Rough Idle Up and Down

[Ozzay]

I have posted this topic up before but was wondering if any of you had this symptom before.

When the car is in drive and stopped the rev after driving a bit can go up and down with the car shaking/vibrating like a heartbeat.

When driving the car is fine. Only once it seemed as the gear dropped the rev was going on up and down.

Had spark plus changed and the car was fine and better.

Post gasket seal change something changed or coincidentally something failed.

I don't know what it could be.

Air pipes (vaccum) look fine checked with mechanic.

Only once the Cylinder 2 misfire code occurred in 2 months alongside the ABS light (how reliable is this or is it misleading).

Could be throttle body, spark plug, spark plug coil. Not sure if there is an IVAC.

Anyone ever had this issue.

The mechanic said he needs me to bring the car back with the code there don't know how that will be helpful to him since I had the screenshot.

[Linas.P]

If there are no DTCs then check is throttle body is clean, dirt can accumulate in throttle body and it can start sticking. As well overtime ECU adjust for throttle body dirt, but it could only adjusts like 2 degrees, if it gets too dirty it may start handing on revs. 

Apart of that you may need to look at live data and see what parameters are changing when revs are jumping around, but looking at life data is same as predicting future with crystal ball, I never get it especially without knowing what values to look for.

It is kind of funny because my car has all the issues ever... just name me the issue with IS250 and it has it. Likewise I have this rough idle... but in my case it is dead throttle body (position sensor in particular).

[Ozzay]

32 minutes ago, Linas.P said:

If there are no DTCs then check is throttle body is clean, dirt can accumulate in throttle body and it can start sticking. As well overtime ECU adjust for throttle body dirt, but it could only adjusts like 2 degrees, if it gets too dirty it may start handing on revs. 

Apart of that you may need to look at live data and see what parameters are changing when revs are jumping around, but looking at life data is same as predicting future with crystal ball, I never get it especially without knowing what values to look for.

It is kind of funny because my car has all the issues ever... just name me the issue with IS250 and it has it. Likewise I have this rough idle... but in my case it is dead throttle body (position sensor in particular).

We did clean the throttle body. I got a feeling its something like this as well and a misdiagnosed code. I could do this myself at home I think. But I remember the mechanic did clean it well it did look shiny. Does this car have an IVAC?

[Linas.P]

Service manual as well advises that once throttle body is replace ECU needs to "re-learn idle", however I was not able to find such function in TechSteam. As far as I understand there is no IVAC, but there is EVAP, however I doubt it has something to do with your idle. Then there is whole fancy swirl control system in plenum, anyone's guess if that could be malfunctioning. 

[madasahatter]

M

[madasahatter]

My quess pcv valve i had same on a Skoda Vrs.

[Ozzay]

Still can't find the issue.

Could not find a vacuum leak. 

Another mechanic found the terminals from both side were not earthed properly. One was no connected (ground) and the other partially tight. Did not fix the issue.

Gasket seal looked OK.

Did a trip to Scotland (NC500) and the car was returning good MPG and drove OK. Just on stand it starts to idle up and down and vibrate from the engine.

I will have to check the MAF sensor by disconnecting it. 

Throttle body looks OK but not exactly sure.

Only once did I get a code for the spark plug at bank 2 misfire but that was just once and it never came back.

Not sure if I should replace that spark plug and attempt to get the ignition replaced at that bank.

This is one problem I would like to fix. Stupid mechanic that did the seal has been useless.

Not sure about the PCV as suggested. Also brake booster etc not sure either.

[J Henderson]

How often is it happening? I think I've experienced something similar a few times. Only a few times though. Like, maybe 5 times or fewer.

After coming to a stop, it felt like the car was idling too low and about to stall before correcting itself. Whole event lasted maybe half a second, to a second before running normal again. Definitely not an ongoing heartbeat type thing.

Internet research suggested it could be anything from a "normal" lean idle misfire - the ECU apparently leans out the mixture at idle to reduce emissions and fuel consumption.

To, carbon deposits on the valves or other areas in the top end of the engine. Which, probably exacerbates the frequency of the idle misfire occurring.

 

[mk_lon]

I had this too, noticed it was happening during the winter when them temp drops below the 10 degree mark.

The spark plugs were changed in mine during a service in Jan 22 and the problem went. It recently came back during the cold snap but usually goes away after about 20mins of driving so I did'nt investigate it any further. I would be intersted to see if the cause is found on this thread as I am useless at DIY car mechanics 🙂

[Linas.P]

I am really just speculating here so don't read much into it, but I suspect this going to be issue with some sensors. Maybe lazy MAF or lazy O2/Lambda, or some other of million sensors in this car. Not to the point where they throw the code, but to the point where in colder weather they have delay responding to ECU and as result less than ideal air/fuel ratio get's sent.

