99 Chrysler 300M 3.5L - Cranks, will not start

They have 189k miles on it on the original timing belt!? Forgive me, but if it did break, they would deserve a few bent valves. Change interval is 100 or 105k - depending on year - and they do not like to go much beyond that.

I believe you'd still get spark based on the crank position sensor even if the cam position sensor is not getting blipped (not 100% sure about that, but I think I'm right).

You can partially remove timing cover to inspect for broken or slipped belt, but at that mileage, it would be a miracle if it isn't broken.

Sounds like it was at low speed (which is often when they break) which would lessen the likelihood of bent valves if it is the belt.

This isn't clear from the FSM -- the ignition timing is based on the crank sensor, but which piston will be at TDC comes from the cam sensor.

Though if the timing belt has failed I'd expect a code from the resulting cam-to-crank sensor misalignment (I don't see anything in the FSM that looks definitive to me about whether that'll detect the case that no cam sensor input is happening, though).

That would be very lucky, to say the least -- my daughter's Neon, with a

4, passed a compression test after breaking a timing belt, but burned a hell of a lot of oil ever after. I'm not sure it's even possible to break a timing belt on a 6 without bending valves.

You could be right. It seems that I've read posts on one of the LH car forums by people who know that it is possible, though I couldn't tell you what secondary backup source the computer could possibly use to sync the pistons to the ignition - and it is entirely possibly that I am mis-remembering. I guess, as you suggest, I could imagine it (as a temporary or limp mode) being able to sync up with no crank signal before I could imagine it syncing up with no cam signal. On the other hand - it doesn't run at all now.

I do know for a fact that it is often reported on the LH forums that a bad cam or crank signal will not always throw a code. In this case since it was a sudden no-run event, the PCM may not be seeing enough information to set a code - though it would seem that enough info. is there for it to know something (which is no good if the firmware doesn't exploit the info.), but nevertheless it is known not to under a few failure scenarios (bad position sensors being one of them, though bad position sensors sometimes will set a code, and I think broken timing belt will not set codes - again, could be mistaken).

The broken timing belt threads we see on the LH car forums very often report the event happening immediately at startup or at low speeds (not difficult to imagine that the more pulsatile/high-peak stresses on the timing belt would occur at the lower speeds when smoothing flywheel effects on the cam are for all intents and purposes absent.

Strange. Do you have any idea why that would be? I'm having trouble thinking of the connection between the timing belt failure and burning oil. Not doubting - just trying to visualize. I guess it is possible that the two just happened to start occurring around the same time.

Yes - it definitely is possible - we see broken timing belt threads in which the valves were *not* bent as well as ones in which they *were* bent. Obviously the chances of successfully "running between the raindrops" is statistically greater at low speed based purely on the far fewer number of after-break revolutions of the crank and cams from flywheels effects on both. I get the impression that the of crank rotation degrees of possible interference-to-360° ratio is rather small which would of course, combined with breakage at low-speed operation, decrease the chances of valve/piston disagreements during the event.

My guess was valve guides -- lots of blue right after startup.

Good to know (though I sure hope I never have occasion to test it!).

But can you figure out a connection to the timing belt breaking? I can't.

My guess was shock from light contact between piston and valves. Enough to damage stems/guides, but not enough to fail a compression test, is a stretch I'll grant you...

Hi!

If GM could do it on the late 80s 3800 V6, I'd have to think that Chrysler could find a way to do it as well. (I have two Buick cars--an 88 and an

89--that both have something wrong with the cam sensing. (It doesn't seem to be the sensor.) They will run and drive fine. But the ECM can't enter sequential fuel injection mode without a report from the cam sensor, so it sets a code.)

But that's neither here nor there, I'm just throwing it out.

William

My aunt's '92 Buick Regal Custom with the 3.8/3800 series I has the MIL on for the same reason. It came on when I floored it to merge back onto the interstate while coming back to Iowa from Oklahoma and has been on ever since. Strangely enough the car seems to run better now than it did before as before it would chug and sputter for the first ~30 seconds after being started and now it starts right up and idles smoothly.

Hi!

Interestingly, the '88 Buick turned its light off for quite some time after I woofed on (="floored it") it one day. I'm not sure why this would have caused the sensor or whatever excites it (probably magnetic) to start working. Then the engine light flickered every now and then for a few minuts and finally it came back on. It has stayed that way since.

On a whim, I tried woofing on the gas in the '89 car while going down the highway, but it did nothing.

I have no idea what is going on here, and it's off-topic for the group. I really don't care too much, and the cars don't seem any worse for the wear, so...

William

replying to hightide610 , Combat Missionary wrote: If you haven't actually jumped time, then...

Apparently a lot of Chrysler 300M's at one point or another go through a problem similar to this. The symptoms include (often in this order):

Acting like the rev limiter is turning on at greater than approximately 2,500 RPM

Rough idle followed by engine shutdown and inability to start

The Fuel Shutdown and/or Automatic Shutdown Relay clicking on and off multiple times per second or every couple of seconds

Intermittent spark when cranking the engine

Trouble codes for crankshaft position sensor fault, camshaft position sensor fault, or both

People will try replacing the crankshaft position sensor, the camshaft position sensor, or both, followed by the ECM (Engine Control Module), and the car may start up, then stop working again. This will make you pull your hair out.

I just went through this problem myself, and I was finally successful in correcting the fault. If you follow this procedure, you will be too.

