Problem with van

jrcase · Apr 15, 2011

I have a 2010 Chevy Express 2500. 58K miles on it. 4.8L V8, 6 speed auto. The problem is when I coast down a hill for several seconds (usually more than 10 seconds worth of coasting) and start re apply the throttle, the van shudders and I have to let off the gas and the shudder stops. Then it drives fine..... the shudder/shaking does not happen every time just on some long down hill coasting. The bigger the down hill and longer I coast the more it shudders when I apply the throttle. Thing is, it don't do it every time. Maybe one out of five times.

I took it in the a dealer and they replaced the torque converter. They seemed confident that that was the problem. It wasn't. That did not fix the issue. I have another appointment with them on Monday but was wondering if this is a common problem or one that may have happened to someone here? Transmission, drivetrain? Anything I can suggest to the dealer? HELP!?!

davekc · Apr 15, 2011

I don't know if it is common as I haven't seen this problem posted. Keep in mind that I don't drive a van but know a thing or two that may give a point to look at.
If they changed the converter, then I would proceed to the yoke, drive shaft (could have thrown a factory weight), u-joints, and possibly a pinion gear. I don't believe a a van would have a carrier bearing, but if so, another place to look.
Last but not least, a bad or loose engine mount would do it as well.

greg334 · Apr 15, 2011

Sounds like the modulator for the torque converter clutch is not working right.

Take it to the dealer, ask a mechanic to come for a ride with you and let them see it in action. I would consider a new trans being in your future.

jrcase · Apr 16, 2011

Thanks for the ideas. Luckily, the 100,000 mile powertrain warranty covered the torque converter swap. I hope the warranty will cover the real problem.

scottm4211 · Apr 16, 2011

jrcase said:
Thanks for the ideas. Luckily, the 100,000 mile powertrain warranty covered the torque converter swap. I hope the warranty will cover the real problem.

I hope it's not a sign to come for this new transmission. Btw what kind of mileage are you getting with it? Thanks

jrcase · Apr 16, 2011

Empty, I am getting 18 to 19 at about 65 mph. I think I can get better when I have cruise control added. Once I got 21 on two lane country roads averaging 45 to 50 mph that was with a 700 lb load.

I have noticed the rpm's are much lower at 70 mph than on my old Ford e250. I am turning 1800 rpm at 70 in the chevy.

scottm4211 · Apr 16, 2011

jrcase said:
Empty, I am getting 18 to 19 at about 65 mph. I think I can get better when I have cruise control added. Once I got 21 on two lane country roads averaging 45 to 50 mph that was with a 700 lb load.

I have noticed the rpm's are much lower at 70 mph than on my old Ford e250. I am turning 1800 rpm at 70 in the chevy.

Thanks for that.

purgoose10 · Apr 16, 2011

J.R. When you say shudder what exactly do you mean?? Do you feel it in the whole truck?? or only when your throttle up??

Make sure the drive shaft is true and inline. If that center support bearing is off just a little it will shake the van and only do it at certain speeds. Been there, done that. It will drive you crazy trying to figure it out. If they did not tighten it on the assembly line it could have slipped when you applied torque to it and it moved.

Hoped that helped.

I hope Chevy can find it, I took mine to the drive shaft shop.

Ad something else. I guess you probably already know this but when you load and extended Chevy and the back end squat's down it changes the alignment of the drive shaft. The spline gear close to the center support shaft bearing (midshift bearing) comes together. If that spline gear comes together and leaves no flex room it will cause the shaft to get out of line and vibrate. So in saying that, does it do it only loaded?? or all the time??

We just changed drivers so it will be later when we get to where we are going before I can answer. To many Mountains and no steady signals.

Brisco · Apr 16, 2011

Just had a similar issue with my 2007 4.7 V8 Dodge Dakota with 50K or so miles. My shuttering as you have described wasn't at highway speeds while coasting, but was during city driving and coasting to a stop, like coming up to a red light between the speeds of 25-30MPH. Not only was my truck shuddering, but it also "CLANGED" hard when it hit exactly 25MPH. And, it didn't do it ALL the time.

Originally thought it was a U-Joint going out, so I had those replaced at a cost of $125. 2-3 days later, the same problem. Dropped it off at the dealership to have thing checked out under my extended warranty. Thought went to the Torgue Converter as mentioned above. Dealer checked everything out, Tranny, TC, and Rear End, all was fine and it didn't do it while the Tech had the vehicle. So, I went and picked it up. A couple of days later while heading home....clang....clang.....clang!!!!!!

I went online and researched the symptons on my own. Found out this has been a prob for the 4.7 V8 since '99 or so. (Why didn't the Dodge Tech know this????)

Turned out to be the THROTTLE POSITION SENSOR. A $33 part at O'Reillys. ($89 at the Dealership) I picked that up, along with an Air Intake Valve for $60 since they're both right there together. And cause the guys on the Dodge Discussion boards said to go ahead and replace both while you're in there. Took me 10 minutes to put both parts on myself and have had no problems since.

So, go to a Chevy Engine "Discussion" board, search your problem, and it may be something as simple as the problem I had. From what you describe, could be just a simple TPS unit. Know what I mean.

jrcase · Apr 16, 2011

The shudder shakes the whole van when it happens. Only for a second and I let off the throttle and reapply then it drives like normal for hours until the next episode which may be hours later. No shake at any speeds ALL the time but when it shudders it is always after coasting down a hill and start coming up the next hill. it seems to happen if the "slack" in the drivetrain is between load and coast if that makes sense.

