99 Taurus not running right

[DavidL]

Originally Posted by shorod

So the Actron scan tool did not show any current codes for your car? Is your scan tool maybe displaying history codes for you rather than pending or current codes, so you're seening the recent codes that the scan tool has recorded for your car?
-Rod

Just to clarify, there have never been any codes given since I started checking this out. I can feel the jerking/hesitation when I am driving, but the service engine light has never come on. It's not so bad that I can't drive the car, but it is annoying, and I suppose there is a chance it could cause other problems if not resolved.

My knowledge of this kind of stuff is very limited, so I have been doing a lot of internet searches. Apparently a vacuum leak is normally more of a problem at low speeds when the air that is leaked into the system makes up a larger percentage of the total air going to the engine, so I'm less suspicious of that now.

[DavidL]

Originally Posted by scrapper1

one question is the spark blue or yellow? it should be blue.

The first time I checked it the spark on #3 appeared to be more yellow than blue, but when I checked it again a couple of days later it looked blue like the rest of them. That was when I decided that this might not be a good indicator.

I hate to ask this question, but is it possible this could be related to the transmission? It doesn't seem to correlate with shifting. It is most noticeable when I'm accelerating, but I also notice it at times when I'm cruising at steady speed on the interstate. And it gets worse when the A/C is turned on. The transmission failed and was rebuilt at 70,000 miles. The fluid level is good, but it is due for a fluid/filter change.

[shorod]

All of the symptoms you've described so far would indicate to me a misfire condition and not a transmission concern. From when I looked at your plots before, it did not appear that there were problems with the TPS over the range you drove the car.

You should check the condition of your transmission fluid though. If it is brown or smells burnt, you should change it and the filter out anyway as a matter of preventive maintenance.

-Rod

[rjorr]

hi, i am having an identical problem with my 92 taurus 3.0, did you ever find out what the cause of the problem was? i have tried everything you have and maybe more, it is really getting frustrating, thank you.

[rjorr]

oh sorry, you can email me at [email protected], re taurus, thanks

[samucurr]

Same problem here with an '01, 3.0.

I replaced the plugs and wires a few months ago, and that seemed to solve the problem temporarily, but since then it's been returning gradually.

It is most noticeable when going up a slight hill, in the 30-40 mph range. RPMs in the 2k range. I never notice it when not under load. When driving it definitely feels like a mis(non) fire.

[shorod]

You'll want to also check the vacuum lines, including the PCV depending on which 3.0L you have. There is a sticky thread on the PCV and P0174 code. I'm not sure if you have the pending code, but in the early stages, you might not get the code yet.

Also, if you have access to a scan tool with a datastream mode, you could monitor the O2 sensor voltages real time while driving to see if you get a rich or lean condition during the misfires to help determine if you have a vacuum or spark misfire, and potentially on which bank.

-Rod