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krasuskyp 05-15-2011 06:54 PM

another ARF / adj WUR thread - need some thoughts
I recently installed an adj WUR from Brian, and am experiencing some AFR funkiness I'd like to run by youses all.


Stock '87, save for RL8 dual-out hooligan, Garretson shortneck, K&N tall/round filter, and 0.84 bar via EBC. Mustang said 286/320rwhp, with AFR's nice in the 11's until 5k then hitting 12.5 and rising quick.

Pressure test revealed surprising #'s for my OE WUR @ 50k - everything except a slightly high CP was spot-on (and no cold-start issues at all). Accumulator's been shot since I got the car, it's now on the to-do list. New plugs / cap 'n rotor / think wires might have 15k on 'em.

Installed WBo2, the car was running great but @ 10.4-10.5 idle AFR.

Fast fwd to last week - installed new adj WUR which was sent for a 375rwhp tune, and idle AFR read 10.6 or so. Dialed the idle mixture down to 13 or so and it ran like crap - smelled like crap ('dry'), sounded like crap (much more pop's on decel), and didn't run that great - and cruise AFR's were hitting 16's+ for the mile or so I tried that.

Put idle AFR back to 10.6 or so. Cruise AFR's are a nice 15ish. On boost they're in the 11's. Again it's running great - but - AFR's after 5500 are 12.5 and rising quickly.


It's been suggested look for vacuum leaks - I'd pretty recently sprayed brake clean around all those bits and found nada tho.

Any insight here would be hugely appreciated - as alwayz. I'm befuzzled (not hard).

Do I need to dial down my warm pressure on the WUR then adj my idle AFR accordingly?

TIA gentz (coughFAIRMANcough)...


smurfbus 05-16-2011 02:09 AM

I don't think you can find leaks with brakleen. You need something that ignites easily like starter helper.

10.6 AFR idle is not good IMO but if it feels like it runs best at that AFR I would check if the AFR is accurate. It should run nicely up to 14AFR on idle!

Did you sensor calibration for you WB. I would do it again just to be sure and make sure the grounding is good with the WB.

krasuskyp 05-16-2011 09:06 AM

Hmmm, I'm pretty sure Brakeclean is pretty durn flammable 8-). I'll try some starter fluid tho and see, sure.

Didn't calibrate the WBo2, emailed my vendoer asking him how (friend of mine @ VEMS) - didn't know had to / how to, tx for the thought.

Anyone else?

smurfbus 05-16-2011 10:30 AM

I haven't tried brakleen so you might be right.

krasuskyp 05-16-2011 04:53 PM

Was speaking with Chris @ TurboKraft today ordering my oil lines for my header install, he was predictably soverygenerous with his time in letting me pick his AFR related brain. Too cool.

My system pressure is 6.6, which per the Euro / pre '86 spec is fine... I've an '87. He said *that* spec is actually 6.9-7.1 range so I'm notably low.

Threw the fuel head shim kit in w/ my order, have it by Fri and hopefully nail this. Wish me luck.

BTW, my VEMS / Bosch WBo2 AFR gauge set up is said to be self-calibrating w/ an internal chip - all set there.

smurfbus 05-16-2011 08:43 PM

I can ask here about the VEMS calibration. It sounds strange that it could self calibrate?

Edit: It seems there is no software calibration on VEMS WB and it is just set at the factory calibration. This works fine when the sensor is new and in speck. If the sensor is getting out of speck the AFR is not accurate anymore.

I would try another Bosch LSU4 sensor to see if there is any difference. You need one spare anyway.

With these CIS systems it runs so rich at startup it's hard on the sensor. I would power the WB after the engine has warmed a bit. Do NOT power the WB and wait and then start the engine. Warm sensor and cold water/fuel to the sensor is very bad for the lifetime of the sensor!

Is the idle AFR 10.5 cold or hot? Cold is fine but if warm I suspect something is not 100% right (try another sensor).

Stein 05-16-2011 11:07 PM

Is the WBo2 mounted correctly? This is for innovate, but should be similar to other brands.

page 9 for calibration. Note: calibration must be in free air
page 16 for tips and tricks. ( do you have air inj?, bad ign. leads. exh. leaks?)
Page 7 for mounting,


Where have you put the o2 sensor?

