Hi:

My daughter had her 98 Sable Duratec V6 oil & filter changed today and on the way home idle was really rough (idle ~ 550 rpm) and bad hesitation when stepping on gas.

No engine light on. I haven't found anything loose or disconnected yet, but I don't know what anything under the hood is yet! (Looking up engine diagrams tonight online). Pumping the throttle repeatedly at idle in neutral will allow rpm to increase instead of long delay.

Only other comment from tech (not written on invoice) was that air filter looked great/new! I'm hoping that means accessing the air filter presented an opportunity to disconnect something hidden.

Found some online discussions of many causes of this but they were for damaged/worn causes, not sudden onset after routine maintenance.

Thanks

 

Believe it or not ,Ford's intake system is quite sensitive if the air filter is not completely/properly assembled. You might want to check if everything is in place before getting worried. Also ,check the area around the air filter housing, it is possible something may have been knocked loose accidentally.

 

Yes, about 1130 last night I figured it out but my wife wanted her laptop back & I figured I'd come back here today.

Thank you for your quick response. The air filter was the last thing I thought of, and after reading about checking for airflow problems, I heard it plain as day...a big sucking sound...the air filter housing/plenum/venturi/none-of-the-above (whatever it's called I can spell it!) feeds a... um...roughly 3" diameter rubber hose that is pleated or folded like a bellows, and it was pulled off the metal tube that goes to I guess the intake manifold or whatever else is in that 'feed me' path. Car smelled like it was running rich which makes sense I suppose - starved for air. The hose clamp was loose, and the other hose end at the air filter housing also had a loose hose clamp.

The rpm started fluctuating when I put the hose on. Oddly, but interestingly, it got worse and stalled but reassured me it was obviously a necessity and factor in the performance. I tightened both clamps and restarted it and puzzled for a moment over why the rpm went to about 2000,then 1500 on the next start.

This had me thinking the car was somehow adapting and remembering something in the air/fuel programming...I wondered whether it had been 'tuned up' with the 'defect' and would need to somehow forget it's troubled past, but it was fine earlier in the day so I hoped it would eventually decide what was some form of optimal, or at least better. It did drop to 900-1000 rpm or so, and I drove it around until it was warm got it up to 55 and had no more ideas of what else to check for other than loss of symptoms.

This is 'not my area' so I just assumed I really didn't know if I had found the only problem...it IS from 1998, and the relay box between the battery and air filter had also been unlatched. I'll never know if both ends were already loose when it went for the oil change & got bumped or if they needed to remove it to access the filter.

You can probably already tell I don't enjoy working on cars since I pay someone to change my oil ...good for the economy, right?

After I considered what a waste of an evening it was, I realized I learned a couple things and the car won't need to go somewhere Monday to be fixed and my daughter wasn't without her car until it was done...and no repair bill :O)

I think my wife and daughter may have the shop take a look for any other surprises. I decided to just ask them to look since they know what they needed to touch during their work, and not assume it was their fault...it could have been a much bigger hassle, so it's pretty easy to shift to 'laid back' about the experience.

Again, thank you for nailing the diagnosis...had I waited for daylight and found your response before going another round with it last night first, it would still have occupied part of my morning as well!