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still running rough after engine install. HELP :/

  • Thread starter Thread starter JMD Engineering
  • Start date Start date Aug 8, 2006
J

JMD Engineering

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Aug 8, 2006
#1
  • Aug 8, 2006
  • #1
im going to make this as short and simple to follow. I installed an RNH 347. Its crank is set for the REGULAR 5.0 firing order (1-3-7-2-6-5-4-8). my stock 93 lx 5.0 computer is running the HO firing order (1-5-4-2-6-3-7-8). So initially, it was running off of 4 cylinders due to the fact that 4 cylinders coincide (1,2,6,8) between both firing orders. After talking to a few techs at my work, they all agreed that since it is sequencial injection - I should be able to switch the pins in the injector harness so that the 4 cylinders that DIDNT match up (3,4,5,7) in the HO firing order would parallel the correct order in the REGULAR (switched 3 with 5, 4 with 7 - and so on). It seemed to run OK upon doing that.. but still rough. So for ****s and giggles, I switched the firing order (but left the injector pins how they were) and it seems to run better on the HO firing order...

all i can say is HELP. i dont know what to do from here.
 

jrichker

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#2
  • Aug 8, 2006
  • #2
A.) You are wrong about the firing order The cam determines the firing order, not the crank. HO & 351 use a different firing order from the non HO engines.
HO & 351W 1-3-7-2-6-5-4-8
Non HO 1-5-4-2-6-3-7-8

You need an A9L or A9P computer to match the firing order. Do not use a non HO computer and move the injector pins around in an attempt to correct. See http://fordfuelinjection.com/index.php?p=92 for more information.
 

bullitstang1313

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Aug 8, 2006
#3
  • Aug 8, 2006
  • #3
Just curious, but what happens when you run the non H.O. firing order with an H.O. ECM? Does it matter?
 

Rick 91GT

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Nov 29, 1999
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#4
  • Aug 8, 2006
  • #4
J, did the new injectors show up?

That FTI custom cam is a H.O firing order, same goes for your stock EEC you need to use the 1-3-7-2-6-5-4-8 FO
 

Rick 91GT

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#5
  • Aug 8, 2006
  • #5
bullitstang1313 said:
Just curious, but what happens when you run the non H.O. firing order with an H.O. ECM? Does it matter?
Click to expand...

Usually it will start and run, sound like a .600ci Pro Stocker and have no bottom end at all, but in the upper rpms it may run OK. It will also get little to no gas mileage.
 
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