Stumped!

[82Stang]

96 Ford Taurus 3.0L plain jane...

It has been acting up during the warm season. My mom has had this problem where the car will start to cut out and not want to run. With the gas peddle mashed to the floor it will die out. It seems as if it is getting hot only during the warmer times and will act up by dyeing out and acting as if it were losing power. Any hill or incline is out. She had to pull over and wait then it would go again for a little and the same happened repeatedly.

I tried a few things and noticed this. I have already replaced the coil, plugs, wires, EGR valve and solenoid, and just now the Trans relay solenoid and I did notice this. In nuetral, I revved up the engine. It cut out at 4000 rpms. Is there a rev limiter for this? I drove it around the block and mashed the gas, and at about 3000 or so rpms it was cutting out and dieing. Once I let up, it was better, but pushing the gas resulted in the same. It has only done it now that there is warm weather. Never did it all winter. I have racked my brain with this thing and can't figure it out. Any ideas are so much welcomed.

It runs ok under no load, which I would think is a coil, but already replaced that. The rev limit thing has me interested. Never had a car do that before at 4k. What am I missing here?

[tripletdaddy]

From what I understand, there is an electronic no load rpm limiter to prevent damage to the engine. Have you changed the fuel filter recently? Sounds fuel related. Measure the fuel pressure at the fuel rail pressure valve before and after the filter change to see if it meets spec. Does the pump sound any louder than before? It may be failing.

You talked about it getting hot having something to do with your problem. What makes you think it's hot and being hot has to do with the problem? Or as you said, this seems to be outdoor temperature related or at least wasn't a problem until the warmer weather came. This would be somewhat consistent with a failing fuel pump as it will be operating at a higher temp and that tends to accelerate its failure, and on its way to failure, the heat will slowly bind up the pump so that it no longer delivers the needed pressure.

[82Stang]

Originally Posted by tripletdaddy

From what I understand, there is an electronic no load rpm limiter to prevent damage to the engine. Have you changed the fuel filter recently? Sounds fuel related. Measure the fuel pressure at the fuel rail pressure valve before and after the filter change to see if it meets spec. Does the pump sound any louder than before? It may be failing.

You talked about it getting hot having something to do with your problem. What makes you think it's hot and being hot has to do with the problem? Or as you said, this seems to be outdoor temperature related or at least wasn't a problem until the warmer weather came. This would be somewhat consistent with a failing fuel pump as it will be operating at a higher temp and that tends to accelerate its failure, and on its way to failure, the heat will slowly bind up the pump so that it no longer delivers the needed pressure.

Thanks, I'll check the rail pressure.

[shorod]

Yep, you do have an electronic limiter on the engine speed when in park or neutral. I also agree with tripledaddy that the symptoms do sound consistent with a failing fuel pump.

Which 3.0L engine does the Taurus have, Vulcan (12V) or Duratech (24V)? The Duratech has secondary butterflies that should open somewhere in the 3-4k rpm range. If stuck, they may cause driveability issues similar to what you describe. However, if they were stuck open, it would more likely exhibit issues at cold temps.

When it gets warm and feels sluggish, does the exhaust smell rich? I suppose if the mixture was going way rich, it could bog the engine, but after sitting (hot) most of the excess fuel would evaporate and/or leak past the rings and then it would run fine again. You mention that the car is dying, but the rest of the text makes it sound like it's just sputtering. When she pulls off to the side of the road, is that because the engine stalled, or just because it is bogging? Does she shut off the engine and let the car sit, then start back up and the engine will seem fine a that point for a short time?

-Rod

[82Stang]

Originally Posted by shorod

Yep, you do have an electronic limiter on the engine speed when in park or neutral. I also agree with tripledaddy that the symptoms do sound consistent with a failing fuel pump.

Which 3.0L engine does the Taurus have, Vulcan (12V) or Duratech (24V)? The Duratech has secondary butterflies that should open somewhere in the 3-4k rpm range. If stuck, they may cause driveability issues similar to what you describe. However, if they were stuck open, it would more likely exhibit issues at cold temps.

When it gets warm and feels sluggish, does the exhaust smell rich? I suppose if the mixture was going way rich, it could bog the engine, but after sitting (hot) most of the excess fuel would evaporate and/or leak past the rings and then it would run fine again. You mention that the car is dying, but the rest of the text makes it sound like it's just sputtering. When she pulls off to the side of the road, is that because the engine stalled, or just because it is bogging? Does she shut off the engine and let the car sit, then start back up and the engine will seem fine a that point for a short time?

-Rod

Hello, I must correct that. It was bogging down severely, not stalling. Any incline, you could have the pedal to the floor and it just wouldn't increase in speed. Funny thing, my Dad mentioned it sounded like it was revving high, just not going anywhere. I haven't experienced that. When I test drove it, it was sounding to me like it was breaking up/sputtering/bogging badly and not gaining rpms.

