98 windstar poor idle when warm

Hi again all, scrapped the old 91 aerostar ( blew a third tranny ) and just bought a 98 windstar.

The windstar starts and runs beautiful until well warmed up. ( a run up and down the street with a bit of idle time sitting won't show the problem as I found out from my so called expert overview before buying!!!).

Once warmed up it sputters and just about stalls. This is every time it is warmed up, not an off and on occurance. Feather the throttle and you can clear it up but comes right back when droped back to idle. Let the motor cool right back down (2-4 hrs) and all is ok till warmed up again.

CEL was on when bought but there was an obvious vaccum leak ( repaired right away ). Fixed leak but not problem above. I haven't cleared CEL and would need to have a garage pull the code(s).

I will try tomorrow disconnecting the battery to reset PCM. To be honest I have no idea what this refers to but was the sugestion in the one thread I did find here with sim symptoms and was supose to be from a TBS but no # was refered to.

Any other thoughts would be of help. Thinking of even running some cleaner through the pvc and injection sys ( a product sugested by our local parts supplier that is supose to strip everything clean ).

Hi, Your vehicle has OBD2 and you cannot clear or reset the ECM by dissconnecting the battery, You need a scanner and a ford flow chart for propper diagnosis and repairs indicated by the stored codes, when useing the flow chart DO NOT skip any proceedures indicated, these steps are precise and need to be followed in proper sequence for optimum results...GOOD LUCK.. Clay..

Hi

Do your engine coolant temperature levels appear normal? I am wondering about a coolant temperature sensor problem - i.e. sending the PCM a cold/cool signal even when the engine is warm. Might be a passive problem versus a hard failure that does not trigger the CEL.

A lot of things can cause rough idling. I suggest you get the codes read and post back the actual numbers. Autozone can do it for you for free.

Welcome to the forum.
You can go to many auto part stores and have your codes read for free.
You will need to ASK them for the actual Numeric code, as most people don't understand them.
Then, you can search on that code and find out what is causing it.

I have a '96, and many things are identical, or very similar.
I have pictures of a number of my repair projects at http://community.webshots.com/album/201931518cScpNK

The '96 through '98 are very similar....so pay attention to posts for those years.
The posts for the TSB for the P0174 and P0171 are for 1999 and newer....and do NOT apply to the older windstars. They went to a different intake manifold starting in '99.
Auto part store clerks often try to sell you oxygen sensors for these errors, (one or both of the codes). These codes are RARELY, if ever caused by oxygen sensors. There are a lot of codes for failures with the oxygen sensors, and they will tell you which sensor (there are 4 of them) and what the problem is with it.

Clogged EGR ports are common, and often cause misfire on cylinders #1 and / or #4. The codes would be P0301 and P0304 respectively.
Clogged EGR ports can also cause insufficient EGR flow, which is code P0401.
P0401 is also common if the DPFE (Differential Pressure FEedback) is defective. The DPFE senses the EGR flow.

Of course, spark plugs, wires, and coil pack are also suspect at this age.

You will NOT know, until you get the codes read. Then you will know what to check out.

If you get codes relative to the MAF, I would try cleaning it with non-residue electronic cleaner, as I have shown in my pictures.

Sorry for the delay replying ( had trouble login in ). C. Cleve ... you said I couldn't reset and clear CEL by disconecting the bat because the 98 has the OBD2. Well I don't know why then but the CEL did clear and the problem is gone. I have driven the van now for 2 days ( including a 2 hr trip one way ) and it runs like it just rolled off the lot. CEL has not come on again. So here's crossing fingers it worked!!! Thanks for the replies.

Disconnecting the battery, and leaving it disconnected for a while will make the CEL go out. It will also clear the "drivability" information. When this happens, you may notice less than optimum shift points, and other minor drivability issues while the PCM relearns the drivability information.
It does not take very long for the PCM to relearn the driveability information, but don't be concerned if it is not "just perfect" right away. It will NOT be a major issue, like rough running, or anything like that.....more like...not downshifting or upshifting at exactly the same time that you are used to.

WisWind is correct. Dropping power will clear the stored and pending codes, but it takes quite a while since they are stored in what is supposed to be NVRAM. Still, it seems to lose backup power after a few hours. Also, he stated it will clear the "drivability data" stored in that same NVRAM. You will have to take the vehicle out for a few complete drive cycles, reaching full operating temperature, and driving under various loads and conditions for the short term fuel trims to be integrated into the fuel and spark trim tables.

If the problem returns, try cleaning the throttle body and PWM idle air solenoid and its passages. Don't overlook the hole in the throttle plate. It is best to remove the intake duct and MAF, hold open the throttle, and spray an aerosol carburetor cleaner through the TB to clean out the accumulated varnish and dirt. You may have to remove the idle air solenoid to clean it successfully, since it will be closed while the engine is off.

It would have been good to retrieve the stored DTC instead of dumping it, but it's too late now. Maybe next time.

Just wanted to let you guys know the van is still running well and the CEL has not come on. So I think we got this one. Thanks guys! .... now I head off to the headlight issue lol :)