Bad crank sensor

[John B]

My car started running poorly. It would stumble and almost stall off idle, miss occasionally and felt down on power. It initially showed up as a bad Mass airflow sensor code, but after replacing that the problem persisted. After way too many hours of searching, the problem was tracked down to a bad crank trigger. Once removed, it was apparent the malfunctioning sensor actually had a crack in it. The crack was on the portion inside the engine, so it was not visible from outside. Once a new Crank Position Sensor was installed, the car ran great again. I did a search for crank sensors, but didn't see anything. As this was a tough problem to diagnose, but an easy one to fix, I wanted to share it here in the hope it might spare somebody else some grief. I'm the original owner and the car has 24,000 miles on it.

 

[RALPHIE]

Good find - perhaps we need a sticky section for solutions to both common and uncommon problems with regard to our cars....

 

[FENZO]

I can only imagine the path from a MAF sensor code to a crank pos sensor.

Thanks for posting.... now if I can just remember this when/if needed.

 

[fjpikul]

Urologist told StormCat he had a bad crank. Said there was no hope. Good find. Thank you for posting.

 

[Cobrar]

Urologist told StormCat he had a bad crank. Said there was no hope.

Dr. Frank, this sounds a bit troubling. From your professional perspective, if this malady has no known cure, should Brian relinquish his current GT as quickly as possible, as well as any rights to a 2017 model?

 

[Xcentric]

Being a pathologist, Dr. Frank can only determine the cause of a bad crank after closely examining a dead one.

 

[Cobrar]

Dr. Frank is MORE than capable of offering his opinion. :rofl

 

[fjpikul]

Hate to steal the post. I have told this to StormCat on numerous occasions

 

[PeteK]

John, thanks for the heads-up. If you have 24Kmi and the CKP sensor was cracked, I think there's a high chance others have the same problem lurking and don't know it yet. I have 37Kmi on mine. I was thinking I'd just go out to the garage and pull it and take a look, but after consulting the shop manual, it appears the car needs to be on a lift with the belly cover removed to get access. I'll get to it the next time I have it on a lift. Those of you who drive your cars regularly should consider checking it the next time your car is on a lift. It's almost certainly a standard Ford part that is fairly inexpensive.

 

[Tomcat]

I have 37Kmi on mine.

Hey Pete,
You are catching me (37,600)

 

[STORMCAT]

Great info to keep for the future, Thanks for sharing. I don't think anyone has incurred this before.

"Reports of my death are greatly exaggerated... " :ack

 

[PeteK]

Hey Pete,
You are catching me (37,600)

Hmmm, today's really nice in Northern Va. I think I 'll drive the GT to the polls and take the LONG way home! Keep looking' over yer shoulder...

 

[Tomcat]

It initially showed up as a bad Mass airflow sensor code, but after replacing that the problem persisted. After way too many hours of searching, the problem was tracked down to a bad crank trigger.

My local Ford Dealership does NOT have a GT mechanic...can they still read/pull codes? I had my GT stall at idle twice (restarted from a roll, no issues) and the check engine light is off...will it still log a code?

 

[PeteK]

1. Yes, they can pull the codes.
2. The error code is usually stored for some number of start/stop cycles, so that should also be available if you have not exceeded that number (10? Ask the dealer service guy).

 

[twobjshelbys]

My local Ford Dealership does NOT have a GT mechanic...can they still read/pull codes? I had my GT stall at idle twice (restarted from a roll, no issues) and the check engine light is off...will it still log a code?

Any place with an OBDII reader can read the codes, even places like Autozone will do it. If the "Check Engine" light is not on there could be a pending code. Pending codes are for things that require two (sometimes more) consecutive test failures. I just had a bunch of evap emissions problems on my truck and the codes would show as pending after the first test drive and then the next day the CEL code would show. In general things that cause an engine stall or limp mode will throw the light.

You do NOT need any kind of sophisticated tools to read the codes. For about $20 get a bluetooth OBDII reader from Amazon and there are several phone apps that can be used to read the codes and monitor the engine. I use the free Torque app. It can even do data logging. WIth a few bucks you can get even more real time sensor info.

 

[PeteK]

Agree. The 05-06 GT is old enough that any code reader should work. However, two however’s:
1. Some are much easier to use. Read the online reviews.
2. If you also want to use it on more recent cars and trucks, you will want to buy something better. That’s what I did. I spent $200 to get a professional tool so that I could read engine and transmission and body system codes on new vehicles, and it does data logging, which will help if you are chasing an intermittent problem.

 

[Tomcat]

My SCT X4 read no codes...so stumble at idle is not throwing a code.

 

[PeteK]

Refer to parallel thread about the crank
Sensor, and cleaning the MAF.