Poor Idle is driving me crazy!

No, I don't believe it is the only possibility, just the most common one.
You could also have a sensor reporting the wrong data to the ECU , a wiring issue (as Patrick suggested) or a problem with the ECU itself.

 

I should mention that I've used the propane method in the past, on OLD vehicles. Eg, carburetor vehicles with no emissions or O2 feedback. The propane method works extremely well in that scenario

 

Doh! You never said that before. Now the ECU goes to the top of the list IMO. But rule out the vacuum leak anyway.

 

I always enjoy when posters dole out information a bit at a time. It makes diagnosis much more fun, almost like a good crime mystery.

Tom

 

:doh:

I need a drink .... and my liver is already the size of a basketball

 

Have you tried disconnecting the MAF? That's the easiest way to troubleshoot the device. When disconnected, the engine ECU should switch to a default fuel map, and should run well.

If that happens, the MAF is bad. If it still idles like arse, it's something else.

 

+1

The OP earlier asked how to get his car to pass emissions control testing, knowing he has an impaired engine ECU. If the ECU can't provide +5VDC, how can it control idle speed?

This is almost like asking how to make a car run without a functioning transmission.

 

Thinking about this a little more: if you have supplied an external 5v reference, how do you know that its referenced correctly in the ECU? You could have an offset and that would throw off any sensors (e.g. MAF) that depend upon an accurate 5v reference.

 

But they were good batteries when he put them in. Maybe the dropping resistor was too large?

Tom

 

Actually that comes up every day on the Ford Explorer forum :madgrin:

 

Just keep flooring it. The transmission will eventually "catch" and go into gear. Or, you'll grenade the transmission. Either way, problem solved

 

Actually that's just the beginning of the problems:

98 Auto Transmission PROBLEM! HELP! - Ford Explorer Ranger Enthusiasts Serious Explorations

He has more trouble than I can deal with:

My reply:

I see at least half a dozen bad transmission posts a day. A lot of them have already had it rebuilt at least once.

 

Hey Jason,

I sold my 1997 Ford Explorer XLT 5.0L V8 AWD w/4 speed automatic overdrive at 95K miles, in mid-2005 after I bought the HiHy. The transmission had been solid up to that point, absolutely no issues. Do you find that drivetrain combination has lots of reported problems?

 

No, the V8 is paired with the 4R70W which is a much stronger transmission. Those seem to be relatively bulletproof. The 4.0L V6 got the bad transmission(s).

The 1st gen Ex (91-94) had the A4LD (which was based on the C3, a Pinto trans). Those transmissions fail regularly.

The 2nd gen (95-96) got the 4R55E which is an electronically controlled A4LD. They were upgraded to be a little stronger, but are failing rapidly now. From 97 - 01, they used the 5R55E, which has another gear between 1st and 2nd, making it a 5 speed plus some other upgrades to make it a little stronger. I have 119k on mine, but I see that a lot of them fail before that.

The 3rd gen (02+ ) with IRS uses the 5R55W which is sealed without a dipstick. Apparently Ford believed that they had improved the design enough that regular checking of the fluid level and condition was not necessary. Apparently they were wrong, because I am seeing more posts on failed 3rd gen transmissions as time goes on.

 

Reminds me of the debacle GM had when they went to the 700-R4 (Remarkably weak and unreliable), or Ford with their first AOD in the LTD (Hit the brakes hard on the highway, brakes lock up, overdrive won't disengage, motor stalls, power steering quits, crash, etc), or how about those flimsy transaxles in early to mid 1990's Dodge minivans.

The car makers have known how to build solid and reliable automatic transmisions for over 40 years. GM had the TH350 and the stump-pulling TH400, Ford had the C6, and the Ford C5 was ok, Chrysler had the 727. These were fairly simple transmissions, as far as automatics go, and with somewhat routine servicing would last a long, long time

 

I ran across another sad story this morning:

Newbie Needin Some Guidance - Ford Explorer Ranger Enthusiasts Serious Explorations

It is actually kind of amazing: Ford can build decent transmissions as evidenced by some of the other models, but for the Explorer, they can't seem to extract their cranium from their poop hole. I guess that the transmissions usually make it through the warranty period, and that is all that matters to management. My understanding is that Ford will soon stop production of the truck based Explorer and replace it with a crossover type SUV.

 

"Cranium in poophole" That would be a good Truth In Advertising jingle

 

I can't think of anything to rhyme it with. Maybe Stev0 can work it into a jingle.