1990 Ranger 2.9L V6 Auto, Idle way too low (500 rpm)!!

[Atlantis]

Ok I'm really worried about my truck, which I've had since winter. She starts great, drives fine, and used to idle at a steady 1000 rpm when the weather was cold, but idles terrible now that the weather's starting to get warmer. When I stop at a light or a sign or whatever, she idles at about 7/800 for a few seconds, then drops way down to 500, and it feels ready to die. The rpm comes back up after a little bit to 550/600, but that doesnt feel right either! In neutral it's supposed to run at 850, but it's a little bit lower than that. Can someone tell me what's wrong? Does the extra spring in my gas pedal have anything to do with it?

[Atlantis]

I also get like 15 miles to the gallon. If that helps.

[Atlantis]

Ok, maybe I should have done more research before freaking out! It might just be my fuel filter! HA!

[Atlantis]

Just replaced it, she's running smoothly... we'll see.

[Psychopete]

Originally Posted by Atlantis

Just replaced it, she's running smoothly... we'll see.

Strange, I can't make the connection that your fuel filter would make your MPG worse.. In all it would be running too lean, not too rich. Let me know how it turns out. I think you've either got a FPR going bad or a sensor going amuck.

[Atlantis]

Well, I was horribly wrong, because its still doing it. Someone I talked to before suggested it was the temperature sensor... like, its loose, or something? Whats an FPR and how do I fix it?

[Psychopete]

Originally Posted by Atlantis

Well, I was horribly wrong, because its still doing it. Someone I talked to before suggested it was the temperature sensor... like, its loose, or something? Whats an FPR and how do I fix it?

Lets not jump to conclusions yet . I am sure you need to get this going again, but you can take it to a shop and wait and get a big old bill, or you can test for things and ultimately save money.

A FPR is a Fuel Pressure Regulator. I apologize for abbreviations.

Take the vacuum line off of the FPR. If fuel exists then the FPR is shot. It's located near the fire wall, drivers side, on the fuel rail. Round thingy with a vacuum line coming out of the back, kind of a pain to get to, but it's really close to where the brake booster connects to the upper intake plenum.

Perhaps it could be the temperature sensor, however, if it were loose, antifreeze would be leaking everywhere . Maybe they were suggesting a loose plug? This sensor contributes to the air fuel mixture.

If the FPR vacuum lines doesn't have fuel, the next step would be to scan the codes.

You need to locate the ECC-IV self test connector. Passenger side, under some fuse thing or air box or something, I don't know, I have an 88 that's been modded all to hell and doesn't have any emissions and has a custom air setup, and I can't remember how it was stock. It's a trapaziod shaped plug with another smaller square plug labeled 'STI'.

I hope this looks ok..
On the trapizod shaped plug:

2 connections on top
- - -----> STI
- - - -
(I think 4 on the bottom, I can't remember off hand..)

You need to get a piece of scrap wire and make a jumper from the small square STI plug to the upper right connection as shown above.

Get into the cab and turn the ignition on 'run' and watch the check engine light.

You computer should spit out a series of codes that can be translated. Here's how it spits them out..

garbage ... (b) ...... (b) ... (b) ...... (b) ... (b) ...............

This would mean the system is OK.

garbage ... (b) ...... (b) . (b) ... (b) . (b) . (b) ...... (b) . (b) ... (b) . (b) . (b)

This would be a code 23. The system should repeat codes. I usually write the blinks and the amount of time waited so I can process the information I recieved at my own pace. Gets a little hairy sometimes when you get a lot of codes. Try it a few times, you should see the pattern. This is the easyist / cheapest way to find a sensor problem. If you have any issues, I would recommend getting the Hayes manual for details on this test. The diagram they give you is much more involved because they throw in an analog voltmeter. Let me know what you find.

Pete

[Psychopete]

Originally Posted by Atlantis

Well, I was horribly wrong, because its still doing it. Someone I talked to before suggested it was the temperature sensor... like, its loose, or something? Whats an FPR and how do I fix it?

Also, how are your spark plugs looking?

[Atlantis]

I have no idea. I do, however, have a guy coming over tomorrow who will check some of this stuff out with me. Thank you in advance, because you just saved me a bunch of money.

Also, I was reading online about a possible problem with soot/oil buildup in the throttle body. Something with vapors carrying it all back there. Can this be checked too?

[AlThums]

Soot and/or carbon buildup in the throttle body should be easy to check. I have a 3.0, so the setup is different on mine, but you should be able to check your throttle body and spray it out with Gumout (or whatever) like a carburetor.

[Atlantis]

I am very thankful for all your help. Unfortunately, more was wrong with my truck than I thought. My IAC, my water pump (coolant started leaking everywhere!) , AND my ignition coil all need to be replaced.

Oy. So I'll get my hands on some parts and take care of this.

But yeah, I know where I'm coming from now on for help. Thanks, guys!

[Psychopete]

Originally Posted by Atlantis

I am very thankful for all your help. Unfortunately, more was wrong with my truck than I thought. My IAC, my water pump (coolant started leaking everywhere!) , AND my ignition coil all need to be replaced.

Oy. So I'll get my hands on some parts and take care of this.

But yeah, I know where I'm coming from now on for help. Thanks, guys!

Ouch, were you able to determine this from scanning the computer for codes? Be careful not to over heat that engine. The heads are easily crackable. A leaking water pump will certianly cause over heating! Just watch for anti-freeze in your oil, or greenish/yellow snot/sludge on you oil cap. Sometime moisture causes sludge, so watch out for that as well.

Pete

[Atlantis]

The leaking wasnt determined by the codes, rather by the puddle of stuff in front of the truck. But its real slow for now (I know, I know, it still needs to be taken care of) and my temp gauge has never even made it to halfway. Hopefully that's not faulty too. The shop I took it to afterward wanted 200 bucks to put a new punp on, plus 80 for the pump itself. I would rather wait and have my uncle do this... next week... I don't even know where the darn thing is!

[Psychopete]

Originally Posted by Atlantis

The leaking wasnt determined by the codes, rather by the puddle of stuff in front of the truck. But its real slow for now (I know, I know, it still needs to be taken care of) and my temp gauge has never even made it to halfway. Hopefully that's not faulty too. The shop I took it to afterward wanted 200 bucks to put a new punp on, plus 80 for the pump itself. I would rather wait and have my uncle do this... next week... I don't even know where the darn thing is!

I was wondering if you found out that the IAC was shot and the coil by scanning the codes. Obviously you computer can't tell if you're leaking antifreeze.. Coils usually last a long time.. My 88 is running on the coil that was made with the truck. If a coil is bad it won't only affect 1 single cylinder. The IAC is cleanable, but usually it's just a good idea to just get a new one one.

Water pump is kind of a pain, you need a tool to get the fan clutch off. Or a pair of huge channel locks and a huge wrench, but the small V6 fan clutch tool works better. The stock temp gauge in the 88 up can't be trusted. If it does overheat on the gauge it's usually too late. I paid $450 for new after market heads alone. The only way to fix is to get new heads. You can tell if you have water in your oil. Usually it's a blown head gasket or cracked head.

Pete

[Bulldog Brewer]

Where can I buy the vacuum line that runs from the intake over to the fuel pressure regulator?

DGB
New Brunswick, Canada