Slight miss

[Salty Dog]

Hey yall,

When I'm cruising anywhere from 50mph and up I can feel a slight miss every 3-4 seconds. You can barely feel it, but it feels like something is holding the car back for a brief moment. It's like a slight pause. It's not that bad, but the wife and I can feel it. I was hoping as I replaced and cleaned things here and there it would fix itself, but so far no luck. Here's a lists of things I've done so far.

Motorcraft copper plugs/wires
Air filter
Fuel Filter
Fuel pump relay
Motorcraft cap/rotor
2 Vacuum lines from under the intake
1 Vacuum line from the vac tree to brake booster
Motorcraft TPS
Thoroughly cleaned the IAC
Thoroughly cleaned the Throttlebody
Fuzzy Dice

Any thoughts on what I should look at next? I thought maybe I should get a new IAC, but I don't feel the miss on idle. Just when cruising at 50 and above.

[jaywish]

Did you use the red OEM Ford style dice? The white, green or orange always gave me similar problems.

[jaywish]

for experimentation, cruise with OD locked off. 3rd gear. That will focus on an overdrive issue. Plus it is easy.

[Salty Dog]

Damn it! I used the white Chinese crap from amazon

[Salty Dog]

I don't ever use the overdrive because the transmission screws up. I only drive in D

[DerekTheGreat]

Fuel pressure verified? MAP sensor any good? Does it do it when cold? How about dem 02 sensors? EGR got gunk in it and not opening correctly?

On a side note, Ashley's 89 used to throw the check engine light every now and again and it threw some weird code. It wasn't until the intake gaskets shit the bed and were replaced that the problem went away.

[Salty Dog]

1. Fuel pressure not verified. How can I do this?
2. Map sensor not tested. Don't know how to test this either.
3. Haven't check the 02 sensors. Not sure where they are at really.
4. I haven't messed with the EGR at all to this point.
5. I haven't ran any codes.

[Salty Dog]

I guess I'll start at the top of my list. Thanks Derek for the suggestions btw. I just watched some a couple video's on testing the fuel pressure. I'll see if I can pick up a tester at the autoparts store on the way home. I don't have the car with me so I can't look right now, but where is the best place to hook up the gauge? I can't remember seeing a schrader valve. Once it's hooked up, what's the pressure reading supposed to be at?

[Salty Dog]

https://vimeo.com/185729834

Sent from my iPhone using Tapatalk

[Salty Dog]

It read 32lbs
When I hooked up the the gauge it read 10lbs.
After I primed the pump the gauge still read 10lbs.
When I started the the car, it was still at 10 but slowly built up pressure to 32lbs. The idle was going up and down until it settled in.


Sent from my iPhone using Tapatalk

[HiFiMerc]

I had a miss just like that years ago with my '90. Turns out a plug wire had shit the bed.

[Tiggie]

Should be 35-45psi KOEO. Your running pressure is on the low side but within range 30-45psi. Unplug the vacuum to the fuel pressure regulator - should get 40-50. Or maybe the gauge is suspect.

[sly]

If the fuel pressure takes a while to build up, either the regulator is buggered, the fuel filter is almost clogged, or the pump is buggered. I'd wager on the fuel filter first since it's cheap.

[Salty Dog]

Shouldnt the pressure rise all the way when I prime it?


Sent from my iPhone using Tapatalk

[Salty Dog]

Fuel filter replaced about 3k miles ago.


Sent from my iPhone using Tapatalk