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 OBDII
 OBDII (1996 and up)
 P0340 - intermittent misfire
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| Author | Topic: P0340 - intermittent misfire |
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windstar Junior Member |
posted 07-11-2003 11:28 AM
   
I have a '98 Windstar - 3.8L. The car was running fine and had ~ 100K. Took it in for a tuneup just for routine maintenance. Car immediately began to misfire intermittently and service engine light came on with P0340 and P1513 codes. The tuneup place said that the tuneup had nothing to do with this fault, so we took it to another place (just out of distrust). The new independent shop replaced the manifold runner vacuum. The service engine light with the P0340 code came back after a few days of driving. They then replace the CMP sensor,CMP housing, and R&R CMP sensor & synchronizer. The service engine light with the P0340 code came back again after a few days of driving. They then repositioned the CMP sensor. The service engine light with the P0340 code came back again after a few days of driving. They then said a ground was dirty and cleaned it. The service engine light with the P0340 code came back again after a few days of driving. They then said it must be the PCM but could not test or replace it. I drove it around with the service engine light for about a week. The service engine light went off two days ago and is still off (but the car is still misfiring). Several questions I have already spent ~$700 on the repairs. Potentially I could spend much more. The car is probably worth no more that $3,000. IP: Logged |
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holstdb Member |
posted 07-11-2003 01:27 PM
Not that the dealer is always the best answer, but if the original shop doesn't want to claim ownership of the problem, I would've taken the car just for diagnosis to the Ford dealer. Don't authorize repairs, just have them scan it and see what they think. My guess is it's a wire harness issue. But look what happens when you guess... people just replace parts at random and hope the problem goes away. Sometimes an original service manual can be handy. I don't know if Ford is like this, but I have GM/Helm manuals and they break down EVERY Powertrain trouble code with specific things to check. It is very useful. Dave Holst www.beretta.net IP: Logged |
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windstar Junior Member |
posted 07-12-2003 12:14 PM
Well the check engine light is back on. I noticed that when I drive around town (driving 30-45 mph) is when the car misfires the most and then the check engine light comes back. If I drive on the interstate for awhile the check engine light goes off. IP: Logged |
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wptski Member |
posted 07-13-2003 07:01 AM
quote: Interesting! I always thought that the CEL can turned off three ways: Disconnecting the battery, using a scan tool and by the PCM itself after so many drive cycles with no faults. It doesn't sound you completed a drive cycle by just "highway" driving. [This message has been edited by wptski (edited 07-13-2003).] IP: Logged |
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windstar Junior Member |
posted 07-13-2003 10:24 AM
quote: Got me. All I know is that the CEL is being cleared by the PCM. I have not cleared it with a scan tool or by disconnecting the battery. IP: Logged |
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Gipper Junior Member |
posted 08-01-2006 01:41 PM
Sounds like your timing chain is stretched. When you drive long periods on the highway, the pull side of the chain is taut because of the constant drag from the cam. But when you drive city, constant accellerate (taut) and braking (cam overspins causing the cam sensor to mismatch the crank sensor TDC signal) sets the P0340. Likely no electronic problem, but a real mechanical problem that needs addressing. If your engine has a tensioner, it may have failed; and if it does not have a tensioner, the stretched chain will only get worse, til it skips. Theny you got problems. IP: Logged |
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Gipper Junior Member |
posted 08-08-2006 07:12 AM
P0340 kept coming up, even after replacing the cam sensor, wiring to the PCM, 2dry ign cables, sp plugs, head gaskets, swapped coils, geez... still came up every time I cleared it- it would run for the first trip, with no CEL turned on, then as soon as I started it, CEL is on and it is the P0340, again. Finally, I read on another forum that the problem may be the alternator. I just put a new one in about a month before the problems all started. How to diagnose: Charge up the battery. Clear out the codes. Run it until the P0340 shows. Bring it back home. Clear out the codes. Disconnect the alternator. Yes disconnect the alternator. Isolate the battery terminal at the alternator from any short circuits by wrapping it in elec tape. Take the car on the same trip. If the code does not set on, you found the problem. The voltage regulator is transmitting stray AC voltage that is being picked up by the cam sensor or the PCM and throwing the whole system off. Do the test in daylight with no loads on--no radio, no headlights, no blower. I didn't believe it was possible, but now I am a believer. -Mac IP: Logged |
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Aeroman59 Junior Member |
posted 01-08-2007 06:18 PM
Hi, I have an Aerostar, it has a 3L Vulcan engine, yours might be a Duratec? If it is the below info might be slightly different for your engine. Anyways, the cam sensor code: P0340. The cam sensor is a Hall effect (on/off state) sensor which is used to fire the fuel injector circuit when Piston #1 is at TDC. The ECU looks for this signal which is timed via a synchronising drive ( looks like distributor) unit driven through a worm & pinion off the camshaft. Your engine might run fine without it since the crankshaft also has a sensor which can measure TDC direct from the crankshaft. The fuel circuit however is more concerned with when the intake valves are opening, hence the camshaft sensor circuit. The sensor is located at the rear of the engine on the Vulcan engine & can be accessed through the inspection cover between the front seats in the van. I assume the Windstar has the same access cover otherwise it might be a pain to get to. Anyways the sensor has a magnetic pickup which can disintegrate & also the synchro drive "circular vane" can break causing a loss of signal to the ECU which will throw this code & it wont go away. The synchronizer unit is just like an old fashioned distributor & has to be timed to the engine, so the fuel injection system operates optimally. 1)If the electrical harness & plug is damaged to the sensor it wont be transmitting the signal & the CEL will come on. 2)Did the garage time the synchro drive properly ? HTH, Aeroman [This message has been edited by Aeroman59 (edited 01-08-2007).] [This message has been edited by Aeroman59 (edited 01-08-2007).] [This message has been edited by Aeroman59 (edited 02-11-2007).] IP: Logged |
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