Engine Stalls at idle

It sounds like it could be a vacuum leak, here is a guide that will help you find it and also a guide that can help you find other problems that will make it stall at idle. Also it could be a coked throttle body


https://www.2carpros.com/articles/how-to-use-an-engine-vacuum-gauge

and

https://www.2carpros.com/articles/stall-at-idle

and

https://www.2carpros.com/articles/how-a-throttle-body-works

Please let us know what happens.

Best

No, I forgot to mention, no engine lights, no Codes. I have a simple code reader.

Does the engine slowly sputter to a stop, or is the stalling immediate? I ask this because I'm trying to help you isolate if it's a fuel/mechanical issue, or an electrical issue.

If the engine slowly sputters to a stop, it's likely fuel related, or an actuator which is operating when it's not supposed to. For example, something might be commanding the EGR to open while at idle (it's not supposed to). Thus, the engine will sputter and stall slowly. Try somehow disconnecting the EGR vacuum hose (plug it on the vacuum side) so that the EGR is effectively disabled.

Conversely, if it dies immediately, it's likely electrical related.

Other words of advice, take electrical voltage measurements at the battery terminals while the stalling is occurring. Take measurements directly at the LEAD battery posts (+ / - ), and also place the voltmeter test leads directly on the METAL battery terminals ( + / - ). By doing this, you are verifying continuity between the lead and metal contacts. Follow the wire (ground) all the way to the engine block; make sure connections are clean and tight.

Also, place one voltmeter test lead on the LEAD battery post ( + ), and one test lead on any of the maxi fuses in the fusebox. The voltmeter must read zero. Crank the engine and see if you have any reading on the voltmeter. You'll need to experiment with different voltmeter ranges (volt...milivolt settings). Any reading of over half a volt indicates resistance eg. bad connection.
Next, place one voltmeter test lead on the battery LEAD post ( - ), and the other test lead on any good engine ground. Perform the same tests by cranking the engine.

Next, place one voltmeter test lead on the battery LEAD post ( - ) , and the other test lead on any good BODY ground. Perform the cranking test.

Last, check the PCM power relay for proper operation. It may be getting hot, or the contacts are bad, causing the PCM to lose power and thus, the engine dies. Refer to your owner's manual, or you can download the manual in *.pdf form at the motorcraft.com website under "Technical Resources" link.

Since my other reply, I removed the plastic intake plenums. I thoroughly cleaned them and cleaned and degreased the gasket surfaces and channels. I replaced all of the Plenum gaskets. Pre-coating the gaskets, gasket surfaces and channels with a moderately thin coating of high temp Silicone. Reassembled and torqued properly. Then I let the vehicle sit for 24 hours to give PLENTY of time for the silicone to cure.

I double checked all vacuum hoses and connections. I'm hoping those steps eliminates any vacuum leak concerns.

The battery was disconnected during that entire time.

When warmed up it would stumble at stop lights which was an entirely new symptom. I swapped the hoses for the DPCE and that symptom disappeared

I tested it by sitting stopped with the parking brake on and in drive lights on, for about 10 minutes. It died after about 10 minutes. Upon restart, putting it back in drive, the rpm settled at approx. 750 rpm for about 20-30 seconds, then dropped to approx 600 rpm. Then it died a few seconds later.

That same pattern would occur every time once warmed up and stopped in drive the rpm would go to around 750, then drop to 600, then some times the engine would quit after anywhere from a few seconds to a few minutes.


”Does the engine slowly sputter to a stop, or is the stalling immediate? “

It is immediate as if someone turned the ignition off.

I checked the voltages and resistances as follows:

Engine off cold.

