Going lean under boost

tekdeus

Pronounced Tek-DAY-us
Jan 23, 2006
2,115
0
0
Vancouver Canada
www.bitrontech.com
Hey guys. Was out boosting tonight, and everything was fine until it started going very lean under boost. Normal AF/R's are around 11.0, and it was spiking to 16-18 under boost (above 10psi). My methanol light was coming on and my fuel pressure appeared to be rising. It drives and cruises fine. I have dual walbros and I'm not sure if this would happen if one failed or not. Running an SAF-C. TPS seemed to be connected and working fine. No CEL came on, but I'll have to check codes tomorrow. Any ideas?
 

tsupranami

Drain Bamaged
Mar 11, 2006
134
0
0
Eastern WA
Idle ok? Steady and smooth? I've popped off the vacuum line going to the PS pump, had spiking afr's, boost pop & drop, and surging idle was the clue. What AFM are you using? OEM, MAFT, other?
 

becauseican

Supramania Contributor
Mar 31, 2005
1,451
0
0
Vancouver
www.bicperformance.com
Somethings going on, maybe the wideband is on its way out, but normally they just read one thing and stick there...ie full lean or 14.7

Watch out though 16-18 afr's on boost is very very lean, you will melt stuff at that, turn your boost down until you figure it out.
 

kamikazemkiii

Active Member
Mar 21, 2009
1,219
0
36
North Carolina
My guess is one of the fuel pumps, ive had the same problem swaped out the pump and did the 12v mod and its worked like a charm
hope this helps some.
 

CajunKenny

PULL MY FINGER. PLEASE!
Nov 15, 2007
3,255
0
0
Washington
Even one pump would provide enough fuel for 10 psi.

Double check your tune. Something may have happened with your AFC Gear and something got set back to default.

Otherwise, I'd second the WB Sensor going bad idea. They're easy enough to test. Remove the sensor and wrap it in a gasoline soaked rag.
 

tsupranami

Drain Bamaged
Mar 11, 2006
134
0
0
Eastern WA
Which wires did you jiggle?

I've had the quick-connect wire splices lose contact on the SAFC and AVCR. I now solder all connections to an Autosport Wiring adapter plug.
 

suprahero

naughty by nature
Staff member
Aug 26, 2005
14,971
0
36
53
Roll Tide
Since that's fixed.............

Brad, is your AVCR programmed to control boost in each gear independently? When I set mine to where the boost is right in fourth gear, it only boosts about sixteen in second and maybe twenty in third. I want to do some research and find out how to do it independently for each gear. If you or anyone else knows how, please let me know. Thanks, Jay

When my wideband went bad it stayed at 14.7 as Ian already stated. Someone else might have mentioned it also.
 

tsupranami

Drain Bamaged
Mar 11, 2006
134
0
0
Eastern WA
Holy crap, are you stalking me JJ?

And yes, I do think you are starting something. You haven't offered any help with this comment. It has nothing to do with the OP's problem. If you have information, share it, don't come busting my balls for trying to help. That just makes you look.....

Alas, I digress.

Yes, I DO think solder is better than those crappy little quick-splices that cut through the insulation of the wire with a split-metal tab. Duh!

Please research the failure rates for crimped vs soldered connections.

I think understand what you are saying. Properly stripped and crimped connections are at least equally effective at reliably conducting electrical current as a soldered connection. In fact they are used more frequently than any other type of electrical connection in aerospace, computers, automotive, and most other electrical applications.

But crimping must be done properly, with proper crimps and proper crimping pliers. Most folks don't have access to the high-quality crimping tools necessary to perform the job adequately. That is why I solder and recommend the same.

Crimping is used in manufacturing because of cost. It is not "BETTER", just faster and cheaper for factories to use. Many Mil-Specs require soldered connections. But they are time consuming, so they are only used in the most critical components. Surely you are aware of this, being in the military and an electrical engineer.

I hope you would agree that these cheap little quick-splices are about the LEAST reliable way of joining wires.

If not, please direct me to the source of your infinite wisdom. Published. Not anecdotal BS.

If your experimants have been published in a professional journal, then please direct me to your findings. Otherwise, I'll stick by the published results that I am aware of in the SAE Handbook and many other professional engineering sources.

Thanks for (almost) confusing the issue yet again and making this out to be an issue between us and not providing any help to the OP.
 

tekdeus

Pronounced Tek-DAY-us
Jan 23, 2006
2,115
0
0
Vancouver Canada
www.bitrontech.com
suprahero;1589825 said:
Since that's fixed.............

Brad, is your AVCR programmed to control boost in each gear independently? When I set mine to where the boost is right in fourth gear, it only boosts about sixteen in second and maybe twenty in third. I want to do some research and find out how to do it independently for each gear. If you or anyone else knows how, please let me know. Thanks, Jay

When my wideband went bad it stayed at 14.7 as Ian already stated. Someone else might have mentioned it also.

Just spend some time with the manual, even though it's a bit tricky. You need to get the unit to learn and judge which gear you're in based on wheel speed and rpm. Once that is done, then the start duty can be adjusted for each gear, up or down, which you have to play with until it his the PSI you want per gear.
 

tsupranami

Drain Bamaged
Mar 11, 2006
134
0
0
Eastern WA
So correct me if I'm wrong, but the recommended repair for the OP's problem is to "wiggle the wires?"

Is this supposed to "fix" the problem?

What happens when the wires get "wiggled" the wrong way again?

Just trying to clarify for anyone else who might expereince this problem in the future.