I've been reading recently and searching previous threads about adding fuel in the zero column of the PCiii to reduce decel pop. Most threads have been about Softails, mines an 06 Dyna with VH Shortshots, SE AC and the stage 1 download. Can I add a little fuel there also to reduce the popping until I can get it in for a proper dyno? I have also had someone reccomend torque cones for these pipes as a "fix" for the popping, and a little bit of the low end back that I gave away. Either of these work as a temporary fix until the dyno?

 

some add fuel in the 0 tps colum some take fuel away? try one and see if it works or hurts the plugs then try the other. i have seen both maps work one witha 40 in the colum and one with a -25 in it

 

I've been told to add, start at 20 and work your way up from there.

 

see i was told that the pop is extra gas igniting in the exhaust due to high temp, so i actully decreased my fuel a little and most the pops stopped completly i still get a 1 or 2 on a really hard decel plus i get better gas milage. i also have a TFI controller which is a lil diff but still getting to the same place. why adding fuel makes it stop is beyond me if whats really causing the pop is unburned fuel igniting in the exhaust.....

 

Jamie at Fuel Moto told me the decel-popping issues originate from leaks around the muffler/exhaust-pipe clamp. I sealed mine with anti-sieze compound and tightened the clamp firmly, and never had any popping.

 

o ya i 4got about sealin the muffs but i got straights one peace. i also think that intake manifold leaks can give you trouble too but i think thats mostly if yer gettin really poor gas milage. im rollin 40-42 a tank and its still got maybe a 1/2 gal if im lucky. good pointer "iclick"

 

While testing an hypothesis the other day I put the O² (not entirely correct; wish there was an HTML "sub2" entity) sensors back on line using the PC-III. I gut a lot of pip-pap-popping on deceleration. First instinct is to say that it was a lot leaner, thus the cause. Second and opposite possibility is that air was being sucked into the left muffler (symmetrical 2" baffles) and causing the mixture to go too rich in the rear. That ought to help make this an easy way to decide whether going lean or going rich is necessary! hahaha!

BTW, no problems with just the PC-III. Lots of rumble with the occasionally occasional very muted pop.

 

Glad you had the guts to try that, as I've lacked the courage. It seems it would perform as well in open-loop mode, but the O2 sensors would force stoich in the narrow ranges it covers (idle and cruise primarily). Now, if I could force it to go 14.0 or 14.2:1 when in closed-loop mode, I would reconnect them, but that would presumably entail an ECM change that can be made only with SERT and/or the dealer's proprietary software. Any ideas?

I've also been looking to buy one wide-band O2 sensor, like the Bosch LSU4.2, and connect it to an LED voltage display. That voltage could be translated into A/F ratio, a table I already have, and aid in tuning with the PCIII. There are A/F gauges available, but those that are useful--i.e., more than just flashing LED's--are very expensive (~$300) with an O2 sensor. All I would need is an LED display that provides voltage from the O2 sensor (1-5v), and I can get A/F from that. Can't find one, though. Ideas?

Another idea I had was to connect a switch that could toggle between the O2 sensor and the eliminator, thus allowing you to effect stoich when you wanted to maximize fuel mileage and heat wasn't a factor. The O2 sensor has two wires, so why not find the source wire (voltage +) and connect both to a SPDT (on-on). You could then switch between them, but would the switching action trip an error code with the ECM? There might be a millisecond delay that it would see as a fault. I might call Dynojet on this one.

Edit: Just got off the phone with PC tech support and was told that connecting the PC with the O2 sensors isn't a good idea because the Delphi ECM is capable of some "learning," and can make changes to its own map up to about 5%. So allowing the PC to alter the A/F may cause the ECM to in turn alter its map to compensate for the PC's intervention. Not a good thing, me thinks.

He also said in closed-loop mode it holds stoich up to as much as 50% throttle, way higher than I would want it to go using 14.7:1. My idea was that since I have 0's in many areas of my lean map (idle up to the top of the cruise range), that might not be a factor--but since closed-loop works up to 50% throttle it would put it out of contention for my needs.

 

Certainly. The voltage divider network described at nightrider.com would suffice for ~14.2:1.
[edit: dropped the "k" from "knightrider" throughout]

I don't know right off-hand what kind of control interface the WB sensor itself requires, so (and I'm sure you've thought of this) you probably can't just get a sensor and hook up the leads to power and a DVOM or similar. For a couple hundred bux (per) you can get one with the necessary controller/interface through nightrider.com, or Jamie (the wideband commander, for a small amount more). Used to be a guy could go to Radio Shack and get all manner of stuff to make a 5 LED display. Maybe still? Any other electronic/hobby shops in your vicinity? Circuits and or the necessary design criteria are quite likely a google away.

I covered this in post 2025563 last night. A double-pole double-throw make-before-break switch would be required and would suffice for both front/rear. Should throw no codes that way. Combine that with the resistors for the voltage divider network and you'd be able to switch between fat and the low 14s on the fly. I'll whip up a schematic / wiring diagram for you if you can't do it on your own.

No, normally not a good thing. But the "learnin'" is not permanent. Switch off the ECU and when it comes back on it'll have a clean slate again. I'm not saying this 100% authoritatively, mind you, but am sure it would prove to be true. I'd be willing to put money on it, at any rate.

50% throttle seems a bit high to me though I suppose it'd be conceivable in certain circumstances.

Like you've said, Jamie's maps tend toward portliness and even in the cases where the Delphi would remove up to 5% for the session it'd still be a safe bet IMO. If one weren't concerned with wearing out the aluminum spark plug threads it would be easy to monitor closely for a while until satisfied one way or the other. In conjunction with biasing the sensor output I think it's a very doable thing.

You've already got the hub. D

 

Furthermore, if you can nab a copy of the Delphi internals and/or interface specs, I'd bet there is a pin you could touch with an appropriate signal to reset the "learned" table while not disrupting service.