Pull the battery and clean and tighten the terminal clamps. Clean the negative cable jump terminal on the passenger side fender under the hood. Clean the terminals connected to the positive jump terminal in front of the air cleaner assembly. Clean the positive cable terminal feeding power into the power distribution center (PDC). Test your battery and make sure it is charged. Lack of power due to a discharged or bad battery or corroded terminals will prevent adequate spark and will stop cranking. After cleaning these terminals, try starting the car. If the car still doesn't start, proceed to step 2.

Test fuel pressure at the fuel rail while having an assistant crank the engine. Upon startup, the fuel pump will pressurize for approximately 3 seconds, so this test is simply to eliminate a bad fuel pump as the cause of your non-start. You will probably read in the neighborhood of 50-60 PSI if the fuel pump is working.

Test for spark at one of the coil packs. If you have no spark, your ASD relay is probably not getting a ground.

Following the procedure outlined in the Haynes or Chilton's repair manual for your car, test your camshaft position sensor and your crankshaft position sensor. One wire feeds approximately 8 VDC to the sensors, one wire grounds the sensors, and one wire sends a square wave (approximately 5 VDC) to the ECM. This test involves ?backprobing? the connectors, but you can simply use a voltmeter and push GENTLY through the wire insulation (if you push too hard, you'll break the copper wires inside and create a high resistance wire which will be more of a pain to fix) and test for power and/or ground as specified by the manual.

Test the ASD relay.

Resistance test terminals 85 and 86. You should read about 75 ohms of resistance.

Resistance test terminals 87 and 30. They should read open (infinite resistance).

Jumper terminal 86 of the relay to 12 VDC, and jumper 85 to ground. Resistance test terminals 87 and 30. You should read continuity (roughly 0 ohms of resistance).

If the relay meets these specifications, the relay is good. If not, replace the relay.

Test the Fuel Pump Relay using the same procedure as with the ASD relay (the terminal numbers are the same and the relays operate the same, even thought the Fuel Pump Relay is narrower).

At this point, you'll have established that you have a good battery, good power distribution, a good fuel pump, a good crankshaft position sensor, a good camshaft position sensor, and good ASD and Fuel Pump relays. If your car still won't start, and you're still reading bad crankshaft and camshaft position sensor codes, and you're still getting ?chattering? ASD and Fuel Pump relays, it's because the relays are getting an intermittent ground through the ECM. Most likely your problem is that there is a fault in the engine wiring harness that has shorted and ruined your PCM. The harness must be repaired and then the ECM must be replaced. If you just replace the ECM without repairing the harness, odds are you'll just fry the new one.

To remove the harness, first remove the upper intake manifold. Place clean rags in the intake holes on the lower intake manifold to prevent debris from entering the manifold. Disconnect the C1 connector from the ECM (this goes to the engine, the C2 connects to the PDC). Follow the harness and disconnect it from the PDC connectors, the alternator, fuel injectors, coil packs, upstream O2 sensors, throttle body, etc. Note the portion of the engine harness that passes under the upper radiator hose connection at the lower intake manifold. On my 300M, the insulation on about half of the wires at this point had been melted due to the heat from the engine coolant passing through the hose.

Repair the harness. Separate the individual wires from each other. Wire by wire, cut out any parts that have melted or brittle insulation. Solder and heat shrink replacement wires into place.

After repairing the damaged portions of the wiring in this section of the harness, inspect the rest of the harness for cracked, brittle insulation, melted insulation, chafed insulation, etc. Repair the wires as necessary (this part took me a couple of evenings in my shop). Inspect all of the connector plugs for damage, missing lock tabs, or any other damage. You can still get most of the connectors at a dealer, so replace them as necessary (I found about half a dozen wires that were chafed at the connector plug and were probably grounding out on my harness; any of these could have fried my ECM), although if you need a C1 connector, you're going to have to go to a junkyard and splice it in (I didn't need one). Use solder and heat shrink, or you'll just end up redoing the job when your crimped splices corrode out.

After repairing all the wires in your engine harness and replacing any connectors as necessary, chafe wrap your rebuilt harness. Between Auto Zone, O'Reilly's and Harbor Freight, I got plenty of 1/4?, 3/8?, 1/2? and 3/4? plastic anti-chafe corrugated tubing (or whatever it's called). Chafe wrap every sensor lead right down to the sensor and secure the chafe wrap with zip ties. After chafe wrapping the entire harness, use plenty of electrical tape where sections of chafe wrap meet to secure the sections together.

At this point, you have a harness that's probably better than factory. Reinstall the harness, rerouting it ABOVE the upper radiator hose and pushed forward more so you don't get melted wiring again anytime soon from radiated manifold heat. Reconnect the harness to your ECM (you might get lucky and NOT have a fried ECM). Try to start the car. If you're still getting the chattering relays, your PCM is shot. I recommend going to Auto Zone for a new one. Dodge wanted $500 for the part, plus another $100 to flash program the ECM; they wanted $900 to install and program the ECM themselves. O'Reilly's wanted $130 for the ECM, $20 to ship it in from out of state (plus a three-day wait), and then I'd have to take it to Dodge to flash program it. AutoZone had the part I needed for $130, and when I went in, I brought in my VIN and my mileage, they got me the part in three days already flash programmed from the remanufacturer. It works like a charm, plug-n-play. Just install the part and you're ready to go.