Hi.

I am brand new to the forum. I have a 2003 Ranger extended cab, 4.0LV6, auto, red, with 110,000 miles on it. I bought the truck new in 03 and have never had a single problem with the truck.

Recently, I have run into a problem.

When i start the truck, it idles rough, for around 3-5 minutes, and then it stalls. Within this 3-5 minute period the idle slowly drops until the truck simply stalls out. If i keep my foot slightly on the gas until the truck has warmed up, it will run without stalling. If i try to drive it cold, it eventually stalls out. I have changed the plugs not to long ago, I do most all of my own maintainance and I am stumped what is causing the issue.

I did figure out a few small things however:

If I turn the AC on after starting the truck, it runs much better, and I can drive it, even cold.

If I unplug the mass air flow sensor, the idle immediately kicks back up and the truck idles great. However, if I drive it like this, it kicks hard when it shifts, so I dont drive it with the harness detached from the MAF sensor. Soon as I plug the sensor back in, the problem returns.

I suspect the MAF, but also heard it could be other issues, and unplugging the sensor could just be masking the problem by sending a pre-set air/fuel mixture.

Has anyone experience this problem? Where should I start? I was going to clean the MAF, and then possibly replace it, but I am not sure thats the true problem at all.

Anyone have any information?


Thanks.

 

Welcome to FTE.

Well I see you've been busy on your trouble shoot.

You may have more than one problem.

I first suspected the IAC, until you got to the part about it idling Better with the A/C on!!!!

So it seems right now from your test, that you have a corrupt MAF PID signal to the computer for some reason.

Could be a wiring, or corroded connector contact problem, dirty, or bad MAF sensor, or bad ref voltage from the computer, or maybe even a umetered vacuum leak, or fuel trim problem.

Do you have a CEL lit???? If so, there are trouble codes stored in the computer. Even If the CEL isn't yet lit, you could have pending codes stored that could offer up good trouble shooting clues, so have it scanned for trouble codes & post ALL of the code numbers found.
If you don't have a code reader, or scantool to scan the computer, most autoparts stores will do it at no charge.

If you've modified your air intake system, or if you have a faulty fitting or damaged air box, or air filter, or are using an oiled foam or cotton gauze air filter, it may have contaminated & corrupted the MAF sensors heated air flow grid calibration & it's PID & confused the computer about true air flow into the engine.

If you determine that the MAF is likely dirty, it can be removed & cleaned with a spray cleaner who's non residual recipe is just for cleaning MAF sensors, like CRC MAF sensor spray cleaner.

You could also have a fuel trim or vacuum leak from something like a stuck PCV valve, or leaking vapor recovery vacuum line, or maybe given the mileage, even an O2 sensor problem.

So give us some more maintenance feedback & get the computer scanned for trouble codes & lets see what clues turn up that could help all of us make a better guess as to whats wrong.

A whole bunch of thoughts for pondering, let us know how it goes.

 

I do have a check engine light, forgot to mention that. I have actually had the light since about 70,000 miles. For all i know, there could be a brand new code thrown associated with the problem, and I would have never known because the light has been on for so long. I don't have a scan tool, but I will take it to an autoparts store and have them scan it, and hopefully can figure out where its comming from. I'll keep you posted.

 

Ok, So I grabbed a can of MAF sensor spray cleaner, removed the MAFS, sprayed it well a few times, re-installed it, and problem solved.

I cannot tell you how happy I am with this truck, 110k, and its going strong, no issues and no major repairs.

I do all my own regular maintanance but I constantly work this truck to the limit. I own my own business and constantly use this truck at max bed payload. Often beyond the max.

I could not be more pleased with this thing. My last two pickups were an 86 toyota 4x4 and a 94 toyota tacoma 4x4, and I moved to this Ranger simply because They want blood for Toyotas today, I got a great deal on the Ranger and it has been worth every penny. I will definately buy another one.



This truck is great.

 

OK, good find, fix & feedback & to hear your problem seems to be fixed with so little effort, mine never seem to be!!!!! lol

Would be interesting to hear which MAF sensor cleaner you used.

NOW, you need to inspect a little further & determine WHY the MAF sensor got dirty & fix it, so the problem doesn't return!!!!
Look through my above list of common causes & see if any apply.

 

I have the can of MAF cleaner out in the garage, I will get the brand later for you.

As far as how it got dirty, I am not sure. I will tell you that the vacum or large return line that is just past the MAF unit, often pops out, leaving a hole in the air intake ducting. I have to get a little clamp one of these days to get it to stop popping off. MAYBE thats how it got dirty, but then again, like I said that is down past the MAF, so it doesnt pull dirty air past the MAF.

 

The hose that pops out sounds like it's the fresh air breather hose for the PCV system, so when it's loose, the engine is inhaling unfiltered air two ways, so thats sure not good for the engine, especially if it's dusty where you drive.

I suppose if this hose were loose for a period of time you could get back streaming that could get to the MAF sensor.

Usually it's the air box damaged, or not properly buttoned up, air filter sealing gasket, oiled foam, or cotton gauze air filter, or modified air intake that gets them dirty.

Anyway I'd sure attend to the breather hose & get it fixed pronto.