- Bat terminal to bat connector = 0 ohms 0 vdc
- Bat connector to body = 1.3 ohms 0.001 vdc
- Bat connector to Block = 0.3 ohms 0 vdc

+Bat term to bat connector = 0 ohms, 0 vdc
+Bat connector to Alternator = 0 ohms 0 vdc
+Bat to + on Maxi Fuse = 0 ohms, 0 vdc

Engine on in drive, warmed up, lights on, after engine has stalled in drive

-Bat connector to block 0.148 vdc
-Bat connector to body 0.042 vdc

+Bat Connector to Alt = 0.224 cooling fans on, 0.139 cooling fans off.
+Bat Connector to Maxi fuse 0.042 vdc


"Last, check the PCM power relay for proper operation. It may be getting hot, or the contacts are bad, causing the PCM to lose power and thus, the engine dies."

That relay was warm, but not markedly warmer than some of the other relays. The coolest relay in the box was the one that was in the start interrupt position. I swapped the relay that was in the PCM slot with the one in the Start interrupt slot.

The relay swap was the last thing I did before coming in and writing this. The Windstar ran parked in drive with the parking brake on and chocked for about 5 minutes without stalling after the swap. I do not consider that an adequate test, so will take it out for a test drive a little later this afternoon.

Just got back from a short term test. I drove about 10 miles in city traffic. Stopped about 20 times, and it did not stall. Then stopped in the drive way and let it sit in drive for about 10 minutes, and it did not stall.

Next will have to be a bit longer drive, but hopefully swapping the PCM/Start interrupt relay's cured the problem.

Back from another test drive and the news is not good. Didn't get 2 blocks before it died at the stop sign. Then it ran ok through 3 more stops. Then at about 40 mph it started "bucking" Then it died as I turned a corner. and again when I pulled into a parking lot.

On the way back it started bucking again at around 40 mph, and gave two codes P0340 Camshaft Position Sensor Circuit Malfunction and P0401 EGR Flow Insufficient Detected.

Now that could be caused by the hoses connecting to the DPFE hoses being reversed, but I did not get a P1403 DPFE Sensor Hoses Reversed.

So looks like the next thing to replace is the DFPE. But before I do that, I'll remove the vacuum to the EGR valve and plug it and do another test drive tomorrow.

I have access to a OBD reader. Here is the link to the instruction manual for it.

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Let me know if it will be of any use for this problem

CORRECTION

The TPS was NOT replaced. So I changed it this morning and did a short test drive with no problems. Longer trip later today.

Did a test drive this afternoon during the heat of the day 84 degrees F. Didn't even get 1 mile before it died at two stops. It also stumbled a couple of times at about 40 mph, and once at about 10 mph turning a corner.

Disconnected the vacuum line to the EGR and plugged it. Then took it for another test drive. It didn't die at any stops, but still stumbled a couple of times.

I wouldn't replace the DPFEGR sensor. It wouldn't resolve the issue as you describe. The DPFEGR monitors the EGR sensor's job. You already took the EGR out of commission by disconnecting the vacuum line. If it continued stumbling at idle with the EGR vacuum disconnected, then the EGR is not at fault; neither is the DPFEGR.

Since you received the P0340 CMP sensor malfunction code, I'd investigate that next. You might not have received this code earlier because Ford OBDII systems go through a series of component tests with each test drive. I cannot pinpoint at which priority level the CMP sensor falls into this heirachy. If a certain component fails the OBDII test (which the vehicle does on its own during test drives), certain subsequent tests abort until the failure is resolved. Since you have a scanner now, you should see a P1000 OBDII Test Not Completed. This will remain until all monitors pass their onboard tests. Having the constant engine stumbling and malfunction(s) may have caused the OBDII system to abort all subsequent tests. Perhaps the P0340 CMP sensor test was far down in the heirachy level and never had a chance to set. Now it finally did, so you may have a better lead to go on.

The Motorcraft website (again) has an excellent technical library. If you're up for some reading, go to the technical link and download the *.pdf article for OBDII Theory and Operation. It is organized by vehicle year. Download the year 1999 section and see if there is anything relevant to your situation. If it all seems overwhelming and technical, don't fret. I've been studying this stuff for a few years now and am still catching on to how all this stuff operates.

