10 days to Spa Classic and its playing up big time !

[anonymous-user]

Recently had throttle body roller conversion and new clutch at Straight 6 and when it left there it felt great, all ready for Spa or so I thought.

So symptoms are rough under light throttle, backfiring at light throttle under no load. Sooty exhausts, I think pinking ! under load in high gears. All sounds and feels very poorly.

Obviously I will get it back to Oxford next week if they can look at it in the next week , not many days to go now before spa and I can't take it as it is.


Any thoughts on the symptoms ?

[nrick]

Throttle bodies would have been my first thought, but not with new ones?

Coil pack I have a spare in glos if you want to try?

What do diagnostics say?

[anonymous-user]

Diagnostics after just plugging in show .

L1 at 0.3--1.0 fluctuating
L2 at 0.60 fairly stable

inj goes apart too under throttle one at about 1.2 and the other about 2.5

A1 -4.9
A2 at 37.3 long way apart
These get closer off tickover ?

I reset and they are much more equal for about 1 min and they start to move apart again back to where they stared after a few mins.

Edited by anonymous-user on Saturday 11th May 12:58

[Toady1]

What do ur throttle adaptives look like? Possible a throttle potentiometer problem.

[anonymous-user]

is that the a1 and a2 reading above ?

[Basil Brush]

Is it only one exhaust that's sooty? Maybe a dodgy lambda sensor?

What do the throttle % opening values look like as you open the throttles? I had one of the linkage balance screws come loose after an adjustment a while back that made mine run like a dog.

Edited by Basil Brush on Saturday 11th May 14:25

[anonymous-user]

Both exhaust sooty really one a bit more than other. Throttles are the same and remain so as I rev it.

[clive f]

lambdas should both fluctuate when warm from .1 to 1volt, could be faulty sensor ?
give Jason a ring Monday morning for advice, should be a simple fix.

[anonymous-user]

The plot thickens.
With engine off all butterflies operate from the throttle pedal very evenly and instantly.
I expect them to I have new cable and rebuilt throttle bodies just 200m miles ago.

When I start the engine the right hand bank of butterflies do not want to open under light throttle.

I turn it off and they work again fine.

It as is if they are being held closed by the engine ?

I have watched a lot of star trek recently so I expect anything is possible if I rule out the impossible .

[Basil Brush]

Have you checked all the small springs in the throttle linkage are in place?

[anonymous-user]

Yes all springs in place and mechanism looks all good, as I expect after being re built.
Just tried again and throttles are smooth and open all together with engine off.
Start the car and the right hand bank need 20% throttle before they will open.
Turn it off and all work in unison again smoothly.

So.......defies any kind of logic

[natben]

It could be the throttle pots on the right hand side the blue one, but only a guess I'm no mechanic but might explain why that side is not operating the same as the other.

[anonymous-user]

Thanks.
I think they are just measuring devices and should not have the ability to prevent the butterflies opening. I think..

[Basil Brush]

cliffords said:

Yes all springs in place and mechanism looks all good, as I expect after being re built.
Just tried again and throttles are smooth and open all together with engine off.
Start the car and the right hand bank need 20% throttle before they will open.
Turn it off and all work in unison again smoothly.

So.......defies any kind of logic

There must be something wrong on the linkage to allow one side to move without the other.

[anonymous-user]

I agree and thanks.
Jason worked on them last so I will call him tomorrow and I am sure he can resolve for me.
Thanks all for the suggestions.

David

[SteveTusc]

Any progress, all sorted?

[anonymous-user]

Picked up by Straight Six today , I will know more tomorrow.
I think it is a fault in the throttle linkages.

[nawarne]

David, please let us know what Jason discovers.

I had an issue with my Mk.1 just before the Le Mans Classic last year. Everything booked and then 2 weeks prior to event, it started running like a dog. Ignition wouldn't advance under load/opening throttle. Engine running very hot, huge pops/bangs from exhaust where un-burnt fuel was just going straight through and burning on cats I guess. Had Jason stumped for a while.

Eventually traced to a redundant OBD plug that was giving a bad connection. Got the car back Wednesday, the day before we travelled....phew!
Nick

[m4tti]

OBD as in diagnostic socket? where abouts was it?

[natben]

M4tti, sounds a bit like my car at the moment!!
Do you know where this OBD plug is so I can have a look at mine.