Misfire issue on stock 4.8 with external FP setup.
01-08-2017, 05:59 PM
#1
Misfire issue on stock 4.8 with external FP setup.
Mentioned this in my build thread, but figured maybe I can get more help in this section.
The entire fuel system on the truck is brand new with the exception of the FPR, which I kept from the previous system. System is now setup in the following manner:
20g Summit fuel cell
100 micron pre filter
DW350iL pump
10 micron post filter
Aeromotive 13109 FPR 12" after the above post filter mounted on bed frame (Vacuum reference hooked up from intake manifold)
-8an return to cell from FPR at bed rail
-8an feed to billet rails
Stock injectors
E-fans programmed
Everything else on the truck is stock, down to the air filter. Below is a scan after I installed the new FP, which fixed my previous fuel pressure issues. It is now dialed in at 58psi idle. Then here is a scan after I took the truck for a 1mile drive down the road. This was a slow cruise, I did not beat on it at all in that mile. Truck ran great until I took it for a short drive... I was charging my laptop when I took the truck on maiden voyage, so I do not have a log of the drive.
Truck was driving with no misfires prior to getting hauled down to my new home in TX. When it arrived, the FP was struggling keeping pressure. That is why I replaced the pump.
Plugs were replaced within 10miles (which was actually in May, but truck has sat in storage). Wires are new, not arching on anything. I have Siemens Deka 60's new in the box waiting to install if I need them for T/S.
Thoughts?
The entire fuel system on the truck is brand new with the exception of the FPR, which I kept from the previous system. System is now setup in the following manner:
20g Summit fuel cell
100 micron pre filter
DW350iL pump
10 micron post filter
Aeromotive 13109 FPR 12" after the above post filter mounted on bed frame (Vacuum reference hooked up from intake manifold)
-8an return to cell from FPR at bed rail
-8an feed to billet rails
Stock injectors
E-fans programmed
Everything else on the truck is stock, down to the air filter. Below is a scan after I installed the new FP, which fixed my previous fuel pressure issues. It is now dialed in at 58psi idle. Then here is a scan after I took the truck for a 1mile drive down the road. This was a slow cruise, I did not beat on it at all in that mile. Truck ran great until I took it for a short drive... I was charging my laptop when I took the truck on maiden voyage, so I do not have a log of the drive.
Truck was driving with no misfires prior to getting hauled down to my new home in TX. When it arrived, the FP was struggling keeping pressure. That is why I replaced the pump.
Plugs were replaced within 10miles (which was actually in May, but truck has sat in storage). Wires are new, not arching on anything. I have Siemens Deka 60's new in the box waiting to install if I need them for T/S.
Thoughts?
01-09-2017, 07:02 PM
#3
I meant 58psi at idle, as that is what it is still showing/set to. If this is too high, I can easily adjust.
Though when I was thinking about it, I believe my pressure was dropping after key on prime. I am going to go key on and see how quickly it drops, to see if the FPR is possibly having issues...
Though when I was thinking about it, I believe my pressure was dropping after key on prime. I am going to go key on and see how quickly it drops, to see if the FPR is possibly having issues...
Trending Topics
01-10-2017, 07:51 PM
#8
Going to pull the fuel filters next, just to humor myself and ensure they still look new and there isnt debris from the previous faulty pump...
Any other suggestions? Maf appears to be functioning properly via the scans. Miffed as to why is idled and ran perfect until it went down the road one block...
Any other suggestions? Maf appears to be functioning properly via the scans. Miffed as to why is idled and ran perfect until it went down the road one block...
01-13-2017, 05:45 PM
#9
Couple quick notes:
Cylinder 7 is the only cylinder that hasnt misfired through all of this. Cly 2 is a close second with only a couple. All other cylinders are basically misfiring at will.
Noticed my ignition voltage was lower on my scan today, like dipping into the 12's. An hour after shutting the engine down, the Alt was still hot as hell. An hour after that, still hot. So the alt is coming out for an HO. Now that I have e-fans, probably better to upgrade it anyways.
All that being said, the alt going out will not fix the misfiring issues. Pulled a couple plugs, just had a fuel smell and slightly wet, what I expected. No other signs of anything. Still at square 1. Going to pull the new fuel filters tomorrow if I have time to check them out.
Cylinder 7 is the only cylinder that hasnt misfired through all of this. Cly 2 is a close second with only a couple. All other cylinders are basically misfiring at will.
Noticed my ignition voltage was lower on my scan today, like dipping into the 12's. An hour after shutting the engine down, the Alt was still hot as hell. An hour after that, still hot. So the alt is coming out for an HO. Now that I have e-fans, probably better to upgrade it anyways.
All that being said, the alt going out will not fix the misfiring issues. Pulled a couple plugs, just had a fuel smell and slightly wet, what I expected. No other signs of anything. Still at square 1. Going to pull the new fuel filters tomorrow if I have time to check them out.
01-20-2017, 01:17 PM
#10
Well, said F it and ordered an LKQ 5.3 for the truck. Figured I can install everything on the stand, mount it to 80e, and drop it all in at once.
I did install the new Alt, currently waiting for the battery to charge and going to fire it up to see if anything changed. I will keep the 4.8 and build for another project that I have down the road.
I did install the new Alt, currently waiting for the battery to charge and going to fire it up to see if anything changed. I will keep the 4.8 and build for another project that I have down the road.