AFR at idle and off throttle (Update 3/14, final adjustment)
#1
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
AFR at idle and off throttle (Update 3/14, final adjustment)
Hi guys,
I've asked about the AFR to rich at idle beofre. So now, the AFR can reach 14.7 at idle now.
But off throttle in low rpm when it start to show the AFR 15.4 - 14.7 (normally it show "- -" because of off throttle), and I heard few backfire. So is it normal? or I should I adjust the AFM bypass screw a little bit rich?
Here is more info and what I found while driving:
-Idle: AFR 14.7
-light throttle on curising: AFR 14.5-13.9
-50% throttle when turbo spool up: AFR 12.5
-Full throttle and full boost: AFR 11. something
-Off throttle at high rpm: AFR - -, because injector off
-Off throttle at low rpm (under 1500 rpm - idle): AFR shows 15.5 very fast and backfire, then down to 14.7
I've asked about the AFR to rich at idle beofre. So now, the AFR can reach 14.7 at idle now.
But off throttle in low rpm when it start to show the AFR 15.4 - 14.7 (normally it show "- -" because of off throttle), and I heard few backfire. So is it normal? or I should I adjust the AFM bypass screw a little bit rich?
Here is more info and what I found while driving:
-Idle: AFR 14.7
-light throttle on curising: AFR 14.5-13.9
-50% throttle when turbo spool up: AFR 12.5
-Full throttle and full boost: AFR 11. something
-Off throttle at high rpm: AFR - -, because injector off
-Off throttle at low rpm (under 1500 rpm - idle): AFR shows 15.5 very fast and backfire, then down to 14.7
Last edited by beebone; 03-14-2010 at 12:15 PM.
#4
Addict
Rennlist Member
Rennlist
Site Sponsor
Rennlist Member
Rennlist
Site Sponsor
#5
Three Wheelin'
What chips are you running? I have a set of Guru Chips 18 psi that the previous owner reported would run rich off throttle and light flames out the back! Sounds cool but I have the Max chips and no flames!
#6
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
#7
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
Trending Topics
#8
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
The car is very smooth in crusing and turbo spool, only the pop started when let say 1st gear rev to 3000, then shift to 2nd gear (I think the rpm is around 1500), then off throttle. the AFR guage show "--", then 15 just a show up (few pops coming at the same time), then return to 14.7.
So u guys think is it harmful to the engine?
#9
Three Wheelin'
Is it rich or lean at WOT? Can you data log?
Hmm,reread your info, it might just be the chip? Your AFR looks OK at WOT, as long as your not lean under load you should be Ok. Maybe someone else has the same chips and give you their observations?
Hmm,reread your info, it might just be the chip? Your AFR looks OK at WOT, as long as your not lean under load you should be Ok. Maybe someone else has the same chips and give you their observations?
#10
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
No problem on high rpm and WOT.
The only above problem is only on low rpm and off throttle.
#11
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
I tried to adjust the AFM screw rich a bit, everything fine now. Except 1 thing!!!!
When downhill, off throttle at low rpm (e.g. 1100-1500rpm), the AF guage shows 17, 16s, 15s. Then I hear the pops coming out. Any idea?
When downhill, off throttle at low rpm (e.g. 1100-1500rpm), the AF guage shows 17, 16s, 15s. Then I hear the pops coming out. Any idea?
#13
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
#14
Got the same chips as you beebone and my car is very similar. Does backfire now and again. The 944's injection system can be a little slow to respond at times.
Car will run lean off throttle above 2k rpm as the DME shuts of fuel for economy.
Car will run lean off throttle above 2k rpm as the DME shuts of fuel for economy.
#15
Racer
Thread Starter
Join Date: Aug 2009
Location: Hong Kong
Posts: 251
Likes: 0
Received 0 Likes
on
0 Posts
So your car is EU spec w/o cat? Did the problem solve yet?