96 Windstar 3.8L jerky acceleration

Hello, Thank you in advance for any help given. I've read many many posts but haven't yet seen the exact symptoms my Winnie is exhibiting. It's not acting the same as it has in the past when (multiple times) it needed the EGR ports cleaned or an injector replaced. It seems to start fine when it's cold and most times after it's warm (though on some warm restarts it sputters and runs rough before smoothing out and idling fine.) Starting and idling are no problem but giving it moderate acceleration makes it buck and jerk and surge. Doesn't matter if it's warm or cold. What's strange (to me) is that if you floor it (at any speed) it gets up and goes! No jerking, just power and speed. Since I don't want to drag race it from every stop I need to solve this but no success so far. In the past it's had O2 sensor codes and I never replaced any of them; it turned out to be something else. (EGR ports, vacuum line off, etc.) This time when it started this fit I had the code read and it was PO133, (upstream bank 1 slow response) same as at other times, so as usual I pulled off the upper intake to clean the EGR ports and they weren't clogged. Hmm. So I pulled off the fuel rail and injectors and cleaned the spray ends as I've done so many times before. Didn't help a bit. So, hey, why not, I went ahead and replaced that one O2 sensor and cleared the code. Still no good. Next, replaced the DPFR sensor, then the EVR solenoid, then the MAF sensor. Even though it didn't set any more codes I still removed the negative battery terminal to clear the Keep Alive Memory each time and then drove it for 20 miles to let it relearn the fuel trim. Still no good. Next replaced upper intake gasket set (I'm thinking possible vacuum leak, and I've never replaced that set before, even with the many times I've had that manifold off) and PCV. No good. This is where I am now. The van has 197K and I'm planning to keep it for another 100k Lord willing. Right now it shows no codes but is still jerking on take off. What else could cause this? Replacing any of the other sensors doesn't make $ense.

Hello, Thank you in advance for any help given. I've read many many posts but haven't yet seen the exact symptoms my Winnie is exhibiting. It's not acting the same as it has in the past when (multiple times) it needed the EGR ports cleaned or an injector replaced. It seems to start fine when it's cold and most times after it's warm (though on some warm restarts it sputters and runs rough before smoothing out and idling fine.) Starting and idling are no problem but giving it moderate acceleration makes it buck and jerk and surge. Doesn't matter if it's warm or cold. What's strange (to me) is that if you floor it (at any speed) it gets up and goes! No jerking, just power and speed. Since I don't want to drag race it from every stop I need to solve this but no success so far. In the past it's had O2 sensor codes and I never replaced any of them; it turned out to be something else. (EGR ports, vacuum line off, etc.) This time when it started this fit I had the code read and it was PO133, (upstream bank 1 slow response) same as at other times, so as usual I pulled off the upper intake to clean the EGR ports and they weren't clogged. Hmm. So I pulled off the fuel rail and injectors and cleaned the spray ends as I've done so many times before. Didn't help a bit. So, hey, why not, I went ahead and replaced that one O2 sensor and cleared the code. Still no good. Next, replaced the DPFR sensor, then the EVR solenoid, then the MAF sensor. Even though it didn't set any more codes I still removed the negative battery terminal to clear the Keep Alive Memory each time and then drove it for 20 miles to let it relearn the fuel trim. Still no good. Next replaced upper intake gasket set (I'm thinking possible vacuum leak, and I've never replaced that set before, even with the many times I've had that manifold off) and PCV. No good. This is where I am now. The van has 197K and I'm planning to keep it for another 100k Lord willing. Right now it shows no codes but is still jerking on take off. What else could cause this? Replacing any of the other sensors doesn't make $ense.

This is a strange one. ??? My 95 runs rough on warm starts some times. I think it's the fuel injectors that need cleaning.

Have you checked your Throttel Position Sensor? TPS. Take a Multimeter and check the TPS. Make sure there is a consistant resistence the whole distance.

Regards

Dan

This is a strange one. ??? My 95 runs rough on warm starts some times. I think it's the fuel injectors that need cleaning.

Have you checked your Throttel Position Sensor? TPS. Take a Multimeter and check the TPS. Make sure there is a consistant resistence the whole distance.

Regards

Dan

I think what Dan meant is the resistance should change through the entire range of movement AND there should be no dead spots. (It should be a linear resistance vs wiper position (variable resistor wiper that is)

(Of course I could be wrong on what he meant but this is what I believe you should see)

I think what Dan meant is the resistance should change through the entire range of movement AND there should be no dead spots. (It should be a linear resistance vs wiper position (variable resistor wiper that is)

(Of course I could be wrong on what he meant but this is what I believe you should see)
Yes, I've checked my TPS, it shows very steady resistance drop from closed throttle to open. 3500 ohms at closed down to 370 ohms at WOT. I did not see any jumping or dead spots.

