im starting to think that my running issues with my twin engined reliant are down to the pipercross filter and straight through exhaust .the stock airbox has a vacuum controlled plap which restricts airflow under high vac conditions ie idle and light load (cruising ) but as ive binned them to get the engines in i might have a huge lean mixture under part load ,i wonder who else has had to resort to a power commander on their efi bec,s for similar reasons ? i havent had chance to drive the car since the chain snapped on saturday but we put the rear up on a jack and ran the car up through the gears and under steady running the exhausts start to glow and snapping the throttle it does sound like its lean with lots of spitting and banging on the overrun ,we were leaning towards fuel starvation as a single coswort sierra pump supplies both engines but the pressure and delivery is fine,im changing to twin pumps purely for peace of mind as the fuel pumps have to supply additional fuel for the nitrous system . the plugs are clean so it sounds like lean mixture to me , any thoughts???



[Edited on 11/11/08 by froggy]

[Edited on 11/11/08 by froggy]

I was pretty much under the impression that a rejet (for carbed engines) or a PowerCommander (for efi engines) was pretty much an essential requirement when making such changes to the exhaust and induction of all BEC's!!

I'd say it's essential on a standard BEC let alone a twin-engined jobbie. I'm guessing you'll need two though which won't be cheap

Ive had a few bikes that have had aftermarket cans, and even just the one mod require a power commander to run sweet.
The first was a Honda RVF that i had put a scorpoin can on. My old man had problems with his GSX1400 and needed a power commander. Im experiencing similar problems with my TL1000R, in that i pops and farts like a fat bird after sunday lunch because of the blue flame cans.

Bite the bullet and get the power commander. I reckon itll sort your problems.

From your description of the system, i reckon it will be running lean, throughout the rev range. Not good.
The free flow exhaust and sock filter are nailed on to make it lean at full throttle, and by removing the vacuum gubbins it sounds like its running lean at part throttle as well.
If you value the engines you need to sort it.
remap on a rolling road is the only 100% reliable way.

Al




i]Originally posted by froggy
im starting to think that my running issues with my twin engined reliant are down to the pipercross filter and straight through exhaust .the stock airbox has a vacuum controlled plap which restricts airflow under high vac conditions ie idle and light load (cruising ) but as ive binned them to get the engines in i might have a huge lean mixture under part load ,i wonder who else has had to resort to a power commander on their efi bec,s for similar reasons ? i havent had chance to drive the car since the chain snapped on saturday but we put the rear up on a jack and ran the car up through the gears and under steady running the exhausts start to glow and snapping the throttle it does sound like its lean with lots of spitting and banging on the overrun ,we were leaning towards fuel starvation as a single coswort sierra pump supplies both engines but the pressure and delivery is fine,im changing to twin pumps purely for peace of mind as the fuel pumps have to supply additional fuel for the nitrous system . the plugs are clean so it sounds like lean mixture to me , any thoughts???



[Edited on 11/11/08 by froggy]

[Edited on 11/11/08 by froggy]

a few mistakes on my part, the vacuum systam on the tl operates a flap in the airbox which chris mason left wired up as it should be so the ecu can see the solenoid but i neglected to cap the ends of the pipes so they were sucking air at idle giving a low map sensor reading.
next one was the ecu,s themselves my original engine was an early full power tl which ran orange injectors ,the second engine has blue injectors which were introduced in 1998 when suzuki softened the bikes power delivery unfortunateley i bought a full power ecu so they were matched but the blue injectors are a lot lower flow rated than the orange ones hence one engine running like shat. with the db killers bin the exhausts to give some back pressure the engines run much better now and a dyno session next week will tell me what the afr is doing under load before i resort to power commanders