2000 Windstar not accelerating

[olopezm]

Hello guys, My moms 2000 windstar with 84000 miles has started having problems, the mechanic has just rebuilt the transmission a week ago and I changed the oil, spark plugs and wires yesterday; my dad, my brother and I rebuilt the engine about 4.5 or 5 years ago because it overheated.

This morning the minivan was running fine, about 2 hours later of driving it, it wouldn't accelerate: the more you step on the gas the less it will accelerate. Since we were far from home we had to drive veeeeery slow... until we got home, during that time the CEL came on and I had it scanned the result is P0171 and P0174. I already read about the TSB regarding the intake manifold problem, my question is: Do these two codes necessarily mean I have to do the TSB? or can it be something else, like both oxygen sensors or a bad MAF?.

Thanks in advance for your help guys I really appreciate it.

EDIT:

The problem seems to be fixed by changing of the MAF sensor and the fuel pump, I would suggest to test the fuel pressure first just to make sure you don't waste money by buying both things, mine just dripped fuel when pressing the pin on the fuel test port instead of spraying it.

[serge_saati]

Normally a small vacuum leak at intake wouldn't cause this symptom.

But a very big vacuum leak or a bad MAF sensor can cause that. Cause the more you press on the gas, the more air enter in the engine. If the MAF doesn't meter all the air correctly, PCM will not give enough pulse to injector so they can't spray enough fuel, so the excess of oxygen reduces the power of engine since there's more compression w/o enough combustion.

Clogged injector and low fuel pressure can cause that too.

It doesn't sound like bad O2 sensor.

So first check if MAF tube's collar is properly tighten and air filter properly installed w/o leak. Then test MAF sensor operation with a multimeter.

Then finally test fuel pressure. See if the problem happen only at high engine temp or always.

[olopezm]

Originally Posted by serge_saati

Normally a small vacuum leak at intake wouldn't cause this symptom.

But a very big vacuum leak or a bad MAF sensor can cause that. Cause the more you press on the gas, the more air enter in the engine. If the MAF doesn't meter all the air correctly, PCM will not give enough pulse to injector so they can't spray enough fuel, so the excess of oxygen reduces the power of engine since there's more compression w/o enough combustion.

Clogged injector and low fuel pressure can cause that too.

It doesn't sound like bad O2 sensor.

So first check if MAF tube's collar is properly tighten and air filter properly installed w/o leak. Then test MAF sensor operation with a multimeter.

Then finally test fuel pressure. See if the problem happen only at high engine temp or always.

Hello thanks for your time and help. Actually as you mentioned the problem happens only at high engine temp, I started the engine this morning and revved it up and it works fine no problems. The air filter is OK I forgot to mention that I replaced it yesterday when the engine started to lack of power the old one was nearly dark gray in color and it was slightly smaller than the right one; the one I put fits tight in there it is the right size.

How should I check the MAF sensor and what pressure should I expect from the fuel pump?.

Thanks in advance for your help.

P.S. I already changed the fuel filter too.

[serge_saati]

To check the MAF sensor, you should ask Winswind or 12Ounce for pinout, since my service manual finish at 1998 model. Here's the procedure:

1) disconnect the MAF harness connector
2a) Measure resistance between signal and GND of MAF pins (should be limited)
2b) Mesure voltage between GND and B+ of MAF harness
3) Turn key to ON
4) You should have ~12.3V
5) Reconnect the MAF harness
6) With a metal needle, spear the signal and GND pins of harness and the measure the voltage at the 2 needles. You can also use needle probe for that.
7) Turn on engine, at 750rpm you should have 0.5-0.7V
8) Increase rpm up to 3500, it should increase to about 1.5-3V
9) The more you rev up, the more voltage should increase

Fuel pressure spec:
key on: 35-45psi
idle: 28-45 psi
engine off after 5 minutes: 30-40psi

[olopezm]

Thanks again, I wonder if this is the pinout you were talking about:
MAF pinout

Also I found somebody else seems to have the same problem, it is quite weird to find someone else has the same problem at the same time! I will put attention in case he gets it fixed by changing the fuel pump.
http://www.automotiveforums.com/vbul....php?t=1023466

[serge_saati]

That's right. It's the good pinout for you van.

pin 1 is the signal
pin 2 is B+
pin 3 is GND

[olopezm]

Hello again, I cleaned my MAF it seemed to be a bit dirty, after cleaning it the small wires were shiny again. I tested the fuel pump pressure and the result is.... 0 psi?. It is pretty weird but it's true, I was thinking that I might had connected the gauge the wrong way so I tested it on m lincoln town car with the same type of valve and it reads fine, so once again the fuel pressure on the windstar is 0 PSI, I pushed the small pin in the fuel valve to see if the fuel spray but it only drips out, there doesn't seems to be enough pressure to make the gauge to raise, however the van still starts and revs fine, I don't think it might be a blocked fuel filter since I already changed it. Is it actually possible to get this 0PSI reading and the van still starts?. Also when the van was running I noticed a humming sound, like a DC motor which seemed to be revving up, this sound lasted for about 1-2 minutes and then stopped. I tried to see where the sound was coming from but it could be heard from everywhere (the front, the back and even inside the van). Do you think the small filter inside the gas tank is blocked and that caused the humming?.

