Rpm / Lurching

ShintaroX · May 26, 2011

Hey all! Need the experts on this one: When the car is idle, there is no fluctuation of RPM nor any while keeping a constant speed. WHile braking, the RPM settles neatly on the idle of 650. Now the problem is that from a stand still, when I apply a slow acceleration, this at first results in sluggish movement but just for a second and then without any further application to the accelerator (i.e. keeping the pedal depressed exactly the same) the car RPM lurches about 200 ahead and there's a bit of a burst. Now I thought this might be AF sensor issue or some kind of vacuum leak, but the Toyota Lanka diagnostics revealed everything is alright. Is it a tuning issue then? Spark plugs? Toyota diagnostics need diagnostics ) Your help is appreciated!

The Don · May 26, 2011

I think what Toyota Lanka needs to do is put a datalogger on and do a run and analyse the results. These problems don't always manifest themselves when a diagnosis is done while stationary. Is the problem intermittent or does it always happen?

ShintaroX · May 26, 2011

Hey Don, yeah it is always like that - Taking off on D slowly, the car starts off slow and there's a brief, slight surge and the RPM goes from say 1000 to 1300, but once its in motion, everything is normal.

They did a road test also as part of the diagnostic. I'm no expert, but was wondering whether it was an issue with the MAF sensor or O2 sensor or a vacuum leak or maybe something to do with the plugs?

Please let me know if any of you have heard of a complaint like this or what the problem could be.

Cheers fellas.

The Don · May 26, 2011

Usually sensor errors would show up on a diagnostic system. You can take the plugs out, inspect and clean them and see if it makes a difference though I'm a little pessimistic this could be the problem. I had a similar problem once and it turned out to be a combination of the idle throttle controller, and ECU. But again some of this should have shown up in the diagnostic system.

Do you have a problem when you race the car while stationary ? As in does the problem only manifest itself once you put the car into gear ?

toyota sucks · May 26, 2011

if u mention the model and year it will be easy to help,

A premio 2008 that i owned had a problem with idling it remained even after the company pluged it up and said it was ok :unsure:

I think some times the diagnostics r not always right,

(my prob was that it the engine stalled after it was accelerated to about 5000rpm and released in P.

Sold the car anyway

charitha19 · May 27, 2011

can it be ur petrol pump pressue.. or petrol filter blockage.. both of these will not show up on diagnosis u know...

slcamel · May 27, 2011

Bro, post the model of the vehicle. so people can share the experience.

The Stig · May 27, 2011

Hey Don, yeah it is always like that - Taking off on D slowly, the car starts off slow and there's a brief, slight surge and the RPM goes from say 1000 to 1300, but once its in motion, everything is normal.

They did a road test also as part of the diagnostic. I'm no expert, but was wondering whether it was an issue with the MAF sensor or O2 sensor or a vacuum leak or maybe something to do with the plugs?

Please let me know if any of you have heard of a complaint like this or what the problem could be.

Cheers fellas.

peculiar problem :unsure:

Could be something wrong with your TPS thought.

I had somewhat of a a similar issue with the K11, turns out it was caused by dry soldering joints in the throttle body. Re-soldered the joints and it was gone.

BTW i got a question for you, does this only happen while in D ?

did you try putting to N and accelerating and see if the problem still exists ?

The Don · May 27, 2011

peculiar problem

Could be something wrong with your TPS thought.

I had somewhat of a a similar issue with the K11, turns out it was caused by dry soldering joints in the throttle body. Re-soldered the joints and it was gone.

BTW i got a question for you, does this only happen while in D ?

did you try putting to N and accelerating and see if the problem still exists ?

I've read about this issue. Apparently quite common in K11s and causes rough idling or the idle speed going up and down !

ShintaroX · May 27, 2011

Hey all, thanks for responses. I wondered about the throttle body as well, except that the RPM is stable on N and in P, this problem only occurs while taking off slowly. If it was a throttle body issue, wouldn't it produce unstable RPM while stationary? Taking off rapidly is smooth and fine also. Weird one, eh?

Sorry guys, its a Toyota Vitz 1.3l.

toyota sucks · May 28, 2011

Hey all, thanks for responses. I wondered about the throttle body as well, except that the RPM is stable on N and in P, this problem only occurs while taking off slowly. If it was a throttle body issue, wouldn't it produce unstable RPM while stationary? Taking off rapidly is smooth and fine also. Weird one, eh?

Sorry guys, its a Toyota Vitz 1.3l.

If it's the new one with cvt and this happens only in D it could be a occurring at the gearbox.

So check it and change the cvt oil, u'r Odo might be showing a low millage but trust me vitz don't come out of japan if they haven't done more than 100 000km or had an accident.

