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[Primosboy]

Been driving an explorer around for a couple years. Did the Rubicon in it. Stock axles and gears, no lockers. Made it all the way in and out with no breakage. Fun rig but was time to get back into a Ranger, so I picked up an 87 for 500 bucks. Almost like my first truck the red 87 stx.
After changing out the old gas, cleaning injectors and every part of intake system, running sea foam through system and in fuel, replacing iac and map.. It runs strong. Only thing is it idles at 2500 to 3000 rpms. Can't get it down. Tried tweaking the timing and looked through all the vacuum lines bunch of times. Sprayed starter fluid near anywhere air can get in. No change. Can't figure this thing out. Any ideas?

 

[bobbywalter]

Vacuum leak bad iac...or wirong

 

[Primosboy]

Vacuum leak bad iac...or wirong

New iac, new pcv, new map, checked all the lines over and over..

 

[Uncle Gump]

Something isn't right... it sure seems to be bypassing air around the throttle plates. Does the IAC move in and out... like with key on and key off?

I check for vacuum leaks using propane. Search "smoke test" and you should find info to check for leaks using smoke.

 

[bobbywalter]

Is iac wiring working?

I would pull it off and plug the holes or choke it down at the forward iac inlet hole with your finger....

 

[Primosboy]

I just put the iac in. Unplugging it after it's warmed up brings the idle down but not much at all. Maybe to like 1800. Temp sensor seems to be working fine. This might be another clue, but when i rev it, it takes a good 5 to 8 seconds for rpms to come back down to regular high. Tps?

 

[Bracket racer]

1) See if the eng temp switch is working( engine might be thinking it's cold, fast idle) and that's different from your gauge.
2) Check to see if the computer is getting a signal that says you're putting it in gear.( clutch in at idle, put shifter in gear and rpm jump for a few seconds)
Or..3) pull the big vacuum hose off the booster and plug it. It might be sucking air through a torn diaphragm.

Start there.

 

[Primosboy]

Found it. Was the rearmost plenum gasket. back half is missing. Put some good ol duct tape on the seam until I get the gaskets. Dropped right down to 800 rpm.

 

[bobbywalter]

Well....that is what is known as a Vacuum leak.


Cheapest gauge you can buy....worth a million.

 

[Dirtman]

Good work. Have a cheeseburger.

 

[bobbywalter]

I found it.

 

[Primosboy]

Well....that is what is known as a Vacuum leak.


Cheapest gauge you can buy....worth a million.

I have two. Ha. Never used them.

 

[bobbywalter]

See.

 

[Dirtman]

Thats the first tool I bring out when there's a mysterious engine problem and no obd2 port...

 

[Primosboy]

So after some more gaskets and one freeze plug between the engine and tranny and new exhaust. I've got it running and driving good. I am getting a slight sputter when I let of the gas. I mean slight. I did not replace the tps yet but I'm thinking that or possibly an injector.