VFRAntwerp

On 8/31/2007 at 4:44 PM, DaveM said:

I know there are a lot of posts on this topic, but my experience was a little different and I wanted to throw it out for consideration. Over the past couple of months my 02 had developed some really serious drivability issues. Once she got over about 180deg she would start missing at constant throttle settings. In the mildest form it felt like the lean surge problem, and in its worst form you could hear individual cylinders dropping in and out and it felt like it was going to die. Moving the throttle a good bit would cause everything to pick back up but it was very annoying, and sometimes scary if you were in a corner. The problem didn’t exhibit itself constantly. Some times she would run smooth as butter for a couple of days. I had been watching the 30A B fuse for a while and it was starting to show the typical wiring insulation discoloration and signs of heat so I did one of the recommended repairs. This lowered the fuse wire temp, but it was still getting warm and the drivability problem was still there. I checked the main and front harness ground wires next – no signs of heat or discoloration, the connectors separated easily etcetera, so I didn’t implement any of the repairs suggested. I did apply some super duper Volvo electrical connector grease given to me by a friend to the blue and gray connectors. (Seems modern drive by wire Volvos occasionally develop electrical gremlins and the fix is to put this stuff on the connectors). Still no change. So, I got out the service manual and started to work my way through the wiring diagram and learned the following:

The B fuse (the one that melts) does not supply working circuits in the front harness. The power passes through the front harness to be switched by the control relays (fuel cut and I think one other), but no working circuits. This means the grounds from the front harness are not really associated with the B fuse, and the fact that both melt is a coincidence, not a cause and effect relationship. So when we fix the front grounding problem we are fixing problems related to accessory circuits and the A fuse.

This led me to start looking at the main harness. It appears the B fuse supplies all of the engine management circuits – ignition coils, injectors, TPS, O2s, etcetera. Loss of voltage in these circuits would logically seem to cause drivability problems, so I popped of the right fairing and pulled all of the engine management connectors apart. Nothing appeared to be wrong, no visible corrosion or anything, but I checked all of the female connectors and attempted to tighten any that looked to be too open, applied magical Volvo grease, and plugged everything back together. Viola! Drivability problem gone – smooth as glass at any steady throttle setting from 3500rpm up and now the B fuse is cool to the touch. Why did the problem seem heat sensitive? The only thing I can determine is a couple of the right side electrical connectors lay against the upper radiator hose, and once the coolant started to flow the connectors heated up and raised the resistance in already marginal connections.

The message here – when you’re working on your B fuse problems, check those engine management harness connectors!

I apologize for the long post, but I hope it helps someone else.

Quick Update. Two weeks, 1000+ miles, ambient temps from 47 - 94, and coolant temps from 170 - 223, still smooth. No surging, no missing, and the B fuse is staying cool. I've owned this bike for two years and 17,000 miles (had less than 2k on it when I bought it) and it has never ran this well at steady state cruise speeds. Now it's no not just fun to ride, but a pleasure to ride!! fing02.gif

Thanks for the feed Dave!
I think it will be quite helpfull....
I have the same issues with my 2003 VFR.
I tried all the rest. (connector by-pass/ground connectors sanding & cleaning/ground node fix)
Still the bike has poor throttle when it got to temperature....
I've always thought is was better when i tilted the fueltank when i worked on the bike (did it dozen times)...because it seemed something was clogging the fuel line....But after a while the same issues came back.
I'll keep you posted.

Regards,

Lars. (Antwerp -Belgium)

(Dis the problems stayed away afterwards on your bike?)


 

On 8/31/2007 at 4:44 PM, DaveM said:

I know there are a lot of posts on this topic, but my experience was a little different and I wanted to throw it out for consideration. Over the past couple of months my 02 had developed some really serious drivability issues. Once she got over about 180deg she would start missing at constant throttle settings. In the mildest form it felt like the lean surge problem, and in its worst form you could hear individual cylinders dropping in and out and it felt like it was going to die. Moving the throttle a good bit would cause everything to pick back up but it was very annoying, and sometimes scary if you were in a corner. The problem didn’t exhibit itself constantly. Some times she would run smooth as butter for a couple of days. I had been watching the 30A B fuse for a while and it was starting to show the typical wiring insulation discoloration and signs of heat so I did one of the recommended repairs. This lowered the fuse wire temp, but it was still getting warm and the drivability problem was still there. I checked the main and front harness ground wires next – no signs of heat or discoloration, the connectors separated easily etcetera, so I didn’t implement any of the repairs suggested. I did apply some super duper Volvo electrical connector grease given to me by a friend to the blue and gray connectors. (Seems modern drive by wire Volvos occasionally develop electrical gremlins and the fix is to put this stuff on the connectors). Still no change. So, I got out the service manual and started to work my way through the wiring diagram and learned the following:

The B fuse (the one that melts) does not supply working circuits in the front harness. The power passes through the front harness to be switched by the control relays (fuel cut and I think one other), but no working circuits. This means the grounds from the front harness are not really associated with the B fuse, and the fact that both melt is a coincidence, not a cause and effect relationship. So when we fix the front grounding problem we are fixing problems related to accessory circuits and the A fuse.

This led me to start looking at the main harness. It appears the B fuse supplies all of the engine management circuits – ignition coils, injectors, TPS, O2s, etcetera. Loss of voltage in these circuits would logically seem to cause drivability problems, so I popped of the right fairing and pulled all of the engine management connectors apart. Nothing appeared to be wrong, no visible corrosion or anything, but I checked all of the female connectors and attempted to tighten any that looked to be too open, applied magical Volvo grease, and plugged everything back together. Viola! Drivability problem gone – smooth as glass at any steady throttle setting from 3500rpm up and now the B fuse is cool to the touch. Why did the problem seem heat sensitive? The only thing I can determine is a couple of the right side electrical connectors lay against the upper radiator hose, and once the coolant started to flow the connectors heated up and raised the resistance in already marginal connections.

The message here – when you’re working on your B fuse problems, check those engine management harness connectors!

I apologize for the long post, but I hope it helps someone else.

Quick Update. Two weeks, 1000+ miles, ambient temps from 47 - 94, and coolant temps from 170 - 223, still smooth. No surging, no missing, and the B fuse is staying cool. I've owned this bike for two years and 17,000 miles (had less than 2k on it when I bought it) and it has never ran this well at steady state cruise speeds. Now it's no not just fun to ride, but a pleasure to ride!! fing02.gif

Thanks for the post...i've got the same problems (thought it was a problem with synchonisation of the throttle valves....but after a few days it was the same...and getting worse faster day by day...) I'll go and check those connectors at ECU and next to the radiator.....Greetings, Lars.