If it would be carbon, or hotspot in the cylinder, or even spark-plugs or injectors then it would be more likely to have engine running rough all the time, or particularly in higher revs, not in lower revs.

I know this isn't much of help, but I am just trying to think through it logically in the process of elimination.

[SeanR]

Is this with the air con on ?

See if it runs better without the air con on.

[mk_lon]

@Linas.P thanks that makes sense. I will keep an eye on it and get back to you, I have a fealing it could be MAF or 02 sensor but I dont know enough to be sure. @SeanR its been when the AC is off, when I first start it up and have been driving for the first 20mins or so.

[eleveneleven]

@Ozzay did you ever figure out what the issues was? Mine has been doing it for the last 4 months now, idles at 500 ish RPM causing heartbeat like vibrations. It's been serviced recently and no fault codes showing 

[Ozzay]

On 3/8/2023 at 2:15 PM, eleveneleven said:

@Ozzay did you ever figure out what the issues was? Mine has been doing it for the last 4 months now, idles at 500 ish RPM causing heartbeat like vibrations. It's been serviced recently and no fault codes showing 

Interesting I just logged in to post about my recent troubles and you give me this message.

You know what did work. I used to have engine sputter and confusion when the car was on low revs driving when slightly uphill. Over a period of 4 months I used the Forte petrol injector product which is meant to be very good. The engine vibrations went away.

If you read my other thread where the mechanic told me it was the intake manifold seals. He did that plus calipers. No rough idle for weeks but even after the petrol treatments my engine is sputtering on acceleration sometimes (usually when warm). I had cylinder bank 2 misfire twice in January/Feb and put the third petrol injector treatment in. The mechanic said try the fuel treatment stuff again. It could be dirty injectors. It could be a ignition coil failing. Bad spark plug. Bad connector. Vacuum leak anywhere though I promise I have seen it all myself can't find anything. I cleaned the throttle body once in 2021 and MAF sensor and again throttle body was cleaned by the mechanic who ruined my car in June 2022 (the one who advised the rocker cover gasket seals to be changed). 

In May 2022 sparks were changed. Car was fine before and after.

When June came and those rocker cover gasket seals were put in the car then experienced rough idling. He did not fix it because he was guessing things. Big regret going to him. After he claimed the injectors were dirty. Well the car had 0 issues before and suddenly injectors was the problem. The issue is even the Lexus specialist will be wasting his time and money on me though he has been OK because they need to see codes.

So there were 2 mechanics at play here. One who ruined the car with the rocker cover gasket seals (mysterious). The 2nd one is a Lex specialist who tried to resolve the problems (intake manifold seal (guess work IMO))

So as of right now I need to do the following:

Re-check vacuum leaks literally everywhere

Check sensors. 

Don't know how I am going to check injectors without stripping it apart.

Could replace ignition coil and spark on bank 2 but that's guess work as well.

I really don't know. The cars amazing in general but very unhappy at this minute so do let me know what you find. Others boil it down to carbon issues. If yours was just services. I could only think of the airbox, air intake and filter being a culprit. Other people did suggest EGR valve as well.

 

PS. Ides rough at 500 sometimes. When warm and stopped in Drive or Reverse rough idle heart beat. Acceleration is not what it used to be. Tried various fuels. The car idles at 1k exactly when the cars sitting from cold (stopped). When it gets warm it lowers to between 500-700rpm. 

[eleveneleven]

On 3/10/2023 at 9:53 AM, Ozzay said:

Interesting I just logged in to post about my recent troubles and you give me this message.

You know what did work. I used to have engine sputter and confusion when the car was on low revs driving when slightly uphill. Over a period of 4 months I used the Forte petrol injector product which is meant to be very good. The engine vibrations went away.

If you read my other thread where the mechanic told me it was the intake manifold seals. He did that plus calipers. No rough idle for weeks but even after the petrol treatments my engine is sputtering on acceleration sometimes (usually when warm). I had cylinder bank 2 misfire twice in January/Feb and put the third petrol injector treatment in. The mechanic said try the fuel treatment stuff again. It could be dirty injectors. It could be a ignition coil failing. Bad spark plug. Bad connector. Vacuum leak anywhere though I promise I have seen it all myself can't find anything. I cleaned the throttle body once in 2021 and MAF sensor and again throttle body was cleaned by the mechanic who ruined my car in June 2022 (the one who advised the rocker cover gasket seals to be changed). 

