Running Rich Rough Idle pls HELP

[2000StreetRod]

small diameter MAF sensor

My 2000 stock MAF sensor had a diameter of 55 mm. It is very likely that the Taurus MAF sensor has a smaller diameter and if so that would definitely cause the engine to run rich. The smaller diameter MAF sensor would register higher air mass flows and the PCM would increase the injector pulse width accordingly. What is the diameter and part number of the Taurus MAF sensor?

 

[glenn_a]

Today I took it for drive again and see what else i can find on this issue...

First i had a look at the plugs again and it seems normal, then Im thinking if I could hook up my original Computer and see if it will make any differenc...
i took it for a drive within a minute the Explorere begun to play hesitate (it feel like the power from the high tension lead were leaking on and off) then I replaced the computer again then went okay but after 30mins it started again...
Im thinking every thing i have change made only small difference but it seems i cannot pin point where the prroblem coming from... ;(

yesterday sisnce i installed the other new double platium plug the Explorer lasted almost 2hrs with no problem... but now the problem comes earlier...

when ever I drive the Explorer and drive it under 2000rpm then soon i stop at the light the idle goes down to 500rpm back and forth to normal idle...
soon i drive off then it hesitate till i rich 2500rpm and when i try to rev harder and over 3000rpm then it feels it cleared the problem but soon i slow down the back to the problem again....
got home and looked at the exhaust it seems its running rich, it blows little black smoke and smell rich too...

dont know what else to do, pls give me more point what and where to check...


PLS NEED MORE HELP...

 

[glenn_a]

My 2000 stock MAF sensor had a diameter of 55 mm. It is very likely that the Taurus MAF sensor has a smaller diameter and if so that would definitely cause the engine to run rich. The smaller diameter MAF sensor would register higher air mass flows and the PCM would increase the injector pulse width accordingly. What is the diameter and part number of the Taurus MAF sensor?

The Taurus Air Flow Meter number was... F6DF-12B579-DB

sorry i cant remember the original number off the other Air Flow Meter, I left it at work...

 

[2000StreetRod]

What year Taurus?

I just did a little internet searching and learned that the 3rd generation (1996 - 1999) Taurus SHO had a 3.4L V8. I doubt it would have as much airflow as your 4.0L SOHC V6 and probably has a smaller diameter MAF sensor. The other models of Taurus in that generation have even smaller engines. The MAF sensor is the primary sensor for computing engine load. If the MAF sensor characteristics do not match the PCM stored tables then there will be all kinds of weird problems. Why did you replace your stock MAF sensor?

 

[2000StreetRod]

F6df-12b579-db

That MAF sensor was used on the 1997 & 1998 Taurus 3.0L DOHC V6. I bet it's smaller in diameter than your stock MAF sensor. According to what I've found your stock MAF sensor was F57Z-12B579DA.

Edit: I reread your original post that states you replaced the MAF sensor because of a P1000: MAF Sensor Intermittent and that you also replaced the PCM. Did the replacement PCM come off a 1997 SOHC V6 or did it come off a Taurus?

 

[Dave 1955]

Didn't the sho have a yamaha motor at one point?

 

[glenn_a]

That MAF sensor was used on the 1997 & 1998 Taurus 3.0L DOHC V6. I bet it's smaller in diameter than your stock MAF sensor. According to what I've found your stock MAF sensor was F57Z-12B579DA.

Edit: I reread your original post that states you replaced the MAF sensor because of a P1000: MAF Sensor Intermittent and that you also replaced the PCM. Did the replacement PCM come off a 1997 SOHC V6 or did it come off a Taurus?

about the diameter of MAF not really 100% sure but i will double check and yes when i got the OBD code P1100 MAF Sensor Intermittent then I replaced the MAF but the since i double checked again the P1000 (OBDII System Checks Incomplete) still there and my electrician says i need to replace my Computer, which I did a day after the MAF sensor...

The PCM came off from Ford Explorer 1997 V6 SOHC, i made sure it has same serial numbers....

 

[kindred4x]

I still want to lean towards the maf sensor or circuit that is causing your problems. From experience, research and watching others a bad maf, wrong maf, different size housings, or messing with the sample tube can cause the strangest running conditions. I heard you mention a electrician, maybe you two can check the actual wire harness for proper voltage and grounding, then having a ford taurus sensor might be the issue also.
I am thinking that a bad wire harness that could be pinched, damaged could cause a intermittent code(p1100) due to the electrical circuit might have just enough left in the conductor to send signals back to the pcm. I see bad circuits all the time working on HVAC equipment from wires rubbing together till raw, or loose wire nuts that make the circuit sometimes and sometimes not.

