Mekanik Posted August 31, 2006 Share Posted August 31, 2006 There is another tech. here that I am trying to help. He is working on a 99 Expedition with 110,000 miles. It has a reoccuring p0340. He recently replaced the cmp and the crank position sensor, checked the crank sensor wiring which is ok. I guess he drove it far enough to go through the drive cycles, then the MIL came back on when the cust. picked up the truck. I have heard of timing chains stretching on 4.6L's but those have very very high mileage from what I have heard. Any help would be appriceated. Quote Link to comment Share on other sites More sharing options...
james richards Posted August 31, 2006 Share Posted August 31, 2006 do a ripple test on alternator can cause 340 . or possibly a bad coil pack with rfi interfereence can cause it too good luck Quote Link to comment Share on other sites More sharing options...
pcassidy111 Posted August 31, 2006 Share Posted August 31, 2006 What I have done in the past for this code on 4.6L is to monitor the frequency of the signal with a graphing multimeter, looking for dropouts. The frequency should remain constant for a given rpm. If the sensor tests good I replace the pigtail to the sensor (plug and about 6 inches of wire-a common problem area on the town cars and crown vics.), did he do a wiggle test and look for drop outs? Quote Link to comment Share on other sites More sharing options...
LR Mike Posted September 1, 2006 Share Posted September 1, 2006 As pcassidy111 said, but I like to use the oscilliscope on the WDS or IDS - easy to monitor the CMP signal at the PCM and then just identify the offending pattern! My suspicion is, though, that the DPFE sensor is causing it, especially if it is a metal cased one. Good luck! Quote Link to comment Share on other sites More sharing options...
gasgasman Posted September 3, 2006 Share Posted September 3, 2006 Check the EEC wiring harness for shorts on the A/C accumulator. I have seen 100s of these. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 7, 2006 Author Share Posted September 7, 2006 Well we were looking at this thing on Friday. The code would come back right away and the cmp failurepid was reading yes. I unplugged the alternator then started unplugging COP's one by one. By the time I got to cyl. #2 the pid read no. By Tuesday he told me that he could get the pid to go from no to yes very consistently by wiggling the wiring by the accumilator. I took the day off of work today and hopefully when I go in tomorrow I will find out exactly what was causing this dtc. Thank you for all the ideas and I will let you guys know what the final outcome is. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 7, 2006 Author Share Posted September 7, 2006 That other tech. that I'm helping told me today that the CMP wiring was chaffed on the right side of the accumilator. He said that he could not see it until he removed the bulkhead connector bracket. I'll keep that one in mind next time. Thanks Quote Link to comment Share on other sites More sharing options...
gasgasman Posted September 9, 2006 Share Posted September 9, 2006 Cool. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.