Hi all!
I've seen so many posts at different forums that involve a plethora of Ford vehicles about the same or similar problems that I am experiencing with no clear answers, so here I am, back to the forum (at least I thought I was here at one time) for some expert advice!

I have a 2000 Taurus with the 3.0L Vulcan engine ("U" VIN code) and an automatic transmission (model unknown atm) in which I am troubleshooting a lean O2 sensor code. But, this is not what I'm asking about today, so hold on.

The Problem: While driving (especially downhill), if I put the shifter into "N" neutral say at 45mph, the engine will rev up from around 2000rpms +/- up to about 2200rpms and float up and down. As I gain speed down the hill, the engine speed will also increase along with it, still in "N" neutral, of course. At 55mph, it will rev to over 3000rpms, in "N" neutral, no "F" foot on gas and for no rhyme or reason! At rest, in "P" park, the engine idles at around 700-750rpms which is fine! What the "H" heck is going on here? I've spray-cleaned the mass air flow sensor, spray-cleaned the throttle body (had an Exploder once with a stuck throttle body from corrosion that spray-cleaning fixed), and did a throttle-body cleaner spray test around every intake joint that I could find including around the base of the manifold with no indication of engine stuttering. Beside the O2 sensor issue, this rolling neutral engine revving is just another thorn in my paw, as it were! I don't think it's a TPS issue, and I thought that the vacuum leak that I was so sure would be revealed with the spray test has evaded me once again! I hope somebody here can give me a solution to the revving issue and as a bonus, include one for the O2 sensor as well, I could possibly get another year or two out of my Taurus while looking for another Exploder! In the meantime, I'm off to build a smoke tester!

Thanks in advance for any help anybody can give.
Curt.

 

There is an unwritten rule as far as I believe, and that is, don't go looking for a solution for some distant problem until all the problems in plain view are corrected.

Soooo, what is the code you are presently getting regarding the oxygen sensor ?

Have you done anything to check this out, if so what, thanks.

 

Historically, code P0171 (O2 bank 1 too lean). General consensus indicated it was most likely a leaky intake manifold or parts on it (PCV, EGR, etc.). The last time I checked it (months ago or more), I reset the counters and waited for the check engine light to come on, which it hasn't. I don't drive it much but finally got back to it today after the misfire happened again (on the same hill!). I should have checked the codes again, but it was back together and drivable and I had other things I needed to do. I will get a current reading from the confuser tomorrow, and I'll post it then. I have also been getting a misfire consistently going uphill at 45mph at approximately 1/3 throttle and 3100-3200rpm, but no misfires ever gets recorded, and it never happens under any other conditions. More gas, slower or faster speed, or more or less throttle and it never happens. Just some strange things going on.
Code update coming tomorrow!
Thanks.

 

We can shoot in the dark or we could do a little detective work, but to do it right we should look at the data stream info and we don't know if that is available.

At this point it could an ign problem or fuel supply problem. The data stream would help a lot to prevent throwing parts at it.

 

Hanky, you are absolutely right. I need to learn to slow down and smell the gas fumes! My memory is failing me faster than I can remember!
I did a quick check this morning and got these readings.
P0113 – Intake Air Temperature Sensor 1 Circuit High Input
P0401 - EGR Flow Insufficient
P0102 - MAF sensor low.*
Not a lean code around! I think I'm disremembering it with one of my Exploders now. *Anyway, the MAF might have been low from running without it connected yesterday. The other two codes I don't know, but I'm guessing I might need a new EGR valve to start. However I'm skeptical this would cause the high idle on a rolling neutral. I cleared the codes and will have to drive it a bit to see when it will kick again. In any case, it looks like I have some work to do! First is to learn how to use this ODBII reader!
What should I try next? What kinds of test might I be able to do? I'm using an Astro AI ASIOS720, so I'm not sure what tests I can do. I was doing a datastream test, but the only thing I can recall is the fuel pressure @40.1, however I've already addressed my memory! I also wrote down a note "Evap leak test failed". I don't know where that came from!
Thanks!
PS. I found the attached on the reader from my 10 minute tinker with the car and reader with a "cold" engine this morning. It probably isn't much use, but it might show something. I will attempt to do a drive test and some other diags after the engine is warmed and driven this afternoon.

 

One check you can do , if nothing else, will verify if 2 sensors are right.

Before starting a cold engine, the ECT (engine coolant temp) and AIT (Air intake temp) should read pretty close to the same temp, do they?

 

Glancing at your txt file and reported conditions,

1. There are 3 areas of immediate concern, short term fuel trim is sitting at 99.2% (maxed rich enhancement), this could be a manifold leak or a faulty purge (reported),
2. and, AIT is not consistent with a running engine.. so as earlier advised , on a cold engine (morning) check that the AIT and ECT are similarly close to ambient temp)
3. and, reported miss fire on loaded engine (lean burn)

Do not ignore this condition as bad things may happen, (lean burn)

 

Thank you both for your input.

I took a trip to Lowes today to exercise the beasty and to get some stuff, and have attached another idle datastream to the thread. It wasn't my intention which was to do a driving stream, but other issues took precedence. Steam coming from under my hood in the Lowes parking lot confirmed what I was wondering as to an unknown source of an antifreeze smell. I had changed a leaky reservoir a year or so ago, and wondered if it might be a bad or misconnected hose, but just couldn't find anything leaking. As of now, I'm going with a water pump seal, so it looks like I'll be getting into a bigger can of worms here. I'll do the cold monitor tomorrow when it's good and cold and post the values I see, but for now, it's a water pump project. I don't know if you can see anything on this stream, but the pending code I got is pointing to the EGR again - P0401. I'm just wondering where to start on diagnosing it before tearing the intake off. Will removing the intake manifold make replacing the EGR easier? I didn't plan on getting into this much, but here we go!
By the way, the previous report I posted might be incorrect. It has the VIN of my F150, and although the temp readings were real close, they weren't what I observed at the reading. The reader won't read the Taurus VIN, I added the VIN to the top of the second report. Sorry for the confusion.

Thanks again for your help, and have a great day!
Curt.

 

Can you tell us if the vehicle does this any other time except when pulling that hill?

 

Before tearing any thing apart, why not start with a cooling system pressure test, followed by a smoke test of the intake.. The test equipment can be rented from some auto supply stores.