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Weak cylinder/injector #7

dustybumpers

don't play well w others
I can't find the one I used to use. This is on Amazon
Couldn't get it to link to this site, hope screen shot works.

I would also try some sea foam in the tanks
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I cleaned the IAC without any improvements. I ran the truck with it unplugged and the truck ran slightly worse. IAC is showing 30-40% at idle and operating temp, is that high?

Throttle shaft/cable looks pretty worn, but the plates look ok.

I think next up I'll try the fuel injector cleaner.

Some additional readings I got:
MAF: 0.9V
Fuel pulse width: 3.2-4.2ms (I think this is high?)
Short term FT bank 1: -1 to 1%
IAC: 30-40%

Thanks for the help!
 

dustybumpers

don't play well w others
Almost acts like fuel pressure regulator. Does the vacuum line smell like gas when you pull it off?

What does the iac do when you kick the a/c on?

What does it do when you unplug the maf while running?

What does it do if you unplug the maf vacuum line and thumb over it then bump up the throttle?

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No gas smell on FPR vacuum line, and it increases by 10psi when I pull it.

IAC increased from 46 to 52% when I cranked the AC.

I unplugged the MAF and it ran about the same with the additional trait of idle hunting. MAF was reading 1.2V with fuel pulse width 1&2 at 4.5ms.
 

dustybumpers

don't play well w others
So that is all normal. No vacuum leaks. I would clean the fuel rail, then if still having a problem do a compression check.

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Well that’s some good news! I guess I need a canister kit to go through the rails, so I’m starting with a tank one and will try to find a kit.

Thanks!
 
So still no improvements, but I did notice something else that might help: when I first start my truck, or first come to a stop at a light, the truck idles ok for about 10-15secs. After that it starts shaking and that continues to worsen the longer I sit. There is also heavy pinging/tapping. Because of that, I feel it is still a build up of (or lack of) air/fuel. I’m going to take the EGR valve off and see if I can blow air through it without vacuum, maybe it’s not closing all the way? The valve does hold vacuum, so it looks like the pintle is good. I’ve also read of bad ignition coils causing similar issues?

Dusty, I think I can get my hands on a compression tester also if you’re still thinking I should check compression.
 

dustybumpers

don't play well w others
I thought you had already changed the coil a while back. I'd go for that. Coil break down inside can be very contrary.

I'd also think about putting a volt gauge on it see if your getting some feedback from your alternator

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The coil is 5 years old, but you know these new parts!

The battery is reading 14.95V +/- .02V with engine on. Is there a better way to test it or should I just take it to NAPA for a bench test?
 

dustybumpers

don't play well w others
14.95 is ok. What does it do while your watching it and someone starts turning everything on?

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dustybumpers

don't play well w others
So the alternator diodes are working properly. Try cleaning where the coil sits in its bracket make sure it has a good ground.
Not sure after that , did you run some seafood through the tanks yet?

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I’ll check coil ground and if that does nothing, I’ll order a new coil.

I did run seafoam through, no improvements.

Thanks!
 
Can someone explain why I need a mod kit to put a stock motorcraft DPFE sensor on my truck? I'm very confused. Did motorcraft change their design after the orignal sensor?
 

dustybumpers

don't play well w others
Missed the other post. Not able to use the phone anymore

The wiring harness changed. Not sure when/ what model. Pretty sure if your luck is like mine you will need the kit if you dont order it
 
Missed the other post. Not able to use the phone anymore

The wiring harness changed. Not sure when/ what model. Pretty sure if your luck is like mine you will need the kit
Thanks Dusty! I’m going to replace and start a new thread summarizing everything. My issue has completely changed from the title of this thread: weak cylinder/injector #7 was resolved with new plugs and wires.
 
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