FCC2 and pwm setting
I've got my PWM set at 40 per the suggestion in the members section, running a 30001 system with a FCC2. Today while taking my test drive after switching to HEI ignition (other threads in tuning section), after about 20 miles under very light throttle, my afr would go to 18-20+, like it was starving for fuel. If I gave it more throttle (probably 1/4 throttle or more) it would come out of it and run properly. This was a consistent issue, I could do it every time, and I was 20 miles or so from town so I got it to go super lean and basically die probably 50 times in that distance. Pulled into a restaurant and had dinner for an hour or two, came out and on the way home it ran like a top, although I was in town and it was only a 3 mile drive home. Is it possible I need to increase the PWM for the FCC2? Is that 40 setting for the original FCC, and the 2nd version might need more? Thanks for your time.
Oh, I'll add I gave it throttle and revved it a few times in park once I got to the restaurant and it seemed to free rev fine.
Quote from 1972Mach1 on September 21, 2019, 7:33 pmI've got my PWM set at 40 per the suggestion in the members section, running a 30001 system with a FCC2. Today while taking my test drive after switching to HEI ignition (other threads in tuning section), after about 20 miles under very light throttle, my afr would go to 18-20+, like it was starving for fuel. If I gave it more throttle (probably 1/4 throttle or more) it would come out of it and run properly. This was a consistent issue, I could do it every time, and I was 20 miles or so from town so I got it to go super lean and basically die probably 50 times in that distance. Pulled into a restaurant and had dinner for an hour or two, came out and on the way home it ran like a top, although I was in town and it was only a 3 mile drive home. Is it possible I need to increase the PWM for the FCC2? Is that 40 setting for the original FCC, and the 2nd version might need more? Thanks for your time.
Try increasing it to 70 or more, and drive it again under the same conditions just as a test. It is an easy test that you can do on the fly with the handheld.
PWM is correct. Your issue is most likely heat soak. This is the biggest problem with FCC.
Quote from Austin DeHaas on September 22, 2019, 4:06 pmPWM is correct. Your issue is most likely heat soak. This is the biggest problem with FCC.
Was only about 65 degrees out and I didn't drive it very far (20 miles) when this happened, it's certainly been driven a few hundred miles farther in the 90+ degree weather and also in stop and go traffic in the heat with no issues like this. I also wrapped my headers on that side of the engine compartment during the HEI swap over, so I'm not with you on the heat soak issue. I put the PWM at 70 and drove similarly yesterday without incident, but I'm not 100% sure that's the fix. I'm too leary to drive the truck very far after getting towed home a few times, so I'll keep giving 20-30 mile drives and hopefully it stays good like yesterday.
Just got off the phone with Hyperfuel after I emailed them 1/2 hour ago (imagine that, a company that promptly gets back to you!), and he told me I need to have the PWM set at the 74.5 that comes from the factory. Setting the PWM at 40 is for the original FCC, but the FCC2 requires 100% pump run time. Neither one of us is positive that this is the issue as it should have affected it at more rpm/throttle positions and not just low settings, but I'm going to try it anyway. Hopefully that works. But, anyway, good info for those with the FCC2 to keep your PWM set at factory spec of 74.5.
Quote from 1972Mach1 on September 23, 2019, 1:11 pmJust got off the phone with Hyperfuel after I emailed them 1/2 hour ago (imagine that, a company that promptly gets back to you!), and he told me I need to have the PWM set at the 74.5 that comes from the factory. Setting the PWM at 40 is for the original FCC, but the FCC2 requires 100% pump run time. Neither one of us is positive that this is the issue as it should have affected it at more rpm/throttle positions and not just low settings, but I'm going to try it anyway. Hopefully that works. But, anyway, good info for those with the FCC2 to keep your PWM set at factory spec of 74.5.
How is this working out for you now '72? Did it sort your issue?
I did wonder about that PWM setting at install/set-up. Instructions seemed to be referring to the original FCC. Fitech neglects to sufficiently update guides and tech info generally. Glad you got confirmation. I've flicked my setting back to 74.5 as I had the odd stall and/or threat of a stall when coasting to a stop and IAC steps were dropping slowly to zero. I'll wait and see if it helps.
Quote from whollsee on November 7, 2019, 5:18 pmQuote from 1972Mach1 on September 23, 2019, 1:11 pmJust got off the phone with Hyperfuel after I emailed them 1/2 hour ago (imagine that, a company that promptly gets back to you!), and he told me I need to have the PWM set at the 74.5 that comes from the factory. Setting the PWM at 40 is for the original FCC, but the FCC2 requires 100% pump run time. Neither one of us is positive that this is the issue as it should have affected it at more rpm/throttle positions and not just low settings, but I'm going to try it anyway. Hopefully that works. But, anyway, good info for those with the FCC2 to keep your PWM set at factory spec of 74.5.
