rich/lean

[junkyardwarrior]

'92 Mustang 408, EFI (QH, A9L2, running tunerpro rt). 90mm accufab/92 pro-m sensor. 6061.com elbow, super victor efi. Pretty typical setup, about 10.5:1. Ed cam 240-250 hyd roller 112 lsa as I recall.

Runs rich on bank 2 (driver side) and lean on bank 1 (pass side). Verified via hego voltage, fouls spark plugs on both banks. My first thought is vacuum leak, so I made a smoke "machine" and smoke tested; only leak I found was out of the accufab throttle shaft. Somewhat larger leak at the throttle arm side, tiny leak at the TPS. That was the only leak I found. Brand new F90, but a number of years old--sat on the shelf forever. Accufab says it's normal and won't cause any problems. Runs like poo of course. Full throttle is "ok" but I'm afraid to push it too much, for one there's no traction up to about 90mph, even in third gear it'll break loose (tires are junk but enough to drive on safely). T56 magnum if it makes any difference. WB02 is in bank 1, constantly shows lean (17-18:1 sometimes), yet still tends to foul spark plugs.

Pulled HEGO harness and ohm'd it. 0.1Ω between all pins so I personally don't suspect anything there. Swapped sides with the sensors alone, no change to speak of. Swapped HEGO harness side to side (put left side on right and vise versa), did not see anything conclusive there either.

I'm lost, y'all got any ideas?

 

[a91what]

Car would run like total at that afr. What wb is it? Has it been calibrated recently? Picture of the plugs please

 

[junkyardwarrior]

AEM WBO2 is in pass bank (bank1), shows 17:1-ish, bounces around. That's all the A/F data I have.

HEGO1 sits around 0.1-0.3v. HEGO2 bounces around 0.7-0.9v. I expect some difference but nothing like that.

AEM says no calib required. Part number 30-4110

plugs are all black carbon fouled all 8 of them

 

[a91what]

Ok, the sensor may be fouled the aem is usually pretty good.
Now if the plugs foul the missfire will show lean on a wideband.

 

[junkyardwarrior]

The hego's don't read the same with clean plugs. No exhaust leaks...I checked into that last week. It makes no sense. Car's got about 60 miles of running around watching the sensors, etc, this is plug set #4.

Pulled intake elbow a while ago, jumpered the fuel pump and watched injectors...could not find none of them leaking using a bright flashlight looking down it's throat.

 

[a91what]

How long has it been since the tune? Any changes since then?

 

[junkyardwarrior]

A9L2 is still in it's infancy. I have only been playing with fuel, other than that, it's just as I downloaded it, aside from injector slopes, cold startup scaling, timing adjustment, and input of my known MAF (FN036). Are you familiar with A9L2 strategy?

 

[a91what]

No, I am very familiar with most tuning strategies but the stock stuff I dont work on much. You may have better luck trying to talk to @Decipha or maybe @96pushrod can help a bit.

 

[96pushrod]

I’ve seen some variations between both narrowband voltages at some cruise conditions, but it’s usually nothing too serious. You’re absolutely sure your plug fouling is because of fuel and not possibly oil contamination? What’s your pcv situation look like?

It is entirely possible the Bosch sensor became screwed up if it ran too rich for too long, I’ve had this happen before. Are you still running narrowbands as well? It’s not a bad idea to check and make sure everything is copacetic between the wideband and narrowband. If you nb voltage is .850+ and the wideband is running close to full lean on the controller than chances are the sensor on the wb is starting to go. Take the wb out and cover it with a gas soaked rag. Should go to full rich condition.

 

[junkyardwarrior]

PCV is aftermarket in the driver's valve cover (wagner). Hose from post-MAF tube to oil filler, verified no leaks there. might be onto something there. I need to look at that. Might plug the hole with engine running/logging to see if makes any difference.

nah, plugs are definitely carbon fouling, no sign of oil fouling whatsoever. Looks like a lawn mower's plugs when someone's been running with the choke on or plugged air filter. Odd, though, and I think I may have accidentally run into something. I put a new set in this last week and pulled a few of them earlier, #4 is black, rest of them aren't too bad yet. Maybe injector not "firing" properly? When I put the engine together about 2 years ago and fired it on the stock A9P tune, it had a hard time starting/idling, found lots of fire coming out of the open header on pass side. Turned the engine off and let it cool, then turned the key on, checked for codes, none, but kept smelling gas. Turned key off and went looking for leaks, and there was raw fuel running out of the header collector in bank 1 (bank 2 ok), diagnosed as a stuck open #2 injector. Replaced with OEM 42lb injector. But it leads me to believe I may have more than one that's "bad". They were reman 2004 Lightning 42lb injectors, so who knows. Bosch 0 280 150 558 on the tops and a Ford engineering number like XL3V or something like that. Yes I'm using the correct 558 injector slopes and bkpt.

 

[jrichker]

Since you have an A9L, what does the code dump show?

 

[junkyardwarrior]

No, I have A9P, running Decipha's A9L2 strategy (GUFX)--but to answer the question, the code dump generated code 11. At one point, I did have a code 41 as I recall. Cleared the KAM and 11 is all I am seeing currently; both current and memory.