Notices
GM Engine & Exhaust Performance EFI | GEN I/GEN II/GEN III/GEN IV Engines |Small Block | Big Block |

Crankshaft sensor???

Thread Tools
 
Search this Thread
 
Old 01-17-2008, 11:17 PM
  #1  
TECH Junkie
Thread Starter
iTrader: (25)
 
terravast4's Avatar
 
Join Date: Jul 2007
Location: Austin, TX
Posts: 3,123
Received 310 Likes on 226 Posts
Default Crankshaft sensor???

Can anyone out there help me. For the past few days the truck has been idling really rough but not all the time. I can sit at a light and it will idle fine. drive to the next light , stop, and then it bucks like hell rpm's dipping below 500. once I get off idle it rins fine. I have also experinced stalling about three or four times in the past week but always start's right back up. now when i slow down to a stop quickly the rpm's are all over the place 800, 300, 500 feeling like it is about to die. Has anyone experienced this? I think it is the crank sensor but not 100%. If anyone has experienced this let me know.
Old 01-17-2008, 11:55 PM
  #2  
High on diesel fumes
iTrader: (70)
 
thunder550's Avatar
 
Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 12,658
Likes: 0
Received 3 Likes on 3 Posts
Default

Sounds like an idle airflow problem to me. What tune are you running?
Old 01-18-2008, 07:46 AM
  #3  
TECH Junkie
Thread Starter
iTrader: (25)
 
terravast4's Avatar
 
Join Date: Jul 2007
Location: Austin, TX
Posts: 3,123
Received 310 Likes on 226 Posts
Default

I had a custom tune done here at a local shop. The thing is it does not akways idle bad. I can drive some short trips and it will idle fine. It seems if it was an air/idle issue it would be all the time. It tripped a code last night so I am gonna have that code pulled today. as soon as the check engine light came on it really idled bad I had to brake and rev the engine over 500 rpm's just to keep from stalling at every light.
Old 01-18-2008, 08:58 AM
  #4  
High on diesel fumes
iTrader: (70)
 
thunder550's Avatar
 
Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 12,658
Likes: 0
Received 3 Likes on 3 Posts
Default

Hmmm...well let us know what the code is, maybe that will shed some light on it.
Old 01-18-2008, 09:04 AM
  #5  
TECH Veteran
iTrader: (5)
 
BLACKND's Avatar
 
Join Date: Aug 2004
Location: Alvin,TX
Posts: 4,123
Likes: 0
Received 0 Likes on 0 Posts
Default

I know when I had my 04 cammed crew cab, that it pulled a move like this on me twice. When I would sit idle or just off idle it would run rough as hell, sound like ****, and buck RPM's like crazy until I got it moving good. Seemed like it did it mostly in first gear at low rpm's. Run almost like it was reduced power mode.

I checked everything, never thru any codes, but turned out to be a bad plug wire. A header burned it up. Put the stock plug wires back on and it ran fine. I know it sounds like a simple solution and it might not help one bit, but it would be the easiest to check.
Old 01-18-2008, 09:42 AM
  #6  
TECH Junkie
Thread Starter
iTrader: (25)
 
terravast4's Avatar
 
Join Date: Jul 2007
Location: Austin, TX
Posts: 3,123
Received 310 Likes on 226 Posts
Default

I am getting ready to pull the code here soon. It is only bad at idle. over 500 rpm's no issues at all. runs great, pulls hard. once I slow down to a stop rpm's drop below 500 then jump up. then may idle just fine. Oh well, the code will tell all.
Old 01-18-2008, 11:47 AM
  #7  
TECH Junkie
Thread Starter
iTrader: (25)
 
terravast4's Avatar
 
Join Date: Jul 2007
Location: Austin, TX
Posts: 3,123
Received 310 Likes on 226 Posts
Default

Pulled a code p101-maf or vaf in ckt. anyone?
Old 01-18-2008, 12:19 PM
  #8  
High on diesel fumes
iTrader: (70)
 
thunder550's Avatar
 
Join Date: Mar 2005
Location: Phoenix, AZ
Posts: 12,658
Likes: 0
Received 3 Likes on 3 Posts
Default

Might try cleaning the MAF sensor...there's some kind of electrical connector/sensor cleaner that you can use that's a no-residue cleaner. That would be the place to start, other than checking to make sure everything is plugged in correctly.
Old 01-18-2008, 01:31 PM
  #9  
TECH Apprentice
 
Bish's Avatar
 
Join Date: Apr 2005
Location: Chicagoland
Posts: 392
Likes: 0
Received 0 Likes on 0 Posts
Default

Contact Cleaner for electronics works well or you can use a MAF specific cleaner. Not sure if you have one but when my Idle air Control (on TB) would get dirty it would act in a similar manner.
Old 01-18-2008, 04:27 PM
  #10  
TECH Junkie
Thread Starter
iTrader: (25)
 
terravast4's Avatar
 
Join Date: Jul 2007
Location: Austin, TX
Posts: 3,123
Received 310 Likes on 226 Posts
Default

Already cleaned the throttle body and maf. Same ****.


Quick Reply: Crankshaft sensor???



All times are GMT -5. The time now is 11:06 PM.