Lumpy Closed Loop Performance

McGMT

Original poster
Member
Jun 17, 2012
621
Noticed on one of the many hills nearby (4 miles of straight constant uphill grade) that while in closed loop the engine is just full out lumpy. Feels as if it is constantly missing and the power is never steady. As soon as you give it enough fuel to go into open loop for acceleration it smooths out completely and runs great.

Only recorded 2 total misfires on cyl 3 so I am gonna call it as no misfires as that is not uncommon at all.
O2 sensors are alive and well (rapid changes on 1 and slower on 2 with only small change (neutral) as normal)
Coolant temp between 195 and 203
Air Cond. Off
Voltage between 13.5 and 14.3
104k on the ODO
Plugs changed (Delco Iri.) at 100K along with other service items due then.


Anything else just ask and suggestions welcome (I am looking at the man with the $200 service manual coughROADIEcough) :wink:
 

The_Roadie

Lifetime VIP Donor
Member
Nov 19, 2011
9,957
Portland, OR
Ever use Seafoam? Check for vacuum leaks? I'd start by getting the fuel trim numbers and see if the injectors have an issue. I'm no expert on fuel trims, but I know I have to start getting into them soon.
 

McGMT

Original poster
Member
Jun 17, 2012
621
the roadie said:
Ever use Seafoam? Check for vacuum leaks? I'd start by getting the fuel trim numbers and see if the injectors have an issue. I'm no expert on fuel trims, but I know I have to start getting into them soon.

Yea, it gets the foam, last time I was in there the old girl is pretty clean... I tightened up a few loose bolts on the intake a month ago. My LTFT hangs around 7% sometimes up to 10% and short term is usually around 3% but jumps around quite alot...

And you ain't the only one that needs to investigate fuel trimming either, I know the concept but not the in depth geometry of them.
 

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