Kawasaki GPZ1100 TPS Replacement
Being as it doesn't have an O2 sensor for fuel correction and the computer doesn't allow for enrichment your assumption would be correct. The Kawasaki Turbo is your friend here, for the variable resistor wired inline to the temp sensor circuit. Ask the guy whose had four of them. Do a Google using the turbo instead of the GPz. I think Holeshot Performance made one.
MPS Racing made a variable resister for the GPz1100 DFI. They don't show it on their website, e mail or call and ask for it. They'll still put one together.
www.mpsracing.com/
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Interesting fuel mod on my GPz1100 DFI (long)
Polar_Bus
Hi all,
Basically since I aqquired my GPz1100 back a few years ago I've been experiencing what seemed to be a lean air/fuel condition.
I systematically checked all "mechanical" type issues, and everything seemed to be in good working order. As I started getting feedback, and an understanding about the "crude" DFI design and the current usage of EPA friendly oxygeynated E10 fuel, I began to realize that I'm thinking I simply have a "too lean" fuel map.
My bike always had a lean stumble around 3000-3500 rpms. Unfortunately there's not a lot of info or hardcore experiences about modifying the stock GPz1100's ECU. However a member of another forum who previously owned a early Kawi Voyager DFI (same inherant lean condition) schooled me on a neat trick dubbed the "680 Ohm resistor mod". What some genius figured out was to splice a resistor into the air temperature sensor circuit to "fool" the ECU into thinking the air temps were slightly colder that it actually was, which in turn would slightly richen the air/fuel mixture. I tried a 680 Ohm, and quickly realized this made my GPz run a bit too rich. I opted to try a 1K Ohm resistor, and now I made positive progress, my bike really runs awesome !
Gone is the low to midrange hesitations, and seems to pull hard right up to redline. I am going to maybe try a few more resistors, or possibly fabricate an adjustable "potentiometer" type device to adjust "on the fly" over the winter. I'll keep updating this for other GPz1100 members as an FYI. Here's a few pics of this simple and effective mod:
And here's everything all spliced in (no hacking required, as I used male and female spade connectors to plug into the OEM connectors)
That's neat, putting a pot on there would look really cool too.
Now that is a great mod! I had grown to accept the 3500-4000 rpm stumble in my brand new 1982 GPz1100 back in 1982...fast forward 25 years in my recently acquired 1982 GPz1100 and its inherent stumble at that rpm
You can get the resistors right at your local Radio Shack, so give it a try on your "B2" . Best thing is if you don’t like the results, just yank the resistor back out ! No permanent damage or hacking done ! You start opting for "modified" ECU's and mechanical fuel pressure regulators in an effort to richen, now you are getting into more "permanent" type modifications (and expensive). A 4 pack of Radio Shack 1K Ohm resistors is $.99
H...splice a resistor into the air temperature sensor circuit to "fool" the ECU into thinking the air temps were slightly colder that it actually was, which in turn would slightly richen the air/fuel mixture. I tried a 680 Ohm, and quickly realized this made my GPz run a bit too rich. I opted to try a 1K Ohm resistor, and now I made positive progress, my bike really runs awesome ! Gone is the low to midrange hesitations, and seems to pull hard right up to redline....
If adding 680 ohms resistance made it too rich, seems like adding 1000 ohms resistance would make it even richer?
Polar_Bus wrote:
H...splice a resistor into the air temperature sensor circut to "fool" the ECU into thinking the air temps were slightly colder that it actually was, which in turn would slightly richen the air/fuel mixture. I tried a 680 Ohm, and quickly realized this made my GPz run a bit too rich. I opted to try a 1K Ohm resistor, and now I made positive progress, my bike really runs awesome ! Gone is the low to midrange hesitations, and seems to pull hard right up to redline....
If adding 680 ohms resistance made it too rich, seems like adding 1000 ohms resistance would make it even richer?
The air temp sensor alters output voltage ranging from 1.7-3.8V . The warmer the ambient air temps are The lower the output voltage, and vice-versa. So my goal is to effectively slightly raise output voltage. To my understanding this is done by increasing the rated ohm output of the resistor ? Geez, I hope I’m doing this right !? LOL
There is a system sold for that. That is tuned for every individual model bike. I bought one for my bike about a year ago. I paid about $7 for mine. I figured out later that installing a adjustable fuel pressure regulator was a better way to go.
Larry cavan wrote:
Old trick from the mid 80's finds new life in the next century
You have two choices to fatten up the fuel curve on a stock Kawasaki DFI from those days.
1 - Air temp sensor Resistor
2 - Adjustable Fuel Pressure Regulator
For a mild street motor the air temp sensor works very well.
For anything that would require main jet increase on carbs, the FPR is the ticket.
If you really want to wake it up, send the throttle bodies to Sid Pogue at Pogue Machine in Oklahoma City. Well worth having done.
