Bucking.. Kinda

First post, long time lurker, my go-to forum for my galant issues...

Currently has no CEL or SES or any other dash light on. Car runs fantastic normally. My motor mounts could probably use replacing...

My car has started missing/bucking while at speed (55ish). But when it starts doing that, i reach into it a little further. It immediately picks back up as if nothing is going on. When i let off and resume normal speeds, it starts again. It seems to do this nearly everytime i drive the car (i dont drive it much). Usually only long distances.

Idles just fine, hot, cold, in gear. Even during it messing up.

I was going to the store (10 miles??) the other day and it immediately started doing this as soon as i pulled out of the driveway. It did this most of the trip there. Left the store, and absolutely no issue. Ran like a champ. (maybe it was a cold/not hot issue?)

But at the same rate, i was driving out of town a few weeks ago, and i got about an hour into my trip and it acted like someone shut the car off. And within a second, pick right back up. Did nothing until my trip to the store.

I do all of my maintinance, and stay on top of it. I've only put about 6k miles on it since owning. Replaced Timing belt, Plugs, Wires, the P0421 'fouler fix', replaced valve cover gasket and spark plug grommets, and EGR vacumm solinoid was replaced after P0403 CEL. Regular oil changes (3 lol)... Various other non-engine related things...

Thanks for the help!



>EDIT - i guess its worth mentioning that the car has, not once, ever died on me. Even now with this issue. Not even a sputter.

I was going to say change the spark plugs but u said u did that maybe shes getting fuel cuts

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Originally Posted by Palmz

I was going to say change the spark plugs but u said u did that maybe shes getting fuel cuts

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That was my first thought... as if a feul filter is clogged.... (might be a dumb question) do these cars even have feul filters? But again, does it warm, cold, idles fine, and only seems to do it when i need to be somewhere........ Again, never died, or even stumbled.

Thanks for the help.

i know my JDM one has a fuel filter thats beside the tank (on the jdm's they are prone to clog them self when rusted) but havent even tought about it on the usdm one he runs like a dream but.

Just keep this in mind when trouble shooting this problem an Engine need three things to keep going = Spark(electricity) Fuel (fuel flow) and Air (correct mixture)

I have had similar symptoms before, but it usually goes away with a throttle body cleaning and MAF sensor cleaning (less regular). Don't know if you might want to try that out and see.

hmm... hadnt thought of that, i will give it a try. I know the TB is a bit dirty. Thanks.

Just to update... I tried tamim13's suggestion and tried cleaning the throttle body. The first 'quick' clean was a fail, i think it may have made things worse... But the second time, taking the TB off and cleaning it, turned out much better results. It's not perfect but it's tolerable; idles a tad low (maybe 50-100 rpm's low) and makes everything vibrate, while in gear.

At least now i know what to work on. I may end up getting a new TB. Mine's probably never been cleaned before me. But it's drivable now, im hoping the computer just needs some drive time to re-adjust itself.

Thanks to tamim13, hit it right on the head.

Thanks TGC!

I cleaned the TB with a toothbrush this time, shiny clean, and she's running just perfect. Thanks again!

You don't need a new TB, you probably got the IAC wet and that's why idle is off.

I'll keep that in mind, thanks.

Ok, Whatd i mess up? It doesnt wanna idle cold. Once it warms up it doesnt want to carry an idle, It fluctuates between 750 and 1000. Where do i start? I have no parts laying around for these cars. Thanks for the help so far.

Is it possible i fried my IAC? I didn't soak the throttle body or anything. Cleaned it with a toothbrush. Still no CEL. How do i test the IAC? what about the TPS?

When you removed the intake, are you sure you reconnected everything and closed the clamp up tight? It sounds like you're having a vacuum leak somewhere, check if you reconnected the connection to the throttle body from the intake tightly, there's a tendency to not get it all the way in properly. Also, I always disconnect the battery for about 1/2 hour just so that the computer can reset and relearn the idle.

If you can get a couple of parts from a donor car at a junk yard, try to pick up a mass air flow sensor and IAC if the problem doesn't go away. I'll try to find my service manual and get you the instructions on testing the IAC and MAF Sensor, probably tomorrow.

Well, i went out last night and messed with it. Initially i forgot to plug the IAC back in. Did that. Reset computer. Starts up cold fine. Idk whats different, aside from the IAC (and it really wasnt plugged back in, it was just resting in the socket, not clipped into the socket). I guess i'll give this a couple days, see what she does. If i'm still having issues, i'll search for a V6 throttle body from a parts yard (been wanting to do that swap anyways), or at minimum a replacement IAC.

Sorry to sound like a novice, i just dont know much about these cars. My last car was an 03 Jetta TDI, and i did everything to it, Water pump, timing belt, injectors, even had VAG-COM. Loved that car. That was my toy. The galant is just a daily (currently).

Thanks for the help!

Still doing that same thing, fluctuating idle at 800-1000. So i'm gonna assume a bad IAC.

Anything on the eastern shore? With some parts?

you can get them on eBay for $30-$40. Or a junkyard. That's where I found mine when I needed one.

Thanks, junkyard probably.... Anyone know if i can cause further damage to the car by running it anyways, until i can fix the problem?

I have brand new ones for sale, inbox if interested. Also did you check your intake and or your intake manifold?

Just to update...

I ordered the replacement IAC from ebay.... OE replacement... nothing chinese made... been down that road.............

$22 shipped. Now she runs great. Thats all it was..... Thanks TGC. And especially 'tamim13'.