Miguel Antonett 05-17-2011 03:19 PM

What does Brian have to say to that?

patkeefe 05-17-2011 05:37 PM

Did you adjust the boost threshhold setting? If you're running out of fuel after 5K RPM, ( I am assuming you weren't running out before the new WUR), it may be that threshhold pressure is too high. I set mine with a mighty-vac. You may want to reset cold control pressure also. Did BL give you the pressures to shoot for in the data sheet?

RarlyL8 05-17-2011 06:11 PM

I sold Paul the adjustable WUR that was built for my car. It was set up for 375WHP so should be a little on the rich side on boost. Cold pressure, warm, and threshold are standard spec for use with a stock fuel head.
We (Paul and I) have talked in length about this off-spec idle AFR that seems to be the sweet spot. I don't see how that is possible and doubt the reading is factual. My suggestion is to get the car on a dyno and verify these readings before any adjustments are made to the WUR.

krasuskyp 05-17-2011 06:44 PM

Thanks all.

WBo2 is brand new, and mounted @ 11:00 just outside the turbo hotside / just prior to the muffler body.

Awaiting my VEMS-bud's response to re-confirm the calibration issue.

But again - my system pressure of 6.6 compares to a spec of 6.9-7.1 (I was previously comparing my results to Euro-spec, which is is slightly lower spec).

Brian's been great, didn't want to keep bugging him as he's already spent some good handholding time w/ me - I had Chris on the phone getting my oil lines and he noted the pressure issue. My shim kit will be here Fri and I'll go from there.

Patrick - yes, I was running out of fuel on the dyno @ 5k prior, now running out @ 5600 or so (12.5 and climbing to 12.8-9 or so fast).

Don't yet have reason to believe my readings are wrong, and am not touching the WUR settings yet certainly.

I'll report back after the weekend. Shims arrive, and hoping to also tackle header install - will be a busy weekend 8-)...

smurfbus 05-17-2011 11:14 PM

Stein: I'm more worried about the cold shock from super rich AFR so if Paul is running his idle at 10.5 I beleive it will shorten his sensor lifetime.


It is NOT a good idea to do a sensor warm-up prior to starting the vehicle.
Depending on the climate and the sensor position in the exhaust, condensation can
form in the exhaust pipes. This condensation could then be blown by the exhaust
stream against the hot sensor when the car is started. The resulting heat shock can
permanently damage the sensor.

RarlyL8 05-18-2011 06:25 AM

Don't think you are bugging me whatsoever, we need to get this right as it is far to important an issue and has potentially harmful consequences if done incorrectly.

6.6 to 6.9bar is less than 5psi and should not cause such a large disparity of idle AFR. Refresh my memory, is your Lambda system enabled?

krasuskyp 05-18-2011 08:01 AM

yes, Lambda is plugged in - I was planning on disconnecting it... yes/no?

thanks for your continued thoughts!

unfort I can't get it back on a dyno for quite some time - I will try to con someone to shove their exhaust gas sniffer in there tho to compare to my WB reading

RarlyL8 05-18-2011 08:06 AM

Yes. You should be able to disconnect and set your CO to 3% (13.5:1 AFR). If so you have found a problem.

krasuskyp 05-18-2011 08:14 AM

great tx! will try that tonight...

krasuskyp 05-20-2011 08:31 PM

o2's unplugged, tried 13.5 again @ idle - nope, no good. Tried 13, 12.5, 12, 11.5, finally got it at 11 - cruise AFR's were otherwise into the 16's... @ 11.0 they're 15.4 or so - still lean. On boost is good tho until about 6.3-6.5k.

shim'd FP regulator tonight to read 7.0 from 6.4 (thought it was 6.6, nope)

Now my cold control is 2.00 or 1.99 or so. Warm control is 3.55. Haven't started it yet (it's on stands for header install).


heliolps2 05-31-2011 05:31 PM

did you get worked out

heliolps2 05-31-2011 05:37 PM

how was the color of you header ports , were they all the same color , I,m thinking you might have cyl running to lean and some running to rich , give you a mixed up AFR's . that what happened to me

smurfbus 05-31-2011 08:36 PM

Paul: Is your engine misfiring on idle or is it running wery smoothly on all cylinders. Your actual AFR could be higher if some sylinders are misfiring.

If you're using Bosch 4.2 sensor ask around if anyone has an innovate lm-1 or lm-2 so you can compare the idle AFR. Innovate uses bosch 4.2 sensor so it's an quick swap of the sensor connector

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