 

[glenn_a]

I still want to lean towards the maf sensor or circuit that is causing your problems. From experience, research and watching others a bad maf, wrong maf, different size housings, or messing with the sample tube can cause the strangest running conditions. I heard you mention a electrician, maybe you two can check the actual wire harness for proper voltage and grounding, then having a ford taurus sensor might be the issue also.
I am thinking that a bad wire harness that could be pinched, damaged could cause a intermittent code(p1100) due to the electrical circuit might have just enough left in the conductor to send signals back to the pcm. I see bad circuits all the time working on HVAC equipment from wires rubbing together till raw, or loose wire nuts that make the circuit sometimes and sometimes not.

true my friend! but sisnce I put the Taurus MAF then the OBD code disappear no more codes beside the P1000 but still cant work it out i have already replaced the computer but the P1000 still there...
Im thinking maybe something faulty makes my computer play up and i may check the MAF again or just get another new one from ebay. Explorers parts here in Australia is very difficult to find or very expensive...
On some cars I worked on the quickest to check if the MAF sensor is faulty is to just unplug it then if it shakes or about to stall then its working but if did not make any difference well its faulty, but this one is when ever I unplug it it kinda run better but few seconds its back to normal as in still have the hesitate when ever I accelerate... I only rely on my OBD scan but since I replaced it to Taurus MAF the faulty code is gone...

 

[glenn_a]

I think the car does run rich and thats is why it hesitate soon I accelerate from stand still and when I'm driving over 3000rpm and its all good...
I think It does flood the system but cannot work out why it does not have a faulty code for the Oxygen Sensor....
I only took the engine out to fix the sump leaks and replaced the spark plug while the engine is off (but wrong plugs) and this all happened..
I replaced the plugs and replaced the MAF sensor then I replaced the Computer but still the same ;(

 

[glenn_a]

I may have to get a new parts as I always want to buy this from before, what would you guy's recommend;

PERFORMANCE COIL PACK
PERFORMANCE HIGH TENSION LEADS
PERFORMANCE FUEL PUMP

 

[2000StreetRod]

test the MAF sensor

I strongly suggest testing the MAF sensor before purchasing any more parts: MAF Sensor Test Procedure

If the voltage readings are significantly greater than those listed the engine will run rich. If the voltage readings are significantly less than those listed the engine will run lean. The P1000 DTC is probably due to a broken or frayed wire or a bad electrical connection. Wiggle the wires around and see if the voltage readings change. Push and pull on the connector and see if the voltage readings change.

Edit: I thought you took the engine out to fix the timing chains. You mentioned using the 4USA kit in post #25 of your Xlt explorer custom_s 1997 thread.

 

[glenn_a]

I strongly suggest testing the MAF sensor before purchasing any more parts: MAF Sensor Test Procedure

If the voltage readings are significantly greater than those listed the engine will run rich. If the voltage readings are significantly less than those listed the engine will run lean. The P1000 DTC is probably due to a broken or frayed wire or a bad electrical connection. Wiggle the wires around and see if the voltage readings change. Push and pull on the connector and see if the voltage readings change.

Edit: I thought you took the engine out to fix the timing chains. You mentioned using the 4USA kit in post #25 of your Xlt explorer custom_s 1997 thread.

I will check it out that MAF test procedures and yes i was thinking about maybe theres a wire problem causing to show that P1000....

2000StreetRod, I did that timing chain long time ago but this time only the sump need to be re-seal...

 

[rocketcouch]

if you tap on the egr valve and it smooths out a bit then the valve is sticking

 

[glenn_a]

if you tap on the egr valve and it smooths out a bit then the valve is sticking

Thanks mate, I will.try that one soonni get back from Family Holiday... thanks guys!

