I have a tC with about 1000 miles on it. It is a manual. When I'm traveling at between 37 and 42 mph I get a surging sensation. It is especially bad when I'm going down a slight incline. I took it to the local dealer (in Denver CO). They said this is "normal". I think it is a computer issue. Has anyone else had this problem?

 

Make sure you post in the right section. I'm moving it to tC 2G.

 

surging... is it like a rocking horse effect where the car kinda rocks back and forth when your trying to keep it at a constant speed?

https://www.scionlife.com/forums/sho...d.php?t=200558
i know that ppl said thats something that helped fix that issue if thats what ur lookin for or if that is the problem

 

Yes - kind of like a rocking back and forth. Kind of like the computer hunting for the right position for the throttle but it keeps going back and forth.

 

I have manual trans too, but I've never noticed it.
What gear are you in when you're going between 37 mph and 42 mph?
Does it happen with other gears going at the same RPM?

 

I am in 4th gear. My foot is barely on the gas. At that speed I am lugging the motor in 5th and in third it is kind of racing. I have talked with a local Toyota tech on this and they are going to try and replicate this on another car and they will do a data capture on mine to see if they can can figure out what is cooking. It is quite bad when I'm "coasting" down a hill at 40 mph. And living in Denver, we have hills so it happens quite a bit.

 

Oops, I misunderstood your first post.
I understood "going down a slight incline" as going uphill.
This happens to me too when I'm going downhill.
It happened with other cars I used to have too.
When it happens, I just put the gear into neutral.
But this doesn't happen when I'm going flat or uphill.

 

Its not you, my car does it too, and its usually around that same speed, you feel this light jerk like 2-3 times! like the car hiccups! But then again my car has this annoying rumbling when idling and it hiccups! toyota says that how the car is sad face for tC2

 

I tried to replicate this in mine, no problems at all. Sounds like bad gas, dirty injectors or a bad spark plug to me. Pull all the spark plugs and see if one of them is a darker,wetter than the rest. You could have a bad plug or something in the firing system causing a misfire. If you find a plug that looks different than the rest, put it back in and take it to the service dept. asap. Make them find the problem from there.

 

I was not having this issue up until a day or two ago... happened to be the same time I switched to 87 octane fuel. Up until a few days ago I was only using 93...

I am going to switch back to 93 on this fill up to see if anything changes...

 

Well funny thing is that when i first got my car i was putting in 93. One day i was extremely low on fuel and pulled off to a gas station and 93 wasnt working. so i put in 87 for the time being. I park my car and about 5 hours im heading to work and i start my car and the car started bucking and shut off. Check engine light comes on and stability control light stays on as well! toyota says that there was water in gas to put 93 for a little while. I've had this same problem for 2500 miles and im starting to wonder if my sparkplugs are bad

 

OMG. I was using 87 all this time (almost 5 months). And I just tried putting in 93 yesterday for the first time. I hope I don't get this problem when I switch back to 87...

 

This is a good reason to use QuickTrip gas. They have a garuntee that if your engine fails due to their gas, they will pay repair costs. Not sure how to legally prove and obtain the repairs... And good luck to all of those that can afford an additional 30 cents per gallon for 93 octane...

 

the dealership specifically said to us 87. is the gas really causing these issues?

also is this happening to autos or only manual?

 

been using 87 since the day i got my car without any issues.. i'm also getting the rated mpg (31+ on hwy) and 26~27 avg. don't see the point in wasting money on 93 octane on a stock tC to satisfy my butt dyno

 

87 octane is not a problem, the quality of the gas is. I have noticed huge differences in all the major brands, no matter the octane rating. Shell & BP seem to offer me the worst fuel consumption and power in my TC. My previous car was different, an 02 Mazda Protege 2.0L. It hated the Shell but liked the BP.I am not exactly sure what brand it is, but I have a small local gas station that I get ethanol free from. The engine seems to prefer this gas. I can lug mine at 45mph in 6th gear all day long, plenty of smooth torque at lower rpm's. Always starts easily and never hesitates and 3 more mpg vs. anything else.
Remember the engine's computer has to readjust the timing for major octane changes. It should not take 2500 miles though! Sounds like you have trash or water in your fuel system that is being stubborn. Just guessing.

 

My studder went away on this tank of premium

 

Darn. I might have the same problem if I go back to 87 oct...
I guess I'll find out next month.

 

I switched to 93 octane with no ethanol on my last fill up. 1/2 way thru the tank now, gas mileage is the same, butt dyno feels nothing noticeable. I will be ticked if it starts running poorly on 87 next fill up.