Hi, I have not been here since 2008. I'm really a vintage bike guy and my modern (by my standards) Fatboy is for taking the wife for a ride. Being a 2001 it is a transistion year bike and is fuel injected. I had thought it had MM FI but learned recently that is is the first version of the Delphi system, being a Softail. I have confirmed this (manual is zero help to ID the system) by looking at pics on the web of both the MM and Delphi throttle bodies and I definitely have the Delphi.

There is a PCIII installeld which I did back in 2003 when I put a V&H Pro-Pipe HS on the bike. There was already an HD high flow filter element (K&N clone) on the intake. Fred Eno (Dr. Dyno) did a dyno tune on the bike back then and it has run fine since. I have a lot of bikes so mileage on the HD is still low at 16K.

The engine started acting up this year. Idle would not settle down when pulling up to a stop. But it would eventually come down. But it was not consistent. I rode it last week and noticed it was not smooth. Power would surge slightly. Accelerating with a fully warmed up engine would show some hesitation, surging and what I'd describe as occastional erratic running. But nothing that I'd call violent or distracting. When you ride the same bike this long, you notice small changes in how it performs.

So, I had modified the PCIII buttons several years previous to eliminate backfiring when decelerating. And it cured the problem. So, I went back into the PCIII and put all the button settings at zero, hence removing any effect on the installed map. Igntion map is stock, by the way. Have always understood that the stock HD ignition map is the best for an unmodified engine.

The day after I adjusted the PCIII I started it from cold and it started chuffing when idling. It would idle and chuff occasionally thru the intake as best I could tell. Idle was strange as well. Exhaust would pop every so often. I thought injector(s) might be dirty or my ECM was failing. I had an ECM fail on a '95 years ago. But it acted up when the ECM warmed up and this was a cold start issue. After the cold start, I'd let it idle a bit, then head down the road. This was where new symptom number two showed up. The idle would hang when I shifted. I would pull in the clutch and it would not drop down to idle. It would hang a bit high. No tach so cannot say how much. But I would guess about 1500 rpm at the most. But enough to notice. I contined down the road and let the bike warm up. With it reasonably warm, I hit it hard from a dead stop and when thru the gears up to about 90 mph where I had to shut down because of traffic ahead of me. It stumbled a bit, but better than before. I turned around and did it again and it was much better. It was fine all the way home and idle seemed decent when I stopped.

Next morning, it did it all over again. Chuffing with cold start idle and high idle between shifts. We took a 90 mile ride (wife on the back) and on a long flat section, doing 60-65 mph, it surged with zero throttle input. It simply added more power. Not a lot. But a noticeable amount. Did not do it again for the rest of the ride. But I did feel similar, but less surging a few more times. Just not as pronounced.

So, pulled the air filter off to look for corroded electrical connections or other simple issues that could cause problems. What I noticed was on the throttle body there is a barbed hose fitting on the top, towards the rear of the bike, that bends up and to the left. The open end points to the left side of the bike. There was a rubber ring that I finally realized was the remnants of a vacuum cap since there was not mating hose dangling anywhere. I made a new cap from silicone hose with a plug in one end and wrestled it on. Fired the bike up and it idled like it used to when cold. So, I think I found the problem. Although this vacuum port appears to be ahead of the butterfly and would not act like a vacuum leak that would cause lean running, the symptoms of the hanging idle and chuffing when cold were indications of a lean idle mixture if this was a carbureted engine. Today, I will take her out for a test run and see how she performs.

I know, long post. But I'm a retired engineer so I'm kinda **** on providing good input details when asking for experience input from others.

Here are my questions:

1. Am I correct in assuming that vacuum port should be plugged/capped. And fi so, would the symptoms I decribed be attributed to that vacuum cap deteriorating and leaking over time and eventually falling off?

2. I read several articles about the Delphi system versus the MM system. The indication is that the Delphi is a closed loop system and uses O2 sensors. Yet I found none on the bike. Granted, the bike had V&H short shots on it when I got it. I'll be honest and admit I never looked closely at the original shotgun exhausts. They hang on the wall in my garage at home and I'm at my camp so I cannnot go look to see if O2 sensors were used on that exhaust. But I cannot imagine a closed loop system would operate properly if the O2 input were removed. So, did the early Delphi system use O2 sensors or not. And, is the system open loop, closed or a combination depending on operating mode?

I need to read up on the new add-on systems like ThunderMax and similar. They might be overkill for a bike that is only used for general riding and not performance oriented. But I would like to hear experienced input from those who might have installed one of these systems on a 2001 Delph FI bike.

