3.0 Still idles rough

[Blackedge03]

My '03 ranger 3.0 only has 46k on it. It runs great but idles a little rough. I replaced the MAF (it was bad,thanks Betomonroy) still idled rough. Replaced PCV,checked IAC (it's good),Checked everywhere for vacuum leaks, none found.
Checked the plug wires for arcing (in the dark)no sparks. Pulled a couple of the plugs they looked good,probably pull the others tomorrow but I bet they are good. Has a new air filter.Wondering about the TPS, I unplugged it nothing happened. How do you check it? I don't think I read that anywhere but maybe I missed it. Any help most appreciated.


Edit: Forgot to mention that I have no codes.

 

[Rearanger]

I checked my FSM but have just discovered that Ford does not include any component troubleshooting, diagnosis or adjustment information in the almost 4" thick manual. Thanks Ford There is a separate manual for diagnosis and specs; wonder how much Ford wants for that? Testing of other TPS was just an OHM test. I know that when I was troubleshooting the OHM test came out good but in the end the TPS was just replaced as last attempt and it fixed the problem. I'm not advising on replacement as it is probably expensive. Maybe someone else can give you test specs.

I went on the Auto Zone web site and searched out TPS. They give testing specs. You may have to register your name and vehicle and it did take some searching to find, but it's there.

 

[Blackedge03]

Thanks for the info. I will do some more research.To clarify,did you have a rough idle problem and replacing the TPS fixed it? I found a price of $35 at Oreilly's. I will gladly pay that to get rid of this annoying idle. Thanks again.

 

[Otto]

80% chance it is a vacuum leak but if everything looks good, I'd have to mention checking/cleaning the egr sensor. Mine got carboned up somethin nasty and I ran the whole winter with a bad egr. Should be a code, though. If not that, then probably a leak in the intake gasket which are hard to find. If you're sure the vacuum is good then I'd have to say fuel pressure regulator or fault in the fuel system.

 

[Blackedge03]

Thanks. Sure acts like a vacuum leak but I checked everywhere with no luck. I just checked the TPS voltage got .86 , I read where .98 or so is ideal but as long as not above 1.0 your good. I was going to try and adjust it but I can't get the screws out. I guess they didn't want it to move. Not sure about the egr sensor. Where would it be located. Thinking about new plugs and maybe fuel filter but it was supposedly replaced at 30k..



Edit Hayne's says 2002 and later no egr valve.

 

[Rearanger]

To clarify,did you have a rough idle problem and replacing the TPS fixed it?

Not on my Ranger, the TPS problem was on a Toyo.

I doubt fuel filter for rough idle, usually filter will show up for high load, high throttle. I wouldn't touch TPS yet, no reason for it to go out of adjustment. Plugs may be closer to problem but if you have original wires I would ohm test them or even replace as poor spark will cause roughness.

 

[Blackedge03]

I am going to replace the plugs and test or replace oem wires.Thanks for the advice.

 

[Otto]

Could possibly be a defective coil as well

 

[Blackedge03]

Put in a set of autolite double platinums. It seems like it helped a little but I still feel a little bit of a rough idle. I ohm tested the wires. They checked good. The 3 plugs on the driver side were worn(gap way over .06) the 3 on the passenger side were all good. The thing runs great and I just checked my fuel mileage and it is getting 22+ mpg,can't ask for better really out of a V6 truck.
I had an 2001 ranger 3.0 and it didn't idle like this truck. I was sure it would be something simple and it still may be, but I think I will have to take it to the dealership or another shop to resolve this problem. Either that or just live with it. Still open to any more suggestions though. Thanks all.

 

[Rearanger]

Maybe one of the injectors is not giving proper spray. Little Sea Foam in tank may help. Does the tac needle jump around at idle?

 

[dorman68]

Perhaps a compression test or a cylinder leak down test might reveal valves not seating properly.

 

[Blackedge03]

Tac does not move,tried some lucas injector cleaner in one tank,the idle seems a little better since I put the new plugs in yesterday but the roughness is still there.Thinking more that it might be a small vacuum leak that I just can't locate. I read about the dealer could do a "nitrogen leak test" and find any leaks. Anyone know about this?

 

[Rearanger]

Haven't heard about that but do know that smoke machines are used to find vac leaks. You can visually see where smoke is being sucked into engine. Maybe the nitrogen leak test is pressurizing the system then using smoke to see the leak?? I don't know why you couldn't plug the exhaust then pressurize at the intake? Let us know what you find out. Compression test was not a bad suggestion.

 

[Blackedge03]

It will be a couple weeks before I can get anything done.Might do a compression test myself. There can't be much wrong with this truck. It runs too good and gets good mpg.
Getting the feeling most people would just let it ride but I know it's not idleing right. Will post any results that I get. Thanks all for suggestions,etc.