JOE
strange problem.. stumbling?
Thread Starter
Racer
Joined: Nov 2004
Posts: 288
Likes: 0
From: Woodbridge VA
strange problem.. stumbling?
I've been encountering a fairly weird problem for a while now, and havent been able to sort it out, so I figured I'd check with you guys.
If I am on the highway and in 3rd gear (automatic) and get on the gas - just a little bit, not enough to force a downshift but enough to start to raise up the RPMs enough that the car would consider shifting to 4th - the car does something that I can only describe as "stumbling" - it shudders/bucks, coming from the back end (or rather, it FEELS like it is coming from the back end). If I get off the gas, it stops, and if I get on the gas more it stops. No error codes thrown.
Any thoughts?
Car is a '99 A4.
If I am on the highway and in 3rd gear (automatic) and get on the gas - just a little bit, not enough to force a downshift but enough to start to raise up the RPMs enough that the car would consider shifting to 4th - the car does something that I can only describe as "stumbling" - it shudders/bucks, coming from the back end (or rather, it FEELS like it is coming from the back end). If I get off the gas, it stops, and if I get on the gas more it stops. No error codes thrown.
Any thoughts?
Car is a '99 A4.
Thread Starter
Racer
Joined: Nov 2004
Posts: 288
Likes: 0
From: Woodbridge VA
I'm sorry, that is in o-drive, not when manually shifting it.
I'm just used to the RPM ranges at speeds, so I generally know which gear its in. It will also do it from 4th gear, if I just gently get on the gas.
roughly 76-77k miles.
I'm just used to the RPM ranges at speeds, so I generally know which gear its in. It will also do it from 4th gear, if I just gently get on the gas.
roughly 76-77k miles.
Drifting
Joined: Jul 2002
Posts: 1,484
Likes: 0
From: Morgan Hill Ca.
I have had this problem when a plug or plug wire goes bad. It didn't throw a code right away, but after a few times it did finally throw a misfire code.
Check your plugs and wires. Have you changed them recently?
I once bought a el-cheap-o set of wires and it did exactly what you are describing.
Drop to a lower gear, say second and try the same senario. Run along at a low speed, lug it if you have to and then slowly add some throttle. to get a misfire code you need to get the mixture rich enough to show up at the O2 sensors.
Check your plugs and wires. Have you changed them recently?
I once bought a el-cheap-o set of wires and it did exactly what you are describing.
Drop to a lower gear, say second and try the same senario. Run along at a low speed, lug it if you have to and then slowly add some throttle. to get a misfire code you need to get the mixture rich enough to show up at the O2 sensors.
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Drifting
Joined: Apr 2007
Posts: 1,496
Likes: 1
From: LEBANON PA.
Hi ravn,
I have had this same problem on many of my cars & other peoples cars.No codes shown in the DIC & the problem goes away when you let-off the gas pedal.You have clogged fuel filter buy the special tool & deplete the the pressure from the schrader valve on the fuel rail (drivers side).A/c delco p/n gf822 $86 A real pain in the butt to change on the a/tranny. Hardly any room to work.BTW: If you had a misfire you would have code p0300 displayed on the DIC.
robsc501
I have had this same problem on many of my cars & other peoples cars.No codes shown in the DIC & the problem goes away when you let-off the gas pedal.You have clogged fuel filter buy the special tool & deplete the the pressure from the schrader valve on the fuel rail (drivers side).A/c delco p/n gf822 $86 A real pain in the butt to change on the a/tranny. Hardly any room to work.BTW: If you had a misfire you would have code p0300 displayed on the DIC.
robsc501
Last edited by robsc501; May 29, 2008 at 07:35 PM. Reason: spelling errors
Race Director
Joined: Oct 2002
Posts: 11,945
Likes: 12
From: Vancouver
2015 C5 of Year Finalist
St. Jude Donor '05-'06-'07-'08-'09-'10
Try the seafoam trick as stated above. I did last year and have now put it through all our vehicles I am astonished at what a difference is has made. 
Instructor
Joined: Apr 2008
Posts: 139
Likes: 0
From: Cameron North Carolina
I have a 99 A4 also and have had a similar problem. Do the RPM's increase roughly 200 to 300 when it "bucks", if so it may have to do with your torque converter. Also, if your battery had been disconnected at anytime, this will cause your computer to "re-learn" itself and your driving habits. I'd get it hooked up onto a computer for a street tune and that should be able to tell you exactly what the problem is and in most cases, the tuner can fix the problem...just my .02
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Take a look at the bottom of the PCV valve connection tube to the intake. It might have a hole in it which will cause your problems. It happened to mine so I know.
Thread Starter
Racer
Joined: Nov 2004
Posts: 288
Likes: 0
From: Woodbridge VA
lots of good stuff, thanks guys.
I ordered some new plugs today - so will try that first (and prolly do some wires while I'm there.. I'm sure its overdue anyhow)
if that doesnt cut it, I'll give the seafoam a chance... if that doesnt do it, well, I'll try the other suggestions til it gets solved!
I ordered some new plugs today - so will try that first (and prolly do some wires while I'm there.. I'm sure its overdue anyhow)
if that doesnt cut it, I'll give the seafoam a chance... if that doesnt do it, well, I'll try the other suggestions til it gets solved!
Team Owner
Joined: Mar 2008
Posts: 24,310
Likes: 0
From: Canon City Co
St. Jude Donor '11,'13
"I voluntarily took 60 days off from OT"
lots of good stuff, thanks guys.
I ordered some new plugs today - so will try that first (and prolly do some wires while I'm there.. I'm sure its overdue anyhow)
if that doesnt cut it, I'll give the seafoam a chance... if that doesnt do it, well, I'll try the other suggestions til it gets solved!
I ordered some new plugs today - so will try that first (and prolly do some wires while I'm there.. I'm sure its overdue anyhow)
if that doesnt cut it, I'll give the seafoam a chance... if that doesnt do it, well, I'll try the other suggestions til it gets solved!
Drifting
Joined: Oct 2005
Posts: 1,435
Likes: 0
From: Saint Louis MO
Don't forget to clean the MAF sensor.
Last edited by tellefan; May 30, 2008 at 04:52 PM. Reason: added text
Thread Starter
Racer
Joined: Nov 2004
Posts: 288
Likes: 0
From: Woodbridge VA
the MAF sensor was recently cleaned
and it appears the local jiffylube cant do the transmission on a corvette, joy, so I'll have to take it elsewhere for that
fuel filter... yes, I understand that's a pain.
hopefully do that when I swap out the suspension next week
and it appears the local jiffylube cant do the transmission on a corvette, joy, so I'll have to take it elsewhere for that
fuel filter... yes, I understand that's a pain.
hopefully do that when I swap out the suspension next week
Racer
Joined: Aug 2007
Posts: 401
Likes: 1
From: Ashburn, VA
When you experience this 300-400 RPM slip while cruising does your cruise control go out?
I have been having this same issue for a while and I know when the car does this I cannot use cruise control.
Did you ever find your fix?
I have been having this same issue for a while and I know when the car does this I cannot use cruise control.
Did you ever find your fix?
Thread Starter
Racer
Joined: Nov 2004
Posts: 288
Likes: 0
From: Woodbridge VA
I rarely use the cruise control, so I'm afraid I dont know
I just (I know, I know, I'm terribly) replaced the plugs and the wires yesterday, and am about to go on a fairly long drive, so I will let you know later if that resolved the issue
I just (I know, I know, I'm terribly) replaced the plugs and the wires yesterday, and am about to go on a fairly long drive, so I will let you know later if that resolved the issue