Thread: Lean A/F issue driving me crazy!
08-17-2008, 01:47 PM #1
Lean A/F issue driving me crazy!
On and off for weeks i've been messing with a friend's RXT that had a lean AF ratio running an X charger and RRFPR. Now the ski is only running an XS style IC, thru hull, and 3" intake. SC is stock as well as ecu and injectors. The AEM AF meter we're using is reporting numbers well into the 15-16 range at cruising. We've tried 2 different brand new AEM AF meters and swapped out intake manifolds with all the sensors and ecu. I'm starting to think that there's nothign wrong with the AF ratio after all and i've heard it's possible for an engine to run so rich that it can read lean. I'm thinking of trying an EGT probe possibly. I'm pulling my hair out here. With the RRFPR the fuel pump would easily push pressure into the 70psi range so i doubt the pump is bad. We've swapped injectors to a brand new set of 38s also. Still reading lean! What gives?
08-17-2008, 01:54 PM #2
I see AFR numbers into the low 14's while crusing. This is perfectly fine and is what you would see on a bone stock ski if you were to measure the AFR. "leaner is greener"
Perhaps that AEM setup you are using is a couple of points off of an LM 1 or similar?
08-17-2008, 04:05 PM #3
It is possible to be a few points off but to be well into the 16s with spikes of 17 is a bit fishy. The exhaust smells pig rich and the plugs look normal.
08-17-2008, 04:09 PM #4
Josh... I noticed this smell in the hot summer months. This was on a S-3 wheel too!
08-17-2008, 04:41 PM #5
yeah you can smell the unburnt fuel in the exhaust but how do you tell someone to just have at it when you're not totally convinced they won't blow up their ski?
08-17-2008, 04:55 PM #6
08-17-2008, 04:57 PM #7
- Join Date
- Apr 2005
Maybe Try Your A/f Ratio Setup On A Stock Ski Would Help.todd
08-17-2008, 06:11 PM #8
Another option is that you might have an exhaust leak. If you have an exhaust leak upstream of a wideband or even a regular 02, they will alway read lean. This is caused by the pulsing of the exhaust system which in turn causes some fresh air to be drawn in between pulses at the spot where it is leaking . The fresh air makes the 02 momentarily "loose contact" with the real exhaust stream, and it causes the sensor to read lean.
08-17-2008, 08:08 PM #9
Well i tried 2 completely brand new sensor/gauge setups and both read the same. At idle it starts off in the low 12s but then creeps up to almost 14 when warmed up. Wide open is in the mid 12s or so. It's in the cruising range of 5k-7k rpms where things look ugly. I'll check for exhaust leaks but the v-band flange at the manifold was cleaned thoroughly not too long ago. I may try the setup on my RXT here shortly since it hasn't ran in 6 months.
08-17-2008, 08:09 PM #10
i'd love to see what another A/F setup like the LM-1 would read.
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)
By rotaryfc in forum 2-Stroke PerformanceReplies: 13Last Post: 08-14-2012, 06:45 PM
By flygooy in forum Yamaha PWC Performance (2-stroke)Replies: 6Last Post: 07-24-2011, 02:13 PM
By ThePerchik in forum Towing and TrailersReplies: 7Last Post: 05-17-2009, 10:10 PM
By getreal in forum Open DiscussionReplies: 6Last Post: 01-04-2009, 02:55 PM
By kctaylor in forum 2-Stroke PerformanceReplies: 5Last Post: 03-20-2008, 07:51 AM