possible automatic trans question

[jsneddon]

2000 Chevy Astro. 105,000 miles.

Off and on (almost always now) if you put your foot all the way into the accelerator the engine drops to idle. You can go up to about 1/4 pedal no problem, shifts no problem, and with not much patience you can get it up to 65/70 and it's running through all the gears.

Thing is that even fully stopped, in neutral OR park, it does the same thing. Put your foot all the way to the floor and it drops back to idle.

So my wife dropped it off someplace to get a free diagnostic. They tell her that it is pushing out codes about the transmission and that she needs an entire new tranny to the tune of $2300. Says it is the "Transmission Slipping Code"

I just find this hard to believe because of how it behaves in neutral and park.

Anyone have any ideas?

I'm going to take it down to Twilight Zone and get the codes read for myself just for my peace of mind. But any other input would be greatly appreciated.

Thanks

 

[AweMan]

Rule #1 NEVER let the wife take car to anyone for diagnostics Not all but a lot of places "see a woman coming" if you get my meaning.
If the trans is slipping you should be able to notice it without much trouble,
If it acts normal {other than the "dropping back to idle on acceleration", shifts smooth and firm. I would suspect a sensor on the engine rather than the trans. My first suspect would be the T.P.S. {Throttle position sensor} it is basically a rheostat, that sends volatage to the computer to tell the injectors or T.B.I. or whatever the fuel system is to send more fuel. If this rheostat has a dead spot that would account for the drop off after a certain point. Secondly, the M.A.F. sensor Mass air flow located in the intake somewhere this sensor tells the computer how much air in going into the cylinders and regulates fuel accordingly. If it is bad it could be giving the computer faluty readings. Thirdly the fuel filter itself, A clogged fule filter will result in the conditions you describe.
Fourth, the Oxygen sensor Located in the exaust system somewhere, this sensor tell the computer the burn ratio, if it tells the computer that the engine is running rich, the computer compensates accordingly reducing the fuel flow.
The transmission would have nothing to do with any of these sensors in Neutral or park. And would not prevent the engine from operating normally.
I guess what i`m getting at here, it is of my opinion that a second and possibly even a third diagnostic is in order before committing to spending a bunch of money on a trans that you possibly do not need.
I wouldn`t rely too heavily on "Twilight Zones" readings, thats not to say don`t have them read the codes. If thier readings indicate a sensor then you just might be in buissness.
Even though it will cost you more in the end the dealer readings are going to be a lot more specific. IE> any G.M. dealer. Even then a second dealer diagnosis may be in order.
Not all dealers are as honest as one would suspect.
Good luck. and I hope this gave you some insight.

 

[jsneddon]

Yeah... thanks.

Basically I just sent her down there because I wanted to know what the codes were. I've had her come back to me in the past telling me that someone tried to sell her things like "Oil Belts" and whatnot so we both are well aware of the woman in a shop syndrome. Fortunately she's well-trained to consult with me first.

I KNOW that the tran is slipping - it throws those errors when it is really warm and 1-2 shifts get rough. Been doing it for quite a while and quite honestly.... well you know.... sometimes you just have to deal with annoyances on a car.

I did a bunch more googling about this slip error and I'm convinced he was just selling a tranny. And in the interim the wife found a buddy at work that will do it for $1800.... but not right now. This isn't going to fix the current problem.

Right now I need to see some actual codes and go for there. I picked up a fuel filter at lunch and I'm going to slap in on tomorrow night - she's going out of town and isn't driving it for a couple of days so I've got tome to futz with it. Semi-valid Twilight Zone codes will do for now. The diag guy today did not mention any codes except for a fuel guage error (fuel guage has been wonky for years) and the tranny slip. I just need to see them myself. I was suspecting an 02 sensor or something like that. The rheostat is very interesting. I'll pull off the cave and poke around there too.

Thanks for the info. You just confirmed the basics that I was leaning to anyway.

Cheers!

 

[jessebogan]

See my rant and explanation under the other Auto Trans thread.

 

[jsneddon]

Thanks Jesse.

I'm going to give it a thorough "looking at" this weekend and I've convinced the wife that she doesn't need to panic quite yet. I'm convinced that it is not the trans and I been convinced of this ever since it finally happened while I was actually driving it instead of second-hand information from her.

Yes the trans needs some work (and I've known this for a while) but it is certainly not the problem at hand. We can plan and budget for trans work later. Right now I'm going for perceived (by sensors) or real fuel/air delivery problems.

She did say that he plugged it in with her standing there and she looked right at the codes on the screen so she was sure that this was the only code recorded... and of course got offended when I suggested that maybe there were more codes he didn't mention Yes... I picked a very strong and stubborn woman....God love 'em.

so if this is true then it isn't complaining about o2 sensors or the like so I'll give everything a good wiggle, replace the fuel filter (with 100,000-plus miles on it), and check out the throttle body stuff (cable, rheostat, etc)

 

[mailbox]

Try this first. Remove the positive battery cable and let the computer "clear the codes" out. I have found sometimes that a "reboot" will fix a few problems and will at least clear out irrelevant codes. If nothing else, it's free. $0.02

 

[RonMacPherson]

When you drop the pan, see if there is any metal shavings in the pan, especially around the magnet. This will give an indication of a "hard parts" failure.

This year trans did have a problem with the torrington bearing that rides in the planetary gearset premature failure. When it goes the symptoms get more severe the longer the metal floats through the hydraulic. It will damage the planet carrier, the planet sun gear, the outer planet drum and possibly other parts, depends on how long it gets run with chewed up metal.Evidently GM bought a few from a supplier in Taiwan whose quality control wasn't as good as it should be. The other "hard part" failure is the sunshell splitting, in this model of trans, but that usually happened a couple of years later.


A good trans shop will rebuild and repair this tranny(if it isn't toast) for well under your quoted trans replacement price.

And if you need to get a reman. Get a GM SRTA trans, as their price is very good and they come with a complete warranty 3-36. Oh and let us know what codes are found. should be a long the lines of P0752, etc.)

 

[jsneddon]

Well... thanks for all the info.

gonna hold off on the trans for a while - that was a -known- issue that the clown at the auto shop was trying to sell her.

I replaced the fuel filter. Runs like a champ now.

I'll deal with the trans later - turns out that she's going to get a new truck out of her boyfriend and I moved out so it isn't so much my problem anymore. I'm keeping it until my Neon dies and then I'll drive the wheels offa it.

 

[RonMacPherson]

Sorry to hear about your relationship problems.

Hopefully the next one is better.