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Rlmtex
Novice
Sep 22, 2008, 8:22 PM
Post #1 of 6
(1679 views)
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97 Chrysler T&C 3.8, 196k, factory alarm
-Backfiring under load,
>Changed plugs & wires,
*Normal except #6 had black soot on it, like burning rich
*Ran perfect for 2 days,
>Shut off by it's self@ 50MPH,
>Code: Cam Sensor signal lost,This was after primary I tried to start it at 40mph
*Changed Cam & Crank sensors,Left paper spacers on sensors
>Cranks but no start,
-Towed Home,
>Removed instrument panel re soldered all joints,
>No start,
*Replaced ASD relay,
>No start,
*Swapped relays around,
>No start,
**** Getting erratic orange spark at plugs, *******
*12 volts at coil pack,drops to 11.6 to 10.5 while cranking
*Coil pack resistance with in spec,
*Engine temp sensor resistance with in spec,
*12 volts at injectors,
*8.6 volts at Cam & Crank sensors,
*Fuel pressure 45 to 50 and holds
*Compression on cold engine 145 to 150, spec is 170@ 250rpm on WARM engine,
* Checked continuity between coil pack plug and PCM plug, checked good.
* Used a LED probe on coil pack plug, It's only lighting up two times right after each other while cranking. I would think it should be once a second. Then it will also light up again when I quit cranking.
* Checked cam and crank sensor signal voltage, both showed 4.99. But I couldn't count the spikes on the crank sensor, I think my meter is too slow to register.
* Used video camera to record voltage readings while I turn engine by hand
* 1 revolution produces 12 readings of 4.99v at crank sensor
* and one reading of 4.99 at cam sensor.
* Checked continuity on cam and crank signal wires, both good to PCM plug
It's getting plenty of fuel, plugs get wet.
The new plug wires read 7.6k ohms, the book says they should be 26k ohms.
How many times should the cam sensor send out a signal during one crank revolution?
A few days before I changed the plugs it had quit on me in the parking lot but started right back up.
Also, before it quit@50mph there was a slight delay between when you turned the key to start and the starter cranking. I would estimate about 2 or 3 seconds. Now that delay is gone and the starter begins cranking as soon as you turn the key.
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DanD
Veteran
/ Moderator
Sep 23, 2008, 4:07 AM
Post #2 of 6
(1673 views)
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Re: Van won't start
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How many times should the cam sensor send out a signal during one crank revolution? For every two rotations of the crankshaft, the camshaft rotates once; so the cam sensor should only send (trigger) once for every two rotations of the crankshaft.
Out of all the tests that you’ve performed, have you checked for codes? If so and there are codes, follow their test procedures; if not, have the codes read. Now if there is a code for something like a vehicle speed sensor circuit; you’re not going to go chasing after that, until you get the van running again.
Does the Malfunction Indicator Lamp (MIL) perform a bulb check when the ignition is first turned to the run position?
The MIL should come on and remain on for three seconds, to verify bulb and circuit operation; then turn off.
This same three seconds is when the ASD is energized, which turns on the fuel pump for its prime cycle. The ASD also powers up injectors, alternator field circuit and ignition coils; probably other items as well but these are the ones I can remember. Once the Mil turns off and the engine is not being cranked (not producing an ignition reference signal); the ASD will remain off.
So with you saying that there is voltage at the ignition coil, during cranking; the PCM must be seeing some form of ignition (RPM) reference signal?
You will need a scan tool for this next test.
You would set up the scanner to read cam & crankshaft signal data. The screen data for these sensors are a simple yes or no. With the ignition on (not cranking) both sensors should be reading NO. Once you begin cranking the engine, they should toggle YES and remain yes during the crank. What this tells us is that the sensors are sending a signal and that the computer is recognizing the signal. The scanner only reads the PCM’s interpretations of sensor inputs.
Keep it fun and I hope some of the above helps?
Dan.
