Help: I remain fixed position on throttle but RPM"s go down!

I may have found the issue (god i hope so, so much damn time into this).

I was doing the R/R and Stator checks as outlined all over the forums. I did not see any issue, but I noticed my connectors were hot. Now, let me be clear, I am not talking warm to the touch, and I am not talking about after the bike had been on for a long time. I mean within minutes of the bike being on, right when its at say 180 degrees or so, the connector cannot be touched, it will burn you. Of course the rubber clear cover had marks on it, but I just thought it was because it was normal. The wires going to the R/R were literally brown, I didn't realize they were suppose to be yellow. If I look back further they are yellow but there is about 4 or so inches of brown. The insulation on one of the wires is literally broke open and you can see the wires in there which are greenish from oxidation!

So I pulled the R/R. I did a thorough static test and all of the diodes check out in both forward and reverse directions. So its possible the R/R is good, but its such a pain to cut wires, solder/splice new ones, change out the connector, etc. Combined with the failure rate of the R/R and the fact mine has an OEM 2003 one, I am just going to buy the MOSFET Ricks R/R.

Because my issue is intermittent perhaps this is the ticket? Perhaps it was making havoc with my fuel injection, spark, etc. I am hoping I can find a replacement in the morning, I'll know right away if it was the fix.

Of course now I worry that my stator could be damaged too. The checks show good voltage on it both cold and hot, at idle, 2500 and 5000 RPM's. I tested it as best I could with my ohm meter and saw no short to ground. The connector looks fine, wires are yellow.

Also Honda is confusing on my stator. I have a 2003, and my engine serial is 2502283, and apparently there is one type of stator before engine 2503808 and one type after. So according to this fiche:

http://www.partzilla.com/parts/search/Honda/Motorcycle/2003/VFR800+AC/ALTERNATOR/parts.html

2002 uses 31120-MCW-D01
2003 uses 31120-MCW-D02 (up to engine serial 2503808)
2003 uses 31120-MCW-D03 (after engine 2503808)

So does this mean I can't use the newer part? I realize the 2002 D01's can't use the D03. But can the D02 VFR800's use the D03? (I should probably make a separate thread for this question)

 

While the issue you've found does need to be fixed, I doubt that it's the cause of the issue. If the RR was causing the bile to lose power, you would have a flat battery, and the bike would be lacking power in all riding conditions because the injectors and coils wouldn't be getting enough current to operate them properly.

I still think you need an O2 sensor emulator, not an O2 sensor eliminator.

 

I will report in once the R/R is replaced and then continue troubleshooting as needed. I agree that its weird that my charging system seems perfectly in order with such a crispy fried connector and exposed wiring. Electronics can be intermittent, and do weird things, I am hoping its tied to my problem. One thing for sure, if it fixes it I will know almost right away, because I can pretty much replicate the issue on demand.

I still have plans to pull the throttle body and replace the insulator boots/clamps just as a good measure to check them, clean that area up and make sure everything is gapped properly. Worse case I got new rubber and some peace of mind.

 

I hope it solves the problem with losing power too... But I don't think it will... ;-)

 

Ok, some updates on this. My new R/R is in, and it works well, connection to stator doesn't get as hot, but still a bit hot. I need to figure out how to get the pins out of the stator connector so I can clean them real well.

In any case, my problem is still here. But I have made some progress!

I noticed I can make my problem happen by taking the wires on the right side of the bike (where the large round ECU connector is, cam pulse generator, throttle position sensor, etc. and shaking it. It will cause my RPM's to drop.

I believe I have isolated it to the connector on the Throttle Position Sensor. I disconnected it, it looks fine, I cleaned it with some Electronics Cleaner, plugged it back up. But if I take a screwdriver and wiggle on it while I hold constant throttle, it jerks my throttle.

Does this sound like a bad sub harness (sub harness is used for TPS, injectors, IAT, MAP, etc) or a bad TPS? I am going to try (although this seems hard to get in there) to meter the TPS (unfortunately I only have a digital meter), and see if that looks steady, if it does, but its giving erratic signal to the ECM, and drops RPM when I wiggle the wire, I am going to assume loom.........which I hope it is, as the loom is like $50 or something like that, vs having to by an intake assembly on ebay and doing that swap which doesn't look to be much fun.

Perhaps I can somehow tighten the connection, I am not sure how, maybe I can squeeze the female side together more to make a more tight connection, I wish I knew of an easy way to get the pins out of the connector for close inspection.

What are all your thoughts here? (and thank you)

 

I am going to guess it is your TPS sensor that is flaky and I would change it...BUT I would test it first. Also, do yourself a favor and get the roadstercycle RR kit and bypass that stock connector all together.

 

Well you can't just change out a TPS sensor, you have to change the entire intake assembly ($1000 or so new, $100 on ebay). I bought a Ricks Motorsport R/R, its working, not really my main concern, my main concern is what has been keeping me from riding and continuously troubelshooting which is this problem of my RPM's dropping.

I would hate to change the intake and find out its the loom. So I a trying to take a step further. I just popped the pins out of the TPS sensor connector (very easy to do, unlike some other connectors), they look great, they appear to be nice and tight, I put them back together, I may take them back out and pinch them with some pliers in an attempt to make it tighter, but not sure if I should do that.

What has me thrown off is that its only when I mess with the harness, so that leads me to believe its possibly the loom and not the sensor.

Can I clean a TPS with just electronics cleaner?

