Ideal Idle

jj19902003 · Post by **jj19902003** » 23 Jun 2013, 07:56

Hey guys!

Im new to volvos and the 5 cylinder world all together, so im not sure what the ideal idle should be on these cars. I have a 97 850glt auto. I idle with the needle right below the 1k mark, so probably like 900 rpms or so, but it does feel a little rough. I can feel it a little more than i think i should be able to in my seat. I am fighting a vacuum leak right now(evap system small leak), but i believe i found it yesterday while trying to inspect the J hose on top of the charcoal canister. i found a random vacuum line unplugged that was located somewhere underneath the airbox, so i plugged it back in where it came off. I cleared the cel codes by unhooking the battery, took it on several test drives and the cel is still off.

Kinda getting off topic, sorry. Can yall tell me how that idle sounds?

Post by **abscate** » 23 Jun 2013, 10:21

When things are right - they purr like kittens - no vibration whatsoever on my 1999.

Motor mounts can be vibration culprits, vacuum leaks and dirty Idle Air Control Valve (IAC) are also things to look for.

The IAC is used in 1998 model year and earlier in North American Markets - with 1999 on and Electronic Throttle Body (ETB) this is no longer used.

jj19902003 · Post by **jj19902003** » 23 Jun 2013, 10:27

abscate wrote:When things are right - they purr like kittens - no vibration whatsoever on my 1999.

Motor mounts can be vibration culprits, vacuum leaks and dirty Idle Air Control Valve (IAC) are also things to look for.

The IAC is used in 1998 model year and earlier in North American Markets - with 1999 on and Electronic Throttle Body (ETB) this is no longer used.

Again, Abscate, Thank you! I was reading earlier about the idle air control valve, but first i need to order two new hoses and clamps that are attached to both sides of it as they are rock hard

I also know i need new bushings for the top motor stabilizer thats hooked to the firewall, sadly looks like the last owner took the old bushings out and wrapped a crap load of electrical tape around them before putting them back in...

Post by **mikealder** » 23 Jun 2013, 10:41

It should idle at 850 RPM if the top mount is shot get a replacement, you can either re-bush the existing top mount or just buy a complete new top mount including bracket with the new square shaped bush pre-fitted which makes swapping the shot mount out much easier and quicker - Mike

Post by **misha** » 23 Jun 2013, 18:35

mikealder wrote:It should idle at 850 RPM...

If it's n/a the idle speed of 900 rpm is correct.

The idle speed of 850 rpm is correct for high pressure turbo engines(t5,t5r).

I'm not sure about what idle rpm on low pressure turbo(LPT on GLT) should be,but since it isn't a real turbo,i guess that idle rpm should be like on n/a models.

Post by **abscate** » 23 Jun 2013, 18:47

...and the HPT does say "THwop THwop THwop " at idle to let the rest of the world know you are cool

Post by **E Showell** » 23 Jun 2013, 21:28

I've got a '98 n/a w/ replacement engine that idles at 840 per Torque android app and a cheap ELM 327.

Post by **jblackburn** » 23 Jun 2013, 22:00

Anywhere from 850-900 is correct.

Keep in mind that a 5-cylinder won't idle as smoothly as a V6. Especially with the cams these engines have.

The idle/engine note from these 5-cylinders is very, very distinctive. I can still pick one out without even seeing it.

Never mind the smoke.