So it's best to change the oil but at a good place cause if u fill wrong oil into it the box will completely fail

slcamel · May 30, 2011

Try clarning the Plugs, replace/clean the Air Filter/flow and reboot the ECU idleing the car for 10 to 15 min. (Remove the battery for 30min and connect the battery and start the car with AC, lights off and keep it for 10min)

Worked for me sometime back.

if not, could be a occurring at the gearbox.

Edited May 30, 2011 by slcamel

The Stig · May 31, 2011

I've read about this issue. Apparently quite common in K11s and causes rough idling or the idle speed going up and down !

Yeah i also got to know about this issue through other forums.

Didnt really know i had such an issue until i fixed it and noticed the difference:D

Hey all, thanks for responses. I wondered about the throttle body as well, except that the RPM is stable on N and in P, this problem only occurs while taking off slowly. If it was a throttle body issue, wouldn't it produce unstable RPM while stationary? Taking off rapidly is smooth and fine also. Weird one, eh?

Sorry guys, its a Toyota Vitz 1.3l.

Well if the Rpm is stable in n and p, and this only happens in D the issue is probably related to your gearbox.

Yes if it was a throttle body issue it would probably be noticeable even while in stationary mode. but you never know, you sound like a guy who knows his way around an engine so just take a look at the throttle body and the circuits around to see if there are any noticeable anomalies.

ShintaroX · May 31, 2011

Just to say I really appreciate your helpful comments. You guys could've been doing anything with your time, but you gave some of it to me and I appreciate that!

Taking a day off work this week, will let you know what happens...one of you HAS to be right!

ShintaroX · June 7, 2011

Hi everyone, Shintaro here. Throttle ok, sensors working, no vacuum leaks, plugs (or flugs as they are also known ) are ok. So by a complete fluke, I think I discovered the source of the issue. I turned the A/C off while travelling and the problem stopped. I pulled over and when the A/C is on, there is some kind of rattling (compressor bearings? Not sure.), switch the A/C off and the car runs fine, no rattling.

Anyway got to Toyota Lanka and they ran the data logger and said everything was ok and did a tune up (which cost 3,000/- incidently if anyone is interested in knowing), but they said that there is a A/C "case ekuk" and a new compressor will cost a whopping 300,000/-.

Could it really be the A/C causing this problem? It seems so unlikely.

toosea · June 7, 2011

Could it really be the A/C causing this problem? It seems so unlikely.

I had a similar problem.. while driving in traffic with the AC on there would be sudden acceleration and acceleration and sometimes it would be very tedious to drive. It only happened while the AC was on and the final solution was to replace a some kind of vacuum operated relay or switch. There are a couple of vacuum lines that come in to this switch.

Once replaced it is quite less frequent than before

May be this might help to diagnose your problem...

Edited June 7, 2011 by toosea

RWD · June 7, 2011

300,000 for a compressor? man parts for these new econoboxes are expensive these days!

The Don · June 7, 2011

Hi everyone, Shintaro here. Throttle ok, sensors working, no vacuum leaks, plugs (or flugs as they are also known ) are ok. So by a complete fluke, I think I discovered the source of the issue. I turned the A/C off while travelling and the problem stopped. I pulled over and when the A/C is on, there is some kind of rattling (compressor bearings? Not sure.), switch the A/C off and the car runs fine, no rattling.

Anyway got to Toyota Lanka and they ran the data logger and said everything was ok and did a tune up (which cost 3,000/- incidently if anyone is interested in knowing), but they said that there is a A/C "case ekuk" and a new compressor will cost a whopping 300,000/-.

Could it really be the A/C causing this problem? It seems so unlikely.

Well a new compressor can be found for a lot less from Delkanda. Did they go into detail on what the "case" with the compressor was. Also 300,000 is quite steep for a compressor considering how much these vehicles cost brand new (without taxes applied).

I wonder if the compressor is seizing up a bit temporally when you accelerate, and when it unseizes the rpm goes up temporally and then drops back.

Edited June 7, 2011 by The Don

charitha19 · June 7, 2011

Well a new compressor can be found for a lot less from Delkanda. Did they go into detail on what the "case" with the compressor was. Also 300,000 is quite steep for a compressor considering how much these vehicles cost brand new (without taxes applied).

hmm 300K for a compressor i dont think so.. thats a little too steep.. if ur cooling is ok i dont think its the compressor. unless the bearings of the pully is gone or something and its putting random strain on the drive pullys..

i think its something to do with your AC idle up circuit.. if its not vaccum operated then its managed from the ECU.. i suggest u go to a good AC shop and ask them where the AC idle up is and how it functions.. i really refuse to belive this is a compressor issue..

RWD · June 7, 2011

also even though they are the agents, i am not impressed with the mechanics at t*yota lan*a, so as others have said, better get a second opinion. they were once trying to rotate tyres on an IS250 when the rear tyres were a different size to the front!