truck wont command pulse width?

onebaddmaxxx

Active member
Feb 22, 2009
1,212
1
38
Cecil County Md
Ok so quick run down I was at the track last night and when i first got there i ran my first 11 sec pass, so i started messing with the tune and upped the pulse width some because I was still holding good rail psi. A quick rundown on the fuel system....the truck has 100% injectors and a stock cp3. I know most are gonna say thats stupid and insane but when my motor was down i bought a set of injectors that were "supposed" to be 60%s and it got messed up with another customer and i ended up with someone elses 100s basically. But didnt know it until they were already in. So my 11 sec run last night was on a 2118uS. It was set to commanding 2200 and 190mpa but wouldnt make it. The truck was still holding 23,000~ psi the whole time. I tried playing with it both ways to see if it would pick up any E.T... It does make 190mpa though. All the limiters are raised up to 4400rpm. Its the same tune from when I had stock injectors and 45%s and I never had a problem getting my commanded pulse width. The whole time im on the floor in the logs it stays at 124-125mm3. Iv went over the tune multiple times looking for anything and cant find any limiter that would stop it from trying to make what i command. So on the way home i tried commanding a 2500uS and sure enough it still stops at 2118uS. Is there some kind of duty cycle im maxing out here from having big injectors/stock cp3 that is preventing my injectors from being open any longer?? Thanks for any help.....
 
Last edited:

slipclutchms

Member
May 24, 2010
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I would highly recommend backing down pressure to 18x mpa. At 190 your a couple thousand psi away from maxing the rail pressure sensor out. So if you have a race valve and spike the rail pressure there is not much " buffer zone" . iirc the rail pressure sensor maxes out at under 30k psi. Around 29xxx.
 

slipclutchms

Member
May 24, 2010
427
0
16
No it shouldn't....you did say your fuel command was moving around a bit.... Depending how the tune is setup it could be pulling your pulse width down. Check the pedal position to torque tables and see how they relate as far as fuel command. Then go to the pulse table and see if it is moving between a few cells.
 

onebaddmaxxx

Active member
Feb 22, 2009
1,212
1
38
Cecil County Md
It stays at 775 ft lbs the whole time, stays at 124-125mm3 the entire time. I will send log over later. This same tune used to run a 2500uS with 45%s and a 3218uS with stock nozzles.