The CMP sensor synchronizes fuel delivery for each cylinder. It's possible that it is failing intermittently, causing your engine stumbling. The CMP sensor has two parts: The plastic "cup" you see from the top, and an aluminum shaft hooking up to the cam gear extending far into the engine block. Take each one off seperate and be certain to note the position of both the aluminum CMP housing and also the half-moon rotating vane in relation to the CMP housing AND ALSO when piston #1 is on TDC. All the tech manuals indicate needing a special tool to synchronize the CMP upon installaion. Nah... Tool not needed. If you need the Shade-Tree Mechanic's instructions (they are easy and really do work) let me know. I'll type them out for you.

I'll run the scanner and check.

I recently read some disturbing articles on Windstar transmission failures. Some have stumbling symptoms as well. What are the chances that it's the tranny?

I'm going to do a fluid flush and filter change, just cause it wouldn't hurt.

Ok do that and make sure to read the trans stick and use the right fluid as this can cause problems with it if you don't. Let me know

Did the filter and flush. Paid extra to get the proper fluid. No change.

Read that the alternator can throw ac spikes that confuse the computer, causing the P0340 code. Disconnected the alternator from the electrical system and took a test drive after clearing the codes.

The vehicle still stalled and bucked. That does not rule out that the alternator is still affecting the P0340 code, but it does eliminate spikes from the alternator causing the bucking and stalling.

I also noted that the bucking seems to only occur during steady state throttle settings. The bucking will stop if I apply throttle. Trouble is, that could just be coincidental. The bucking could be short term, and by the time I apply throttle the bucking may have quit on its own

Verify I can test the MAF by disconnecting it and running the vehicle.

Yes you just unplug it and see how it idles. It won't have much for throttle response but if it is the problem the idle will improve. Now on the TPS have you tested it with a digital multi meter with key on engine off? If not let me know and I will give you the procedure.

No, I have not tested the TSP. Just assumed it was good since it was new.

I never assume anything you would think it should be good but lets check it to be assured that it is. You will need a paper clip and a digital multi meter. You use the paper clip to back probe the gray wire with the white stripe (do not unplug it). Now hook up you multi meter set it on the 20 volt scale or 12 if you have such a setting. Now turn the key on engine off. You should see .8 to 1 volt with throttle closed. Now slowly lift the throttle and watch the voltage it should slowly and steadly increase with no drops or glitchs. Now at full throttle you should see 4.5 to 5 volts. Let me know what you find. If this don't pan out then we can check the cam or crank sensor and also check the module if needed.

Ran it without the MAF connected till it was warmed up. Once warm the stalling occured, but no bucking that I noticed.

I'll test the TPS next.

Just came back from an Alternator/Starter shop. They tested the Alternator, and it is not thowing AC spikes.

It started bucking and did it long enough to apply a steady increase in throttle. The bucking continued untill I had increased the throttle about 25% So it's not a steady state problem that only occures at a fixed throttle position.

"turn the key on engine off. You should see .8 to 1 volt with throttle closed.

0.946 vdc

"slowly lift the throttle and watch the voltage it should slowly and steadly increase with no drops or glitchs."

Smooth increase in voltage

"at full throttle you should see 4.5 to 5"

4.54 vdc.

Looks like it's not the TSP.

Good this eliminates that from being it. Now did you check the mass air flow meter? I would like you to also check the coolant temp sensor and air charge temp sensor. Just unplug them when the car is cold like in the morning before it has been started. Now with the multi meter set it on ohm's and with the sensor unpluged check ohms across the terminals of the sensors (not wire harness) and get back to me with the reading on both and the air temp at the time.

Found a vacuum hose that was mis-connected and the CMP had been broken at one time, then glued back together, the glue has let loose. I have a Motorcraft CMP and will replace it soon then do a test drive.

Maybe some where along the line I cured the problem and at the same time misconnected the vacuum line and bumped the CMP which caused the CMP to come loose.

Ok maybe I'll never know. I reconnected the vacuum line and replaced the broken CMP sensor

with a motorcraft replacement, and the darn thing has been working perfectly since. It's hot out, so I drove down town and parked it and let it heat soak, then drove it back about 6 miles each way in stop and go traffic with no problems. Unless it rears it's ugly head again, I'd say it's cured. It could have been a plenum leak all along, and when I resealed the plenum I failed to connect the vacuum line correctly so the symptoms remained the same. That and the cam position sensor that was glued together with epoxy that would soften when heated would result in the bizarre conditions experienced.

