TurdFerguson Posted February 2, 2019 Share Posted February 2, 2019 07 with all the easy mods (PAIR, flapper, K&N and snorkel....done by PO) I bought the bike a couple months ago. Motor runs and sounds like crap just off idle, even backfiring into the air box occasionally. My buddies stock 2002 is worlds better. 07 runs like a champ once above 2500 rpm so it's not like a real big deal....not below 2500 very often....but still curious as to why the fluff. Yes, I synced the Idle Air Valves. lemmeknowdaddy-o Link to comment Share on other sites More sharing options...
GreginDenver Posted February 2, 2019 Share Posted February 2, 2019 I'm a 5th Gen VFR guy so what I'm going to say may not apply to your '07 VFR (but I believe it does). Whether my little bit of information applies to your bike is dependent on whether Honda continued to use the same tuning principles for the PGM-FI system across multiple generations of the model (the 5th Gen VFR was the first fuel injected VFR so it can be considered to have set the VFR model template for the use of Honda PGM-FI). On the 5th Gen VFR Honda set up the PGM-FI system to use two completely different methods to determine fueling depending on the "demand" that the rider puts on the engine. "Demand" is most easily related to throttle position and the recent rate of throttle position change. While this description isn't the whole story behind "demand" it's good enough for a basic understanding. RPMs also factor into the equation. At low levels of "demand" the PGM-FI system uses the Manifold Absolute Pressure Sensor as the main parameter in determining the proper fueling of the VFR engine. At high levels of "demand" the PGM-FI system uses the Throttle Position Sensor as the main parameter in determining fueling. So, it something is whacked about your VFR's low "demand" (low RPM) operation the problem is very likely to be related to the Manifold Absolute Pressure Sensor. I get a lot of blow-back every time I say it, but removing the flapper and snorkel might have the effect of changing the amount of intake system vacuum the engine experiences during low demand/RPM operation. Link to comment Share on other sites More sharing options...
Member Contributer TriumphTraitor Posted March 23, 2019 Member Contributer Share Posted March 23, 2019 When doing the flapper mod, ensure that the vacuum line is completely blocked off. Also ensure that there are no vacuum leaks any where in the complex piping system under the throttle bodies. From what I understand about the MAP sensor on the 6th gen is it is only active when the TPS is in the 0% open position. it controls the fueling for idle and high idle when the Wax unit is active. Having a vacuum leak will give a faulty reading to the MAP sensor and poor idle conditions. A vacuum leak will also allow more air to enter the engine and will cause a lean running condition Link to comment Share on other sites More sharing options...
Urbanengineer Posted March 23, 2019 Share Posted March 23, 2019 Mine did this when the idle was too high. Just a thought. Link to comment Share on other sites More sharing options...
TurdFerguson Posted March 28, 2019 Author Share Posted March 28, 2019 All back to stock, except for PAIR valve, and the bike runs significantly better. Go figure that a Honda engineer was smarter than some shade tree mechanic....... Shes a keeper. Aloha, TF Link to comment Share on other sites More sharing options...
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