost came in then stuttered and dropped off. This was picked up at TMS on the RR following my remap but i had noticed it before. The subsequent diagnosis seems to suggest it is the actuator but i'm having a VXR turbo fitted on friday complete with new actuator so hopefully that will resolve it.

[ratboiler]

If your AMM is at fault you will get an engine management light come up on the dashboard at some point, pluss the performance will feel like sh*t.

[jimbob]

Mickey mouse sort of reply... What tools do I need to remove the two DIS nuts and spark plugs?

[walkes]

Do you have a woosh of air with it?

[jimbob]

It's boosting and whoosing no problem. Seemed to affect most gears a few days ago. Today after a good run, it's only really doing it when in 4th gear - just a little shudder - especially when dropping down from 5th, then opening up steadily in 4th. Anyone got an answer to mickey mouse above?

[TurboTomato]

Sounds like the problem I was having with it after I had the stage 1 with the Timbo airbox mod Turns out it wasn't the airbox, it was the DIS pack which was changed under warranty (so not long ago). They also changed the spark plugs as one had taken in a fair bit of water. So maybe that problem has come back? Be careful though - when I took it back to the dealer for the first time to have it investigated the bloody mapped it back to standard

[P11 COV]

Mickey mouse sort of reply...

What tools do I need to remove the two DIS nuts and spark plugs?

The two nuts are those star type heads...dunno what thy're called but you can buy a set at any good tool shop.

The DIS pack then pulls out and you have to disconnect the wiring loom from it.

The spark plugs are resessed a long way down so you need a reasonably long spark plug remover (mines about 20 CM) I assume spark plugs are standrad sizes.

[jimbob]

Thank you everyone. How's life Paul?

[jimbob]

Have taken the DIS and sparks out and given them a clean/WD40 as advised. Car is still juddering at boost point. Some more evidence: - Fifth seems OK, Fourth seems worst at boost point for a stutter and third as below - In third, if you accelerate past boost point it feels like it has a minor misfire at 4k+ - Happens worst when on half throttle vs full throttle (when it can behave normally). None of this I may point out makes the car unusable - just a little quirky..

[Thorney]

Sounds like DIS pack itself. Can you get to a tech 2 machine and see what the error code is? Misfires always show up a fualt code identifying the cylinder and where/when - be handy to see that.

[jimbob]

Seems like the WD40 on the pack tubes has done the trick for now...

[brucevxt]

""The two nuts are those star type heads...dunno what thy're called but you can buy a set at any good tool shop."" TORX

[P11 COV]

""The two nuts are those star type heads...dunno what thy're called but you can buy a set at any good tool shop.""

TORX

Thers always some bright spark out there trying to make you look stupid