Hey guys... i always downshift and leave my car in gear when coming to a stop.. only gear i dont downshift into is first, cause it's point less... anyway

I've been having a problem for a while now. After new tranny mounts and new Rear end mounts i am getting a very strange... and pretty violent motion while engine braking in any gear... When the engine starts to come down on the revs and gets close to 2000 Rpms it's bucks and lurches like im riding a bull or something. this is when i'm OFF the throttle while engine brakeing... it's very annoying at the least... i can also hear a clunk sound from the tranny/driveshaft area when it does this.

Possible U-joint failure? they do have 210,000 miles on them. How much do U-joints cost? (if that is even the problem)

At first i though it was maybe the AFM flapper door bouncing up and down... and maybe even the throttle body plates bounceing open and closed. that's what it feels like.. but i've lubed everything up and still havnt solved it.

THanks for the help. Markus

 

If it's the u-joints, you have to replace the driveshaft, as mazda didn't make them replacable. You can get a new driveshaft that has replacable u-joints at http://www.mazdatrix.com

 

All EFI engines cut fuel when decelerating with the throttle closed. You are just pumping air to save gas.
When you get close to idle RPM, the ECU turns on fuel to keep from stalling. Ergo - the lurch.

I downshift above 2500 to avoid it. Or just step on the clutch as you are just about to stop.

 

same here.. if its in gear w/ clutch out and it goes close or below 2k rpm, im herkin and jerkin too.. thats how any vehicle is thats standard.. well pretty much any vehicle anyways - respectively..

 

speaking of downshifting.. i cant seem to downshift into 1st.. normal on an FC? i can only put it into gear smoothly if im at a slow crawl or stopped

 

You have to match up the revs, especially in 2nd & 1st.
It takes practice to brake & gas with you right foot.
It's called heel-toe downshifting. It's fun in an autocross.
I've been doing it since 1960.

 

you really shouldn't shift into first unless you are stopped anyway, unless you do the method mentioned above.

 

2 cents: you should always match revs to a downshift. Practice makes perfect.

 

cool, thanks guys. i thought there was something wrong with my car.

My cousins 85' Bmw EFI doesnt do that. he can come to a complete stop in 2nd when decelerating. humm.. anyway .... can i adjust something on the throttle body to ease the jerkin'??

 

You could unplug the TPS & clip on a 5K resistor.
That way the ECU never sees the closed throttle.
Good news: nice backfires & exhaust flames.
Bad news: reduced gas mileage.

Note: series 5 owners - the ECU needs the long range TPS to run the OMP.

 

i do match revs.. it wont go into 1st > smoothly< .. ill match the rev and i still have to almost force it.. (which i have only done a few times, because i dont want to damage anything)

i match all the revs.. just like the trucks at work.. the powerband in turbodiesels is 1500 to 3000.. so.. i was taught to match the revs so i never have to use a clutch when shifting, only clutch from a stop

ANYWAYS 1st seems to be a little rough to get into.. something i should take to "mister transmission?" or is this normal (a little more push to get it into 1st)..

 

hahaha, my friend is non stop w/the heel-toe in his n/a.

Everytime he nails it perfect, you will know about it.

"YES!! it can't get any better then that one, I'm the man!!!""

What a nut!

sorry to get of the sub.

 

I'm the same way when ever i'm going to a different gear (lower) i always heel/toe it it's a long time habit i have. NOw about that 5 k resistor.. where do i get one? and where do i wire it into?

will it effect idle or anything other than fuel consumption? And you'll get a bit more flamage on upon downshifting right?

 

Where can i clip the 5k resistor to?

I would like to know.. and how much fuel will it use when i let off the throttle completely?

I am just kinda wanting to get rid of this lurching.. whats funny is i didnt notice it until about 2 months ago.

thanks guys. Markus

 

On S4's only:
To make it reversable if you change your mind later:
1) Get 2 of those blue press on taps and a 3-5K resistor from Radio Shack.
2) Disconnect the TPS plug & trace which pins on the harness go to the TPS black & orange wires.
3) Connect the resistor across those wires on the harness side.

The ECU will now see an open throttle all the time.
To restore normal TPS function, remove the resistor & plug in the TPS.

Happy flamage

 

happy flamage huh.. lol.. what type of fuel loss are we talking here? Will it run rich? Will it be terrible gas miliage? I get about 17-18 now in the city. what will it go down too?

So it's as simple as that.. just a resistor? nice, let me just get some more info.

THanks guys, Markus

 

Your fuel mileage loss would be almost the same as shifting to neutral & idleing the engine every time you slow down.

 

Assuming your AFM is working, the A/F ratio will be unaffected.
The ECU will only call for enough fuel to match the air getting by the closed throttle.

 

I am still lost as to how to clip the darn thing on. I've got the 5k resistor. and i know where the clip and TPS are.. but which wires do i crimp this thing across?

Thanks, Markus

 

Im having a similar problem, I will be driving the car and when I've been driving for 10 minutes it starts jerking when i shift gears and I lose poower and last nite it barely got ant power in 3rd and no power in 4th????any help