Verbout

Lumpy idle when cold......

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My IS 250 automatic, has in the past few weeks, had an intermittent lumpy idle problem when starting from cold, my wife even noted it sounded funny when she approached the car as we were leaving the house.

Also when coming to a halt just as the car stops the tachometer jumps from about 800 up to 1500 and straight back down again.

I have a few ideas that I will investigate when I've done with the painting and decorating. :wacko:

Any pointers would be appreciated.

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Perfectly normal for this time of year. Mine has always done the same over the winter. Nothing to worry about.

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13 minutes ago, Verbout said:

I have a few ideas that I will investigate when I've done with the painting and decorating. :wacko:

Any pointers would be appreciated.

Does it need an Italian tune up ? 

  • Haha 1

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I can understand it feeling "lumpy" at startup during the cold weather due to the engine adjusting to the cold temperature but it should soon go when the engine has warmed up, and you say the revs jump when coming to a stop at a junction. Does it do this all of the time or now and then - does it feel like its doing this when driving the car?

Could be the engine is hunting - could be a few things .... check the air filter - TPS could be at fault if severe ... Battery? ... even a bad batch of fuel if happening during driving

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23 minutes ago, is200 Newbie said:

I can understand it feeling "lumpy" at startup during the cold weather due to the engine adjusting to the cold temperature but it should soon go when the engine has warmed up, and you say the revs jump when coming to a stop at a junction. Does it do this all of the time or now and then - does it feel like its doing this when driving the car?

Could be the engine is hunting - could be a few things .... check the air filter - TPS could be at fault if severe ... Battery? ... even a bad batch of fuel if happening during driving

Newbie, the car soon idles smoothly after a minute or two.

The revs jumping is also intermittent and yes it does sometimes do it while driving along.

The throttle body is on my list while checking the air intake.

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My guess is the maf sensor could be dirty. Apparently these are self cleaning but a quick spray with electrical cleaner can work wonders.

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9 hours ago, Rebecca said:

My guess is the maf sensor could be dirty. Apparently these are self cleaning but a quick spray with electrical cleaner can work wonders.

Cheers Rebecca, it’s something I will address when I get to work on the induction system.

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1 hour ago, Comedian said:

You might have the carbon build up issue associated with direct injection: https://www.clublexus.com/forums/is-2nd-gen-2006-2013/484055-lexus-is250-4gr-fse-engine-carbon-build-up-merged-threads.html

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Cheers Comedian, another issue I’m aware of, a dose of some toxic chemicals may help, I’ll look into it.

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Strangely enough, today while driving in the snow I had the TRC/engine warning etc lights come on

Codes thrown up were P0172 and P0175

Felt a bit lumpy - these two codes relate to the engine not being able to set the fuel / air ratios correctly so am guessing its the MAF due to the bad weather getting dirty etc. Was due to go to Scotland tomorrow but I don't think so now due to the weather so will clean the MAF instead. !

Have you tried reading the error codes if there are any stored?

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Don’t have a code reader. The revs surging is getting more noticeable.

I’m going to check the induction from the air cleaner to the throttle body sometime next week, weather permitting, gone are the days when I could get under the bonnet any weather.

I’m favouring a cleaning of the throttle body to start with.

I’ve just watched a video of a man changing the plugs on an IS 250 and clean the throttle body by taking it off. I was under the impression that they had to be recalibrated once disturbed. Anyone know differently, can they be removed, cleaned and replaced without issue?

 

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23 minutes ago, is200 Newbie said:

I think that's just the diesel model ??

What’s just the diesel model?

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1 hour ago, Verbout said:

What’s just the diesel model?

I think its the injectors on the diesel that need coding to the diesel models - pretty sure I have seen members having to do this on the forum

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3 hours ago, is200 Newbie said:

I think its the injectors on the diesel that need coding to the diesel models - pretty sure I have seen members having to do this on the forum

 Recalibrated......some throttle bodies have to go through a calibration procedure to get them to recognise open and close throttle. I wondered if you remove the 250's you have to follow that procedure?

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After the fault codes on mine from last week, I cleaned the MAF sensor this morning - a bit grubby but nothing too bad, reset the error codes and alls good.

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I had this issue on a Merc C220 CDI a few years back - turned out it was the fuel in the end. It didn't like Sainsbury's diesel and would intermittently rev at idle - solved after using BP standard diesel

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30 minutes ago, rayaans said:

I had this issue on a Merc C220 CDI a few years back - turned out it was the fuel in the end. It didn't like Sainsbury's diesel and would intermittently rev at idle - solved after using BP standard diesel

I’ve run the car right down to the dregs several times in a row recently. That people say doesn’t do the car any favours, but I do use  branded fuel most of the time.

All suggestions still appreciated, just bought some carb cleaner from Toolstation, cheap as chips.

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My understanding is that you can remove the throttle body for cleaning without any problems. However you must NOT physically open the flap as this is what causes issues.

If you are using the carb cleaner to spray the MAF sensor I would be very careful and would advise that you get a specific cleaner for the job - one that states that it does not leave any residue is required. Wurth make one which I believe can be bought online.

I have noticed the same lumpiness at startup these last few very cold mornings but it only lasts for a second or two and I'm still on the original 2006 spark plugs at 88K miles!

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Cheers Beamish, I’ve heard moving the butterfly flap is a no no.

I’ve got cleaner for the MAF, the carb cleaner is for the throttle body.

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Throttle body removed, well not entirely but bolts undone so I could get to the front and back of the butterfly flap.

The flap did not seem to be seated correctly, you could feel a crusty ridge of carbon all around the hole.

Sprayed it with carb cleaner and left for 5 minutes.

Wiped all the excess away, repeated several time until the ridge was washed away.

Had a little run around the estate, so far so good.

I intend removing it completely but it’s connected to a pipe in the left bottom corner which I couldn’t get to, it’s cold, wet and I’ve got a washing machine to repair.   :lol:

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Been on a good run, it's a lot better but not quite right.

There is a slight blip on the revs when I come to a halt, not as bad as it was.

Next job is to fully remove the throttle body and give the barrel and all the passage ways a good clean.

bring on the good weather.

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Anyone know what this is? It’s located on top of the cam cover, near the bulkhead and next to the brake servo.

It’s ticking like crazy, similar to a ticking fuel injector, that’s initially what I thought the noise was.

 

C676EFD5-4CD5-4850-A987-2342D095B456.jpeg

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It's the high pressure fuel pump for the direct injection.

Similarly, mine makes quite a loud ticking noise - particularly noticeable when the engine cover is removed.

Have you tried using a good quality fuel injection cleaner additive in your petrol? It might be worth trying with regard to your lumpy idle.

Declan.

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1 hour ago, Beamish said:

It's the high pressure fuel pump for the direct injection.

Similarly, mine makes quite a loud ticking noise - particularly noticeable when the engine cover is removed.

Have you tried using a good quality fuel injection cleaner additive in your petrol? It might be worth trying with regard to your lumpy idle.

Declan.

Cheers Declan, I’ve removed all my engine covers and as you say it’s very noticeable.

I’m on with an injector cleaning regime at the moment.

I just cannot find a solution to this issue, no codes, no leaking vacuum pipes, that I can see.

My friendly garage have pointed me in several directions and I’ve checked each an every possible solution they’ve given me, still no solution.

Hey ho, forever onwards.

 

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