How is this working out for you now '72? Did it sort your issue?
I did wonder about that PWM setting at install/set-up. Instructions seemed to be referring to the original FCC. Fitech neglects to sufficiently update guides and tech info generally. Glad you got confirmation. I've flicked my setting back to 74.5 as I had the odd stall and/or threat of a stall when coasting to a stop and IAC steps were dropping slowly to zero. I'll wait and see if it helps.
Yes, the fcc2 should be at 74.5. The information provided was for the original FCC.
Try disabling your DFCO to remedy the stalling problem when coming to a stop. Raise enable temp to maximum, essentially disabling it.
Quote from Austin DeHaas on November 13, 2019, 12:03 amQuote from whollsee on November 7, 2019, 5:18 pmQuote from 1972Mach1 on September 23, 2019, 1:11 pmJust got off the phone with Hyperfuel after I emailed them 1/2 hour ago (imagine that, a company that promptly gets back to you!), and he told me I need to have the PWM set at the 74.5 that comes from the factory. Setting the PWM at 40 is for the original FCC, but the FCC2 requires 100% pump run time. Neither one of us is positive that this is the issue as it should have affected it at more rpm/throttle positions and not just low settings, but I'm going to try it anyway. Hopefully that works. But, anyway, good info for those with the FCC2 to keep your PWM set at factory spec of 74.5.
How is this working out for you now '72? Did it sort your issue?
I did wonder about that PWM setting at install/set-up. Instructions seemed to be referring to the original FCC. Fitech neglects to sufficiently update guides and tech info generally. Glad you got confirmation. I've flicked my setting back to 74.5 as I had the odd stall and/or threat of a stall when coasting to a stop and IAC steps were dropping slowly to zero. I'll wait and see if it helps.
Yes, the fcc2 should be at 74.5. The information provided was for the original FCC.
Try disabling your DFCO to remedy the stalling problem when coming to a stop. Raise enable temp to maximum, essentially disabling it.
Thanks Austin. Yes saw your DFCO recommendations elsewhere on forum. Will maybe get a chance to test proper this coming weekend.
So here’s a hypothetical for you...I have the GS 400 which apparently has a 43 psi reg due to the injectors and the FCC2 has a 58 psi reg. Could one swap the regs on the units thus having the fcc2 provide the preferred fuel pressure to the GS 400? The 58 psi reg now on the TB of course is disabled by the closed off return port there. Worth a crack or a big waste of time? I know you are not a huge fan of the sump pump units generally but humour me!
Quote from whollsee on November 13, 2019, 5:02 amQuote from Austin DeHaas on November 13, 2019, 12:03 amQuote from whollsee on November 7, 2019, 5:18 pmQuote from 1972Mach1 on September 23, 2019, 1:11 pmJust got off the phone with Hyperfuel after I emailed them 1/2 hour ago (imagine that, a company that promptly gets back to you!), and he told me I need to have the PWM set at the 74.5 that comes from the factory. Setting the PWM at 40 is for the original FCC, but the FCC2 requires 100% pump run time. Neither one of us is positive that this is the issue as it should have affected it at more rpm/throttle positions and not just low settings, but I'm going to try it anyway. Hopefully that works. But, anyway, good info for those with the FCC2 to keep your PWM set at factory spec of 74.5.
How is this working out for you now '72? Did it sort your issue?
I did wonder about that PWM setting at install/set-up. Instructions seemed to be referring to the original FCC. Fitech neglects to sufficiently update guides and tech info generally. Glad you got confirmation. I've flicked my setting back to 74.5 as I had the odd stall and/or threat of a stall when coasting to a stop and IAC steps were dropping slowly to zero. I'll wait and see if it helps.
Yes, the fcc2 should be at 74.5. The information provided was for the original FCC.
Try disabling your DFCO to remedy the stalling problem when coming to a stop. Raise enable temp to maximum, essentially disabling it.
Thanks Austin. Yes saw your DFCO recommendations elsewhere on forum. Will maybe get a chance to test proper this coming weekend.
So here’s a hypothetical for you...I have the GS 400 which apparently has a 43 psi reg due to the injectors and the FCC2 has a 58 psi reg. Could one swap the regs on the units thus having the fcc2 provide the preferred fuel pressure to the GS 400? The 58 psi reg now on the TB of course is disabled by the closed off return port there. Worth a crack or a big waste of time? I know you are not a huge fan of the sump pump units generally but humour me!
Not sure why I hadn't seen this post. My apologies. 58psi will not hurt the unit. You can try your theory, but not necessary.