Misfire Mystery

[Koop]

My 2009 RS has developed a problem that has me scratching my head. I'm technically savvy - I spent my entire career in technical service and quality for a major European auto manufacturer and I maintained ASE Master Certification. Here's what's happening:

On start-up the engine runs fine. Once up to operating temperature - a few miles down the road - the problem begins.

Stopped at a traffic light at idle I get a mis-fire. It seems like a lean running condition as accelerating away from the stop makes the problem worse until I achieve 2,500 - 3,000 ROM then the engine runs fine.

At first I thought it was an issue with bad fuel or winter formula fuel in hot weather (I've been in Arizona and Nevada for the past few months) but a few tank-fulls of fuel haven't changed anything.

I don't have any warning lights so I suspect I don't have any codes, but I don't have the software to check for for diagnostic trouble codes.

I'm open to suggestions.

 

[JKMSPYDER]

MISFIRE

There are two vacuum hoses connected to your throttle body on the left side. Some riders have reported these hoses can crack or split. This could be your problem. Each hose is only a few inches long.

 

[Koop]

There are two vacuum hoses connected to your throttle body on the left side. Some riders have reported these hoses can crack or split. This could be your problem. Each hose is only a few inches long.

Thanks!

 

[Koop]

Moderator, please move this to RS/GS shop talk. Thank You.

 

[spyderCodes]

You don't need diagnostic software to retrieve active codes:
RS: (Provided by NancysToys.)
1. Turn Ignition key to "ON"
2. Push the "MODE" button to display total hours screen. Start engine and run until check engine light (or other fault indication) is displayed.
3. Press and hold "MODE" button while pushing the "High Beam Flash" button rapidly five times (within 2 seconds).
4. The active faults will be displayed or "No Active Fault Code" will be shown.
5. If you do not get a message, you didn't get the flash beams sequence done during the allotted time. Try again.
6. Jot the code-number down and check the list in the manual to determine your problem. Share this with your mechanic.


or look it up using spyderCodes

 

[Tazzel]

My 2012 RS SE5 use to backfire every once in a while from day one. 16k Miles later and no issue ever developed.

 

[Koop]

You don't need diagnostic software to retrieve active codes:
RS: (Provided by NancysToys.)
1. Turn Ignition key to "ON"
2. Push the "MODE" button to display total hours screen. Start engine and run until check engine light (or other fault indication) is displayed.
3. Press and hold "MODE" button while pushing the "High Beam Flash" button rapidly five times (within 2 seconds).
4. The active faults will be displayed or "No Active Fault Code" will be shown.
5. If you do not get a message, you didn't get the flash beams sequence done during the allotted time. Try again.
6. Jot the code-number down and check the list in the manual to determine your problem. Share this with your mechanic.


or look it up using spyderCodes

Thanks, great info.

 

[ataDude]

My 2009 RS has developed a problem that has me scratching my head. I'm technically savvy - I spent my entire career in technical service and quality for a major European auto manufacturer and I maintained ASE Master Certification. Here's what's happening:

On start-up the engine runs fine. Once up to operating temperature - a few miles down the road - the problem begins.

Stopped at a traffic light at idle I get a mis-fire. It seems like a lean running condition as accelerating away from the stop makes the problem worse until I achieve 2,500 - 3,000 ROM then the engine runs fine.

At first I thought it was an issue with bad fuel or winter formula fuel in hot weather (I've been in Arizona and Nevada for the past few months) but a few tank-fulls of fuel haven't changed anything.

I don't have any warning lights so I suspect I don't have any codes, but I don't have the software to check for for diagnostic trouble codes.

I'm open to suggestions.

My guess... high voltage spark plug wire(s).

 

[GOZFST]

My 2008 GS did something very similar, I found that if I put a can of injector cleaner it went away.

 

[Yazz]

My guess... high voltage spark plug wire(s).

+1. Had that happen to my '09. The OEM plug wires Are prone to fail.

Take the front/side panels off, in a dark garage turn on the RS. If you see a light show, it's the spark plug wires.

BahaRon has more robust plug wires for your Spyder.

 

[Chupaca]

Well....

Check the vacuum lines as mentioned above and replace them with silicone hoses. The plug wires plugs and coils would be next. BajaRon has what you need if you find them faulty. If you download the spyder codes app (free) to your phone this will help you a lot with these machines...:thumbup:

 

[Koop]

I checked the vacuum hoses today. All look good and I sprayed some carb cleaner on them with the engine running to see if it would get sucked in - nothing doing. In my experience ignition breakdown is more likely under load, not at idle and clearing up under load, so I'm not inclined to replace coils and wires - yet. It seems like a fuel issue. I can't use the method above to read a fault code since I don't get any indication of a fault on the display.:sour:

 

[Culpjp]

Check the gasket on your exhaust. When that goes bad it can cause a backfire condition at low rpm's or when you let off the throttle.

 

[Bob Denman]

If you're thinking that it's a fuel issue: try running something likje SeaFoam through a couple of tanks of fuel, and let us know if it helps.
Good Luck! :thumbup:

(But I'm betting that it's just the plug wires...How many seasons do you have on them?)

 

[Koop]

Today I pulled the tupperware and removed the airbox. With the airbox off, I checked all the vacuum hoses again. I checked the plug wires for tightness and any sign of arcing. I started the engine and checked the operation of the IACV. Everything seemed okay. I let it run and warm up - it never misfired!

I reinstalled the lower portion of the airbox and started it again. It began to misfire. The only things that the lower airbox affected were the position of the fuel hose from the filter and the spark plug lead to the front cylinder. With my head down at the front of the airbox I could hear arcing when the misfire occurred. I shut the engine off and re-positioned the front lead. The misfire went away.

I put everything back together and went for a ride. No misfires.

I'm traveling in our motorhome for next few weeks. Once I get to a place where I can receive packages, I'll order new plug wires. I'm still mystified by the symptom of misfiring at idle and running fine under load.

 

[Grandpot]

Good job finding the real cause of the misfire. I just installed BajaRon's wires on my RT. They are quite substantial. I also bought the iridium plugs and K&N air filter from him. My butt dino says it made a good difference. Just my $.02.

 

[Bob Denman]

The important thing: you found it!! :clap: :congrats: :2thumbs:

 

[Koop]

In my original post I mentioned that I have an RS - I accidentally posted this in the wrong place.

I thought I should close out the topic now that I have completed the repair. I received the MSD 8.5mm Super Conductor wire set from BajaRon today. I also got a pair of NGK iridium plugs from him. I was surprised to find two small packets of dielectric grease and a small packet of heat sink paste included.

After changing the plugs and wires, all I can say is WOW! What a difference. My Spyder has never run this smooth. :yes:I checked the resistance of the original spark plug wires. The shorter lead to the rear cylinder was 3,700 ohms. The longer lead to the front cylinder was 6,000 ohms. Both of these figures are much higher than I expected. The longer MSD lead was 113 ohms! I didn't check the shorter MSD lead.