96 3.0 chatters/hesitates - cause?

[chconkli]

96 chatters/flattens out at interstate speeds...usually around 70mph it hestiates. The car then chatters/stutters and if you give it more gas the effect is negligable if nonexistant. Works fine right after restart but eventually acts up again. I just replaced the fuel pump 3k ago, so I don't think it's that. Also, it almost feels as if something is braking against my car. It's not just your typical missing. If anyone knows of any possible causes to this, any help would be greatly appreciated. I have a persistent check engine light, have had new o2 sensors put in about a month ago. I'm thinking it could be a bad EGR valve that is not opening/shutting properly, a bad catlytic converter, or a clogged fuel filter. What do you guys think? I don't think it needs a tune up as the engine was replaced 20k ago (I presume they tuned it up when they did that - new plugs, wires and the like, thus no ignition problems?).

I think it's time for a new car. Ahh, if only it were that simple.

[KimMG]

Go to Autozone when they are not too busy and have them read the codes. Then let us know what they are.

[TaurusKing]

Any black smoke from the exhaust when this happens???

[mwt878991]

It is a duratec or vulcan?

There was a knock sensor on the 96 .
That retarded and advanced the timing



Mike

[chconkli]

Originally Posted by mwt878991

It is a duratec or vulcan?

There was a knock sensor on the 96 .
That retarded and advanced the timing



Mike

Thanks people. I will take it to Advanced or AutoZone tommorow and have the codes read again. I did it with a cheap scan tool about 3 months ago; it showed insufficient EGR Valve flow, a cylinder 4 misfire, and something about a heated upstream oxygen sensor. Well, since then the o2 sensors have been replaced, and the mechanic did a computer diagnostic and determined that no misfire exists. The car has run fine since on long trips, the exception being just recently. I am thinking it could be a bad EGR valve, in which case I'm going to try salvaging the one that is in it by cleaning it. I took it out today and it started vibrating really bad between 40 and 50 mph, but would eventually acclerate and smooth out. I'll update as soon as I get it read again, really not looking forward to buying a new EGR valve (if that is in fact the cause), so I might see if I can salvage the old one by cleaning the carbon deposits. I hope it's not a transmission going bad. I can deal with just about anything but that. To answer someone's question - I did not notice any black smoke coming out of it. Also, in response to the other question, I don't know if it's a duratec or vulcan - I'm assuming it's a duratec because I heard Vulcans were rare or something. Any tell-tale signs to tell which it is?

[Crasen]

If you are getting an EGR code the EGR passages could be clogged, or the EGR valve could be bad. But another common causes of EGR codes on Fords is a DPFE sensor. I am not sure if this particular engine uses this valve but many do. Maybe someone can tell you how to check this sensor without a scantool (i do not mean a code reader), or maybe getting the codes scanned will narrow it down to something else

[TaurusKing]

duratec is 24vdohc engine, you would have badges on the front fenders in front of the doors, vulcan is standard engine..

[alex boss]

Think Crasen has it pegged-check prices on EGR and DPFE sensor, would be good to replace them both mainly because of age of car and some fairly high milage, I imagine. Easy access with common tools. HTH Alex

[chconkli]

Thanks Guys, and now an update

It picked the worst possible time to die on me and now it's in the shop. Estimate is upwards of 1000+ including $150 in diagnostics, a new fuel pump, a new fuel filter, and a DPFE sensor (as Crasen suggested). In addition there is a possibility that the cat needs replaced. I think I'm being railroaded there because one can usually tell if a cat is bad right off the bat, right? Wouldn't you smell a strong sulfer smell? Any other tell-tale signs? The cat is not part of the quoted rate, either. Should I get it replaced anyway just to be on the safe side?

So, two more questions, can I replace the DFPE sensor on my own with some minimal mechanical aptitude and save a few bucks, and is this going to affect the operation of my vehicle if I don't (other than setting off the check engine light)?

Can I replace the fuel filter on my own?

I'm not even going to try and replace the fuel pump. Look, I'm not a mechanic, but it seems to defy common sense to put an electrical part that can cause sparks and fire inside a gas tank. I'm pretty angry that I just replaced it a few months ago (junkyard part) and now I have to do it again.

I'm leaning toward having the shop replace the fuel pump and getting it down the road 90 miles to my regular mechanic for the rest of the work if I can't replace the DPFE and fuel filters on my own. Will it make it this far?

Then again, I could suck it up and have them do all the work. It is a AAA approved shop so I think there are some warranties on the repairs in addition to probably a mfg warranty on the fuel pump. What do you all think?

One more question - any better layman's repair manuals out there than Haynes? Chilton is a little detailed, but maybe that's the way to go.

I'm about ready to fold with this, I have never had so much trouble with any vehicle in my entire life. The only redeeming quality of the car is the newer motor. Otherwise, it would have been down the road a long time ago! Thanks again, sorry for the long post and any suggestions or advice appreciated!

[Willyum]

Fuel filter easy to replace, is under the body @ the rear passenger side door. Just make sure the retaining clips are securely in place on the new one because the pump creates enough pressure to blow an unsecured hose off the filter.