I thought I'd start a new thread as my previous thread (right turn stalls) was combined and may go amissed.

After the engine gets hot (normal driving around) and sits for 15-30 minutes, the engine is hard to start up. It will crank and crank, then sputter like it's low on gas, pumping the pedal helps to bring the revs up and then it picks up speed and things are okay.

I had the fuel pump replaced about 48,000 mi. ago (Borg-Warner), plugs, plug wires and distrib./rotor replaced about 7 months ago. My fuel injectors are original, I run injector cleaners every 3-4,000 miles. I replaced the fuel filter about 3,000 mi. ago

It does not happen when stone cold or if it sits for over an hour after turn-off.

One other thing, if I let it idle (after the engine has been driving around for 20 miles or more), it will start to shake sometimes.
There's no smell of leaking gas fumes.

I was thinking a different form of vapor lock?

I stand corrected on my miles stated on the odometer, it should be 300,891.2 (not 308,891), I mis-read the "8". I'm the original owner (94', 3.0)

Aerocolorado mentioned that there was a previous topic, I searched the archives, but I could not find it, hope someone can chime in.

Thanks.

 

It sounds kinda like what my 2nd aerostar is doing.....It has a Bad Head Gasket that I need to replace.

 

Hi, Jay:

Head gasket...yikes!!

I'm not blowing any white or blue smoke, my coolant level remains pretty constant, no overheating, etc, other than when it gets hot and sits. I do lose about a quart of oil every 2-3,000 miles, but my exhaust shows no constant smoking. Most of my driving is on the highway.

But I guess after over 300,000 original mi., I got the max use out of it. Hope I can get more still. Very dependent on it for my deliveries.

 

Sounds like some kind of sensors gone bad on you. The reason is this:

When started cold, the computer was not engaged. The engine runs on what is called "Open Loop" mode using no feedback whatsoever from sensors. One the engine warms up, however, it runs under "closed loop," i.e. inputs from sensors are fed to the computer and the computer will decide on what to do with throttle, idel, etc... You might want to try pulling the code, if there is one, from your computer.

Regards,

Copper

 

The computer thing, is this something that I can take to a Auto Zone or Kragen? I tried to do a search, but I'm not a CLUB FTE member and the server is overloaded.

I went back thru some past threads, I didn't see a reference to a computer.

If possible at AZ or Kraggy, do you charge for this service?

 

I would tend to agree with copper_, that a sensor is faulty after warm up and causing a too lean of mixture on hot starts. Specifically, I would look at the mass air flow sensor (MAF) located between the air cleaner box and the air tunnel. It is a heated, fine wire sensor that measures the air density after warm up. They are prone to gathering "gunk" from the airstream which affects its performance. There is a wire connector attached to the MAF sensor.

This is a good place to begin troubleshooting as it is a simple procedure and cost pennies to do. The screws on your model may have the Torex screws with the anti-tamper "nibs" in the center. You can either punch off the center nibs or buy the special bit. Remove the unit and clean it with an electronic aerosol cleaner. It is a delicate unit so use caution when handling it. Examine the fine wires to see if either of them appear broken as the filament in a lightbulb would appear if broken. If so, you may need to replace the sensor.

Try cleaning this and see let us know what happens.

 

Wow, good follow-up..I just got home, I did view the MAF unit...there is that one special screw TOREX as mentioned, so I'll get that bit tomorrow.

It appears that MAF unit "swngs sideways" after removing the outside TOREX screw and the inside screws, as there's a attachment on the outside that's neither a screw, bolt or nut.

Or is that simply a pivot device and will be no problem in the removal or re-installation?

 

Okay, I finally got a chance to buy the special bit (T-20 Star bit...Auto zone...$2.99), I didn't to mess with punch the center piece out and maybe I could not get it back on properly.

Anyway, I saw the MAF sensor's two wires inside, it was clean as a whistle (but shot some of that computer air blast in there for good measure), the filaments looked connected and took a wood toothpick to make sure, it was secured.

Took it out for a test drive, oh, noooooo....not again. It was hard to start and when it did, it was choking and sputtering, and back-fired a couple of times while I was trying to pump the pedal. Once, it seems like the gas kicks in, it roars to life with a bit of shaking but not a lot.

Put in drive or reverse it may shake a bit, but once it gets going, you'd never know it had a problem. City and freeway speeds with no problems.

What other sensor or issues could it be? I was thinking about the O2 sensor, but the guy at Auto Zone, says maybe not needed.

 

Well, look on the bright side, that's one less sensor to have to worry about. Unless your mileage has fallen off below 15 mpg, I would tend to agree with the AZ guy. Generally speaking, a failing(failed) O2 sensor enrichens the fuel mixture, thus the poor fuel mileage. If your mileage is rotten you might want to consider this. Other closed loop sensors include the engine coolant temperature sensor(ECT) -not to be confused with the temperature gauge sensor - and the air charge temperature sensor (ACT). The good news is, these are rather simple devices and rarely fail. They are sort of secondary data fields and allow the engine computer to further maximize air/fuel ratios and timing profiles. At this point, I just do not see either of these causing the type of problem you are experiencing.

Are you capable of doing any minor mechanical proceedures - such as removing the throttle position sensor and testing it with a meter? I don't want to send you on wild goose chases trying to solve this problem but having eliminated the usual culprits means the problem may require more in depth sleuthing on your part. Let me know how involved you want to be in sorting out this problem. When you were at Auto Zone, did they try to pull any stored engine trouble codes? Finally, did you ever resolve the right-turn-stall problem?

 

Yes, you're right, it's going to be a process of elimination, one down and ?? to go. It's my daily use vehicle too.

I have my Chilton manual and read about the TSP. I'm more of a weekend mechanic (oil changes, tranny fluid/filter, water pump, thermostats). I don't have a multimeter, but I can certainly add to my collection of tools. No worries about the goose chase, it's better than what I would have thought of. TSP is next, I'll get one today after making some deliveries.

At AZone, they didn't try to pull any stored engine codes, it was a bit crowded there and short-handed.

No, I've not yet resolved the right turn stalls, I'm thinking maybe these two problems are related (hope so and can kill two birds with one stone).

But you can bet when the issues are resolved, I'll be posting up for everyone.

Oh, I'm still getting 16-18 mpg city, 17-21 frwy.

 

Hey I didn't know that Autozone carries these security star bits. Where did you find those? Did you have to special order them?

Thanks.

 

Copper, I took the air box and MAF sensor on it to AZone, I asked the guy there and it was right there, they also had some red plastic "molds" to see what's the proper fit.

It was hanging on their "revolving section" with the other sockets, not on the peg board. It came in a little plastic tube. No special ordering needed.

 

Goldfishy,
I may be wrong in my interpretation but I gather you intend to purchase a TPS. I did not mean for you to buy a TPS, just to be able to test your currrent one with a meter. The TPS is just a variable resistance rheostat. A meter will allow you to check for worn or 'dead' spots on TPS. I am surmising there may a dead spot just off idle that is confusing the computer which causes the bucking. Once off the dead zone, everything is hunky-dory again. At least that is the current theory. If you are truly considering getting a meter, a decent digital runs anywhere from $35 to $75 or up. Once you have one you will find an ever increasing amout of things you can check with it. (light bulbs, batteries, open circuits, etc, etc.)

 

Aerocolorado, yes, I was going to get a meter first, not the TSP. In fact, I'm looking forward to getting one. I've been doing some smiple electrical things around the place and there's been those times, I wished I had one.l

Thanks for heads-up on the price range and going digital.