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Rough idle when heated up - V70 T5 SOLVED

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pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Rough idle when heated up - V70 T5 SOLVED

Post by pdavis »

Hi everyone, I have been browsing the forum today for several hours and performed quite a few searches but couldn't find anything that fits the problem I am having :(
First of all, this looks like a great, friendly knowledgable place and I wish I had joined earlier instead of struggling and trying to follow the Haynes manual.
Hope you can help with the following (sorry it will be rather long but don't want to omit something that might be relevant).
About 2 years ago, after a major service (approx 110K) I noticed that the idle was a little odd and seemed to hunt slightly on occasions. Over the last 2 years the problem has got worse to the point where the idle dips to about 500 and jumps up to 1000 very violently and quickly, making the lights flash (rather embarrassing at traffic lights). This happens all the time now, was intermittent. More recently it misfires and belches out smoke when started from cold and won't accelerate smoothly until warmed up. If I disconnect the battery and leave it for 20 mins the cold start problem goes away for about 5 days and then returns (weird).
Today I started the process of going about cleaning the ETM but due to bad weather had to abandon the task and reassemble the car. Going to try again tomorrow weather permitting.
I did notice that the intercooler hoses, both top and bottom have an oil residue it them, the lower one worst of all. Not sure if the 2 are linked in some way. I have replaced the MAF but no difference, also repaired an oil leak on the crank case, which turned out to be a loose bolt (2nd to last one I checked) which filled the top of the engine with oil and resulted in lots of oil on the floor. This is all cleaned up and no longer leaking, not sure if this could account for the oil in the air system or not??
If anyone else has had this idle problem and has any ideas how to fix the problem then please let me know.
Many thanks in advance!! :) Regards Paul.
jblackburn
MVS Moderator
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Year and Model: 1998 S70 T5
Location: Alexandria, VA
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Rough idle when heated up - V70 T5 (new shape)

Post by jblackburn »

Welcome.

I think you have a bad coolant temp sensor - seems to fit the symptoms of crap running when cold.

Small amounts of oil in the intercooler hoses are normal, but it sounds like your PCV system may be clogged as well. There's a cleaning tutorial pinned at the top of this forum.
'98 S70 T5
2016 Chevy Cruze Premier


A learning experience is one of those things that says, "You know that thing you just did? Don't do that."

mercuic: Long live the tractor motor!
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

Many thanks jblackburn will order one and give it a go, most likely at the end of the month. Will post the outcome. Thanks again.
mikealder
Posts: 817
Joined: Sun Oct 25, 2009 7:41 am
Year and Model: V70 2000
Location: Blackpool
Been thanked: 7 times

Re: Rough idle when heated up - V70 T5 (new shape)

Post by mikealder »

Does the ETS caption illuminate on the dash when you turn the ignition on then extinguish when your start her up? If not it could be the bulb has blown or been removed as it should illuminate then go out. My ETM only went haywire when the engine was fully up to temp, so the fault within the ETM can be temperature related in some cases. Well worth taking it off to clean the inlet fully from both sides but if the pots are worn cleaning it will make very little difference - Mike
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

Hi Mike,

Thanks for the information.
I have never seen an ETS caption light on the dash in the 3 years I have had the car :( where abouts is it supposed to appear?

Regards Paul.
jda2000
Posts: 584
Joined: Thu Apr 01, 2010 5:22 pm
Year and Model: 04 V70 2.5T 01 V70T5
Location: Sarasota, FL

Re: Rough idle when heated up - V70 T5 (new shape)

Post by jda2000 »

2001+ don't have an ETS light on the dash. Only '99 and 2000s.
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

That would explain that then.. thanks :)
Replaced battery today as the old one was leaking and appears to be the incorrect battery for the car! Second hand car dealer trying to save a little money i guess. Fitted a nice new Bosch silver with 5 year guarantee.
The car starts much better now and the idle doesn't dip under load from A/C. Weather has been nice and warm (27c) and the car is only playing up when first started for a few seconds and then sits perfectly at 800rpm :)
If in addition to the other tasks needing doing, how would the ambient air temperature affect the issue? The warmer it is outside, with the engine up to full operating temperature the problem vanishes. I plan on doing the PCV, coolant temp sensor, and cleaning of the ETM very soon. Have a week off at the beginning of April so will attack them then.
Question is, is there a sensor or component that would cause this problem when the ambient temperature is cool/cold??
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

Had a auto mechanic out today who was recommended by my father and the problem has been narrowed down to a possible air leak from the intercooler or hoses, but without spending longer an exact diagnosis not made. All the values are as they should be from all sensors etc so at least we have some idea where the problem may be. Going to get a new set of hoses leading to and from the intercooler and hope for the best, if no improvement after this work is done then will call the chap out again for a longer and more expensive investigation. Will post the results as and when. Thanks for your help to those who posted :)
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

ETM cleaned yesterday, have small hands which turned out to be a blessing for a change!! After 40 mins scrubbing with a toothbrush and used a whole can of carb cleaner, problem completely resolved :) lots of hard gunk out of the way and the car runs silky smooth and performed better than it ever has since I have owned it! Well worth doing and not too difficult, easy to get to when the fan assembly removed. Feeling pretty happy and relieved that £15 worth of stuff (new gasket and can of cleaner) has had such an amazing result!! :)
pdavis
Posts: 9
Joined: Fri Mar 16, 2012 11:46 am
Year and Model: V70 T5 2000
Location: UK

Re: Rough idle when heated up - V70 T5 (new shape)

Post by pdavis »

As it's been a couple of weeks just thought I would put in a final update :) Car still running fine and mpg improved from average of 19 to 23 :D Had lots of changes in the weather and still running smooth :D
Do I need to close this thread or mark it as solved? And if so how??
Thanks

Paul.
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