[FONT=Times][SIZE=1][COLOR=blue] :mellow:

I own a 2000 Hyundai Sonata 4 cylinder (2.4 liter I think) it has 69,450 miles on it and I only bought it in January with 63,000 miles on it. About 2 months after I bought it the A/C went on it. Then my transmission, my gas mileage sucks. I thought by fixing the transmission it would fix the gas problem. Big problem too...like 50 miles to every quarter tank of gas. Thats definitley not good. Well, I took it back to the place I got the transmission fixed and they couldn't figure it out. There was only four pounds back pressure which from what my understanding is, is nothing!! They replaced my catallitic converter which didn't do much. This was due to there computer saying my car was mis-firing. The only other thing they thought was the timing belt, I looked into it and thats what it needed especially for me being over 60,000 miles. It was off quite a bit. Well after that was replaced my car started vibrating. The motor mount that they have to remove to get to the timing belt just happened to be falling apart (not caused by them because it was plain and simple ware and tare) They're replacing that. Anywas heres what I'm asking. My car doesn't have much power at red lights it doesn't move. Its like stuck or something. Its hard to explain. I have to get up to at least 5,000 RPM's with my foot stuck to the floor just to get up to the speed limit which is only 45 then it stays there. Its like at least maybe 4 to 6 inches of pressing the gas to the front of the car doesn't even move the car. I don't understand it. As you can tell neither do the mechanics that have worked on my car. Any ideas??? Please get back to me at Shyone62184@aol.com if you have any suggesstions. Nearly everything has been fixed. Please help me figure this out. Sorry this is so long. Thanks

<_< replaced my belt in my past Sonata, It to ran rough, found timing was out & we where very carefull to, so cheack your timing settings. best of luck. strokie :rolleyes:

did you take the car to your local HD-dealer ???

Not exactly, but the place i did take it to called a hyundai dealership and the mechanic that he talked to had no idea what he was talking about. I believe that the hyundai dealerships around here don't have a clue to what there doing due to experience and asking them questions. i don't trust them

Hi
I used to own a 99 2.0l sonata and the one thing that would catch me out was if I floored it with too low revs - the "anti knock" circuitry would retard the timing to the point it would have been quicker to walk!
My solution - (manual car) always select the right gear and keep the revs above 2000 for taking off. The other thing I found was It really liked the higher octane fuel. My average fuel consumption was 8.4l/100km - city/country driving
hope this helps abit
Mike

Sounds to me like you have two problems here.

The first problem:

The way you have described it, sounds as though it is setting itself into limp mode.
This is where the TCm detecs a problem in the transmission and locks the transmission in third gear, to prevent any further damage that you or the manufacturer may have to fit the bill for.
Only problem with this method of thinking is that many people do not understand this safety mode and tend to destroy their torque convertors from excessive slippage whilst they continue to drive it around.

Does it feel like the vehicle is stuck in third gear, moreso can you feel it shift from first to second to third and onto overdrive?

Second problem:

If it only began to vibrate after the timing belt was replaced, there may be a problem with the way that the mechanic lined everything up.
With the 2.4l motors, they ran a balance shaft to kep the motor from experiencing vibrations from rotating engine mass.
These shafts can easily be set 180' out if the mechanic is no familiar with the engine design.
Other possibility is that your engine mount has failed like you mentioned. It just seems funny how it began to vibrate after the timing belt replacement.

As for the first problem I would have a code check carried out on your engine and trans this will maybe distinguish where abouts your problem lies.
It could also be something as simple as a MAP sensor, which will also display similar symptoms, like delayed throttle response.
As some people put it "the engine is trying to catch up". You never know you may also have an engine sensor problem that may be picked up, which is the cause of your second problem. But I think that you should have the timing belt inspected again if the mount replacement does not fix your vibration problem.

Let us know what you find!
I will attempt to put a method of code checking your vehicle for yourself so that you do not need to take to a dealer for the use of their diagnostic equipment. :)

This post has been edited by Dr. Hundi: Nov 3 2004, 07:57 AM

ive gone through the same sort of thing with my sonata ive had the timeing belt changed and the transmission fluid flushed and replaced.
now the overdrive will not engage until the car is left to stand for a while, this only seems to happen on cold mornings,
the mechanic assures me he replace the transmission with ASP3 oil, the car worked great until all this work was carried out now :(
i realise from reading this article that the ECU may have put the transmission into a protective mode but is this an easy fix or something majour. thanks vic

I though that I might make a certain fact aware to everyone whilst we are on the topic of sifting problems whilst cold.

1. You really shouldn't be driving your vehicle without allowing it to warm up first;

2. Your transmission ECU recieves a signal from your fluid temp. sensor within your auto trans.
When your transmission is still cold, your TCM (Transmission Control Module) will prevent your transmission from shifting into overdrive in attempt to keep the transmision in a lower gear to induce heat in your trans to quickly get your trans fluid to operating temperature.

:)

You guys are missing one more thing
the hyundai transmission is very sensitive to the ATF oil used .I do not know why but i found a little contamination causes heck of a problem

In most trans shop they use the decron **** that suppose to behave like the oil used by ur car....well it flat never works

my transmission oil was low and poured off the shelf stuff and guess what the trans locked in 2nd and car died 2twice
now it settled down .
bbut ineed to flush and refill next month

Honda had or still has a good slogen:

DON'T OPEN YOUR HOOD TO STRANGERS

This post has been edited by duke: Dec 17 2004, 01:45 PM