engine stumble under light throttle, stalls at idle Topic is solved

Dr. Mo · Post by **Dr. Mo** » 17 Aug 2016, 14:38

My 1999 S70 with 115,000 miles will occasionally experience engine stumble under light throttle and will stall at idle occasionally. The check engine light does not come on. The Volvo dealer was not able to replicate.

Post by **Ozark Lee** » 17 Aug 2016, 22:25

What can you tell us about the throttle module? White Sticker, Yellow Sticker, or a full blown Xemodex modification?

On a '99 or 2000 with those symptoms the throttle module is always a suspect but a bad or dirty MAF sensor can do the same thing. The throttle module will typically trigger the ETS light at the drop of a hat but not always if it is just on the edge.

Is this a turbo or non turbo? If it is non turbo it is easy to get to the throttle module and clean it with carb cleaner, with a turbo it is tougher to get it out due to the way it is installed. If you do clean it be careful not to drown it, especially around the shaft that the butterfly is mounted on since the carb cleaner can actually seep into the sensors that are mounted on the sides and make the problems worse instead of better.

...Lee

Dr. Mo · Post by **Dr. Mo** » 19 Aug 2016, 13:20

Thank you for your response. This is a non turbo. Is the throttle module bolted to the intake manifold? If so, it has a small round white sticker. Is the MAF sensor attached to the air filter housing? Can it be cleaned, and does the throttle module need to be removed to be cleaned per your comments? Thank you again.

Post by **Ozark Lee** » 19 Aug 2016, 13:57

It should be removed before you try to clean it or the cleaner will build up in the intake manifold. The sticker is usually rectangular and pretty good sized. If it is a white sticker version they are trouble. Volvo upgraded them to a different version that has a Yellow colored sticker several years ago and some of those exchanges were made under a recall of sorts. I'm not sure if it ever was a full blown recall and I don't know how long they made it available. It would be worth a call to a local dealership with your VIN number to see the status of your car. Both of my ETM cars already had the Yellow sticker versions when I bought them so I never went through the process.

Even the yellow sticker modules can cause trouble and the real fix is to install new position sensors that are made by Sacer. Xemodex does the retrofits for sure and others may as well.

Often a good cleaning will help a lot so I would try that first. On a non turbo it is pretty easy to get the module off.

...Lee

Dr. Mo · Post by **Dr. Mo** » 19 Aug 2016, 14:34

Lee,
Thank you again. I will try the cleanings first.

Post by **abscate** » 20 Aug 2016, 04:29

Dr Mo...When was the last time the coils and spark plugs were changed? These cars can run 100k miles on these at which point intermittent stuff shows up. You usually get an ETS light when the throttle body acts up.

Pulling the coils (5) and plugs (also 5) Is An easy DIY and a picture of the plugs tells a lot about the engine condition.

Dr. Mo · Post by **Dr. Mo** » 30 Aug 2016, 14:15

Ozark Lee wrote:What can you tell us about the throttle module? White Sticker, Yellow Sticker, or a full blown Xemodex modification?

On a '99 or 2000 with those symptoms the throttle module is always a suspect but a bad or dirty MAF sensor can do the same thing. The throttle module will typically trigger the ETS light at the drop of a hat but not always if it is just on the edge.

Is this a turbo or non turbo? If it is non turbo it is easy to get to the throttle module and clean it with carb cleaner, with a turbo it is tougher to get it out due to the way it is installed. If you do clean it be careful not to drown it, especially around the shaft that the butterfly is mounted on since the carb cleaner can actually seep into the sensors that are mounted on the sides and make the problems worse instead of better.

...Lee

Thank you Ozark Lee. Cleaning the MAF sensor got the car running fine.
Dr. Mo