I will print out all of these replies and give them to the service advisor. Maybe they will be of help to them. I appreciate all the ideas. Keep them coming. Thanks!

purgoose10 · Apr 16, 2011

jrcase said:
The shudder shakes the whole van when it happens. Only for a second and I let off the throttle and reapply then it drives like normal for hours until the next episode which may be hours later. No shake at any speeds ALL the time but when it shudders it is always after coasting down a hill and start coming up the next hill. it seems to happen if the "slack" in the drivetrain is between load and coast if that makes sense.

I will print out all of these replies and give them to the service advisor. Maybe they will be of help to them. I appreciate all the ideas. Keep them coming. Thanks!

Well that eliminated the drive shaft. It might be an electronic throttle control sensor like was earlier mentioned. Can't believe the tech did not test for that, but techs get paid by the job and a tranny pays more than the sensor???????

Turtle · Apr 16, 2011

The torque converter is what I'd have looked at first, even with only 50,000 miles on it. A dirty Mass Airflow Sensor can cause that problem. But the "always after coasting down a hill and start coming up the next hill" deal sounds like a classic case of the ignition coil going bad. A $40 part and 20 or 30 minutes to change it out should do it. It could be wires or plugs, but since it drives fine otherwise it's probably the coil, or the connecting wire to the coil. Shuddering after coasting, especially while towing something (like a boat) but otherwise is fine, is generally an ignition problem (particularly with so few miles on the vehicle), usually the coil or the connecting wire, either or both of which can become corroded easily and quickly.

purgoose10 · Apr 16, 2011

I took it in the a dealer and they replaced the torque converter. They seemed confident that that was the problem. It wasn't. That did not fix the issue. I have another appointment with them on Monday but was wondering if this is a common problem or one that may have happened to someone here? Transmission, drivetrain? Anything I can suggest to the dealer? HELP!?![/QUOTE]

Please read this again. Replaced the TORQUE CONERTER. Thankyou.

Turtle · Apr 16, 2011

purgoose10 said:
Please read this again. Replaced the TORQUE CONERTER. Thankyou.

Got it. And I read it again. Doesn't change my response at all. When people hear "shudder when accelerating" they naturally think transmission or torque converter, but when I hear "only happens after coasting and then starting back uphill" I immediately think ignition coil or some other ignition-related culprit. I could certainly be wrong.

Brisco · Apr 16, 2011

I'm almost betting it's your Throttle Position Sensor/Unit or possibly the Air Intake Valve.

Let's hope that's all it is.....................

jrcase · Apr 16, 2011

If it were an ignition problem would a code be stored? I don't even know if they checked that or not.

Turtle · Apr 16, 2011

jrcase said:
If it were an ignition problem would a code be stored? I don't even know if they checked that or not.

Probably won't throw a code for an ignition core. The reason is, the core is working, its sending ramped up voltage to the plugs, but it's just not enough after it essentially idles while coasting. If the core fails utterly then it'll throw a code, but otherwise probably not. Same with the throttle position sensor, where it won't throw a code until it gets bad enough to cause the intake manifold pressure to drop below tolerances, then it'll throw a intake pressure code instead of a throttle position code.

Since this happens at highway speeds and only after you've coasted downhill and are just beginning to accelerate back uphill, it could be the throttle position sensor, but I doubt it, since problems with that tend to manifest at both lower and high driving speeds, particularly when decelerating and downshifting through the gears. But I've known people to swap EGR valves, O2 sensors, even pull the heads, all because of a bad ignition core that caused the exact problems you described.

comet_4298 · Apr 16, 2011

Turtle said:
Probably won't throw a code for an ignition core. The reason is, the core is working, its sending ramped up voltage to the plugs, but it's just not enough after it essentially idles while coasting. If the core fails utterly then it'll throw a code, but otherwise probably not. Same with the throttle position sensor, where it won't throw a code until it gets bad enough to cause the intake manifold pressure to drop below tolerances, then it'll throw a intake pressure code instead of a throttle position code.

Since this happens at highway speeds and only after you've coasted downhill and are just beginning to accelerate back uphill, it could be the throttle position sensor, but I doubt it, since problems with that tend to manifest at both lower and high driving speeds, particularly when decelerating and downshifting through the gears. But I've known people to swap EGR valves, O2 sensors, even pull the heads, all because of a bad ignition core that caused the exact problems you described.

I would think,it being a 2010 it would have multiple coil packs..........maybe one cylinder loading up. They should be able to hook up the engine analyzer(portable) and give it a test drive and see if is a miss fire;wire breaking down;weak signal;etc.

It's better sometimes if you can get the tech to ride with you and show them what it's doing.......but if your luck is like mine,your never get it to do it with them in there.

Good Luck

Brisco · Apr 17, 2011

HHmmm........

Just looking around the internet searching this problem (and watching the race at the same time) and ran across something.

Does your vehicle have the AFM system in it? (Active Fuel Management System)

Vibration, transmission? : Transmission/Drivetrain

I read somewhere that both the 5.3 and 4.8 has an AFM system, and in the 2500-3500 series Express Vans too.

Does this problem look similar to yours??