[Three_thirty_I]

Posted this on NA Engine forum, but decided to post it here too since I tend to mostly look at threads here for some reason, and I am sure many do too.

This car is driving me up the wall! LOL

Still trying to sort out a seemingly impossible to diagnose pinging/rattling noise when the engine is under load with mostly part throttle. Just had the Valvetronic motor replaced since it threw a sluggish movement code and while the throttle feel is maybe a bit better, not much difference overall and of course the pinging continues. But something I was hoping would be corrected is this tendency for the idle speed to sit at ~900 rpm on warmer days when the car has been driving for a fair bit. When starting it generally idles smoothly at around 650 - 700 rpm, but on some odd occasions as I am rolling down my driveway with my clutch in (so moving under gravity) the idle speed will climb to about 1000 rpm for a second or two then return back to normal again. Driving off and while the engine is still warming up the idle stays at normal idle speed, but after more driving after reaching operating temperature on these hotter summer days that we are having the idle speed tends to sit around ~900 rpm.

What could be causing this? MAF sensor (I did clean this earlier this year and made no difference). The other pending issue that I need to correct is the engine running temperature which seems to be lower than it should (79 - 84 degrees Celsius when warm), so after changing temperature sensors to rule them out it seems like it can only be a faulty thermostat that's not throwing any errors. And just to add, no errors to work with - the Valvetronic motor threw a code a few weeks back when my mech had the car to see what he could find regarding the pinging issue... I need to check the eccentric shaft sensor plug to see if there is any oil, but I suspect that it will be as clean as a whistle, so not sure what else to look at.

[nate5ks]

The throttle valve could be getting stuck slightly open, have you cleaned it?

[nate5ks]

And I think the rattling might be the exhaust, I think my exhaust flap is having the same issue

[Three_thirty_I]

Will have to pull the throttle body out and give it a clean, but my reason for thinking it might be something to do with the MAF is because it seems to be a heat related issue of the ambient air. Oh, the car only has 72k km on the clock, so not high mileage for the age. When I had the throttle body out last year in order to replace the DISA flaps (another waste of money) it was pretty clean, but I am sure it is worth giving it a proper clean and go from there.

The noise is more mechanical to me than pinging, but have already ruled out the exhaust flap by unplugging it and driving for a few weeks, noise persisted, and anyway, doesn't sound like it's coming from the rear of the car.

Have to get to the bottom of this!!

[Three_thirty_I]

So just an update.

Last night I decided to get a few things done:

1.) I pulled the Vanos solenoids and gave them a thorough clean and soak in some unleaded petrol (once again, the exhaust side was the dirtier of the two). Once the petrol had dried off I dipped them both in some fresh engine oil (same as what is in the engine) and refitted them but swapped them around.

2.) Removed the air filter box and intake boots as well as the throttle body. Cleaned the throttle body with some carb cleaner and swapped the O-ring seal around as well as cleaning. Cleaned the MAF with LiquiMoly MAF cleaner and allowed it to dry while I continued with the other tasks.

3.) Removed the engine covers so that I could inspect the Eccentric shaft sensor plug for traces of oil, spotless and bone dry as well as the gasket around it.

Everything put back together, I took the car for a drive this afternoon and from start up the engine ran as normal, so everything done last night was done right at least. We are having some odd wet summer weather over here, so not really all the hot at the moment - will have to see what it does when we have hot weather again. But the pinging was almost unnoticeable, so again, need to see how it goes with more driving.

[GoRomeo]

Originally Posted by Three_thirty_I

So just an update.

Last night I decided to get a few things done:

1.) I pulled the Vanos solenoids and gave them a thorough clean and soak in some unleaded petrol (once again, the exhaust side was the dirtier of the two). Once the petrol had dried off I dipped them both in some fresh engine oil (same as what is in the engine) and refitted them but swapped them around.

2.) Removed the air filter box and intake boots as well as the throttle body. Cleaned the throttle body with some carb cleaner and swapped the O-ring seal around as well as cleaning. Cleaned the MAF with LiquiMoly MAF cleaner and allowed it to dry while I continued with the other tasks.

3.) Removed the engine covers so that I could inspect the Eccentric shaft sensor plug for traces of oil, spotless and bone dry as well as the gasket around it.

Everything put back together, I took the car for a drive this afternoon and from start up the engine ran as normal, so everything done last night was done right at least. We are having some odd wet summer weather over here, so not really all the hot at the moment - will have to see what it does when we have hot weather again. But the pinging was almost unnoticeable, so again, need to see how it goes with more driving.

Just couriuos to know if this fixed your "higher than normal idle" I isometimes experience this as well. I did swapped my vanos and cleaned my MAF sensor about 3 years ago and seemex like it helped. Im planning to do this again but wanted to cheeck with you.

[Meeni]

I bet on vanos solenoids or related issues. But its not the only possibility. Performance and noise symptoms match.

[GoRomeo]

Originally Posted by Meeni

I bet on vanos solenoids or related issues. But its not the only possibility. Performance and noise symptoms match.

I have same symtops as OP going on for a while. No big deal but still bothers me to see higher than normal idle on hot days like OP mentions. I did clean my vanos about 3 yrs ago aoomg with air filter. I guess i will clean them again if not reaplace them.

Anyone else having this issue?

[Three_thirty_I]

I am waiting for the warmer weather to return, but am hoping that once I replace the check valves that I bought ages ago and give the solenoids another clean it will make an improvement. If the improvement is short lived, then I am likely to just bite the bullet and replace the solenoids.