Weak cylinder/injector #7

[dustybumpers]

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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[fordgirl]

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]

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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[fordgirl]

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]

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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[fordgirl]

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!

 

[fordgirl]

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]

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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[fordgirl]

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]

14.95 is ok. What does it do while your watching it and someone starts turning everything on?

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[fordgirl]

KOER: 14.4
+Radio: 14.4
+ac low: 14.42
+ac high: 14.38
+2k rpms: 14.38
+both windows: 14.29
+in drive: 14.22

 

[fordgirl]

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

I did run seafoam through, no improvements.

Thanks!

 

[fordgirl]

New coil is in, she still shakes.

So moving down my list of possibilities...I checked the voltage on my DPFE #1 circuit and I'm getting 0.68V at (cold) idle and 0.9V at 4.5 inHg when the engine stalls. Does the truck need to be warmed up to run this test?

If I follow the chart at https://www.stangnet.com/images/stories/docs/sn95_TSBs/97-22-01.pdf
it's way off.

So sounds like a new DPFE wouldn't be a bad idea?

(Truck has CA EGR system.)

 

[fordgirl]

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]

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

 

[fordgirl]

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.