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intermittent long start... fixed.

61757 Views 36 Replies 28 Participants Last post by  Hemihackman
I had begun seeing this earlier in the summer, but only a couple times a week. Didn't matter if the car had been running recently or if it was the first start of the day... the engine would turn over fine, but would simply crank for 3 - 4 seconds before finally firing. No lights or DTCs.

First step was to take it to the dealer. Their recommendations revolved around "carbon build-up" in the throttle body, clogged fuel injectors, and spark plugs that had 60k miles. Since the start-up delay was completely random and the length of the delay was like clockwork, I figured it had to be something electrical that was putting the PCM into some temporary mode.

A powertrain engineer at Chrysler first had me look at the battery voltage, since there's a "rollback detection" that can be mis-triggered if the battery is low and the rpm during crank is too slow. Basically, the sensors can't determine rotational direction, only speed... so if the engine rpm matches what is known to be the backwards rotation of the crank following a backfire, the PCM will not deliver fuel. This was not the issue in my case.

Next, I tried the crank position sensor swap. Like I said, there were no DTCs but my issues were similar enough to other posters that I thought it was worth a try (and the sensor was only $24). My car is a RWD w/ the starter on the passenger side of the engine. It is absolutely necessary to remove the starter in order to get to the crank sensor on my car... it's tucked directly above the starter motor. 3 bolts and the starter is out, then the biggest pain is the sensor connector. This did not fix my starting issue.

Finally, I picked up the cam sensor and did that swap ($20). So easy I wish I would've done it before trying the crank sensor... Oh well. I did the cam sensor on Monday, and I haven't had the issue since. I'm confident that this was the culprit. The original sensor had no visual damage, so it was just a flakey signal that caused the PCM to mis-trust it from time to time.

Intermittent signals from either the crank or cam sensor can apparently cause this issue, so I'm glad I checked both. The PCM will not deliver fuel until the engine position is determined (cam/crank sync is achieved). Once engine position is determined, the cam is not referenced again. The pattern between the cam and crank signals needs to be of "good" quality in order for the PCM to be happy. No lights or DTCs unless the issue occurs two times in a row.
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great reading and information...thanks for sharing...it'll help someone in need I bet!
Nice write-up Chas and great info ... thanks.
++1 on the find I have been dealing with the delay start for a long while. Will look into Cam Sensor replacement. Mine has over 90k and runs great other than that.
great work Chas !!... as mentioned that should help others!!
Yeah seen this problem before on coulple of Hemis. Won't set any codes usually and always seems to be random. Cam sensor has fixed all so far. Wish I read this thread before you did the crank sensor. Cam sure is alot easier to do.
Thanks for the info. I have had the same issue for over a year and the dealership could never track it down. Now at least I can try something. thanks again for posting your find.
I've been having this same problem all summer. I just replaced the cam sensor this morning - will see how it works out. Thanks for the info!
Seems to be a common problem, and now, thanks to this thread, I have a lead as to where to start trying to fix it on my car.
Anyone have a picture of the cam sensor or what it looks like? What does it cost?

Another thing that happens, cuz it also happens to my car sometimes, is how the engine stops. It senses when to spark by the slots if the cam/flywheel. If the opening in the slots are at a certain spot that when you start it just throws off the PCM values, almost liek when you mis-time a distributor, it knows to fire just dosen't exactly know when. I've had this issue on many dodge cars, and its usually never the sensors, just s simple misalighnment between the slots and the sensors.
Nice find Chas....good info for future reference.
Great find Chas! My car is doing what appears to be the same thing (however it happens more often on a cold engine).
I am going to get this item this week... I have had starting issues for awhile now... I hope that this solves my issues...

thank you so much for this info...

beans to you!!

I get this problem too. I keep the key held til them engine starts. When it does the ESP BAS lights stay lit til I cycle the key (restart the engine). Anyone else??
While my car physically doesn't have an ESP light (early build '05), when I have this issue, the BAS light does stay on until I restart the car.
I have a quick question as well...

After you change the sensor, did you need to pull a fuse out and reset the car???
Green bean for a good post that should be moved to the knowledge base.
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