Back on August 30th, I suggested you investigate the CMP sensor since you got the P0340 code. Despite my recommendations, you took unnecessary steps with the alternator, MAF, and TPS instead.

Not all is lost, though; you gained some experience with different components even though they didn't relate to your problem. Believe me, I've chased my own tail round-and-round before coming up with a solution. I just wish you would have taken my advice with the long article I left you on August 30th regarding the CMP sensor.

I don't mean anything offensive by this note and in no way am I a Mr. Know-It-All; I truly hope you resolved the issue. ...but I told you so...Check the CMP...

Hey No Problem. I deserve an "I told you so" Thanks for the input. Like you said, it was a learning process and I am much more comfortable playing around with the windstar than I was before.

Even if I wasted some time and money, it's like my wife said. "It was still cheaper than a car payment"

Thanks Again

Ok first I am sorry that guy ripped you a new one that was uncalled for. I had you do the other tests to one rule them out and also it let me know that you are getting power to those sensors so it also rules out the PCM for now too. Now with that said lets look at the cam sensor. Use pic below to help with the testing. I am going to give you the test a step at a time if you don't mind. First unplug the sensor and then hook up you volt meter between the VPWR term on the wiring harness and ground. Turn key on engine off and note voltage. If more then 10.5 volts then wire is good it not find break in the wire. Now if you do have 10.5 volt or more then you to check the ground. Turn key off again and hook up you meter between pwr/gnd (pin 24) and ground and now you will measure ohms should be less the 5 ohms. Now if this checks out get back to me and we will go to the next step ok. You are not testing the sensor yet you are testing the wire harness that you unpluged ok. Here is the pic of the plug.

After my last post I've taken a 250+ mile road trip, and did the normal driving around town with no problems. Like I said I'll never know if the original problem was a plenum leak (vacuum leak) and the broken cam sensor was just confusing the issue or if it was the broken cam sensor, or both that was causing the problem. Either way. It's cured.

Thank You all for your help!

Great glad to hear it is fixed. Again sorry the other guy did the I told you so not needed. If you have any more questions please just ask. Thanks again and have a great day.

Engine Performance problem
1999 Ford Windstar 6 cyl Two Wheel Drive Automatic 133000 miles
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Van threw a code and my mechanic said to replace the EGR valve. Seemed simple and after the 1st EGR was installed by me I had the same problem. So I replaced the gasket (1st one was slightly knicked) with a good one. Same problem. Runs ok but at a stop the engine trys to stall out. If I put the gearshift in Neutral , the idle levels out and car runs reasonibly well. I put a new fuel filter on in the beginning thinking I had bad gas. but now I am lost. I threw another code, but have not had it read. I cleared the computer after the 2nd EGR replacement by unhooking the battery cable. HELP please

help is here. what you need to replace is the egr pressure sensor or DPFE. it costs about 50 bucks and has 2 vacuum hoses from the exhaust going to it and a electrical plug. buy the new one and you will see it. its very simple to install. these egr valves dont go bad, its always the sensor. hope this helps

MTT I Tried a new pressure sensor, you were right, it was a simple no brainer of an install, done in 5 minutes or so I thought, you see, this did not solve my problem. Any other suggestions? Still lookin for that 5 min. Cheap Repair

Thanks for you help so far
Rick Goswick

[email protected]

i need to know the exact code that turns on the engine light. you have a odd one, this usully always fixes the egr code for low flow and high flow. did you look inside the rubber lines and make sure they are installed correctly, not split ends?

MTT A friend @ work used his computer to pull the codes and Steve also reset my computer.... Steve said ---System too Lean
Bank 1 PO171
Bank 1 02 Sensor(Oxeygen Sensor)????
Exhaust Gas Recirculation flow Insufficient Detected
Now MTT , I did not clear the computer the last time , when I put the Pressure Sensor on . This is all Greek to me, hope you can make heads or Tails out of this imfo. If needed, whenever I throw another code, I will let you know.