Just thinking out loud here.............It looks like we are looking for a failure on something that does not set a code or it is not severe enough to set the appropriate code.

I would try the simple things first. Test drive after each temporary modification
1 -Disconnect and plug the vacuum to the EGR valve.
2 -Disable the IMRC.
3 -replace fuel pump relay (right 12Ounce).

Just thinking out loud here.............It looks like we are looking for a failure on something that does not set a code or it is not severe enough to set the appropriate code.

I would try the simple things first. Test drive after each temporary modification
1 -Disconnect and plug the vacuum to the EGR valve.
2 -Disable the IMRC.
3 -replace fuel pump relay (right 12Ounce).
I tried number 1, no change. Is number 2 Intake Manifold Runner Control? Haven't tried that yet but I've verified both runner vacuums are operating and holding vacuum. Don't know where the fuel pump relay is, I'll have to do some reading, but if there was something wrong with that would the van still run great when I floor it? Also, I just removed the upper intake again and noticed some oil dribbled out of the throttle body when I sat it on the bench. Never noticed that before although the manifold has always had an oily, carbony residue, never enough that it ran out or dripped. Never have cleaned it because of the Do Not Clean, Special Coating on Throttle Body and Plate label. Also, I removed the fuel rail and injectors and two of the injectors seemed to have an oily residue on the spray ends. I'm going to try cleaning all of this with a spray cleaner while I've got it off and just try to avoid the throttle body area. Also, I removed the spark plugs again and they all look great. One other thing, I read somewhere about using Sea Foam to clean manifolds by introducing it slowly into the PCV port on top while the engine is idling but when I pulled the vacuum tube off the PCV port the van stalled immediately, which surprised me, I thought it might run rougher but not stall. Should this happen? If so, how do you add the Sea Foam? Sorry such a long post, hope I'm not over-explaining everything.

I'm not sure, but think the (dedicated) fuel pump relay appeared on the '99's for the first time.

Thank you. I disabled the IMRC, no change. About the oil dripping out of the throttle body, I assume it had to come in through the PCV port. I read somewhere that a non-Motorcraft PCV would allow too much vacuum draw on the vent and could pull oil into the manifold. My old one was a Motorcraft, the new one isn't, maybe I'll switch back to the old one since the new one didn't cure my problem. Some additional history: The van has never used much oil, especially considering the miles it has. It never has shown any blue oil smoke exhaust, usually when it has started running rough the exhaust has been sort of black and the tailpipe is always carboned up. A couple years ago it began losing coolant somewhere, the reservoir was continually low. Couldn't find any leaks, figured it was internal, maybe a head gasket. (I've never removed the lower intake or either head, & hope I never have to) It also seemed to sound like it had a miss at idle and wasn't running good, so I bought a compression tester and all cylinders were very good. I decided to try a tube of Stop Leak and it worked. It has not been low on coolant since. Cleaning EGR ports cured the miss and running rough. All that to say I think the compression is still good (although I didn't recheck it this time) and I think it sounds like it has a miss again, though I don't have a very good ear for detecting that. I pulled the injector leads off one at a time to listen for which cylinder wasn't firing right and I can only get my hands on number 1 in the rear bank and 4,5,and 6 on the front. Each one made the RPMs drop, can't check numbers 2 and 3. One last thing, I have not removed the EGR valve, mainly because it holds vacuum and I thought if it was bad it would leak and not hold vacuum. Is this correct, or could the EGR valve be bad even if it holds vacuum? And if it's bad, could this be causing my hesitation/surging problem?

Holding Vacuum windicates that the rubber diaphram is not ruptured but I was suggesting that perhaps carbon build up was holding the actual valve open so that when vacuum is removed the valve is mechanically stuck open.

I have had intermittent rough running after restarting......a warm engine. Clears up within a minute....and sets no codes. I have not tracked down the cause.

The Fuel pump relay on the '96 is inside the Constant Control Relay Module (CCRM). This contains the relays for the fuel pump, radiator fans, and AC. It is located between the battery and the radiator..... Best to look in my pics. The PCM drives these relays. There was a TSB to replace the CCRM for non-start of a hot engine...... They have an improved one from the original that has better sealed relays. I have had this happen since I replaced mine. However, I only have my problem during cold weather....and only once in a while.

The '96 is more prone to have leakage at the lower intake manifold gasket than a head gasket. I had some of the same coolant leakage.... I keep some Bar's Stop Leak in the coolant all the time.....and have had NO problems. I did flush the coolant.....and not add the stop leak.....and a few months later....had some more loss of coolant....but cleared that up by adding some stop leak. I would only use Bars brand.

