Mekanik Posted September 3, 2009 Share Posted September 3, 2009 I am working on a 2006 Taraus with a 3.0l 2 valve engine. The customer's complaint is that intermittently the engine will crank and not start. As always actually verifying the problem is the biggest challenge. It took two trips and one week each time to verify the problem. It is getting worse and happens more often now. It will more likely happen after sitting overnight. No DTC’s by the way. One thing I never really liked was the way it fired-up. It seemed to start just a teeny bit slower than other 3.0l's. The first time it came in I put a fuel pump in it because it leaked down, but guess what? That didn't fix it. Last week I was able to get the problem to act up quite a bit. If you cycle the key after it doesn’t start it will usually start. Sometimes the needles for the gauges start twitching after the engine finally starts. The first time it was in I made sure the CMP syncro was set properly. The syncro was recently replaced and I would only feel better if I knew it was timed right. I was able to determine that when the problem occurs I have good fuel pressure and spark. I do not have the ground pulse from the PCM. CMP Fault pid reads “No”, SYNC pid reads “yes” I have a good RPM signal, I load tested all the powers and grounds for the PCM and replaced the PCM this morning. This afternoon I have the same exact problem. I called hotline and they suggested I do a voltage drop of the starter circuits and if they are ok, replace the starter motor. Supposedly they have had some starter motors creating RFI and shutting down the PCM. The circuits test fine, and I put a starter motor on the vehicle. So far so good, but time will tell and I think I’ll keep it for the rest of the week. One thing I noticed is the way it starts now. It fires right up. Like I said before, I was never really happy with the way it started before, but now it starts right away. Hopefully this car is fixed. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted September 3, 2009 Share Posted September 3, 2009 I've seen this before a couple of times. Didn't we have one on the forum with this problem? Quote Link to comment Share on other sites More sharing options...
GregKneupper Posted September 3, 2009 Share Posted September 3, 2009 I had an lcf that kicked my ass for that exact concern. The starter had an rfi issue and would knock out the crank signal but only after about a 30 minute hot soak. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 3, 2009 Author Share Posted September 3, 2009 It didn't fix the problem. Even though I load tested the ground curcuts to the PCM and they tested good, I made redundant ground curcuts to the PCM. We'll see what happens. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 4, 2009 Author Share Posted September 4, 2009 I've seen this before a couple of times. Didn't we have one on the forum with this problem? The forum on this site? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted September 4, 2009 Share Posted September 4, 2009 Yes, it was Greg Knuepper working on a 4.5. The forum search engine sucks! No matter what I typed as far as EMI/RFI, RFI, EMI, interference, or any combination, it would not show it. I found it by looking through the archives: http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=21354&page=2 I clearly talk about EMI/RFI in the post but the search engine would not pick it up. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 5, 2009 Author Share Posted September 5, 2009 Well the redundant grounds for the PCM didn't fix the car either. I talked to a third engineer at hotline and he had me taking a very close look at the CKP circut. He told me thet the PCM sends 1.5v down each CKP wire to the sensor with KOEO. I checked the voltage KOEO, and found that at one wire I had a steady 2.5V and the other it was 2.5V, but if I bent the wire back and forth at the CKP connector it would fluctuate beetween 2.5V and about 50mv. This voltage is used to bring up the voltage so RFI won't mess up the CKP circut. The engineer was thinking I had a weak voltage reading at the CKP circuts. I replaced the CKP connector and so far so good. I want to keep it for a while to see if it is fixed or not. If it is not fixed my next step will be to measure the CKP voltage while cranking. I'm open to other ideas though if anyone has any suggestions. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted September 5, 2009 Share Posted September 5, 2009 Damn! You actually talked to an engineer that knows WTF he is talking about! Praise God! On this 6.0 capture note that I have DC selected so I can see just the DC portion of the bias voltage, which shows about 1.5VDC. Even though it's a diesel it appears the CKP circuits work similarly: Note when I select AC, it shows both the AC and DC components of the waveform. The CCM is the PCM verifying circuit integrity- making sure the circuit has continuity through the CKP sensor. The PCM sends a voltage down one wire and expects the return wire to show the same voltage, obviously. If it goes open for even an instant, it should blow an open circuit DTC. Now, what's with wiggling the connector changing the voltage? It sounds like you had a bad connection at the CKP that might have been coming loose. I agree with what you did and think it might be fixed. Have a great weekend! Quote Link to comment Share on other sites More sharing options...
Brad Clayton Posted September 6, 2009 Share Posted September 6, 2009 +1 on thinking it's fixed. This is a very common problem on the modular motors, esp. in van chassis' Quote Link to comment Share on other sites More sharing options...
Mekanik Posted September 15, 2009 Author Share Posted September 15, 2009 I kept the car for 4 days and it appears to be fixed. The car wouldn't start when the customer came to pick-up the car. He was trying to use an un-programmed key from his keyring and NOT one that I programmed when I replaced the PCM. My effing service writer didn't tell him about that and to topp it off, he lost one of the keys that I programmed. Then I had to go throught the process to program the customer's other key. He paid me for it though. Quote Link to comment Share on other sites More sharing options...
Mekanik Posted February 9, 2010 Author Share Posted February 9, 2010 It's been almost five months, so I think I can offically declare this vehicle fixed. Quote Link to comment Share on other sites More sharing options...
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