[Diy_efi] Lumpy engine in closed loop cruise

[Lee M. Lemoine]

Making sure you don't have any vaccum leaks as well -- speed density systems
are very touchy to that sort of thing, and when your near atmospheric and
theres an open somewhere in the system, it will act flaky.

Trust me, i tuned my car on a dyno with a vaccum leak, and repaired the leak
(it was in my brake booster hose believe it or not) accidentally when
swapping some W-body parts to my car, and it ran like crap. Trust me, i took
the motor apart 10 or so times before i figured it out. Look for a vaccum
leak somewhere first -- its probably going to be small seeing as your
experiencing it at real light loads (ie : highway enleanment is enabled,
which explains your O2 settings) ...

--LL

On 10/20/05, Mike <niche at iinet.net.au> wrote:
>
> Bit of a heavy load for cruise,
>
> And yes does sound a bit lean, can you richen it up by
> 20% and observe the effect ?
>
> Rgds
>
> Mike
>
>
> At 11:35 PM 10/20/05, you wrote:
>
>
> >I have 4-cylinder Lotus Esprit Turbo. ECU is a GM 1228708 using a speed
> density system.
> >
> >In 5th gear, trying to hold steady 85 mph, 3500 rpm, MAP about 100-130
> kPa, ECU is in closed loop. O2 cycling between 0-0.65 V. The engine is
> lumpy, like a slight hesitation. It feels like a very slight misfire, press
> the throttle and it goes away as it richen up the mixture and accelerates
> under power perfectly. The target A/F ratio in cruise is 14.7.
> >
> >Are there any obvious causes of this, over lean ? etc...
> >
> >
> >Dermot
> >
> >
> >
> >
> >_______________________________________________
> >Diy_efi mailing list
> >Diy_efi at diy-efi.org
> >http://lists.diy-efi.org/mailman/listinfo/diy_efi
>
>
> Regards from
>
>
> Mike
> Perth, Western Australia
> VL Commodore Fuse Rail that wont warp or melt !
> Twin tyres for most sedans, trikes and motorcycle sidecars
> http://niche.iinet.net.au
> _______________________________________________
> Diy_efi mailing list
> Diy_efi at diy-efi.org
> http://lists.diy-efi.org/mailman/listinfo/diy_efi
>



--
Sincerely,

Lee M. Lemoine
http://www.turbochargedsoul.com/
-------------- next part --------------
An HTML attachment was scrubbed...
URL: http://lists.diy-efi.org/pipermail/diy_efi/attachments/20051020/8e392938/attachment.html