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Engine Stumbled....

2K views 5 replies 3 participants last post by  GaryFisher 
#1 ·
While sitting at a red light today idling my engine stumbled..RPMS dropped way down and then came back up quickly without giving it gas. Also when I was tuning the other day I noticed that the digital readout on my RPMS fluctuates by about 50 and it never stays on one number (it is always changing) Does any one know if thats normal?

At first I thought the stumble was do to a cell that had no value on my fuel map but Im pretty sure I filled in all the cells with valid numbers....Any ideas?
TIA
 
#2 ·
No one has any thoughts?
 
#3 ·
I don't know about the stumble, but the idle rpm does float a bit, they never stay in one spot on a digital display.
 
#4 ·
Hey Gary, is this the FTC unit you are talking about for tuning? If so, I have a stumble coming off throttle. It kept throwing out the MAF code. I tried changing the cell value in Map A and nothing happened until I wrote back to the FTC. My stumble was fixed and light was out. I think changing the cell value will not take into effect until it is written back to the FTC. Correct me if I'm wrong.
 
#5 ·
toyoman_4ever said:
Hey Gary, is this the FTC unit you are talking about for tuning? If so, I have a stumble coming off throttle. It kept throwing out the MAF code. I tried changing the cell value in Map A and nothing happened until I wrote back to the FTC. My stumble was fixed and light was out. I think changing the cell value will not take into effect until it is written back to the FTC. Correct me if I'm wrong.
No you are right...I have a few maps that Im trying to work out see which one is best. But yes you have to shut the truck off then after you have changed all the values turn it back on and clikc the write map to ECU button for it to take effect. Since I dont have a wideband sensor Im having it tuned in a week or two so we will see what kind of results I get.
 
#6 ·
BTW where in MA are you from?
 
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