Engine hesitation under load


01WHTSE
03-11-2006, 10:06 PM
I have a 2001 SE Sport with 95,000 mi. In the past few weeks it has developed a sometimes severe hesitation between 1800 and 2500 RPM. Generally this occurs only under a load. I have replaced the fuel filter, plugs and wires, upper intake port gaskets and bolts; PCV and valve cover gasket, and fuel pressure reg. vacuum line. I was hoping someone had some experience with a similar symptom.

phil-l
03-12-2006, 08:36 AM
My first thought: The Throttle Position Sensor (TPS). If a TPS develops a bad spot, it can cause behavior like you're seeing. You can test basic TPS operation with a digital voltmeter. The TPS isn't very expensive, and is easy to replace.

01WHTSE
03-29-2006, 10:15 PM
I tested the Throttle Postion and Mass Air sensors with good resistance and voltage readings. A friend spoke with a Ford service manager who suggested the coil pack. He commented that he has seen a number of these coil packs fail on Explorers and Windstars at roughly 5 years of service. I tried a new coil pack tonight and cured the hesitation problem!

cyberapache
03-04-2007, 01:27 PM
Similar problem first appeared over two months ago:

Symtomps:
Hessitates when accelerating. Seems to be missfiring or backfiring. Occasionally hear thumping noise from under the hood. Sometimes the whole van shakes violently with just a little tap on the gas when driving. The CE light blinks when this happen.

Idles funny too, and when I rev the engine at standstill, around 4k rpm I hear two thumping noise which vibrates the engine block. This noise occurs too when I step hard on gas during driving. It feels like running over a tree stump!

What I've Done So Far:
Changed spark plugs/wires, fuel filter, MAF filter. Problem went away for two months with plugs change.

CE light came on last week with code P0171/P0174. There was no drivability problems so I put in high octane gas and injectors cleaner. That same day the symptoms described above came back.

I've done the isolator bolt fix and PCV valve oil splash fix. Cleaned EGR ports. CE light is out now, but symtomps described above still persist. Not sure if CE light is out because I removed battery during service, but it hasn't come back after a few bumpy rides arounds.

I've inspected MAF sensor and it looked cleaned, but I still cleaned it just to be sure.

I hear hissing sound from around upper intake manifold. Checked vacuum hoses, but not visible sign of tear. (Any idea where to get replacement hoses? My local auto store carries generic hoses that can be custom cut. Good enough?).

I removed and reseated upper manifold just in case something didn't sit right during isolator bolt fix. Tightened bolts in recommended order and torque.

Out of options now. Time to call dealer and bleed some dough?

Please help, this van can't afford to sit around for much longer.
Thanks.

wiswind
03-04-2007, 04:55 PM
See if CEL comes back on....and re-read codes.
Is the vehicle using any coolant?
Is there anything not working, like air only to windshield, or problem with rear heat / ac unit?
Individually look or feel vaccum lines and connections, including the 90 degree elbow on top of the upper intake manifold for PCV line (crack on inside of elbow).
VERIFY vaccum line connection at fuel pressure regulator.
Try the looking under hood while dark outside process that I mention under "general windstar information" to look for possible arcing in igition system (possible coil pack....but hard to see arcing there).
For spark plugs, hopefully you used double platinum ones with the number listed for your year......Motorcraft or AutoLite brand name.

For fuel system cleaner, try a treated tank of regular unleaded gasoline with a can of Berryman's B-12 Chemtool (metal can).

cyberapache
03-04-2007, 07:06 PM
wiswind, thanks for replying.
Coolant level is OK. Recently backflushed with no problem.

I know I have the heater blend door problem. I waiting for nicer weather to fix it. I haven't noticed any a/c multifunction, but I'll check.

Replaced vacuum line at fuel pressure regulator (came with kit for isolator bolt fix). It's nice and tight. This used to pop out as described elsewhere in this forum.

For spark plugs I used double platinum, but it was Bosch. The parts store computer said it was compatible after associate keyed in my vehicle info.

