"Drag" when braking?

[Kari]

I've taken mine to the dealership TWICE for this problem and no matter how specific of instructions I give them, they can't seem to duplicate it.When I'm going around 50 mph, usually over 2000 RPM, and brake moderately hard (say a stoplight just changed and you have to stop at it), it will "drag" when it reaches 40 mph, and the RPMs will dip sharply down to 1500, then back up to 2000 in about a second. It almost felt like a brake problem at first, but since it affects the RPM, I'm starting to suspect it's the transmission.I have an automatic, BTW.Anyone else ever heard of this? Have any ideas as to what it might be so I can point the service dept. in the right direction?Thanks

[dmitri]

weird...if im coming to a stoplight and put it in nuetral and brake instead of downshifting (too lazy sometimes), my engine almost does once in a while if its a little cold. It starts shaking and i have to bring the rpms up a little until it goes away.

[joatmon]

Not sure what you mean by "drag". Also, does it happen when the engine is fully warmed up?I could see where with an auto, as you decelerate, the car downshifts, and at that transition(same vehicle speed, lower gear) then the engine would run faster because of the different gear ratio. Whether the numbers you see are realistic for an auto, I don't know, got a 5 speed. When I downshift slowing down, the engine provides addtional braking. Is this what you mean by "drag" ?

[ragingfish]

Your best bet is to ask them to ride with you, and you duplicate the problem...perhaps let them sit in the bcak and glance over your shoulder to watch the gauges...I have an auto, have no problems...

[micheles_bad_vibe]

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[Kari]

YES! FINALLY! Someone else who has this problem...I am NOT crazy, I am NOT lying...take that Mr. Service Manager. I can best replicate it going downhill as well. By "drag"...I meant it makes a motion as if you had just crammed your foot down on the brakes, even when you didn't. Sounds like the same thing yours is doing. I'm also afraid one of these days it's going to lock up on me and someone's going to total my car for me from behind. :Have you watched the gauges when it does it to see if the RPMs dip?

[ragingfish]

I know what you're referring to -- I experience it often when I downshift to slow down rather than ride the brake (which I often do). However, I usually do it as a duo -- downshift while applying the brake lightly, for no other purpose than brake lights...But I'm not sure why the car would downshift so much...like I said, ask the service guy to let you take him for a drive, as you know best how to replicate it.

[goodvibe]

Sounds like the tranny but may not be a problem, just a quirk. Make sure your tranny fluid level isn't high as this could case harder shifting. Find a safe place and put it in nuetral before you brake. If there's no problem. It's the tranny.

[MadBill]

Don't know if this is at least part of the cause, but under decelleration, engines are frequently calibrated to flow a lot of air (enough to rev to say 2,500 RPM if you were to pop it into neutral) to reduce emissions. After a few seconds however, they often switch to "fuel cut off" mode, which reduces this power and makes it feel like more braking action is occuring.

[savedbyzero]

Just start grabbing the e-brake, and jerk it REAL hard. Then you won't experience the problem!

[goodvibe]

This dawned on me and I could be way off. I'm not that familiar with your combo but if the tranny is pulling the motor down faster than normal rpm decay, the tranny could behave that way by releasing the engine and letting it bounce back up. This sounds wierd but pollution controlled vehicles often hold rpms and yours may be programmed to act this way.

[goodvibe]

Madbill, I just saw you got there first while I was writing my pollution post. Anyway, I think you're OK Kari.

[micheles_bad_vibe]

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[Kari]

I don't think so, because mine hasn't been doing it since the beginning. It just started doing it in about April or so, when it was 6 months old. I'm fairly sure it is the transmission because of the RPM thing...but it's not kicking anything in the computer, so that's why the service dept. is so stumped. I don't think it's normal behavior though.

[goodvibe]

I'm stumped. Good luck.

[micheles_bad_vibe]

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[ragingfish]

That theory about too much fluid sounded promising...maybe you should hav it checked for the heck of it? It's easy enough to do...

[Kari]

It does shift a bit hard...but no harder than my Sonoma truck used to, so I haven't paid that much attention to it. Both times i've taken it in for this mystery issue, they haven't done anything but drive it around. I'd have felt much better if they'd even just used their little noggins and checked SOMETHING...instead of relying on the computer to tell them something was wrong. I'll tell them about the fluid thing the next time I go in...let's see whether or not they look at me like I have no idea what I'm talking about. LOL

[ragingfish]

quote:They will not fix anything unless they can reproduce the same problem you are having. That is the downside of warranty work. Which is why I encourage YOU to drive the service guy around, and reproduce it for him...

[ragingfish]

I meant to write service mgr. My error.

[Kari]

Thing is, my mom swears up and down she doesn't feel it, even when I point it out to her. So I don't know if you can only feel it on my side or what. I watched the gauges all day today as I braked, and I noticed that the RPMs kind of go up and down as I'm slowing down anyway, and it's just a lot more pronounced when it actually does the dragging thing. Whether or not that means anything, I dunno.I think myself and my family are just super-critical of service depts because my grandfather used to be a service manager, and he was pretty much one of the best in the country. So we're spoiled. All of the Chevy dealerships here suck, as far as my dad is concerned. LOL

[Kari]

2003...automatic...base...And yes it seems to go through gas quicker, but I am also running the A/C more often. When I first got it I wasn't using the A/C at all and was getting almost 40 mpg on the interstate.

