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Fuel Injection Surging

3K views 6 replies 2 participants last post by  joey1970 
#1 ·
13 TBird Storm, Running LT Commander Stock tune - Surging is back!
History, Bike had a bad exhaust cam and developed a surging issue. Dealer Service Manager at the time was a complete Sh_tbird. After many iterations, cam was finally fixed, I had a partial failure on plugs (resistance decrease) and replaced with next colder plug. Surging went away. Later added a PCV and Autotune 300. Only other mod is airbox delete.
Current, had dealer load the latest stock tune. Had the TOR tune in it before. Was looking to use the increased timing. Ultimately had to increase AFR, was running 13.7/6, now running 13.6/5. Also added fuel to idle 13.6. Surging has returned on number 1 cylinder. Replaced plugs again, no change.
PCV SW shows erratic fuel control at idle with the normal RPM fluctuations but also AFR is all over the place.
Anybody observed this before? Any suggestions?
 
#2 · (Edited)
It's almost certainly the MAP tubes. I just went thru it. I thought it might be something else. I was getting it dyno'd and it was whacky. The tuner popped off the MAP tubes and put them back on again and everything was fine.

I am however curious as to why you'd have the dealer load a different tune if you are running a PC5 and Auto tune? Did you get a dyno done? I'd suggest you do a dyno even if you're running the auto tune. I also run the Airbox delete.. and a dyno is necessary to get it right.
 
#3 ·
Joey1970,
I took your advice. I have always wondered why Triumph decided to locate the pressure sensors in the location they did. I relocated the sensors immediately next to the throttle bodies. Had to crack open the wiring loom (as an engineer, I am not impressed, copious use of electrical tape!) to move the connectors, found two pinch splices and soldered them, then re-bundled the whole thing back up with additional insulation to protect the wiring from head heat.
I then idled the bike for a good long time. While cold nice and stable, as she warmed slight surging but I had the AT running in the idle area to pull the AFR out of the 15/1 range. Geared up and test drove/accept AT recommendations for about 6 loops. She was popping immediately off idle and sometimes dying at a stop light (it is HOT over here). On 2nd to last pass she dropped idle from 850 to 650 rpm, and the AFR dropped to 9.9/1. Complete with blk puffs of overly rich exhaust. Turned off the AT in the idle area and started manually pulling fuel out until I got back to 0 for the PCV. Idle came up to 850-ish, AFR settled into 11/1, I then pulled back the fuel I was putting in immediately off idle.
I have no idea why the idle circuit flipped to being so rich. It definitely stopped the pop off idle. Acceleration is drastically improved with the pressure sensors relocated.
Any idea WTH they were trying to do with the stock sensor placement?
 
#5 ·
I don't think you're talking about the same thing I was when I referred to the MAP tubes. They are plastic tubes and you'd never need to solder them. And you'd never have to crack open any wiring loom to address this problem. They are connected to the throttle bodies at one end and run under the tank to a tiny nips. And I'll bet they are still the cause of your issues.

And as for the tune.. if you're running the PC5 and auto tune.. it's really not gonna matter what tune is loaded in your ECU. The PC5 and AT300 are now what is running your tune. I could be wrong.. but that's how I think I understand it.
 
#6 ·
Joey1970,
The tune does matter unless you create a completely custom ECU tune. PCV does not control timing for the Tbird. The TOR tunes have less timing, The more timing you have the better the acceleration, The more heat you produce as well. Where are you getting I soldered the pressure tube?
I had to open the loom to move the pressure sensor connectors so I could locate the pressure sensors next to the throttle bodies. In doing so ran across the pinch splices in the loom, soldered the pinch splices and the whole thing settled the FI down to get rid of the weird cycling behavior at idle.
 
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