Surging idle on a stock 5.0

[Anthony]

1986 was the year

5.0 was the ride

Now in 2018. The idle is surging


Stock 86 AOD mustang

Sometimes it don’t want to start cold. Then does.
Idles ok then surges and dies.
Sometimes it idles ok for 10min then starts surging and will die

TPS was @.007
Set it to .98/.99

Idled fine for 5-10 min then started surging again

Pulled iac, looked clean, sprayed it out anyway. Pulled the end off. Plunger was not stuck.
Ohm across the iac was 9.1.... I read that’s good

Each tab to the body should be 10k ohm but I’m getting OL

I read that is ok too

What’s next???

I have battery disconnected now, going to “reset” the idle rpm

 

[y2kr]

Had an 86 GT vert back in the day. Did kinda the same, bad FPR, through a gauge on the schrader valve.

 

[Anthony]

Looking for that adapter locally

No one has that shit anymore

 

[Beigg]

Fluid systems engineering on 14 mile in clinton twp might be able to source it.

 

[BrainFearGone]

What adapter are you looking for exactly? I might have something.

 

[Anthony]

It’s the fuel rail adapter

1/16 to 1/8 pipe I believe

 

[BrainFearGone]

Been a long time but thought I might have something in the junk drawer but no luck.

 

[mikesfastss]

I’ll check mine tonight when I get home, if I have it I’ll text you and we can meet up tomorrow or something.

 

[Anthony]

Been a long time but thought I might have something in the junk drawer but no luck.

Thanks for checking!

 

[Anthony]

I’ll check mine tonight when I get home, if I have it I’ll text you and we can meet up tomorrow or something.

My man!

 

[derbydad276]

vacuum leak ?

 

[mustangmike6996]

Vacuum leak, failing fuel pump, IAC

 

[Anthony]

Iac has passed all tests.

Searching for a rail adapter

Sprayed everything down

Can’t find a vac leak

 

[sidewayscoupe]

It’s that X cam causing your grief ;-)

https://lmr.com/item/LRS-9939A/1986...MI_cGR1pvP2gIVkLjACh3NHgjgEAQYASABEgLOGfD_BwE


Sent from my iPhone using Tapatalk

 

[sofa king]

You can get the 1/8 to 1/16NPT at Parker, or Exotic fittings. I actually just bought a couple last week, their about $12.50 each. If you need one I have a spare...
I'm talking the fuel rail adapter, I put the adapter on my rail to install a FP gauge to measure pressure.

I want to say someone used to make an idle air adapter/adjuster for the 5.0 as well. I don't recall who, but someone made a plate that would go between the IAC and allow more air to flow? Something like that...As you said, it's been a while.
Being that old, I've seen the throttle body shaft leak around the bushings. I've got a few 85/88/89 year 2.3T Fords, this is a big problem with them as well. See what happens if you spray some carb cleaner on the ends of the shaft with the car running, does the idle smooth out? If you can get to that before it dies.

 

[sofa king]

Shit, Dan posted the idle thingy from LMR...

I have the FP rail adapter, but Exotic in Farmington has them also.

 

[black88coupe]

I had one of these laying around for years. Damned if I know where it is now. [QUOTEhttps://lmr.com/item/LRS-9939A/1986...MI_cGR1pvP2gIVkLjACh3NHgjgEAQYASABEgLOGfD_BwE[/QUOTE]

 

[Anthony]

On a completely stock car. I can’t see where that would be needed. I sprayed all over the Intake..... I’ll focus on the TB tonight. It will start and run and drive. Just every now and then idle will drop to 500 rpm and sometimes die

 

[Beigg]

is it losing a crank signal?

 

[nitrousrick]

If you haven’t yet I’d also pull the tb off and clean it.(if the fp checks out)