[ragingfish]

quote:2003...automatic...base...And yes it seems to go through gas quicker, but I am also running the A/C more often. When I first got it I wasn't using the A/C at all and was getting almost 40 mpg on the interstate.I am asking, because PMH013 has problems with her AWD. She was using gas like crazy and she was complaining of a loss of power also and she thought it was the transmission.It turned out to be a clogged up CAT. Good memory, I forgot all about that!

[micheles_bad_vibe]

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[NSimkins]

quote:this braking problem ONLY happens when i'm driving downhill though. i drive down my hill to get on the freeway, and then down another hill to get to work... and then vice versa on the way home... its never done it on a flat surface.... Would this be anything about engine braking that I hear about in some vehicles with auto trans? Somewhat to assist stopping from a higher speed with heavy braking the trans will shift to provide assistance? To flip this a little, when going up a slight hill, I notice the auto trans does not shift to the next gear when going a consistent speed until I crest over the hill (consistent accelerator pressure), almost like it senses the need to stay in that gear. The one time I had to brake hard, I did notice the trans shift down a gear and heard the engine rev a little while doing so in the process. This would be like shifting from 3 > 2 > 1 in a manual when approaching a stoplight, that will slow you down without the use of the brake. Maybe the same principle with the auto trans when braking.I know I have read in car magazines about the 'lack' of 'engine braking' in certain automatic trans vehicles they review - would this be the same issue?

[micheles_bad_vibe]

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[Kari]

Mine freaks out going up steep hills on cruise...it's fine when you do it with your foot though. It just gets super excited on cruise. I figure it's a 4cyl thing though...my old Sonoma did it too.

[NSimkins]

quote:Mine freaks out going up steep hills on cruise...it's fine when you do it with your foot though. It just gets super excited on cruise. I figure it's a 4cyl thing though...my old Sonoma did it too.That's exactly it, the fact it's a 4-cyl/base/with A/C on - I don't recommend using the cruise with the A/C on going up moderate to steep hills. One time when going up a moderate hill on the interstate with the A/C on, I could tell the cruise was trying to keep up by gradually pushing the accelerator down. Obviously the current gear wouldn't keep up with the speed so it would shift to 3rd and sometimes 2nd - almost seeming to go crazy. Doing this over and over when going up and down hills can get annoying.I personally wouldn't worry, but if you feel the need, take it in (again) and take the tech for a drive in the passenger seat. If they don't feel concerned, I wouldn't either.

[ragingfish]

Yeah, many of us commented how "jumpy" the cruise is when it hits resistance...

[Kari]

Nah, I'm not worried about the cruise thing. At least this one still has some HP when you have the A/C on...more than I could say for the Sonoma. I swore I'd never buy a 4cyl again...but look at that, I did. (Although I don't think it really drives like a 4cyl.)

[ragingfish]

The Sonoma was only a 4? A truck that's a 4? Weird...

[Kari]

Yep. We had 2...a 4cyl and V6. The 4 was a cheap lease...big time. I forget how much but it was ridiculous...like $100 a month. Which is why I was 16 and driving a new truck. So I won't complain too much.

[ragingfish]

Ahh, I gotcha now.

[Kari]

Hmm..I just had an idea with regards to the catalytic converter thing. When I first got the car, it made a real bad sulfur smell at red lights, and I was told it was the pollution control system...though dad and I were convinced the CC was bad. They said it was a normal thing though. Assuming this weird dragging thing is somehow related to that...and my gas issue is not just A/C but also this...might that have been an early stage of this problem? Because it doesn't make that smell anymore.

[ragingfish]

Hmmm...might want to ask them to check the CC...seems to be several flags that say it could be experiencing problems. Doubt it's plugged, but might just be defective...

[joatmon]

Quote, originally posted by Kari »I've taken mine to the dealership TWICE for this problem and no matter how specific of instructions I give them, they can't seem to duplicate it.When I'm going around 50 mph, usually over 2000 RPM, and brake moderately hard (say a stoplight just changed and you have to stop at it), it will "drag" when it reaches 40 mph, and the RPMs will dip sharply down to 1500, then back up to 2000 in about a second. It almost felt like a brake problem at first, but since it affects the RPM, I'm starting to suspect it's the transmission.I have an automatic, BTW.Anyone else ever heard of this? Have any ideas as to what it might be so I can point the service dept. in the right direction?Thanks So I asssume it is still doing this? Anybody have any new ideas on the cause, or if this is normal for these cars?

[danewman0424]

I believe this is normal for these cars. In my sales brochure I received from the dealer there is an option listed under mechanical features that is called the Brake/transmission interlock feature. I am guessing this causes the transmission to downshift when the computer thinks you need to slow the car quickly. My Vibe does the same thing.

[ragingfish]

Quote, originally posted by danewman0424 »I believe this is normal for these cars. In my sales brochure I received from the dealer there is an option listed under mechanical features that is called the Brake/transmission interlock feature. I am guessing this causes the transmission to downshift when the computer thinks you need to slow the car quickly. My Vibe does the same thing.Incorrect. The brake/shift interlock is what requires you to press the brake down before being able to shift into gear.