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Can the Idle Air Control cause a kick when shifting?

So I have a 2002 Kia Spectra. I know the IAC has needed replaced for a while but It hasn’t really been a n issue at all until today.

So last night my car’s transmission started to kick when shifting gears. Mostly between first and second but at other gears sometimes as well. This morning it was still kicking and I figured my transmission was going out. However when stopped at a stop light I noticed that my car was idling rough. So I turned it off and tried to turn it back on and it wouldn’t start. At least not for about 10-15 minutes. So I was wondering if the IAC could be causing the transmission to shift rough at all?

Is this an automatic or a manual transmission? Is the Check Engine Light ‘on’?

I am assuming you have an automatic transmission. If the engine has a miss or is low on power, the transmission control module will be modulating the shifts as if the engine were producing more torque than it is. That would cause a shift bump.

I suspect you might have an engine driveability problem what with idling rough, stalling, not starting, and the suspected bad IAC (which may be because of something else).

Hope this helps.

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Thanks for the help!

I have an Automatic transmission. There are some codes being thrown but it’s hard to know which ones are real and which ones are not. I can’t remember what it is called but about 3 or 4 days ago I started getting random check engine lights and the guy at auto zone checked my codes and said it was the “brain” of my car throwing bad codes. I have the codes written down at home though. I am currently at work.

Yes provide those codes – even the ones previous pulled which may not be active now. It is amazing what the ECM can diagnose. Also, this has a Transaxle Control Module. I don’t know if there is a separate diagnostic port for this. I did not see one in my search. I don’t know if AutoZone can pull TCM codes. You may need to go to an independent transmission technician if it looks like there might be TCM DTC codes set.

I did find out that this transmission has an LPS solenoid (Linear Pressure Solenoid) which probably modulates the line pressure. It also has solenoids A, B, & C for shifting as well as a TCC solenoid of lockup. So the shifting is controlled by the TCM which communicates with the ECM.

Hope to help.

Hey what you just described sounds exactly like what my 2003 Hyundai Elantra is doing, it will drive fine for a while, then it will start to hesitate a little bit wether it’s in park or I’m going 60, when the hesitation happens it will like hiccup and it’ll do it for a while then go back to normal, then when I park, it’ll have an erratic idol for a while but then it becomes totally random when it might hesitate/stall and die or repeat, but no mater what it’s doing it always seems to bump in to gears and sometimes it’ll slip down a gear, I’ve got my codes pulled and I got 5 codes, every single one was for my O2 sensor, which I replaced as well as my spark plugs and throttle position sensor cause I did get one for that a long time ago, but none of them fixed the problem