[brad_0_trax]

Hello All,
I am working on a TRX700XX 2008 for a customer that has an issue when the bike at idle, it idles pretty well BUT when i hit the throttle (whether its like 1% or 100% throttle) it will rev, then come down BELOW normal idle for a second, then come up to normal idle. EVERY time.

This issue promotes stalling from R to 1. At first I thought this was clutch drag killing it, but not really. Because I put in in reverse, accelerate ( rev up, then let it go back to idle when i shift to 1st), shift to 1, sometimes itll die because it drops below normal idle.

Modifications are: Big Gun exhaust, UNI foam filter, air box lid is ON. (remove lid with no changes)

The bike does NOT have a fuel controller on it (talking my customer into it) HOWEVER, I am almost certain the issue is not related to the change in exhaust, plus he purchased it already modified so I cant verify with stock exhaust if it is the issue... But i do not think it is.. Im leaning towards an IAC/throttle body issue.

The bike runs awesome, lots of power, no backfiring, popping on decel, etc. Just fabulous, besides this idle issue.
I have noticed in N, if you stab the throttle EXTREMELY quickly, there is a VERY slight bog, but i mean SLIGHT. Almost not noticeable to the untrained ear. To the point where customer doesnt notice, but i do..

Anyways........ Any ideas?

Just for the sake of the conversation, The ECU sets the idle at 1500 RPMs, the idle will maybe come down to 1250-1300, then go back up. Very small amount, but still an audible difference. That is my issue. And yes, the ECU DOES control idle with the IAC/TPS whatever you want to call it Lol. No idle screws like on some FI bikes!


******** ALSO, I am UNABLE to pull/verify codes if any. Dash has been removed and replaced with Trail Tech Spedo. I told him you could have both Lol. He threw dash away!

 

[Goober]

Can’t help very much on this one except to ask if you think it’s lagging lean or rich. When this happens is it blowing a lil puff of black smoke out the exhaust when this happens? Or if you pull off the airbox lid and filter does it blow black smoke back out of the throttle body? Or does it run the way you want with the lid and or filter off?
The uni filter body is supported by a spring cage–does it collapse a bit when this occurs?

 

[ATC4ever]

Can you watch the butterfly shaft when it idles down to see if the ECU turns the throttle back up? Or maybe a fuel enricher shaft moving?

 

[M_Quick]

The irregular idle sounds like the air temp sensor in the air box. But the stalling from reverse to 1st, also sounds like it may be neutral/reverse switch assembly's. You say the customer tossed the dash! Did he disconnect the whole wire assembly with the 4 warning lights? Also where are you located?

 

[brad_0_trax]

The irregular idle sounds like the air temp sensor in the air box. But the stalling from reverse to 1st, also sounds like it may be neutral/reverse switch assembly's. You say the customer tossed the dash! Did he disconnect the whole wire assembly with the 4 warning lights? Also where are you located?

Im in North AL, Everyting is tossed. Unplugged from harness and tossed.
The R to 1 gear only stalls if i let it. Not every time, not an electrical issue.

I have not had a chance to remove the airbox and look @ the throttle plate while the issue is occurring, but i do believe its a TB issue, May just need a good clean.. iI just havent had a chance to look.

 

[brad_0_trax]

Can you watch the butterfly shaft when it idles down to see if the ECU turns the throttle back up? Or maybe a fuel enricher shaft moving?

Have not tried, will do that asap.

 

[brad_0_trax]

Can’t help very much on this one except to ask if you think it’s lagging lean or rich. When this happens is it blowing a lil puff of black smoke out the exhaust when this happens? Or if you pull off the airbox lid and filter does it blow black smoke back out of the throttle body? Or does it run the way you want with the lid and or filter off?
The uni filter body is supported by a spring cage–does it collapse a bit when this occurs?

When the bike is cold, sometimes i tiny puff of black will come out of the exhaust.. which is normal for any machine to an extent. If smoke of any kind comes out of the TB itself you've got bigger issues. Lol

The issue does not change when the lid of on or off. same issue.


The issues is only at idle, no other point does this machine act up in any way. If i start the bike ad let it idle for 3 days straight itll never miss a beat... but anytime i give it throttle, no matter how much, it will rev normally, then as the rpms go down, it will drop BELOW 1500 for just a split second, then return to its set idle with no issues UNTIL i do the throttle again... Thus tells me its a TB/IACV issue.

 

[trxkid]

Have you fixed it yet? Mine has a similar problem