I have found that the catalytic converter is dripping, here are some pictures of it. Could this also cause the DTC's?. What else could this dripping cause?

Thanks for your help...

[IMG][/IMG]
[IMG][/IMG]
[IMG][/IMG]

[serge_saati]

Normally it shouldn't start if there's no pressure. It requires a lot, a lot of fuel pressure to start a 3.8L engine. It's pretty misterious.

About the humming sound, maybe it's the motor of the fuel pump, I'm not sure.

About the water under the catalytic converter, it's not important. It's just condensation, probably a bad downstream O2 sensor that monitor catalytic efficiency. It doesn't affect engine performance, only monoxyde emission.

[tomj76]

The fuel pump is supposed to run for 2-3 seconds when you first turn the key on, before you attempt to start the engine.

The fuel pressure (~40 psi) should be maintained for several minutes after the pump shuts off. If not (intially high but bleads dow quickly), there is a leak. The leak could be the check valve in the pump, an injector, or the fuel pressure regulator, or a hose leak. If it's never high to start, then the pump is bad, or there is a blockage. Logical places to look for blockage are the fuel filter and the inlet screen on the pump.

I think you should resolve the fuel pressure reading you're getting. This could be an indication to the cause of the symptoms that you see.

[olopezm]

Originally Posted by tomj76

The fuel pump is supposed to run for 2-3 seconds when you first turn the key on, before you attempt to start the engine.

The fuel pressure (~40 psi) should be maintained for several minutes after the pump shuts off. If not (intially high but bleads dow quickly), there is a leak. The leak could be the check valve in the pump, an injector, or the fuel pressure regulator, or a hose leak. If it's never high to start, then the pump is bad, or there is a blockage. Logical places to look for blockage are the fuel filter and the inlet screen on the pump.

I think you should resolve the fuel pressure reading you're getting. This could be an indication to the cause of the symptoms that you see.

Thanks for your help, I will check everything later today or tomorrow morning. This morning I turned on the van and it works fine, I was maneuvering to make some space for the other car when I put the van in neutral and the started reving up, it was doing about 2000-2500 RPM's, could this indicate maybe a MAF problem? I haven't tested it yet, just cleaned it, I will test it soon.

[serge_saati]

There's one quicker way to see if the MAF is the problem.
Disconnect the MAF sensor harness and turn on your engine. Do a VERY short test drive. It'll run in default mode with the data of throttle sensor. If it run much better, the problem is the MAF (which I doubt). If it's worst, the problem is not the MAF.

[olopezm]

Thanks for your help. I did what you said but it takes some random time for the van to start to "starve". I'll be changing the fuel pump tomorrow, since it is cheaper to replace it than the MAF I will give it a try, since the van has 84000 miles on it, it shouldn't hurt to change it; hopefully this will be the solution just like in this other thread:
Runs great...

I will post back the results ASAP.

[olopezm]

I've just finished replacing the fuel pump after all day laying on my back under the van... LOL. I couldn't take it for a test drive but so far I can tell that the engine isn't as noisy as before with the old pump; could this be true?

Also the RPM's used to be higher about 1500-2000 RPM's more or less and now it's on the line of 1000 RPM's. I pushed the center pin on the fuel test port and the fuel actually sprays fuel unlike the dripping with the old pump. I will post back tomorrow with the test drive results.

Just to make sure: the P0171 and P0174 TSB shouldn't cause the van to stop accelerating like mine did, right?. I'm asking just to be sure that I don't need to take off all the upper part of the engine.

Best regards...

[serge_saati]

Originally Posted by olopezm

I've just finished replacing the fuel pump after all day laying on my back under the van... LOL. I couldn't take it for a test drive but so far I can tell that the engine isn't as noisy as before with the old pump; could this be true?

Yes, when I replaced my fuel pump, the engine become more quiet and more steady too. Because the fuel pressure is more constant. And it started more quickly and easily.

Normally, the RPM should be steady at 750 after idling 30sec or less, depanding of engine temperature. Or immediatly if the engine is enough hot. 1500-2000 was too much.

No the TSB 171 & 174 doesn't cause the van to stop accelerating. It can cause small lack of power, unstable idling (500-750rpm) under engine load (A/C compressor), small reduce in fuel economy. But it should still run fine with just this TSB.

[olopezm]

Well you were right buddy, the van runs much better with the new fuel pump but after a few miles of driving the RPM's were behaving erratically and the van had a slight shaking while waiting at a red light with the gear on D, if I changed to N or P the RPM's would go all the way to 2000-2500 so I drove with the MAF disconnected and the engine ran a bit better I decided to buy the MAF for once and for all and the result is the van runs great now, the RPM's are just like you said in the line of 750 when idling. I guess I had a combination of both fuel pump and MAF going bad.

Thank you very much for your help serge_saati, hopefully this will be the last post regarding a problem in this thread.

P.S. I saw a kit for repairing holes in the whole exhaust system, do you think it would be good to fix the small hole in the catalytic converter?