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help on fuel issue - surging idle / fluctuating injector duty cycle

Old 06-28-2012, 09:12 PM
  #1  
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Join Date: Jan 2003
Location: Washington
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Default help on fuel issue - surging idle / fluctuating injector duty cycle

93 R1, 80k miles, engine rebuilt ~4k ago. Car has been running well, just started developing a surging idle (bounces between 700 and 1300 intermittantly, other times rock steady at 850). While idle was bouncing, I checked the power fc, saw that the injector duty cycle was bouncing between 5.5% and 0%.

Additionally, I've had an issue with blowing fuel pump fuses. The first time was after an autox run, left the engine running in grid, pulled out for 2nd run, car stalled on the way to the start line. 2nd time was driving home from the autox, cruising the highway, downshift to 3rd to pass a car, got around the car and car dies again ... coast to a stop and fuse blown again.

Mods:
power FC, base map set by SR Motorsports based on mods on car
downpipe
catback

I'm thinking about replacing fuel pump (because of the blown fuse), fuel filter (because it's been ~20k miles, but ~8 years), and pulsation dampener. Any other thoughts of what to check / test before just replacing parts?
Sivart_R1 is offline  
Old 03-15-2016, 06:35 AM
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Join Date: Mar 2016
Posts: 5
Default Re: help on fuel issue - surging idle / fluctuating injector duty cycle

Originally Posted by Sivart_R1 View Post
93 R1, 80k miles, engine rebuilt ~4k ago. Car has been running well, just started developing a surging idle (bounces between 700 and 1300 intermittantly, other times rock steady at 850). While idle was bouncing, I checked the power fc, saw that the injector duty cycle was bouncing between 5.5% and 0%.

Additionally, I've had an issue with blowing fuel pump fuses. The first time was after an autox run, left the engine running in grid, pulled out for 2nd run, car stalled on the way to the start line. 2nd time was driving home from the autox, cruising the highway, downshift to 3rd to pass a car, got around the car and car dies again ... coast to a stop and fuse blown again.

Mods:
power FC, base map set by SR Motorsports based on mods on car
downpipe
catback

I'm thinking about replacing fuel pump (because of the blown fuse), fuel filter (because it's been ~20k miles, but ~8 years), and pulsation dampener. Any other thoughts of what to check / test before just replacing parts?
Did you ever figure out what the problem was? Mine is doing the exact same thing! I was thinking the tps but haven't dug into it yet. Please let me know!
Dhanson31 is offline  
Old 05-13-2016, 02:52 AM
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Default Re: help on fuel issue - surging idle / fluctuating injector duty cycle

Had this exact problem. Get a used throttle body with the tps still connected and throw it in there. The problem was my tps. Also if you can find some wires, I took the harness and cut it off and made it about 6 inches longer because mine was really tight on there and it was pulling the harness away from the connector. Make sure you take your negative terminal off the battery before you cut it though. Not sure if it'll send it in limp mode. Did it just in case.
Dhanson31 is offline  
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