Detenation advice..??

[jack joy]

I had a quick search on hear before asking... Sorry if it's a rehash of a common question!

Got a reconditioned carb from gtturbo spares.Had it set up on a dyno at Perfecttouchperformace running 1 bar . The guy there used to work on gtturbos.
Anyway..to cut a long story short...
There's detonation on anything other than moderate throttle even at around 8psi ish ,unless you're gettle and let it build gradually and then you get det at about 12psi ish.

I'm in the South of France so still got to get back to England.

How easy is it to check the knock sensor?I have a multimeter.

Plugs looked right and the tailpipe looks richer rather than too lean ..unless it's leaning out on load ? Would be odd as it's just been set up..

My concern is not hearing knock on the motorway,as its on boost nearly all the time.

Any advice would be great ��

[James5]

Could be numerous things but all fuel related, what fuel pump you using? do you know what the fuel pressure is? should be 4psi above what ever boost you are running if this is all fine the issue is carb related. I would be stripping and cleaning the carb out. Is it a standard jetted carb

[jack joy]

Thanks for your reply!
The fuel pump is this one http://www.mattlewisracing.co.uk/pro...t_lewis_racing .Only just replaced along with filter and 11 Turbo specific sender unit as well.
Carb is standard spec, option 1 from gtturbospares .Only just gone on the car.
It never detonated with the old carb when it was last on the road ...
Just strange how there was apparently no det on the dyno and during the numerous test drives, and then set off for a 600mile drive 2 days later and immediately notice det.... It's getting driven sedately .. It's lovely,just don't want engine damage..
Jack..

[Matt Cole]

It could be the diaphragm split in the AEI module. If boost reference isn't detected by the AEI, then it screws the timing. I think the original knock sensors retarded the ignition 5 degrees, that's if they ever worked.

Take the vac pipe off and see if you can suck/blow through it. If you can then it's the diaphragm could be split. You could also pop it on a foot pump up to 5 or 6 psi. See if it holds ok.

Can you tell us what afr readings where being reported from the rolling road operator? He should have been aiming for low 12's high 11's, dependant on your target boost.

Chuck the graph up here so we can see what's what 😉

[Markey Mark (BD)]

Sounds like an AEI unit issue, as mentioned diaphram has split and not adjusting the timing correctly

[jack joy]

Blimey,what brilliant help I'm getting here! Had a few other non vehicle related probs..my excuse for not getting back sooner..
It was the aei unit. Diagram seemed to hold pressure,but got rather lucky as I popped to the local garage & found out that the boss rallies 11 turbos. He had a crashed one in there ,so sold me his aei unit which solved the problem!

[Matt Cole]

Thats great, at least you know!

Do you know the revision number of the AEI? The 11 turbo may have used a different ignition map compared to the GTT.

[Ian S]

The original 1988 AEI on my 5 failed in the same way. Working fine, increased the boost to 15psi (manifold) and over a day it started to get increasing pinking until it meant driving back from Pod slowly on the motorway.

Changed AEI and it was well again.

[jack joy]

Thats great, at least you know!

Do you know the revision number of the AEI? The 11 turbo may have used a different ignition map compared to the GTT.

It now has a RE 209 instead of it's original 208.

1900 mile round trip and it made it home ! Just got to find a replacement boost pipe, which split on the motorway ( much easier said than done ), and investigate why the oil pressure light stays on 2 secs after first start.. Also retrieve the marshmallow i left somewhere in the steering system...

[Ian S]

I seem to recall noticing a slight change in performance between a 208 and a 209. Don't know if that was different mapping or either going faulty.

Do you mean slack in the steering has developed? There are so many things to cause that. I never got mine all correct at the same time. I concluded the only way was to change the whole at the same time!

If they do go ahead and impose the London Ultra Low Emission Zone out to the North Circular, have you a plan? Would moving further out be the only option to keep your pre 2006 cars on the road?