 

[glenn_a]

2000StreetRod & kindred4x here's the reading i got from my MAF (air flow meter):

(light blue/red wire) on RED
(tan/light blue wire) on BLACK

00.1mv OFF
16.2mv Ignition ON
.943V idle @ 850rpm
1.200V @ 1,000rpm
1.630V @ 1,500rpm
1.920V @ 2,000rpm
2.130V @ 2,500rpm
2.370V @ 3,000rpm
2.000V @ 3,500rpm
2.450V @ 4,000rpm

just noticed the voltage dropped when its on 3,500rpm... its totaly off the chart but cannot understand why all the sudden, I only took the engine out and re-fitted back?
Previously soon i got the code then i replaced the MAF then the code disappeard...
and why the reading is off the chart but never got a single code from the scanner?


2000StreetRod quoted:

A nonfunctional mass air flow (MAF) sensor can significantly degrade engine performance. The PCM utilizes the MAF sensor output voltage to determine engine load which is used to adjust the air/fuel ratio during acceleration. The typical engine performance symptoms caused by a dirty or defective MAF sensor are lack of power and hesitation during acceleration. The MAF sensor element wires become dirty with age and become contaminated from excessively oiled air filters. Cleaning the element with MAF sensor cleaner should be performed frequently and often will cure MAF related engine performance issues.

Testing

With the MAF sensor electrical connector connected backprobe the sensor signal (light blue/red wire) and the sensor return (tan/light blue wire) at the connector.

Connect the positive lead of a voltmeter to the sensor signal and the negative lead to the return.

With the parking brake set and the gear selector in Park start the engine.

Monitor the MAF sensor output voltage while increasing engine speed. The voltage should increase smoothly with no dropouts as the engine speed increases. Listed below are representative values.

Voltage/RPM

0.8 @ 500
1.0 @ 1000
1.25 @ 1500
1.4 @ 2000
1.55 @ 2500
1.65 @ 3000
1.9 @ 3500
2.1 @ 4000

 

[glenn_a]

MAF sensor on Ebay...

http://www.ebay.com.au/itm/300810852182?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

Spark Plugs...

http://www.ebay.com.au/itm/121142602051?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1438.l2649

is this okay?

 

[2000StreetRod]

MAF sensor test results

Your test results indicate two things to me. Your installed MAF sensor is smaller in diameter than stock causing higher voltage readings which fools the PCM into "thinking" the engine load is greater than actual. Installing the correct size MAF sensor should correct your over rich condition. The other thing is that your MAF sensor has an unusual reading at 3,500 rpm. My test results are for my engine without VIS which shortens the intake runner length when the engine speed exceeds 3,000 rpm. However, with no load on the engine (transmission in Park or neutral) I can't see how shortening the intake runners would decrease airflow thru the MAF sensor as engine speed increases. There could be turbulence in the vicinity of the sensor at that airflow, the sensor could be dirty, or the unit could be defective. In any case, you need to replace it with the correct size unit.

What happened to your old, stock unit? If still available, I suggest installing and testing it before purchasing another one.

The MAF sensor listed on ebay linked in your post is an aftermarket unit and should probably work. I did some searching and apparently OEM stock replacements are no longer available. Perhaps because they had a metal housing. My MAF sensor housing is some type of composite material. Around 2000 the IAT sensor and the MAF sensor were integrated. The previously unused outside pin on each side of the 6 pin connector were added for the IAT sensor connections. My stock PN is XF2F-12B579-AA because pins E and F are utilized. It should have the same flow characteristics as the earlier SOHC V6 stock MAF sensor and the connector should fit. There just wouldn't be any wires/pins for the IAT sensor. Here's a link to a remanufactured unit that should also work: 97 98 99 00 Ford Ranger Explorer Mercury Mountaineer Mass Air Flow Sensor Reman
According to the fitment table the OHV & SOHC V6 and the V8 all used the same MAF sensor. Here's a link to a used one like mine: 99 00 01 02 03 04 05 Ford Explorer 4.0L MAF Mass Air Flow Meter XF2F-12B579-AA99 00 01 02 03 04 05 Ford Explorer 4.0L MAF Mass Air Flow Meter XF2F-12B579-AA The price is cheap however with your shipping being so expensive you probably should purchase a new or remanufactured unit.

I still suggest waiting on the spark plugs until you solve your MAF sensor problems but those should work fine. You could actually only buy three and replace the ones currently in bank 1 (I think but have to confirm) with the new ones singe you currently have the single platinums in both banks.

 

[glenn_a]

here's the difference from the Taurus MAF and Explorer MAF....

 

[glenn_a]

it seem the Taurus MAF and Explorer MAF I have has almost same measurements except the number printed on the Top Sensor... would this be an issue still...?