Thanks in advance for any input. I'll definitely provide feedback on any changes if I make them. Again, sorry for the long post, but it helps eliminate the back and forth questions that might be required if I did not provide all the info up front.

regards,
Rob

 

Your 2001 bike is not closed loop and will not have any o2 sensors on it from the factory. I would take the pc111 off of your bike and tune it with TTS and be done. Yes the vacuum not being capped will cause it to run ruff it basically is a intake leak with that cap not there.

 

Thanks for the quick feedback, Nick. Since posting I did a little more research and read thru the product descriptions on the TTS site and did see that there were no O2 sensors on my Dephi.

The TTS is very tempting. I see that they lock the unit once a bike is connected to it so it precludes buying one on the used market. I got my PCIII on ebay for peanuts because it came of a wrecked Deuce if I remember right and was being sold by a junkyard. So, it owes me nothing at this point. Actually the bikes owes me nothing. Kid I got it from appears to have purchased every HD doo-dad they sold at the time. I did chrome the front end (weak moment with a new to me bike), put a pair of panhead bags on it, wires wheels off a friend's Heritage and a winshield. Otherwise, it's needed nothing but oil, filters and tires since I got it.

About to take it for a spin to see how the vacuum cap replacement has changed it.

Thanks,
Rob

 

The PC might be going out - not uncommon.

The cap does not affect mixture (like a true intake leak) - it enters the throttle body on the air cleaner side of the throttle plate not behind it. The bigger issue would be unfiltered air. The only effect a missing cap would have is acting like a slightly less restrictive air cleaner. If it caused a miss, your bike was already lean. Also, it should not affect starting.

On a bike of that year with those mods, I would check for an intake leak, check the fuel pressure and if it's still bad remove the PC3 and see how it runs.

Also, with a power commander on that year you need to be hitting the start button before the engine light turns off due to the way the PC intercepts the CKP signal.

 

Interesting point about hitting the start button before the fuel pump sequence finishes. When I first got the bike and did the mods, it started instantly. I acually did not like that feature after waking it up from a winter's nap. I'm talking instant fire.

The cold start resulted in continued chuffing thru the intake when it was idling cold. So, I shut it down and richened up the mixture with the PCIII buttons. Chuffing stopped. So, at this point I'm wondering if the bike is on the ragged edge of too lean. Over time I'm sure that the fiberglass has departed the street baffle, making it leaner.

I took a ride and did several more adjustments to the buttons. I ran all three up to full rich to see what the response would be and it appeared that the engine would not like it until the revs picked up. It seemed to accelerate in stages. It would pull fine, then suddenly step up slightly in power, pull hard at that power and then step up again. Never noticed this before. I dropped the richness down a step and that seemed to smooth it out.

The question that enters my mind is, just before it pulls harder, it is too lean at that point or too rich. It is pulling harding because it can swallow the richer mixture or is it leaning out at higher revs and hence pulling harder. I guess a dyno run or a portable exhaust gas analyzer would answer that question. But, since I'm not looking to set land speed records, if the plugs look okay and she runs smooth, then I guess I'll be content.

Interesting point about the PC dying. That strange hanging idle when shifting cold is a mystery to me. I would expect the PC to act up when it was warm, not cold. Yet, it seems to run fine and starts well when the engine is hot.

Like the evangelists say, "It's a mystery".

I know a guy that is a consultant to several HD accessory outfits and has built some scary big HD based drag race motors. I don't mind paying someone to sort the bike out. But I want someone that truly knows what they are doing and not just says they are experts. He may be able to sort it out or know the right guy. But for now, unless it starts to act up again, I think it is pretty well sorted. Will take another spin today. Cold start will tell me if I've solved the chuffing problem.

Before closing, that vacuum port that was uncapped, is that for tuning? I saw that it appeared that it entered the air flow path ahead of the butterfly so was not confident that it was the source of my issues. But was not a 100% sure that the port I saw in the bore was connected to that vacuum connection. Agree that it was a souce of dirt and could at least have contributed to a sightly leaner mixture.

Guess I need to talk to TTS about my options.

I could not wait. I just went out and fired it up after sitting all night. Started normally and settled into a high idle with zero chuffing. I shut it down and tried starting it before the fuel pump sequence finished and it started much more quickly. So, will try that techinique for cold starts to see if it consistently starts better. Although, when it was running right, it always started well when cold.

Thanks for the added input.

regards,
Rob

 

Before making any changes, verify fuel pressure please- very common for Softails to develope a pin hole in the fuel line inside the tank, and that will reduce the fuel available at the injector. With the run/stop switch in run position, turn key on, the system relay should turn fuel pump on for two seconds, and pressure should read 58-62 PSI, and hold there for at least a few minutes. If the pressure jumps up, then quickly bleeds off as soon as the pump stops running, you likely have an internal leak. Time to replace the (62189-01) check valve. I split the old hose and wrap it around the new hose to provide an additional layer of protection against future rubbing inside tank.
HTH