peachlilli

My 2005 automatic keeps jerking after I press the gas pedal on the freeway. It happens at speeds over 40mph. When I need to pass someone on the freeway or just open it up to have some fun, I press the gas pedal and it jerks rather violently (actually scares me) and THEN it accelerates faster. Any idea what this could be? It's been doing it for a couple of weeks. The dealer replaced the engine about 8 months ago but of course now it is out of warranty with 60k miles on it.

Bluerenesis

My guess is that you have never had the ignition coils changed. Your probably only working off one good ignition coil and not capable of making enough power. Sit in your driveway and rev it slowly in neutral. See if it doesnt sound like a smooth rev. How many miles are on it? and does the car start up easy or not?

peachlilli

Thanks. I can't remember ever having the ignition coils changed. Unless that is part of a routine service, I'm sure it hasn't been done. The car has 60,000 miles on it. It seems to start up okay, since I changed the battery last week anyway.

yiksing

You are extremely lucky to have the first set of coils lasted 60k miles. In case its not coils, did you note the engine rpm when the jerking happened?

Bluerenesis

If you havent had the ignition coils replaced, you might as well do spark plugs and wires too. Its around $450 with labor. If you got money, Try out the BHR ignition system. I dont have it but heard great things including it being superior to the oem ignition coils. Not sure about the claim that youll never have to change them again but sure sounds better than every 30,000 or so. Costs about $500 and if you are a DIY kinda guy, than I heard its not too difficult.

peachlilli

I only want to do what needs to be done to stop the jerking - would that be from JUST the ignition coils, or would the spark plugs need to be changed as well to stop the jerking?

zoom44

chnge the coils and see.

peachlilli

I called the dealer and they said it sounds like the transmission. They didn't mention anything about ignition coils. They haven't inspected it yet, so we will see. I hope it isn't the transmission because that would be pricey!

zoom44

when was the last time you checked the tranny fluid? when was it last changed?

peachlilli

They checked the tranny fluid the last time the oil was changed, which is about 3000 miles ago. I'm going for an oil change and to have it checked out this weekend. It would be great if it was just low fluid! Hope it is nothing too serious...

zoom44

check your fluid now, today, step away from the computer and go check it.

zoom44

https://www.mymazda.com/MusaWeb/pdf/...2005RX-8OM.pdf

starts on page 252 of the pdf

peachlilli

lol, I will check it after work (or have my husband check it!). Thanks for the instructions - we will need that.

Mazurfer

I could be wrong, but by the username the OP would appear to be a woman.
If so.............the freakin dealer is likely to tell her anything!

So....does it jerk when changing gears or just jerk as you accelerate?
Do you get any indication of a CEL(Check engine light)?


EDIT: Okay, she posted back before I got done typing!

I'm not an expert, but I guess it could be the clutch slipping??????
I'm still going to bet on the coils at this stage however.
If she's or they have had routine mantainence then the plugs have probably been changed, but they wouldn't have done the coils.
I would do both as for sure it's time to get those coils out of there.

peachlilli

Yes, I am female and I don't trust dealers at all. I try to bring my husband with me to dealers for repairs, though it's not his car and he doesn't know much more about cars than I do. But he can still say "Are you sure we need that?" ;-)

It is an automatic car, so no clutch. But it does seem to jerk when it changes gears to accelerate faster so that is sounding like it could be transmission related. I'll hope for low fluid or bad coils. The dealer did the routine maintenance at 35k miles and the sparkplugs were probably changed then but I doubt the coils were changed (why would Mazda do something proactive like that?).

zoom44

http://www.entertonement.com/clips/b...ghorn-Leghorn-

http://www.mcneel.com/users/jb/foghorn/foghorn4.wav

DocBeech

iTrader: (1)

lmao the clutch in an automatic is slipping:P

im thinking its more along the lines of the torque convertor.

Mazurfer

Okay, okay...........I totally brain farted then, but I thought auto's still had a clutch(per say).........my bad!

I said I wasn't an expert! I'm not really a car guy, I work in sub micron technologies!

Learned most of what I know from this forum and a wee little bit of common sense.

Thanks for this though.................

http://www.mcneel.com/users/jb/foghorn/foghorn4.wav

I can use that!

zoom44

you're welcome- again

https://www.rx8club.com/showthread.p...rn#post3595787

http://www.youtube.com/watch?v=KTwnwbG9YLE