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Marooncobra

Hesitation / loss of power at a constant rev

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G’day

 

I am hoping the brains trust might be able to assist.  I am currently experiencing a hesitation / slight loss of power after I sit at a constant speed on the highway. I don’t experience it during excelleration or town riding, just when cruising at the same constant speed. It is almost as if someone has twisted the throttle back by a few degrees and you can feel the engine drop off. Once you twist the throttle it picks up again and won’t show an issue again for another period of being at a constant speed.

 

2002 non abs

60,000 km

injectors ultrasonic cleaned 4 months ago

new stator and rectifier fitted 12 months ago

no loss of instrument panel during the fault

volt meter reads 14.4 volts at cruising speed

power commander USB using the cosi map

 

I am thinking one of the following components maybe playing up.

 

fuel pump not delivering sufficient fuel - unlikely as it accelerates from the issue with no problem

fuel pressure regulator - no external leaks or vacuum leaks - probably requires a new one to be fitted to confirm as it is a sealed unit and cannot be adjusted

throttle position sensor - might have dirty tracks on the sensor, again probably a swap with a new one as it is a sealed unit

 

thoughts or suggestions

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Just wondering if starter valve synch could be an issue here, you are probably not at very wide open throttle state whilst cruising. Would also consider the state of the FPR. Both of the above wouldn't force an EFI fault code which I assume you are not getting any Fi light codes. A little outside the square, wonder if the ECM is seeing correct engine temp from the ECT.

Good luck.

Cheers

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When sitting at a constant throttle opening the EFI goes into closed loop and O2 sensors come into play, readings from these are used to lean out the fuel mixture to conserve fuel. 

When the throttle is opened again O2 sensors are ignored (open loop) and system again uses stored maps for the fueling. 

Its why I got a PCIII and got rid of the O2 sensors on my 5G, it used to drive me nuts. 

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Grum,

 

I have done the starter valve synch and realistically this only controls the idle to initial throttle butterflies opening. At the cruising speed, 100kmh, the valves would be open past the synch period. I have no FI codes. FPR is one of the items I am thinking as stated in original post.

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VFROZ

 

I have got the O2 sensors removed with resistor plug ins. My Power Commander 3 USB is running a cosi map downloaded  from here. 

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Does it still do it with the PC removed? That's the first thing I'd check.

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FJ12Ryder

 

I will disconnect the power commander this weekend and try running at a constant speed again.

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A quick question, have you synchronised or zeroed the throttle position to the PCIII?

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I did when I uploaded the map but that must be 12 months ago. I will test the bike with the PC unplugged first and if that doesn’t work I will reconnect and reset the throttle on the computer. I have checked the parts fiche and note that Honda don’t sell the TPS as a part only.  I have seen these go bad on vehicles, the tracks pit over time and give high resistance.

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Hi

 

Well I thought I would give you an update to my issue.

 

So I tested the fuel pressure of the fuel pump and that was in spec. I replaced the fuel regulator but got no improvement to the issue. I was then going to go and get the bike dyno tested to see if there was an issue with map or even a fault with my PC 3 USB as it is subject to vibration under the seat but decided to first replace the fuel filter in the tank.

 

On replacing this item my woes have gone including an annoying vibration that used to come in around 4500 rpm.  After coming back off the ride with a big smile on my face I decided to get the filter out of the bin and rip it open to look at the filter. Now you have to understand that my VFR is a 2002 model with only 61,000 km (38,125 miles) on it and I have put the last 6,000 km (3,750 miles) on it since I purchased it in 2016 meaning on average the bike has annually only covered 3,500 km (2,187 miles) a year. I don’t think this filter has ever been changed in 17 years.

 

On ripping the filter can open I didn’t find any debris but once I opened up the pleated paper I could see the issue.  The filter paper, dirty side, was covered in brown lacquer. The clean side had no lacquer build up at all. I actually got an airline to blow through from the clean side to the dirty side and it Hardly made any difference. 

 

 

976AE399-9F7D-47EF-BEC9-3279C14DAFE9.thumb.jpeg.6d02f50cc95784c627bbb6cc443c3b48.jpeg

Dirty side of filter. You see the area I used an airline on to try and see how dirty it was

 

6FBF65BA-AA82-4D12-9C70-7DCD86B8D2A7.thumb.jpeg.08ff93818a61b7464db5ff635d373cd0.jpeg

clean side

 

BC93D3AC-8A2C-4737-8BBD-D8EFC5C6148F.thumb.jpeg.88cd468c0a1ffccd688129e65f06f6bc.jpeg

Close up of area where I tried to clean with the airline.

 

If anyone conducts this filter change don’t bother buying the pre filter as it is just an aluminium scouring pad that I could have bought from Woolworths for $0.99 cents. Not Honda’s cost of $15.00!!!!!

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Maroon Cobra, 

 

The hesitation you were feeling in your VFR - was it almost like a lurching or intermittent pulling? Kinda like the bike wanted to move forward but was having trouble giving you a 100% effort? 

I'm asking because I recently purchased my VFR and this weekend began having trouble I believe is similar to yours.

