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99 Chrysler 300M 3.5L - Cranks, will not start
Ok, I am at a loss. Son called me from a friends house and said car
wouldn't start, was running fine when he shut it off, got ready to leave 2 hours later and nothing. Went over to check things out, motor turned over normally, almost started "kinda acted like it is just not getting enough fuel" but would not run. Threw the car on a trailer, brought it to the house. Checked fuel pressure at the rail (46-48psi and holds for over 5 minutes) put OBDII scanner on the car, no codes. Checked spark, got spark on all 6 cylinders. Checked injector pulse, (this is where it gets strange) on cylinders 1 and 2 I get 1 pulse on intial crank then nothing. Was really liking the cam or crank postion sensor for this so I back probed the cam position sensor and got a fluctuating 5vdc, checked crankshaft position sensor, nothing, pulled it and replaced, now I got good crank PS signal, went back to injectors, 1 and 2 now get erratic pulse (and I say that by comparison... because what I would expect to see, I don't so I worked my way toward the back cylinders... 3 and 4 seem more like what I would expect, but something still just doesn't seem right, so checked 5 and 6 and got more of what I would expect to see and I say that with this caveat.. I almost watch the noid light in shock, because I would not expect to see it react the way it does (borderline to much for just cranking the motor over). The only thing I have left to check is compression, thinking that would indicate whether timing belt took a dive (I shudder at this thought, but the car has 189,000 miles on it and has been very reliable). However... I have spark and unless I am missing something there is no way I am getting spark if its broke AND coupled with the cam position sensor giving me the a flucuating 5v reading when I turn the motor over with a breaker bar. Also, for S&G, checked resistance on both sensor outputs to ground got no short on either. I am leaning more towards the ECM at this point, and I have seen them just take a dive, but not willing to go out on a limb and drop $250 without SOMETHING definitive. Is it possible for a Chrysler shop to bench the ECM off the car? Is it possible for it to jump time and cause the injector pulse to act this way? I am at a loss... |
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99 Chrysler 300M 3.5L - Cranks, will not start
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99 Chrysler 300M 3.5L - Cranks, will not start
Bill Putney > writes:
<snip actual problem> > 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). 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). > 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. 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. |
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99 Chrysler 300M 3.5L - Cranks, will not start
Joe Pfeiffer wrote:
> Bill Putney > writes: > > <snip actual problem> > >> 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). > > 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. 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. > 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). 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). >> 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. > > That would be very lucky, to say the least... 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. > ...-- 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... 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. > ...I'm not sure it's even possible to > break a timing belt on a 6 without bending valves. 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. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |
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99 Chrysler 300M 3.5L - Cranks, will not start
Bill Putney > writes:
> Joe Pfeiffer wrote: > >> ...-- 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... > > 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. My guess was valve guides -- lots of blue right after startup. >> ...I'm not sure it's even possible to >> break a timing belt on a 6 without bending valves. > > 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. Good to know (though I sure hope I never have occasion to test it!). |
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99 Chrysler 300M 3.5L - Cranks, will not start
Joe Pfeiffer wrote:
> Bill Putney > writes: > >> Joe Pfeiffer wrote: >> >>> ...-- 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... >> 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. > > My guess was valve guides -- lots of blue right after startup. But can you figure out a connection to the timing belt breaking? I can't. -- Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x') |
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99 Chrysler 300M 3.5L - Cranks, will not start
Bill Putney > writes:
> Joe Pfeiffer wrote: >> Bill Putney > writes: >> >>> Joe Pfeiffer wrote: >>> >>>> ...-- 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... >>> 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. >> >> My guess was valve guides -- lots of blue right after startup. > > 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... |
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99 Chrysler 300M 3.5L - Cranks, will not start
Hi!
> 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. 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 |
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99 Chrysler 300M 3.5L - Cranks, will not start
"William R. Walsh" m>
wrote in message news:CmmTl.717303$yE1.515731@attbi_s21... > Hi! > >> 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. > > 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. |
#10
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99 Chrysler 300M 3.5L - Cranks, will not start
Hi!
> 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. 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 |
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