weird rpm bouncing revisited (fixed) - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


2000-2005 Discuss your 2000-2005 Bonneville SE, SLE, and SSEi Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 12-30-2010, 08:32 PM   #1
Senior Member
Posts like a 4 Banger
Thread Starter
 
swampthing's Avatar
 
Join Date: May 2008
Location: Homosassa, Florida (yes it says Homo)
Posts: 115
Thanks: 0
Thanked 0 Times in 0 Posts
swampthing is on a distinguished road
Default weird rpm bouncing revisited (fixed)

mentioned in my evap thread but I'm not so sure they are related anymore so starting a separate thread.

ok my weird symptoms are continuing and I am searching for other things to check.

to start the symptom is that when lightly accelerating the rpm'* will bounce UP and make the car surge, the car will continue to speed up like normal, in fact i often wind up doing 70mph while watching the car do this since it'* still speeding up the entire time. If I make the car downshift or let off the gas it stops and it doesn't do it under WOT or even under mid-high throttle just under normal light acceleration.

what I have checked:
most of my ignition is new (within 1-2 years) including plugs, wires and coils. i am planning a tune up and the plugs will be again

I swapped my tps out with a spare junkyard unit I had and bench tested the one that was in there, I found that it'* resistance was all crazy when holding the sensor steady at any point and thought I had found the problem, after installing the other one the car ran very weird, holding the gears til redline while driving normal and such. I came back removed the negative terminal on the battery and re-hooked it and the car ran normal. however the bouncing problem persisted.

I have inspected the vacuum lines in the engine bay and found nothing out of the ordinary

I had my cousin ride along with his obd computer scanner and we watched all the sensors and saw nothing odd, the new TPS was also reporting correctly we also took the opportunity to watch my fuel trims and they stayed mostly +5-10 and spiked at +14 under WOT

what I have not checked/replaced

my evap system is in trouble i have several codes in the computer setting the SES light all related to the evap

the o2 sensor, maf, iac, and pretty much anything else you could think of are all original

I noticed yesterday that my fuel pump (replaced before I joined the club with an airtex ) seems noisy I.E I could hear it over the motor on a cold startup outside the car

please any ideas or suggestions do not hesitate to post my goal is to get this thing completely tuned up so that I can install my zzp mps guilt free and this is problem #1 right now
swampthing is offline   Reply With Quote
Old 12-30-2010, 08:36 PM   #2
Senior Member
True Car Nut
 
sawgunner's Avatar
 
Join Date: Jan 2009
Location: Dover, NH
Posts: 7,122
Thanks: 0
Thanked 0 Times in 0 Posts
sawgunner is on a distinguished road
Default

if ya need the 2 purge valves for the evap system i have both of them
sawgunner is offline   Reply With Quote
Old 12-30-2010, 08:46 PM   #3
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

Does it happen to do this if your on cruise control and going down a slight incline, or up a slight hill? Wonder if you have a bad motor mount.
Danthurs is offline   Reply With Quote
Old 12-30-2010, 08:48 PM   #4
Senior Member
Posts like a 4 Banger
Thread Starter
 
swampthing's Avatar
 
Join Date: May 2008
Location: Homosassa, Florida (yes it says Homo)
Posts: 115
Thanks: 0
Thanked 0 Times in 0 Posts
swampthing is on a distinguished road
Default

the front mount is new and the problem has spanned two mounts
swampthing is offline   Reply With Quote
Old 12-30-2010, 09:30 PM   #5
Senior Member
Posts like a 4 Banger
Thread Starter
 
swampthing's Avatar
 
Join Date: May 2008
Location: Homosassa, Florida (yes it says Homo)
Posts: 115
Thanks: 0
Thanked 0 Times in 0 Posts
swampthing is on a distinguished road
Default

after researching the 5 (yes 5!) evap codes in the DTC thread I have maybe it is related after all I have the following codes

P0440
P0446
P0452
P0453
P1441
swampthing is offline   Reply With Quote
Old 01-27-2011, 11:36 AM   #6
Junior Member
 
lobalt's Avatar
 
Join Date: Jan 2011
Location: Grundy, VA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
lobalt is on a distinguished road
Default

My car (08 cobalt) is doing this same thing... the guy at the shop said it could be my purge valve in the tank... not sure tho... I'll need to find time to have it really checked out. The car is bad to idle weird & then just shut off too...
lobalt is offline   Reply With Quote
Old 01-27-2011, 11:41 AM   #7
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

If the purge valve is bad it would be like a vacuum leak. Do you have any codes? Have the car scanned. Locate where the EVAP connects to the throttle body and pull the vacuum line off, then cap that off on both sides. This shuts off the EVAP system. If things calm down then you have a issue with the EVAP.
Danthurs is offline   Reply With Quote
Old 01-27-2011, 11:47 AM   #8
Junior Member
 
lobalt's Avatar
 
Join Date: Jan 2011
Location: Grundy, VA
Posts: 4
Thanks: 0
Thanked 0 Times in 0 Posts
lobalt is on a distinguished road
Default

Quote:
Originally Posted by Danthurs View Post
If the purge valve is bad it would be like a vacuum leak. Do you have any codes? Have the car scanned. Locate where the EVAP connects to the throttle body and pull the vacuum line off, then cap that off on both sides. This shuts off the EVAP system. If things calm down then you have a issue with the EVAP.
ok, thanks! I'll give that a try!... I had it scanned last weekend but my fiance didnt remember the codes (i was at work) It'* been doing this for a while now but never thru a CEL, I hit a rock one day (i'm too low & i should have know i couldnt have drove over it) and the rock hit hard under my car around the spare tire compartment. That same day the CEL came on, I may have hurt something there too... I'll let yall know what I find out!

lobalt is offline   Reply With Quote
Old 01-27-2011, 11:49 AM   #9
Retired Senior Admin

Expert Gearhead
 
Danthurs's Avatar
 
Join Date: May 2006
Location: Sheboygan Wisconsin
Posts: 29,661
Thanks: 0
Thanked 16 Times in 13 Posts
Danthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to allDanthurs is a name known to all
Default

It'* possible you hit the fuel tank. I would get it up on a lift or ramps and look around for the impact point.
Danthurs is offline   Reply With Quote
Old 02-22-2011, 06:47 PM   #10
Senior Member
Posts like a 4 Banger
Thread Starter
 
swampthing's Avatar
 
Join Date: May 2008
Location: Homosassa, Florida (yes it says Homo)
Posts: 115
Thanks: 0
Thanked 0 Times in 0 Posts
swampthing is on a distinguished road
Default

well between the new o2 and evap purge solenoid I think my symptoms are cured. I haven't gotten to drive it much in that past few days so if it flairs up again I will update and continue investigating in case some other poor soul has to deal with this. also the solenoid seems to have cured all evap codes, P0452 popped up once since changing it but then went back off with the next crank so that might have just been a fluke
swampthing is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
06 Impalla SS RPM"S Bouncing 03SSEISUPERCHARGED Chevrolet 7 04-10-2013 08:55 PM
RPM bouncing SeriesII Performance, Brainstorming & Tuning 3 02-01-2009 02:50 PM
weird weird and really weird 3064datazz 1992-1999 42 07-19-2007 02:03 PM
(UPDATE...FIXED!) bouncing driver's side mirror rogers 1992-1999 21 04-13-2007 10:48 PM
Help! bouncing RPM and a lunging car llBlazin_llLo 1992-1999 12 05-05-2005 02:26 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 01:22 AM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.