In May 2022 sparks were changed. Car was fine before and after.

When June came and those rocker cover gasket seals were put in the car then experienced rough idling. He did not fix it because he was guessing things. Big regret going to him. After he claimed the injectors were dirty. Well the car had 0 issues before and suddenly injectors was the problem. The issue is even the Lexus specialist will be wasting his time and money on me though he has been OK because they need to see codes.

So there were 2 mechanics at play here. One who ruined the car with the rocker cover gasket seals (mysterious). The 2nd one is a Lex specialist who tried to resolve the problems (intake manifold seal (guess work IMO))

So as of right now I need to do the following:

Re-check vacuum leaks literally everywhere

Check sensors. 

Don't know how I am going to check injectors without stripping it apart.

Could replace ignition coil and spark on bank 2 but that's guess work as well.

I really don't know. The cars amazing in general but very unhappy at this minute so do let me know what you find. Others boil it down to carbon issues. If yours was just services. I could only think of the airbox, air intake and filter being a culprit. Other people did suggest EGR valve as well.

 

PS. Ides rough at 500 sometimes. When warm and stopped in Drive or Reverse rough idle heart beat. Acceleration is not what it used to be. Tried various fuels. The car idles at 1k exactly when the cars sitting from cold (stopped). When it gets warm it lowers to between 500-700rpm. 

Thanks for the update buddy much appreciated. 

A few days ago I decided to fill up with V-Power instead of the usual Tesco momentum. After about 20 minutes of driving I stopped at a traffic light and..Silence. the issue seems to have pretty much stopped, it's not gone completely, it's more intermittent now but it Idles slightly higher now in D/R when warm. Not quite sure what that's telling me though other than I could do with using Vpower (which I'd rather not) could it be an oxygen sensor issue maybe? I'll take your advice and start by running some injector cleaner over the next couple of fill ups and see how that plays out. Mines currently on 90k and hasn't had a fresh set of spark plugs in a while not checked for vacuum leaks and MAF hasn't been cleaned on my watch so those will be the next steps at some point this year. 

Hope you manage to get yours sorted too mate, it's an annoying niggle with the only solution being a process of elimination by the sounds of it. 

Keep us posted. 

 

 

 

[Ozzay]

On 3/15/2023 at 11:13 PM, eleveneleven said:

Thanks for the update buddy much appreciated. 

A few days ago I decided to fill up with V-Power instead of the usual Tesco momentum. After about 20 minutes of driving I stopped at a traffic light and..Silence. the issue seems to have pretty much stopped, it's not gone completely, it's more intermittent now but it Idles slightly higher now in D/R when warm. Not quite sure what that's telling me though other than I could do with using Vpower (which I'd rather not) could it be an oxygen sensor issue maybe? I'll take your advice and start by running some injector cleaner over the next couple of fill ups and see how that plays out. Mines currently on 90k and hasn't had a fresh set of spark plugs in a while not checked for vacuum leaks and MAF hasn't been cleaned on my watch so those will be the next steps at some point this year. 

Hope you manage to get yours sorted too mate, it's an annoying niggle with the only solution being a process of elimination by the sounds of it. 

Keep us posted. 

 

 

 

@eleveneleven

Mechanic made me drive the car today after MOT.

He has the Toyota techstream/CPU connect to the OBD port and while driving monitored the numbers.

Got the feint heartbeats hear and there fortunately. On the computer it was coming up as misfire on cylinder 2 but went away quickly. So not enough to hit the threshold of causing a warning back to me. But at least he confirmed the numbers and said we need a new coil pack and of course might as well change the spark plug in bank 2 as well. The only thing that gets to me is that he wants to replace the intake manifold seal/gasket everyone he opens that box up.

I will see what the prices are for this. New plug will be at least £10 to £15 I think. Used coil is around £20 minimum but he said buy it new Denso. Will keep you posted after the fix. Bare in mind I could probably do this myself but just won't be able to on my road too much chaos and more things can go wrong I think.

 

[Ozzay]

Update:

It was an ignition coil issue because it was arching when hot because it was missing the end part.

New ignition coil and new spark plug in bank 2 with new tube gasket seal.

Car is working and much much better, light acceleration feels effortless again and no more rough idle.

[scudney]

At least its finally sorted, well done 👏 

[SeanR]

Reminds me of an issue i had on a Merc a good while ago, that ended up being a coil.

Mines on 90k now and wont be surprised if similar issues start.(hope not yet though, touch wood)

Thing is though, great mechanic and sorted it in 15 mins, some garages will take the ****