Have nearly fulltank of gas now with fuel cleaner. Cleaner was in narrow white plastic bottle (I don't remember the brand).

I'll check the A/C functionality and inspect for any sparks or arcs.

Will post my findings.
Thanks.

DRW1000
03-04-2007, 07:39 PM
For spark plugs I used double platinum, but it was Bosch. The parts store computer said it was compatible after associate keyed in my vehicle info.


I am not aware of Bosch having double platinum plugs. Are these the Bosch Platinum 2s?

True double platinum plugs have platinum on both the centre and ground electrodes. Bosch plugs have platinum on the centre electrodes only. The Bosch 2s and 4s have multiple ground electrodes.

Most plugs do have a listing for Windstars and they will "guarantee" to perform as well as the originals but if you do some reading in this forum you will notIce that anyone who uses plugs other than Motocraft or Autolites (true double platinums) experience problems. Windstars (and many other modern Fords) have their plugs firing in pairs and 1/2 of them fire from ground to centre and the other half from centre to side

cyberapache
03-04-2007, 08:18 PM
I checked A/C. Cools and heats ok in all positions. No arcs either, under hood.

Yes, it was Bosch 2s. I remember there was the expensive one with 4 ground electrodes, and this one with 2 ground electrodes. Also remember it said platinum. Am I screwed? I removed two plugs for inspection and I can tell only one side of the center electrode shows signs of spark. Could this be my problem after two months?

Local auto stores are closed. Will check ***Mart to see if I can get any luck finding real double platinum Autolites. Really need to get this cruiser up and running.

wiswind
03-05-2007, 12:11 AM
I would change the plugs out for the Double platinum Motorcraft or AutoLite.
Don't feel bad, those auto part stores have impressive displays for those Bosch-2 and -4 plugs, which may be great in some applications, but people have posted that they have had problems with them in the windstar application.

DRW1000
03-05-2007, 08:26 PM
I checked A/C. Cools and heats ok in all positions. No arcs either, under hood.

Yes, it was Bosch 2s. I remember there was the expensive one with 4 ground electrodes, and this one with 2 ground electrodes. Also remember it said platinum. Am I screwed? I removed two plugs for inspection and I can tell only one side of the center electrode shows signs of spark. Could this be my problem after two months?

Local auto stores are closed. Will check ***Mart to see if I can get any luck finding real double platinum Autolites. Really need to get this cruiser up and running.

Electricity takes the path of least resistance. Therefore you will most likely see evidence of spark on one side only. The beauty of plugs with 2 ground electrodes is that when one side wears the other side can take over. Unfortunately these plugs are not good on Windstars.

cyberapache
03-06-2007, 12:27 AM
Changed out plugs to Autolite double platinum. Didn't help. Shaking got slightly worse. Took apart intake plenum, upper intake piece, and isolator bolts and reinstalled making sure all is nice and tight. If this is vacuum leak, I can't tell where it's coming from.

Old Bosch plug from cynlinder #1 had a lot more sooth on it than the rest. I remember when I changed the plugs last month the OEM plug from cylinder #1 had more sooth and wet thread with heavy smell of gas. I don't know if this is normal or part of the problem, but the engine sounds like it's running on fewer than 6 cylinders.

Transmission shifts hard too, especially from 1st to 2nd (fluid level OK, replaced at 40K, now at 75K). Hessitation worse in 3rd/4th gear with noise coming from under the hood (see original post for noise description). I've driven it to dealer's lot to diagnose problem. Will decide if I'll have them fix it after I hear what the problem is what they want for the work.

Thanks to all for your responses. Will keep you posted.

cyberapache
03-18-2007, 10:47 PM
After two days of diagnoses at the dealer and over $400 later, the problem turned out to be a bad coil.

It helped that I told the mechanic all the troubleshooting and fixes I had previously done so they didn't chase nonexistent problems. It's been over two weeks now and van is cruising fine. I'll keep my fingers crossed and hope this helps others.

They forgot to reconnect my windshield washer fluid hose under the cowling.
I guess I'll take care of this myself.

Add your comment to this topic!