Thanks again for your time and Smartz
Rick Goswick [email protected]

[quote:a5b3ccdde6="mastertechtim"]i need to know the exact code that turns on the engine light. you have a odd one, this usully always fixes the egr code for low flow and high flow. did you look inside the rubber lines and make sure they are installed correctly, not split ends?[/quote:a5b3ccdde6]

just repost on this post ans i will see it.

sTEVE @ WORK READ MY CODES TODAY and we have 3 and a question
1. po171- Bank 1 to lean
2. po174 Bank 2 to lean
3. po401 Exhust Gas Recirulation system
Tim, I pulled the hoses off the Pressure Sensor and with the engine running, I had alot of airflow with both hoses,. Both hoses seem to be in good condition with NO splits or cracks. HOWEVER_ the "Vacumn" line on the EGR Valve is different in that there seemed to be NO VACUMN @ that hose. I dont really know where this hose goes , because it goes behind the engine and out of sight. HELP again PLEASE
[quote:e6cecb048b="mastertechtim"]just repost on this post ans i will see it.[/quote:e6cecb048b]

Engine Mechanical problem
1999 Ford Windstar 6 cyl Front Wheel Drive Automatic 79,000 miles

It has 79,000 miles on it. I`ve replaced the fuel filter. Problem occurs after driving for awhile. The engine will stall, and shut off like it is running out of gas. When I attempt to restart it flutters for a second or two then dies. Try to restart turns over but will not start up. After waiting for approximately 10 minutes it fires right up. It will do this just about every time when driving across town or a lengthy trip, but not when I go short distances. Thank you for your time.

there will only be vacuum at the egr with engine in gear and a load on system. the 2 lean codes are caused by either a dirty mass air flow sensor or a vacuum leak. this is a easy one to detect if you have a scan tool and can read o2 sensor data with the engine cold. there is a bulletin from ford for the intake gaskets leaking causing the lean issue when cold and when the engine heats up the gaskets expand and the problem goes away. it seems you have covered the basics on the egr problem, now we need to get a little crafty. you need to check the egr passages for blockage, this can be done by using a vacuum pump and put pressure on egr vacuum port with the engine running and the vehicle should almost stall or actually stall, if it does then we know the passages are clear. get back to us

Next time it will not start do below immediately to determine if its fuel or spark problem.

Disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,distributor pick-up coil, ignition control module, cam and crank sensors- Note: If it doesn't apply disregard it

MTT found a vaccum hose off @ back left of engine, running fine now BUT now my heater has no heat, guess I have to tear in to the area beneath the heat controls and see what was making the "funny" noisae before it stopped making hot air. Any pointers on this??? What am I looking for this time

Rick Goswick
[email protected]

[quote:b3735d8bf1="rasmataz"]Next time it will not start do below immediately to determine if its fuel or spark problem.

Disconnect a sparkplug wire or 2 and ground it to the engine -have helper crank engine over-do you have a snapping blue spark? If so-you have a fuel related problem, check the fuel pressure to rule out the fuel filter/fuel pump/pressure regulator and listen to the injector/s are they pulsing or hook up a noid light. No snapping blue spark continue to troubleshoot the ignition system-power input to the coil/coil packs,distributor pick-up coil, ignition control module, cam and crank sensors- Note: If it doesn't apply disregard it[/quote:b3735d8bf1]

Thanks for the reply. I`ve checked the spark, and the fuel pressure. It all checks out. I am starting to believe it is from oil leaking from the EGR valve causing a vacuum leak somewhere the AT THE FUEL PRESSURE REGULATOR VACUUM LINE, OR AT THE GASKET BETWEEN UPPER & LOWER INTAKE MANIFOLD ASSEMBLIES BECAUSE OF LOSS OF TENSION AT ISOLATOR BOLT ASSEMBLIES DUE TO CONTAMINATION OF THE RUBBER GROMMETS.