Twin plenum fuelling problem

[Meatball]

Before i start looking at sending the car off to the garage to fix i thought i would try my luck on here.
Im having a difficult time trying to get my twin plenum up and running, im still using the Lucas ecu still with a torque flow map which i believe is a standard 5 litre map.
The main problem im having is its running very weak at idle its making 16 AFR which is as lean as my gauge goes (widebands fitted). The torque flow air flow metre im using has been made adjustable so i can crudely increase the fuelling to compansate but this also increases the revs? So to get a desirable 13-14AFR at idle im at 1800rpm

Is this purely a mapping issue?

Any ideas chaps?

[K4000JB]

Hi Ben
Sorry to here you are having problems. When I fitted my t.p. I tried a 500 map but found it was actually worst at higher rpm than my standard 400 map. I don't mean state obvious things but have you checked for an air leak also have you checked the fuel pressure. I didn't have any problems with idle fuelling but it wasn't as highly tuned. Hope you get it sorted soon.

[Meatball]

K4000JB said:

Hi Ben
Sorry to here you are having problems. When I fitted my t.p. I tried a 500 map but found it was actually worst at higher rpm than my standard 400 map. I don't mean state obvious things but have you checked for an air leak also have you checked the fuel pressure. I didn't have any problems with idle fuelling but it wasn't as highly tuned. Hope you get it sorted soon.

Hello mate, YHM
Cant find an air leak, ive stripped it down quite a few times now, and the fuel at the rail is 2.7 bar.
Everything suggests an air leak but i cant find it i was just throwing it out there before conceading defeat.

Edited by Meatball on Sunday 21st March 21:13

[adyw]

Ben,
give the dizzy a twist , see if it makes any difference, if it does then you hav much or little advance, could also be a leak in the vacumm pipe.

[Meatball]

adyw said:

Ben,
give the dizzy a twist , see if it makes any difference, if it does then you hav much or little advance, could also be a leak in the vacumm pipe.

Hi Ade, The dizzys never been touched so ill leave that for the moment, will take a look at the vacumm pipe as i did change it as the existing one was too short.

[CarlosV8]

Are you using an SD1 plenum or an aftermarket jobbie? If it's the SD1 plenum make sure your throttles are sealing properly and not letting air pass at idle.

I had this plenum on my Vitesse and because of the throttle mechanism being on one side and not in the middle it can cause some odd wear to the throttle spindles and bushes and eventually cause some unwanted friction / displacement of the throttle discs. After getting fed up of idling issues on mine I stripped it down found my throttle discs were badly worn and one of the spindles broken. I've now temporarily swapped to a single plenum until I source some parts and get it fixed as the spindles are NLA.