Scion IA Forum banner
21 - 24 of 24 Posts

·
Registered
Joined
·
44 Posts
Rough Idle and check engine light at 105k solved. Our Scion Ia's are direct injection engines. Direct injection engines have a problem with Carbon fouling and if you have a rough idle please have the Carbon cleaned from your intake tract and valves. This should cost about $300. Mine went all the way to a P0300 misfire code and it costs me $600 to remove the intake. Dealer tried to sell me new car and said engine was no good. I reputable shop call Salem Brothers (AZ) was willing to try and fix the Carbon build up and the engine is fine. Most dealers will just say you need new engine and try and sell you a new car. There are risks with having let the carbon build up for a 100k. It may not be possible to clean all the carbon out and dealers won't take the chance. Shop said to clean Carbon every 20k. I tried everything I could think of to fix my rough idle. I had a warranty to 100k and dealer's just told me that there was nothing wrong. Manuel says nothing about this needed maintenance. This affects other cars with direct injection as well. Rough idle is more noticeable with A/C off.

Seems rough idle at 500rpm with A/C off is motor mounts. Violent miss fire is carbon build up in the intake valves.
 

·
Registered
Joined
·
44 Posts
I have the same problem. Idle drops from 750 rpm to 500 rpm when in gear (auto trans) and brake pedal is applied. No AC on, in daylight with lights off. If you pop the brake light switch out of the mounting bracket pushing the brake pedal has no effect on idle rpm so it doesn't seem to be vacuum booster related. Seems like it's engine management related. In response to others saying "this is what small 4 cylinders do at idle", I strongly disagree. No engine should ever be dropping below 750 rpm at idle, unless an immediate load is engaged and then the idle control should return it to 750 rpm. Mine will stay low until the brake is released. The shudder is from too low an rpm, not from being a small 4 cyl.
Check motor mounts
 

·
Registered
Joined
·
44 Posts
My 2016 Scion iA idles rough, and I think I have pinpointed the problem to it happening only when the brake is applied. I took it in to the Dealer to have that checked, but of course they couldn't find anything wrong! It is not right that it should do that and it annoys me no end when it does! I will take it to another Dealer for sure, but have no confidence that they will agree to the problem, and correct it. Are other Scion iA owners having this problem? Please let me know!




Thank You,


Joseph A. Bifulco
26 Johnson St.
Franklinville, NY 14737
Home Phone (716) 676-3234
Cell Phone ….(716) 866-5456
mailto:[email protected]
rough idle at 500 RPM with A/C off and no misfire is motor mounts.
 
21 - 24 of 24 Posts
Top