1987 Ranger 2.3l Idle issues.

[ljones]

I've started having idle issues with the ranger. When starting the truck it idles around 1500RPM and if I rev it a couple of times it will go down to around 1000RPM with the AC on. With the AC off its just under 1000RPM. It only idles a little while until it starts surging several hundred RPMs it eventually dips down so low it dies. I replaced the IAC with in results and all intank gaskets are new. What would cause this?

 

[ljones]

Could worn out injectors cause this? I've herd this from several people. My MPG is about 15-18 mixed driving and it has a weird power band similar to a 2-stroke dirt bike. They are all original with 152,xxx miles.

 

[ljones]

What the stock injector flow rate?

 

[tomw]

Stock injector flow rate possible is more than you'll ever need. The MAP sensor will fiddle with idle injector flow rate, and likely full power flow rate. If messed, the flow will wander all over the place.
The idle is supposed to increase a smidge when the A/C is engaged to compensate for the load.
I'm do not guarantee that you have a MAP, but think so. It is a small box with a three wire connector and a vacuum line directly to the intake manifold. On the firewall, or near the box / cover over the EGR solenoids on the passenger side inner fender.
If the idle is flaky, you can try disconnecting the MAP wires and the idle may settle as the computer will then 'know' the MAP is gone .. literally, so it will substitute its table values as a 'limp home' fix.
tom

 

[ljones]

I unplugged the MAP with no improvement and also replaced it with no improvement. It has random "good" days where it will idle around 900 with the A/C on and 800 with it off. Every morning when I start it after sitting all night it runs all the way up to 2,000 RPM and slowly works it's way down to around 1,300. Any more ideas?

 

[scotts90ranger]

Mine did odd things when I had a vacuum leak (mine was the lower intake manifold gasket was broken in a few places missing some pieces)

Other than that, what speed does it idle at with the IAC unplugged? it should be around 500rpm, if it's closer to 1000rpm I suspect a fairly severe vacuum leak that the IAC is confused about, if not, look at the idle set screw and see if it's been monkey'd with, if so screw it in until the idle is around 500rpm with the IAC unplugged.

 

[ljones]

Dead on 500RPM with IAC unplugged. It's a little shaky but it does it. All intake gaskets are new.

 

[scotts90ranger]

any trouble codes? if you don't know how to get the codes, go HERE and follow the analog volt meter method, I don't think your year has a check engine light, but if it does you can ignore the volt meter part and watch the check engine light, if you don't have a check engine light or a volt meter, use a test light...

How many miles on this guy?

 

[tomw]

How about a coolant temperature sensor going out of order. That would tell the computer that the 'cold' high idle speed was needed even after warmup. The IAC is working in that the idle will change based on temp and demand (A/C compressor), but not totally as expected.
tom

 

[ljones]

My truck has 152,xxx miles. It also has a CEL but my test port looks nothing like that.

 

[tomw]

The OBD-I test access connector is under the hood, inside or under the removable plastic cover near the starter relay. I think it is red in color. It looks like the STO in the picture at the link.
tom

 

[ljones]

That is my test port. It's not under the hood. It's on top of the trans hump in the cab.

 

[scotts90ranger]

No, the test port on Ford's is under the hood until they went to OBDII, it looks like in the link I gave. The ones in your picture are for something else that your truck didn't have, like a center console or something

 

[Mark_88]

I had one under the hood as Scott mentioned...I think it had EEC-IV stamped on it...

There are many articles on this, but I found this video that might help you locate it...

 

[ljones]

I don't have one under the hood. That's it. My dad used it when he had it. He didn't remember which pins to jump.