Shudder at low iddle
Shudder at low iddle I was sitting at the drive through today in my 02 TA and noticed that their was a shudder every few seconds at low idle while the vehicle was in park . I pressed the accelerator and the shudder wasnt nearly as evident at a higher rpm...so I put the car in drive and sat with my foot on the brake and the shudder was gone and wasnt evident at all while driving or just sitting at a stop light. Does anyone know what this might be ?
anybody ??
Update** Crack about two inches long in the base of the exhaust headers ....would this cause a shudder at low idle can it be welded or just better to replace the whole thing ?
Update** Crack about two inches long in the base of the exhaust headers ....would this cause a shudder at low idle can it be welded or just better to replace the whole thing ?
Last edited by xenergyx; Dec 15, 2012 at 11:00 PM.
When my MAF sensor *Mass Air Flow* was going out, it would do that mainly when it hadnt reached operating tempature, id go have codes ran. even if the light doesnt show, wouldnt hurt to try
^ MAF isn't really used at low RPM's, only for high. So that's probably not it. Are you down on power at all?
May be a number of things. Slight misfire at idle (plugs or wires,) dirty injector or a possible bad injector, Motor mount..........
May be a number of things. Slight misfire at idle (plugs or wires,) dirty injector or a possible bad injector, Motor mount..........
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Replaced Wires and plugs ....and d/c the Maf just incase still same thing...Now as a random thing my DRL and dash lights dont work was blowing fuses .....fixed that for a little bit now my whole spedometer cluster is dead all fuses are good but not even the radio doesnt work. Was poping a p200 and a p300 code as well as a ecm low voltage. I check all the wiring and my grounds I'm totally lost ....I broke down down and took it to the GM dealership NOT something I wanted to do but my extent of electrical with this car is somewhat limited 
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I removed the seats and rolled the capet and checked the wire bundle that runs along and all the grounds underneath it. Everywhere! was driving me insane
Updated ** Called GM today now they tell me theirs so many codes low volt and high volt they said itll cost 1200 bucks to fix and they dont even know if they can fix it.
Update to the update**Good news I wont have to fork over all that money to have it fixed ...why? Because the technician thinks that the fix will not be worth it to have it fixed or worth the money or pratical or what ever. So now I think Im worse off I will get acomplete list of codes and if someone could help me maybe atleast get my dash light and driving lights to work that would be extremely helpful and yes apparently the problem is electrical
Codes are as follows.
P0200 Injc Circut x2
P0300 Multi Misfire....I just replaced spark plugs and spark plug wires so I really dont understand this one
P0332 Knock sensor Low Input (Bank 2)
P0452 Evap Emissions System Pressure Sensor/ Switch Low Input
They were all listed twice
But for some reason all ny night running lights work and dash lights are back spedometer works and so does my radio....which is good but I think it will happen again probably at a worse time
Updated ** Called GM today now they tell me theirs so many codes low volt and high volt they said itll cost 1200 bucks to fix and they dont even know if they can fix it.
Update to the update**Good news I wont have to fork over all that money to have it fixed ...why? Because the technician thinks that the fix will not be worth it to have it fixed or worth the money or pratical or what ever. So now I think Im worse off I will get acomplete list of codes and if someone could help me maybe atleast get my dash light and driving lights to work that would be extremely helpful and yes apparently the problem is electrical
Codes are as follows.
P0200 Injc Circut x2
P0300 Multi Misfire....I just replaced spark plugs and spark plug wires so I really dont understand this one
P0332 Knock sensor Low Input (Bank 2)
P0452 Evap Emissions System Pressure Sensor/ Switch Low Input
They were all listed twice
But for some reason all ny night running lights work and dash lights are back spedometer works and so does my radio....which is good but I think it will happen again probably at a worse time
Last edited by xenergyx; Dec 21, 2012 at 01:51 PM.
TECH Fanatic
Joined: Mar 2011
Posts: 1,050
Likes: 2
From: Odessa, TX
Mine has a slight shudder mostly when up to temp but ONLY in drive. I can watch my rpm needle go up and down from 500 to 600. In park sits steady at 600. Every now and then the shudder will drop the rpms slightly under 500. I'm going to change plugs/wires and o2s all at once.
So help me understand the maf thing. Let it idle and when I unplug it what should happen? Should the car struggle to idle? And if the ar idles fine it's a bad maf??
So help me understand the maf thing. Let it idle and when I unplug it what should happen? Should the car struggle to idle? And if the ar idles fine it's a bad maf??
I guess....All I know is something feels and sounds like its loose and coming from the passenger side atleast I get that feeling .......I do know I can see the fly wheel through the shroud through a perfect circle hole in my transmission is that supposed to have a cover on it and or be filled with some liquid of some kind just a question ? Just noticed it while I was under it today
Update**** 3 shops later a transmission shop was doing their inspection and found that the motor mount was completely blown out which I dont know why the chevy dealership could of told me that so I replaced it and now its as smooth as glass !
Teching In
Joined: Oct 2007
Posts: 34
Likes: 0
From: Mount Airy, MD
Thi may be related. I work on all sorts of vehicles, but a customer of ours has a fleet of 2008-2013 g series work vans with mileage from 20,xxx to 60,000 miles. From time to time, the vehicles come in with lack of power /stumble with no other symptoms. They run a fixed route since they have seating in them used for shuttle service. I have had several of them come in each with several injector codes,but no misfire codes, no knock codes and almost all have had a ms pulsewidth below the minimum pulse width constant that is in the tune file. I have sent a diagnostic request to a buddy at AC Delco to see if this is a software generated injector code. It manifiests itself as a very lean idle cause by, you guessed it, bad motor mounts that cause some knock at idle and coast down, that results in some pulled timing, which the 02 sensors see as a slightly rich condition and the system pulls fuel. This drops the idle pulse below the minimum and the vehicle sets injector codes. We would clean the MAF sensor, and check for causes of false knock.
Its a long, drawn out thing to follow, but if your looking at fuel trims and knock counts and all of the things that get payed attention to during diagnostics, this stuff can be found. On these chassis it was bad exhaust system hangers and isolators. Similar cause, same effect.
Chris
Its a long, drawn out thing to follow, but if your looking at fuel trims and knock counts and all of the things that get payed attention to during diagnostics, this stuff can be found. On these chassis it was bad exhaust system hangers and isolators. Similar cause, same effect.
Chris