 

First step is to change our spark plugs and air filter. Curious if next step will be changing the fuel filter like you mentioned above. 

 

Let me know your thoughts. 

 

Thanks!

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Good find MaroonCobra. Glad it's all sorted. Surprised you didn't have any issues when accelerating, rather than just when coasting at a cruise speed. Must remember that one.

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Sounds like I need to add a job to the list on my gen5.

 

I take it your in Aus. Was wondering who did your injector clean and what it cost?

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On 4/20/2019 at 6:30 PM, Marooncobra said:

 

If anyone conducts this filter change don’t bother buying the pre filter as it is just an aluminium scouring pad that I could have bought from Woolworths for $0.99 cents. Not Honda’s cost of $15.00!!!!!

I'm a bit confused about this statement.  Are you talking about the wad of stainless steel that sits directly beneath the return fuel line for the pressure regulator bypassed fuel?  As far as I know this wad of coarse stainless steel wool is in place to prevent the pressure-bypassed return fuel flow from spraying/splashing all over the place when the fuel level in the tank is low.  This wad of stainless steel wool has the effect of helping the returned fuel (bypassed at the fuel pressure regulator on the throttle body) to arrive in the vicinity of the fuel pump pickup point with very low turbulence and splash occurring.

 

(Fuel injection systems are always set up with a fuel pump that puts out more pressure and volume than the system needs, this is what allows the fuel pressure regulator to control the system's operating PSI.  This specified surplus of pressure and volume allows for the gradual reduction over time (in years) of fuel pump output that occurs due to normal wear-and-tear on the clearances of the fuel pump internal parts.)

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Thanks Marooncobra!  I just recently picked up a lightly used '04 model that is doing the same thing.  Just ordered a new filter and rubber gasket today.  Will report back soon!

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On 5/8/2019 at 1:18 AM, Jeremysell11 said:

Maroon Cobra, 

 

The hesitation you were feeling in your VFR - was it almost like a lurching or intermittent pulling? Kinda like the bike wanted to move forward but was having trouble giving you a 100% effort? 

I'm asking because I recently purchased my VFR and this weekend began having trouble I believe is similar to yours.

 

First step is to change our spark plugs and air filter. Curious if next step will be changing the fuel filter like you mentioned above. 

 

Let me know your thoughts. 

 

Thanks!

Hi

 

sorry been away and only just seen your message. It sounds like the same issue I had. You get to a cruising speed and after a few seconds it’s as if the throttle has wound off by a few degrees so you feel a dump in power. You then turn the throttle to increase speed and you get hesitation and then suddenly it comes back. If you do change the filter rip it open and check the paper element. I used a vice and a junior hacksaw to cut through the filter can.

 

I look forward to hearing if this sorts you out

 

 

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On 5/8/2019 at 9:51 AM, Zarquon said:

Sounds like I need to add a job to the list on my gen5.

 

I take it your in Aus. Was wondering who did your injector clean and what it cost?

Hi

 

I sent them to a company called EFI Hardware who are based in Victoria. Their web page is at www.efihardware.com

 

I had them back in a week and it cost $40 an injector + p&p. They also provided new filter baskets that fit inside the injector but couldn’t supply one of the small o rings.

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On 5/9/2019 at 2:58 AM, GreginDenver said:

I'm a bit confused about this statement.  Are you talking about the wad of stainless steel that sits directly beneath the return fuel line for the pressure regulator bypassed fuel?  As far as I know this wad of coarse stainless steel wool is in place to prevent the pressure-bypassed return fuel flow from spraying/splashing all over the place when the fuel level in the tank is low.  This wad of stainless steel wool has the effect of helping the returned fuel (bypassed at the fuel pressure regulator on the throttle body) to arrive in the vicinity of the fuel pump pickup point with very low turbulence and splash occurring.

 

(Fuel injection systems are always set up with a fuel pump that puts out more pressure and volume than the system needs, this is what allows the fuel pressure regulator to control the system's operating PSI.  This specified surplus of pressure and volume allows for the gradual reduction over time (in years) of fuel pump output that occurs due to normal wear-and-tear on the clearances of the fuel pump internal parts.)

Hi

 

Yes I was talking about the the wad of metal wool at the fuel pick up/ fuel return area. I noticed that the fuel return from the Fuel pressure regulator is directed onto this wad but didn’t realise it would be to prevent splashing/spraying/turbulence as being a flooded system I assumed it would just be a flow of constant bypassed fuel. The injection pump did have a small micron pre filter that had some small debris collected.

 

My comment was that the metal wool that I replaced for $15.00 from Honda could have been replaced with a kitchen metal scouring pad for 0.99 cents. The metal wad filter I replaced was definitely not stainless steel but aluminium.

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18 hours ago, Marooncobra said:

I noticed that the fuel return from the Fuel pressure regulator is directed onto this wad but didn’t realize it would be to prevent splashing/spraying/turbulence as being a flooded system I assumed it would just be a flow of constant bypassed fuel.

I think the wad of spiral metal is only there the help out when the fuel quantity gets low.

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