I found that adding SeaFoam in the PCV line did work...but I had a lot come out the throttle body.....and that is adding only with the engine running. So...if you do that..once you are done.....turn the engine off...remove the air intake hose from the throttle body....and wipe up any that came out.

If you replaced an oxygen sensor.....they should be replaced in pairs....so that you have the same switching charactoristics on both cylinder banks. Oxygen sensors DO slow down in their switching over time. A slow response code would cause me to replace the oxygen sensor....but I would replace the sensor on the other cylinder bank. I am guessing that we are talking about the "upstream" oxygen sensor....which is located in between the engine and the catalytic converter...... Also....I would use ONLY Motorcraft brand. You can get them for about $57 each at www.rockauto.com You should only have to replace the upstream sensor (as with your code) as the downstream sensors only monitor the catalytic converter......and they switch at a much slower rate.....by the nature of their job. Coolant is something that can cause the oxygen sensor to fail....and is likely what happened.

My pictures are at http://community.webshots.com/album/201931518cScpNK

I'm not sure I understand how the fuel pump relay could be causing the hesitation/surging I'm getting during moderate acceleration without also causing some kind of problem during maximum acceleration or idle. Maybe I haven't described the problem accurately. It's not bucking and jerking violently. It's more like momentary sporatic hesitations that are worse if I'm giving it steady, increasing throttle (either from a stop or from any steady speed) but if I let off the throttle slightly so I'm not accelerating as much, the hesitations are reduced, though you still can feel them. I have to give it very, very light throttle increase ("feathering" the pedal) and ease up to speed very gradually to be able to reduce (but not eliminate) the problem. However, if I floor it, (from a stop or at any speed) there's no hesitation at all, just power and speed. The severity of the problem seems to depend on how much steady, increasing pedal I'm giving it, whether I'm going to pass someone on the expressway or in city traffic or starting off from a stoplight. I'll replace the relay if that will cure the problem but it doesn't make sense to me. Also, I still don't understand how to add Sea Foam to the PCV port slowly while the engine is idling. As I said before, the engine stalls immediately when I pull the PCV vacuum tube off the manifold port. Also, the original O2 sensor I removed (upstream Bank 1) said Bosch right on it, and as I said before, until now I've never replaced any of them. Bosch was the brand my local Murray's Auto Parts stocked, so that's what I went with. Was Bosch Ford's OEM supplier of O2s for '96? If I'm going to replace the other (Bank 2) upstream sensor, do I need to replace this new Bosch in Bank 1 with another new one so they are both Motorcraft? Or can I just replace the one in Bank 2 with another Bosch? Thank you for all your patience and help. Not Ready to Give Up Yet, Drysdale

I agree with your skeptism on the fuel pump relay. (But it may be worth the few bucks to put it out of the picture). In fact, to me, you seem to be describing an air or ignition problem.

Would you us on update all the current symptoms again.
1.You only get hesitation during moderate engine loading. (????)
2.You have no codes currently. (????)

Have you checked the ignition wires? (Try looking at them during dark. Shove the cables about using a stiff hose or other insulator. Any flashes? Does a light aerosol spray of water cause any flashes?)

Are the ig packs free of internal grounds?

Done any checking of the IAC valve?

If the vacuum line to the EGR is removed and plugged, do the symptoms go away?

Drysdale, do you have any update on this problem? I have the same problem on my Windstar which is also a 96 3.8L engine.

Fuel Pump relay is inside the Constant Control Relay Module (CCRM).
I have pictures of this replacement in my pictures.
They did have a problem with the original fuel pump relay that caused a no start in freezing weather, after the vehicle has been driven and stopped for about 15 minutes.
The upgraded replacement had better sealed relays to solve the problem.

If your '96 is showing any drop in coolant level, it is possible that your problem is leaking lower intake manifold gaskets.
I was not able to seal mine with stop leak, and replaced them.
That solved my warm start stumble.
Head gaskets rarely fail on the '96 3.8L if the engine has not be seriously overheated.
The '95 3.8L DID have problems with head gasket failure, and the lower intake manifold gasket failure gives some of the same symptoms.....namely coolant getting into the cylinders.
Coolant is super bad for oxygen sensors also.

Stop leak (Bar's brand) DID take care of a very slightly leaking (seapage) of the front cover, aka timing cover gasket.

In the case of BOTH the lower intake manifold gaskets and the timing cover gaskets, the replacements should be bought from FORD, as they have made improvements to them to address the weaknesses that made them fail.

Lower intake manifold gaskets MUST be replaced whenever the lower intake manifold is removed, they are NOT re-usable.
Also, the engine oil MUST be changed before starting the engine as there WILL be a significant amount of coolant get into it when the upper manifold is lifted off.

Upper intake manifold gaskets are reusable.