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Help with deceleration bog on turbo CF7

D
Dec 29, 2007
95
2
8
Norway
I'm running the numbers below on my BD box, and the sled is running way lean when coming down after a climb - just breaking on the engine (if you know what I mean). When going below 5000rmps through 3000 rpms, the air fuel goes lean (A/F 15-16) and egt drops down to 4-500 farenheit.

If I add on MD(edit: I see where the problem is, gonna adjust the LO setting...) at 3 and 5000rpms, it gets a little richer at deceleration. But then the acceleration sucks... Tried to leave the numbers as is, and add on negative boost - but same results then also.

Running on avgas, with 4-5 psi boost. The boost kicks in at 4500-5000rpms, and runs great at acceleration.

Really appreciate suggestions on these numbers!
Thanks

2006 CF7 Sno Pro - BD Turbo kit with intercooler.
RPM Low Mid High TR,Pto
3000 00 00 00 00
5000 07 05 00 00
6700 06 07 00 00
7500 00 07 00 00
8600 00 07 25 00

TBOL -04 -02 00 01
00 00 -02 04

TBOH 02 03 12 18
08 16 48 75

ACEL AM DR SENS
-07 10 10

EXV-ON
Fuel ExV RPM
05 140 ON
RPM(exv) Min Max
5055 7800


I already know that other fuel boxes are easier to tune, but this is the box I'm using this season.
 
Last edited:
T
Nov 26, 2007
129
3
18
I would not worry to much if it is just the coast down the hill. I will have to look at my numbers on the m8 and compare with yours.
 
S

speeddemon

Well-known member
Feb 27, 2006
1,314
94
48
50
buckley wa
when on boost and coming off boost it will throw xtra fuel in the cylinder which makes it look lean but is actualy rich !! it is just unburned fuel not being burned and causes the A/F to read lean
mike:D
 
H

Hairy Mark

Well-known member
Nov 21, 2007
514
63
28
kettle falls
coming down some hills my af gauge will read as high as 20 and i am not worried about it. make your acceleration good and let it go from there.
 
D
Dec 29, 2007
95
2
8
Norway
But but but is it possible to hear the difference on too lean or too rich bog? When I'm coasting down the hill and the A/F reads 16 (the highest value) sometimes it sounds like a bog, like the engine skippes a beat. I've tried leaning it out around 3000rpms and I believe it sounded better, but I'm afraid too lean to much! Egt still read around 450 idling, 550 at 3000rpms, and about 440-450 again when coasting at 3000-3200 rpms.
If I'm actually to rich, I wouldn't mind leaning a bit more at 3000-4000 rpms for even better acceleration.


Whats the "ideal" ballpark for temperatures at the following rmps?
@3000 approx 550 (should i lean it more?)
@4000 approx 750
@5000 approx 1200
@6-7-8000 approx 1100
I know I could go as high as 1300 farenheit, just playing it safer at 11-1200.
 
D
Dec 29, 2007
95
2
8
Norway
Still dialing...

The speedometer wire was a bit too tight. Coasting looks(A/F) and sounds better now!

Next problem:

The egt's are running approx same numbers when a/f reads 11-14. I have some problem rpm ranges that I try to add and substract fuel, to see what happens. When I go richer (on the rpm settings, not boost) the egt sometimes reads almost 200degrees different temps, and the sled starts acting up. Sounds almost like its running on one cylinder.

Is there something wrong with the stock injector or the wiring? There are no error messages displayed on the BD fuel box!
 

type_a_positive

Well-known member
Premium Member
Nov 27, 2007
392
70
28
Mongo Norway
Speedometer wire? Have you been guzzling down them Kilkennys again? What he is trying to say is that the throttle cable was to tight. Drunken bastard....:beer;
 
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