2007 R6 Idle Issue (mainly cold start) - Yamaha R6 Forum: YZF-R6 Forums
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post #1 of 2 (permalink) Old 05-29-2019, 09:43 PM Thread Starter
Burn Baby Burn
Join Date: May 2019
Location: Sandy, UT
Posts: 1
Bike: 2007 Yamaha R6 Cherry Red
2007 R6 Idle Issue (mainly cold start)

Thanks in advance, as this will be a novel to provide as much info as possible.

Long time lurker of this forum, but recently joined. So do what you will. I've searched and read many other threads on this topic. However, I haven't been able to resolve my issue. I consider myself pretty mechanically adept, yet this is driving me nuts. It could be something simple I'm overlooking, or something more involved. Hoping someone had a unicorn problem like this that was solved without much hassle.

The bike has a really jumpy idle once it hits "warm up" temp. When cold starting it, it will idle fairly okay until the display reads 104F. Then it stutters down to ~900rpm or below and bounces back up to ~1600+ and continues that way until it stalls. If I blip the throttle it will rev up and then die when returning to idle. If I crack the throttle slightly and hold it until it gets above 160F it won't die. Though it struggles to get there. I have to hold the throttle open to get it to start again on warm-up if it does die. Once to full temp it will idle like a bike with a full exhaust, only bouncing a little, which as far as I know is normal.

The problem has been around for about two years now. I'm a firefighter and get sent out on Wildland stuff during the summer so I never messed with it a ton, nor had the time to ride it much during warm weather. Even if I did, I wouldn't because of it's issue. I baby this thing and do all regular maintenance at intervals and don't abuse it. Garage kept all it's life and winterized as normal (I'm in Utah). After installing the exhaust and PVC it ran pretty good for a while, then slowly got bad. I couldn't find any mechanical issue, so I got an Autotune to see if it would help rather than relying on shelf maps. Didn't do much, or I'm just too slow to know how to run all this ECU stuff.

Engine Mods:
- Muffler/cat delete with y-pipe and Yoshi slip on, wrapped headers
- Graves SAI block off plates
- PCV with Autotune
- K&N air-filter

Occasionally it would stall when coming to a stop. It would also bog in first gear when leaving a stoplight, nearly stall, then backfire like a mofo and take off. I figured it was running rich, so I swapped maps and it seemed to help get rid of that for the most part. I only accept the fuel trims that auto-tune is trying to do every so often, as to get an average rather than accepting after every ride. Looking at the trim and A/F tables 0-5% throttle all have zeros. To my knowledge that's how it's suppose to be. I've tried a few different A/F numbers within those columns/rows and it is hit and miss with making it better. I'm still exploring that option in my little free time.

Over time I've slowly dug into it, more so now then ever. I've checked the throttle sensor, it's within spec. I've synced the the throttle voltage with the PCV, it's good. I've checked the resistance of the coils (all primary were around 1.4, all secondary were 9.5). Spark plugs are fresh and gaped correctly. I looked for any signs of a vacuum leak and found none. Fuel is fresh. Intake filter is clean. No exhaust leak that I'm aware of. I've tried a few different maps, but that doesn't do much to the idle. Threw a new map on it yesterday and it seemed to do great around town, but it went back to normal today.

Watching the A/F ratios at it varies from 12 to 14-15 and bounces with the RPMS. Of course I think it's the bike trying to adjust to get the right A/F, however, wouldn't the zero values in the map at closed throttle prevent it from trying to achieve a desired A/F? (if that makes sense). I have videos if anyone is interested. I highly doubt it could be valve related, since the bike only has 15k miles on it. I'll probably attempt to sync the throttle bodies this weekend, but it might be hard with a bouncing idle.

Before I start throwing parts and large amounts of cash at this thing I'm hoping for some pointers. Do the coils resistance change much with temp? Could they be falling out of spec when up to temp? The manual doesn't state testing them hot, but I've seen people do it.

Could the PCV be faulty (even though it seems to operate correctly)? Maybe the narrow-band sensor for the auto-tune is bad? Any way to test?

Could I place a A/F value in the 0-5% column/row and try to keep it running and let the auto-tune make trim adjustments and accept it over and over again?

A dyno tune would be great, but I invested in the PCV and Auto-tune to get around that since I ride up canyons and change elevation a lot. Obviously if I can't get it solid, I'll get it professionally tuned/looked at. I just hate that cause I'm a real DIY person. If you notice something I should test and didn't mention, please let me know.

Thanks again for reading such a long post and any input is appreciated.
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post #2 of 2 (permalink) Old 05-30-2019, 10:02 AM
Just made this great wheelie.. did you see it?!
Join Date: Apr 2019
Posts: 95
Re: 2007 R6 Idle Issue (mainly cold start)

I didn't even had to read your entire post. I had this exact issue few weeks ago and I can almost assure you its your muffler/cat delete. My 06 had muffler/cat deleted and did exactly what you described, I ordered stock headers from ebay for like $60 and the problem went away immediately. I kept the slip-on though.
Ravager33 is offline  
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