Cam sensor failure, put this info in your back pocket.

[Amelio]

Ok well some of you guys will know to check here and some won't,I overlooked it so I hope this helps some of you guys that run into this issue.

I was fighting a drivability issue with my car for weeks...this was just after rebuilding it from a head gasket thrashing. Anyway....after getting it running the car would start and idle smooth,when leaving the house it would break up real bad under very light throttle and then seem to clear itself up after it got warm(about 10min)

This one really got me! At first I checked all the simple stuff that you would figure,coil pack,plugs, ignition module fuel,grounds,etc.....on and on as I said this had me for weeks. I then thought I had some bad gas due to some other buddy's telling me they had issues where I fueld up. I drained the tank ...new gas, no change. I pulled my cam sensor inspected and reset...no change

The car acted like it had bad gas or like the timing was way advanced and what really stumped me was that it really cleared up after it got warm. Not completely but to the point that you could accelerate and it not pop spit or sputter. It only acted up under 6psi or more.

Well I swore it was some type of a timing issue, inspected the cam sensor cap again and found a tiny hair line crack. I had a spare sensor so I threw the cap on and went for a drive. It seemed to fix it......but no it cam right back. I pulled over on the side of the road and unplugged the cam sensor and BOOM! the car woke.

I wnet back to the house and put my spare cam sensor in, before that I laid the old one next to the spare. The only thing I could find was the original one has the slightest bit of play in the shaft. The first time I inspected it I thought it was normal. I was wrong that lil bit of play was causing all the issues!

So if you run into this weird running issue like I did, pull that cam sensor and look it over very closely!

 

[turboclam]

Thanks for the info! How do you like the 210-215 roller over the 224-224 flat that you had in it?

 

[GNRick]

What do you mean "Boom! the car woke" ?

 

[Chuck Leeper]

"could find was the original one has the slightest bit of play in the shaft. "

Side play or end play?

 

[GNVenom]

Cam sensors will fail if the end play of the shaft gets excessive, especially if it cuts into the underside of the cap. High mileage cars are susceptible to this and I've seen it happen quite a few times. The LED cam sensor cap can be damaged the same way as well.

Every die-hard GN owner out there should have in their possession, a spare cam sensor assembly. Or two. These are "wear" items....so every 50,000 miles or so, they should be routinely replaced. Just. In. Case.

 

[Amelio]

Thanks for the info! How do you like the 210-215 roller over the 224-224 flat that you had in it?

I love the way my old flat tappet sounded, I got compliments and questions everywhere.....i had some guys swear it was a V8 when I pulled in due to the loppy idel. As far as performance the roller deffinitely comes on harder on the low end but feels about the same at peak power. I never really got to due much tuning with the flat tappet at the track so I dont really have a gauge to which makes more power. I do know that I probably needed a lil more converter with the flat tappet and the roller makes up for that so the street manners are better.

 

[Amelio]

What do you mean "Boom! the car woke" ?

Boom! as in a good boom as in ba-da-bing!(if there is such a thing)sorry the Jersey slang can be misunderstood lol!!!! as in Ta -da......magic it fixed the problem no stumble no studder no issues under boost.

 

[Amelio]

"could find was the original one has the slightest bit of play in the shaft. "

Side play or end play?

side to side play Chuck.....it did also have up and down play but I figured some is normal since both units had it, only the one that was in the car had side to side play so that is what I pointed my finger at. There was not really any markings in the cap or anything that said "hey too much shaft movement here and I am a problem" I gues that is why I over looked it the first time, that and I had never had this issue before. I have had a cam senor failure but it did not act like this at all......I have never had a component faiule that would get better with heat??????????????

The only thing I can attribute the getting better with heat is the cam sensor shaft expanding with heat and taking out some of the slack from being worn out. Other than that I have no idea why it would get better with heat which is why it threw me for such a loop!

 

[GNONYX]

Is there anyway of rebuilding the cam senor? Or are cam sensor a throw away part after failure. Thanks

 

[TurboBuRick]

The cam sensor cap can fail even on a sensor that has no shaft play.

 

[Amelio]

Is there anyway of rebuilding the cam senor? Or are cam sensor a throw away part after failure. Thanks

yes I do believe they make a rebuild kit for these things.

 

[GW2]

My car has been doing this for a year! I dont beat on it too bad because I'm sure it'l do something bad. I'm gonna have to pull the cam sensor and have a peek.

And just a quick question, the cam sensor is really only used for starting the car isnt it? after that its not really used? or is that incorrect?

 

[poppy1440]

I've been having the same kind of issue. Please take a look
http://www.turbotweak.com/forum/sho...-to-see-if-any-might-explain-bad-fuel-mileage
Is it possible I have the same issue? We've tried everything else.

 

[Amelio]

hey "GW2" and "Poppy1440" if you are questioning your cam sensor just crank the car up and disconnect it and go for a drive. If the problem clears up then you just need to determine if it is the cap or if the shaft has excessive play.

"GW2" yes that is correct the car will run without the cam sensor....it will not crank without it, t needs that reference signal to know when to fire the injectors. While the car is running and you unplug the sensor it will go into batch mode and you will hear all the injectors get louder.

Give it a shot and post up your results.

 

[GNVenom]

...And just a quick question, the cam sensor is really only used for starting the car isnt it? after that its not really used? or is that incorrect?

No, the cam sensor initiates injector every other revolution of the engine. If the signal isn't present, the ECM goes into default "batch" mode instead of sequential mode.

It is necessary not only to start (initiates both fuel and spark for the CCCI) but also during engine run.

 

[GW2]

Gonna try unplugging the cam sensor after starting and going around the block tomorrow. I guess then I'll know for sure.

 

[Goldberg]

Did your buick run worse the colder the outside temp got? When it was running bad could you still boot it and it seemed to pull fine? When it ran for 15 min or so did it clear itself up and feel fine at part throttle? My GN has an identicle problem that I have been chasing for a year. Like you, I haved looked at everything else. Mine also
bucks and pops at the least little light acceleration but is fine when I boot it. I still wonder how the temp and warmup play into the problem. Mine didn't seem to be related to cooant temps but underhood temp maybe. I was thinking maybe a problem with the trans box like a bad solder joint or connection.
I will pull the sensor and take a close look at it. I did replace mine about 50K ago I think. I have had the car since day one I might add and will probably be buried in it.

Thanks for shedding some light on my problem. At the least it will give me something else to rule out. Thanks again.

 

[GW2]

Disconnecting the sensor did not help. Well, all I can think of now is fuel system, but why would it only have issues at low revs when cold?

 

[ross87t]

My cam sensor problem ended up just being the cap. When I bought the car, it would develope some bad stumbling after the car warmed up or after I had shut it off and restarted it. It also tripped a code 41. It was equipped with an LED style cam sensor (cap). I bought a stock style unit, took the cap off of it and bolted that in place of the LED unit. I haven't had a problem since. Runs great.

 

[TurboBuRick]

My cam sensor problem ended up just being the cap. When I bought the car, it would develope some bad stumbling after the car warmed up or after I had shut it off and restarted it. It also tripped a code 41. It was equipped with an LED style cam sensor (cap). I bought a stock style unit, took the cap off of it and bolted that in place of the LED unit. I haven't had a problem since. Runs great.

I can't tell you how you how many of these I thrown in the garbage.