Canadian "EH"
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DanD
Veteran
/ Moderator
Sep 24, 2008, 3:32 AM
Post #4 of 6
(1663 views)
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Re: Van won't start
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For $90 you might be able to buy a code reader but they are far from an actual scanner. A code reader is just that; it will access and display codes only. A scanner does this, along with showing the computer's interpretation of sensor data. An up to date scanner will also have by-directional capabilities that can make requests of the computer to perform certain functions. ie: turn relays on & off, run diagnostics, along with a number off other items to help with diagnosing the vehicle.
You don’t have to go & buy the cam spacer; just use a dab of glue and a small piece of paper about .030” thick; the cardboard from a pack of paper matches works fine.
Dan.
Canadian "EH"
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paulklux
User
Oct 2, 2008, 1:22 PM
Post #5 of 6
(1628 views)
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Re: Van won't start
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The cam sensor will only prevent the vehicle starting when it is hot
I think you should go back to basics
If you have a MIL lamp on then you should have a fault code in the ECU that will determine the problem
If not and you have visually checked the ignition side then check the following
1) Ensure that there is no air leak on the manifold or surrounding pipes- this can be done by spraying liquid such as maintenace spray oil (STP) around the manifold when started and the engine should run slightly better if so you have a leak (most common fault with backfiring)
2) Check that the spark plug leads are not mixed up and are in correct firing order
3) Ensure engine timing is correct
Best of luck
(This post was edited by paulklux on Oct 2, 2008, 1:27 PM)
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Rlmtex
Novice
Oct 16, 2008, 2:35 PM
Post #6 of 6
(1601 views)
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Re: Van won't start
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Just thought I'd give everyone an update.
I replaced the spacer on the cam and crank sensor. The van started for a few seconds then shut down. I continued to try to start it and found that if I played with the gas pedal it would kind of run, missing and backfiring and trying to cut out. I changed the cam sensor out with a Mopar sensor,Van started right up. Bad aftermarket sensor........... Nope!
I drove it for 2 days, everything seemed fine......... Nope!
Was sitting in parking lot at work and it shut down again. Did not want to start. Played with the gas pedal when it would fire and got it running, then died. Checked codes, no crank signal. Kept trying and got it running again and checked codes, no crank signal, intermittent cam signal. Every time I put it in drive it would die unless the rpm was around 1500.
I nursed it over to the dealer by keeping the rpm above 2000rpm and bought a Mopar crank sensor. Drove it home that night, seemed alright, missed a little. Changed the crank sensor the next morning, fired right up. Problem solved........ Nope!
Wife took van and it died twice on her. Code, intermittent cam signal. Let it run in driveway for half an hour, ran smooth and perfect. Got under the hood and wiggled the cam sensor wires, van died. Started it again, wiggled cam wires, van died. Started again and pulled each of the 3 wires on the cam plug. When I pulled the wire for the ground it died. Took dikes and cut plug out and wired it straight through. Tried to start it. Cranked but no start. Ohmed out the plug from the sensor that I had cut off and found that the orange power wire goes straight through. The other 2 wires reverse inside the cam sensor plug. Rewired with the signal and ground wires reversed and it fired right up. Soldered the new splice and it has been running for 15 hours of road time now. I think I finally got it fixed.
Re-examined the plug and socket that I cut off and found that the ground wire was broken inside the socket. So sometimes it would make contact and other times it wouldn't. With the ohm meter attached I could make it connect and disconnect with very little movement of the wire. Explains why it would die when I put it in drive, the engine would move a little and break the connection then settle back and let the wire connect.
Hope this helps someone out........
Things I found out:
The engine has run for 7 seconds to drop a code
The cam sensor sends out 9 pulses for every 2 rotations of the crankshaft.
Each cylinder fires twice, once on the power stroke and it fires a reduced, orange, spark on the exhaust stroke.
When it comes to sensors buy OEM replacements, lower defect rate.
There is a TSB that if the cam or crank sensor goes it can drop a code indicating the other sensor. Like in the parking lot it said no crank sensor signal but it was the cam signal that was missing. If there was no crank sensor the tach wouldn't register anything when I tried starting it. It was showing about 250rpm while trying to start it.
I've learned a lot about the various systems and how they work and interact. Also got a subscription to Alldata.
(This post was edited by Rlmtex on Oct 16, 2008, 2:50 PM)
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