The previous responses about the fuel pump have me very curious about that, but I don't have a fuel pressure guage and I'm sure if I press the schrader valve gas will come. Just no way of knowing what pressure at the moment. I either have to buy or borrow one.

All the diagnostics haven't given me too much yet. After replacing the egr valve & solenoid, o2 sensors, plugs, wires, coil pack, map, maf, fuel filter(last summer), it's getting pricey and just plain dumb of me to throw parts at something w/o a good idea. I usually have a good idea. My Dad thought for sure it was trans related, I didn't. But it did give the 1742 codes for the tranny. The only part I could find at local parts store that was a sensor type and changeable, was the Trans range sensor. And got one from boneyard, but no luck with that. Other codes were for random misfires and o2 sensors, but figured they were a product of the real problem. I know those parts were changed.

Do you have any ideas on checking fuel pressure w/o a guage, maybe some old tricks just to get an idea?

Thanks again.

[mwt47]

Get a fuel pressure gauge from the loan a tool program at your local auto parts store.

Mike

[Will Help]

Any body out there think the Cat could be plugged???

[tripletdaddy]

A crude, rudimentary measure would be using a tire gauge, posssibly the dial gauge being the best. I've tried using the stick gauge and eventually the gas seems to bypass the pressure piston/plunger inside no longer giving you any meaningful measurements. You are at this point mostly looking for trends as this isn't an accurate means of measurement. At key on engine off, you should get at least 10psi, and maybe at least 15 psi at idle, and at least 20 psi at high rpm. If you have an actual fuel pressure gauge then the measurements should be in psi:

koeo 35 - 45
idle 28- 45 vacuum hose on fuel pressure regulator
38 - 50 vac hose off
max fuel pump pressure
65
Pressure after engine off for 5 minutes
30 - 40

Injector Resistance 1.3 to 19 ohms
in case you want to check them

[shorod]

With the description provided in post #5, I don't think you should rule out a misfire. Closely inspect the plug wires. If it does this regularly enough, park in a dark area with the hood open, then look for blue arcing. If you don't see any arcing, and you have a Harbor Frieght Tools store nearby, pick up an inline spark tester for about $3. Install this in series with one plug wire at a time and check for an intermittant flash.

You could also pull one wire at a time and check for one that doesn't seem to make the engine run any worse, but they don't recommend unloading the coil packs that way in modern cars.

-Rod

[tripletdaddy]

That's real nice of you, Rod, to share with him how to have a shocking good time! But, even though I know you like to work with those little e- things, I bet after a few jolts of your own, you have a method that I hope you can share with us on how to avoid such a wonderful, I'M ALIVE!, experience. Thanks

[shorod]

The inline spark testers reduce the liklihood of a shock significantly. I never used to use them, but appreciate them much more now. They do a nice job of indicating a bad plug wire, even if it is relatively random. The last car I used it on had a random misfire under load. With the inline tester, we could see that about every 5th pulse was missing. Swapped the suspect wire with a similar length wire that had a good pulse and the missing pulse followed the wire, so we were able to determine the coils were fine and the wires were the problem.

-Rod

[82Stang]

Originally Posted by shorod

The inline spark testers reduce the liklihood of a shock significantly. I never used to use them, but appreciate them much more now. They do a nice job of indicating a bad plug wire, even if it is relatively random. The last car I used it on had a random misfire under load. With the inline tester, we could see that about every 5th pulse was missing. Swapped the suspect wire with a similar length wire that had a good pulse and the missing pulse followed the wire, so we were able to determine the coils were fine and the wires were the problem.

-Rod

That is interesting also. Might have to get one of those too.

[shorod]

I should add that when we switched wires, the wire of similar length was fortunately on another coil so it was conclusive that the coil was not the problem.

-Rod

[82Stang]

OKAY....

Finally got around to getting a fuel pressure guage and here are the findings.

KOEO - 0 psi
KOER - 32 psi

So, I take it that the fuel pump is bad. But one thing. I am pretty sure I changed the fuel filter a year or two ago. I may change it once more before getting into the fuel pump, just for good measure. And check the fuel pressure once more.

One question though, is how can it run fine usually and when I check the fuel pressure with KOEO, it is absolutely 0 psi? I hear the fuel pump for a second or two. Granted when the KOER is checked it is 32 psi and way low, but how can this thing still run normally most of the time, except hot weather? That just boggles me?

Guess I just don't know enough about fuel injection and I am like a sponge. I want to know why!

[82Stang]

My blonde moment elapsed....

Guess I had the guage not on good enough.

I got

KOEO - 38 psi
KOER - 30 psi

It seems that it drops pressure when it is running. I unhooked the pressure regualtor also and got the necessary spike in pressure to 40 psi. When reapplied, it dropped again to 30 psi.

Why would the pressure drop when it is running and would this account for the shitt performance during hot weather we have experienced?

Thanks so much.