 

If it's the terminals, you can re-tension them. I'm not sure if the round connector uses the same terminals as the ECU connector, but They should be similar.

Use a jeweller's screwdriver, carefully push the locking clip in the connector out of the way, and pull the terminal out (take note of its orientation for later reassembly):



Bend one side flap of the terminal out to gain access to the curved tongue piece (there will probably only be one that can be bent out of the way):


With a very fine jewellers screwdriver, carefully bend the terminal's tongue so it will contact the other terminal better. Be careful not to bend it too far, as that would make the connectors difficult to assemble into each other:


Bend the side flap back in, and insert the terminal back into the connector (in the correct orientation). It should click into place:


In all of this, remember that it's easy to ruin a terminal, so be very very careful!

 

thanks danny i am going to tension it. They come out very easy, I was able to pop them out with a small screwdriver. They look very clean and fine, but I could certainly "tighten" them a bit.

Anyone know if its ok to spray QC Electronics Cleaner on the TPS? I also have some MAF/MAP cleaner, just wondering if I should just leave that alone or try to give it a spray of cleaner.

 

Oops! Wrong picture for the caption! This one shows testing the female terminal on the male terminal to ensure that it fits properly. This step happens before putting the female terminal back into the connector.

 

Just an update to this crazy escapade.

I still have dropping RPM's at steady throttle.

I had my bike Dynotuned, custom map for the PCV. I was really hoping that could fix things.

Things I suspect it could still be:

Insulator Boots (either worn, leak)
TPS (I would just replace the entire throttle body assembly with one from ebay, and swap over my good FPR, injectors, etc)
ECU

Any ideas are appreciated. I already bought the insulator boots and clamps so I would just have to put them in. I was hoping my tstat would fail so I would just do that at the same time, but tstat is working fine.

 

Wow you still having this problem...!
That is suck
Good luck hope you get it fix

 

yes, it sucks! I notice it happens more at night, when its cool. almost makes me wonder if the IAT is involved somehow. Bike temp is fine, its around 170-190. I am going to start replacing stuff if I can't get this fixed ECU, throttle body, ........drives me crazy,

 

As everybody else has told you, closed loop operation is IMPOSSIBLE without a working, REAL, O2 sensor. Period.

That's what closed loop mode is! The ECU looks at feedback from the O2 sensor and adjusts fuel ratio accordingly. It will try to lean out the mixture until the O2 sensor tells it it's too lean. A resistor will never send it that message. The resistor will make the ECU think the mixture has never changed. Eventually the engine quits running right until you bump it oout of closed loop by moving the throttle.

So either put some real working O2 sensors in there, or when the throttle gets wonky, wiggle it and live with it. Sorry, no other choice.

When you install O2 sensor eliminators, you give up closed loop operation. All the eliminator (resistor) does is keep the trouble light from coming on.

 

h3nry, i hear what you are saying, but RPM's dropping is not normal operation for a bike with no O2 sensors and a dynotune. Closed loop mode is not impossible, in fact, its unstoppable. The bike will always go into closed loop based on a set of conditions, but yes with no O2, there is no adjustment to be made. But that is fine, O2 sensors have not always been on bikes, and they performed fine before them.

My mention of closed loop was just an analogy. The bike was behaving almost as if it was receiving a signal back to make an AF adjustment. But with proper O2 eliminator there should be 0v, so no adjustment. Most of my troubleshooting went into looking at electrical and fuel.

Today, my battery was dead. This is after not riding the bike in about 6 months. I rode it, parked it, got up the next morning and it was dead. Date code on the battery was 10/2005!! It was a POS Parts Unlimited battery anyways, so I replaced it with a Yuasa from Honda. That could be the culprit we shall see. Batteries can be weird, they can show good voltage, but have an intermittent short that won't show itself until it decides to do so. I am surprised that battery made it this long.

when you have a bike dynotuned, and you have it at say 4000 RPM in 5th gear...........if its running correctly, it will NOT drop RPM. This is because its getting the right amount of A/F. My bike was consistently dropping RPM, and fast.........so I was thinking fuel starvation (FPR, fuel pump, relay, injectors, etc) or intake leak. I have still not ruled out the intake leak, although I can say the fuel system is 100%, as everything has been meticulously checked.

 

Here's an explanation of EFI systems, open and closed loop.
http://www.bikeboy.org/open_closed_loop_efi.html

The very definition of closed loop is feedback from the exhaust gas sensor to the ECU in order to adjust air/fuel ratio. No exhaust sensor, loop cannot close, so bike is running open loop though the ECU doesn't know the "feedback" is garbage.

Bikeboy covers a number of interesting topics like surging, tuning with aftermarket black boxes, etc. on his BMWs and Ducatis.

Running without a working O2 sensor depends on the ECU not adjusting mixture too far off the basic map when it tries to go "closed loop". Some ECUs have a limited range of maybe +/- 10%. Honda may not have as small an adjustment range, so fuel/air goes way off. Generally aftermarket "tuning" aids try to richen the mixture on the theory that EPA requires engines to run leaner than optimum power mixture. Since Honda doesn't attempt closed loop except at medium cruise speeds, you really don't need or want to run a full power mixture then.

It looks like you have discovered your bike has the usual can of worms in the charging system, too. It's a PITA, but working thru the system will eventually get it running reliably. (I'm going thru R/R problems on my Magna at the moment - waiting for parts to arrive.)