Deceleration problem

[c4tchmeifyouc4n]

I have this annoying problem when I drive normally and I slow down to a stop, at a about 20mph there's a small jerk in the car. Does anyone know what the problem is?

97 GST Automatic

 

[lexx620]

im having the same problem on my 5speed gst in second gear below 2k rpm the car stars to shake untill I fully depress the clutch

 

[_Madman_]

Ok, I will bring this thread back since I experience the same problem but I can't seem to find an answer.

So the car twitches under decel. Below 2.5k RPM it seems, or in closed loop.

Some people say that it might be because it runs rich...

Is it a bad O2? AFAIK they tend to run lean when cooked.

 

[kewlguy]

are you letting the rpm get too low for the gear you're in? you're not supposed to completely stop in gear.

a few questions though.

Does it happen at that rpm in every gear?
Does it happen at that rpm in neutral?
Does it only not happen with the clutch depressed?

I'm thinking it's transmission related, but it could be another problem

 

[OneLove]

Yea, i think it happens in every gear, although 1st one is the most jerky...
Neutral seems to float a bit, and with polly mounts it is a little noticeable, but neutral is neutral, not like you can feel much.
Yea, happens only with clutch engaged. As soon as I press the pedal down car decelerates normally and smoothly.

The same thing happened to my '89 GLSi Galant a while ago, but it never got fixed.

Ok, I did more testing today and this is what I noticed:

1) the idle is not really bad, well it vibrates a little, but it's pretty smooth at 800rpm without needle floating on tacho.
2) when i floor it from stand still car bogs a little and then goes forward smoothly

 

[kewlguy]

ok woah . which one are you? 2 different profiles?

assuming you checked basics (boost leaks, recirculating bov, good on maint, etc)

is there a check engine light?

it's really hard to tell if an engine problem or tranny problem. I recommend your #1 priority for parts is guages so you can see what all is going on. i can imagine tons of different things that could possibly cause that.

if this is your DD, when you get some time (i know it's on your wishlist already) but check out the clutch

i'll list a few areas to check out, but i have no clue which one it could be.

FPR
Ignition system
Boost Leaks
Clutch
Transmission
Timing could be slightly aggressive
Excessive knock


a thread that might help
http://www.dsmtuners.com/forums/newbie-forum/302111-low-speed-hesitation-please-read.html

you really need to find a way of determining if it's an engine problem or transmission problem. once you figure that out you're well on your way.

 

[_Madman_]

Hey!!! My post has been given away to someone else Must be some sort of bug of the forum

How can you report these sort of things?

Now ontopic:

I'm not entirely sure about boost leaks because my time on 1/4 mile is less than good, but all of the maintenance has been done, and car doesn't seem to have any problems. BOV is recirculated and no unsafe mods have been done so far.

Concerning knock... hmm, the weather is quite hot right now... around 86F. And I'm driving full throttle most of the time. Car seem to loose power after few miles and intercooler pipes are usually hot enough that you don't want to keep your hands on. Maybe the timing is being adjusted... I use 95 fuel. But it seems that car is jerky even right after I start to drive. Though I always warm it up for 5-10 mins so that water temp needle is right in the middle.