Any one had this happen? I was with Jamie at Fuel Moto last night doing some dyno runs. We would do three pulls in a row and the power would drop 8 hp over the three runs. We went through the diagnostics and all is normal, except the ignition timing is erratic and does not seem to be consistant. We changed plugs and new engine temp sensor with no change. It definitely is worse as the engine heats up. the engine and air temps are reading normal and constant. She starts and runs well, but overall she's down ten hp from this summer and we are showing the drops consistantly with the three consecutive pulls always dropping about 8 hp.

I'm thinking maybe crank position sensor? Coil? Anyone have a suggestion?

Thanks -- tom

PS -- Can't say too much about Jamie and Fuel Moto.He and his new assistant spent three hours last night trying to solve this for the second time.I left near nine and they still had another bike to dyno that evening. Jamie is calling his sources for help today and will not give up until it's solved and we get back to his earlier numbers.

 

You don't say which tuner you're using or whether the spark timing only retards, only advances, or does both.

If it's a SERT and it's only retarding, disable the knock control. If that "cures" the erratic behavior then you could be fairly certain it's the coil (with its internal ion sensing circuitry). If it's not a SERT, perhaps you could pull the ion sense lead from the coil connector and live with the trouble code to basically check the same thing.

Are you using stock plug wires?

The ECU spark tables are RPM/MAP, so it could also be one of those two sensors.

AFR is also keyed to those sensors. What is the AFR doing while this is going on; is it jumping around too?

 

Of course its a PCIII, thats what fuel moto is all about, ever since harley changed the way it powers up the PCIII on 06 and 07 giving the start delay because harley changed things and dynojet did not I have not trusted them completly. Id buy a SERT and get it tuned rigght without a add on device.

 

Here's a list of the PC-III connections. I carefully moved the protective sleeves around on the harness and traced the wires. I was interested in seeing if maybe moving the wire from pin 4 to pin 28 would successfully give us PC-III power whenever the ignition is on, but in the end, since I crank while the system relay is still closed the bike fires immediately anyway.

Wye-spliced into the ECU lead(s) ("read" only)[*]pin 4 - System Relay (the "negative" power lead from the ECU which switches on/off the System Relay [which itself provides positive voltage to the fuel pump, the injectors, and the coil] - this lead, when the circuit is completed by the ECU remains about 0.8 volts (a semiconductor's worth) above chassis ground and provides the negative voltage to the PC control circuitry)[*]pin 13 - Switched +12VDC (from ignition switch, for positive voltage to the PC control circuitry)[*]pin 24 - TPS input (positive signal)[*]pin 26 - 5VDC sensor ground (negative TPS signal)[*]pin 28 - Power ground[*]pin 30 - CKP +lead (I'd thought pin 12 - CKP -lead also was, but I didn't mark it on the drawing and I don't plan to look again - say it is, too since it would have to be)

ECU output leads intercepted/modified ("read-write")[*]pins 11/29 - Both coil signals[*]pins 19/21 - Both injector signals

 

Glens,
Thanks for the info. It is a PC III. The ignition is very erratic and advances to only about 22-28 degrees. The front cylinder lagging behind the rear by a few degrees. The AFR stays consistant from run to run.There is no spiking or change betweenpulls. We changed the ignition settings on the PC III to advance and retard and it had little effect. We also ran the bike without the PC III and the ignitionactedwith the same isues. The plugs were new and stock. The wires were new (SE) this past spring.

What is interesting is to see three pulls within a minute or two have falling HP and decreasing spark advance. All other reading remain constant. I wish I could post a graph, but we didn't print any.

I didn't realize the Ion sensor circuitry was in the coil. If that has become temperature sensitive that may be something to change out. It's an 02 with nearly 50k miles.

Gunrunner -- I considered the sert but I think I'll stick with the PC III for now. It has worked very well for me so far and with Fuel Foto so close I get great support.

Tom

 

try search section good info should help.

 

Yeah, if you've got a coil to swap in it might be worth a try. I'd probably just try lifting the Ion Sense lead from the coil, first. In my '07 manual it's the "GY/BE" colored wire on pin "B".

Here's a link to Delphi's propaganda on the setup: https://delphi.com/shared/pdf/ppd/pwrtrn/gas_ignics.pdf

If it were me, I'd first try going to some stock plug wires, since they're part of the Ion Sensing circuitry. The SE wires may have just different-enough characteristics that they're throwing it off.

 

Glens -- Thanks again. I'll go through my manual tonight and give the Ion lead a try. It is only retarding the ignition and acting erratic. It may just be good preventative maintanence to pull the tank, change out the coil and wires.

Cheers --- Tom

 

I'm thinking that the absence of the sensing signal, the spark will either never retard, or it'll stay retarded. Either way, it should (hopefully) provide indication whether the problem lies in the coil or in the ECU. Looking at Delphi's info sheet again, I see they're using a capacitor to power the sensing phase. One of the caps could be failing, thus not powering the circuit during the measurement phase. Also could be one of the diodes.

This brings another question to the table. Is it just one or both of the cylinders which is exhibiting the erratic timing control?

Say hi to Jamie for me. He probably won't remember me personally (just talked on the phone a few times) but I'll bet he'll remember the "cigar box" scenario. That was me.

 

Glens - I sure will say hi to Jame for you. He will have to explain the cigar box event.

Don't know if I'll have time to play on the bike this weekend, but next week I'll dig into it. I have a daytona sensor setup so I should be able to document changes as I go. --- Tom