Rough idle...

Post by **mrreilly** » 04 Oct 2006, 15:46

For a few weeks now my car's been having a sightly rough idle.
When I'm just sitting there the engine shakes a bit more that it seems it should.
And after puting in the new ignition wires the car's rpms drop close to 600 or 700 when I slow done to a stop.
I just put in new plugs and just put in the new ignition wires today. Any thoughs on what else it is.

bobsnow100 · Post by **bobsnow100** » 04 Oct 2006, 18:48

Did you gap your spark plugs? Make sure you pushed your spark plug wires down all the way also.
Also check all your vacuum lines

Tsquared · Post by **Tsquared** » 04 Oct 2006, 19:07

Rotor and cap for the distribuater. Gunked up throttle body. This would be my next two guesses if the plugs and wires are good.

What type of plugs did you use?

When did this rough idle start - before or after the new plugs, how long after the new pugs?

When was the last time the air cleaner was serviced?

How many miles on the car, turbo or NA, and what year?

Any codes or is the check engine light on?

Black850 · Post by **Black850** » 04 Oct 2006, 20:37

Don't forget to check the engine mounts too. Seems like if you were under the hood you might've seen em, but it's a problem I had.

Post by **dosbricks** » 04 Oct 2006, 20:38

Mr. T,
I have the same problem as mrreilly on our 98 S70 NA 143K. It's just a very slight intermittent shutter at idle and has been doing it for about 6 mos. So far, here is what I've done, all of which has had no effect.

1. Changed plugs (Volvo 3 electrode pre-gapped).
2. Cleaned throttle body and PCV connector and blew out vacuum Line with compressed air.
3. Checked all vacuum elbows.
4. Added $10 fuel system cleaner to a tank of gas.
5. Replaced the thermostat and temp. sensor when 116 code appeared. I thought, ah ha! this has got to be the problem. It took care of the code but didn't get rid of the shutter.
6. Removed the Idle Air Control Valve: cleaned, checked operation, checked resistance (ohms) all OK.
7. Did the "Italian tune-up".

Fuel filter was changed at 105K.
Dist. cap, rotor, and plug wires were replaced at 109K all with OEM.
Torque mount and front engine mount have been replaced.
The exhaust is dry with no raw fuel smell.

Not knowing anything else to do, I took it to a shop which didn't know any possible cause, but offered to remove and clean the injectors for $125. I declined for the moment. Should I have them cleaned? Any advice would be appreciated and might be of use to mrreilly also. Thanks.

Post by **mrreilly** » 04 Oct 2006, 21:20

Tsquared wrote:Rotor and cap for the distribuater. Gunked up throttle body. This would be my next two guesses if the plugs and wires are good.

What type of plugs did you use?
The were champion, copper cored ones. I can't quite remeber the number. I did gap them.
When did this rough idle start - before or after the new plugs, how long after the new pugs?
Before the new plugs and wires.
When was the last time the air cleaner was serviced?
If you mean the air filter. I got that about 2 months ago.
How many miles on the car, turbo or NA, and what year?
1998 S70 GLT. 151,500. Yes turbo.
Any codes or is the check engine light on?
No check engine light. Haven't had codes checked... Can autozone check the codes on my car?

Post by **mrreilly** » 04 Oct 2006, 21:23

Black850 wrote:Don't forget to check the engine mounts too. Seems like if you were under the hood you might've seen em, but it's a problem I had.

I just replaced the upper engine stabalizer bushing.
And also the lower front engine mount (under crankshaft).

Post by **mrreilly** » 04 Oct 2006, 21:25

dosbricks wrote: 1. Changed plugs (Volvo 3 electrode pre-gapped).
2. Cleaned throttle body and PCV connector and blew out vacuum Line with compressed air.
3. Checked all vacuum elbows.
4. Added $10 fuel system cleaner to a tank of gas.
5. Replaced the thermostat and temp. sensor when 116 code appeared. I thought, ah ha! this has got to be the problem. It took care of the code but didn't get rid of the shutter.
6. Removed the Idle Air Control Valve: cleaned, checked operation, checked resistance (ohms) all OK.
7. Did the "Italian tune-up".

I will check these thing out soon, just to be safe.

Peace_Frog · Post by **Peace_Frog** » 05 Oct 2006, 08:34

I'll go with Black850 and suggest checking the engine mounts. I just had my engine uppper mount replaced on my 855 (275 000 km and counting) and the improvement has been fantastic. Before, my engine would sound like a truck sitting at idle and during accelerations, now it sounds like, well like a sweet Volvo car.

Post by **dosbricks** » 05 Oct 2006, 09:27

mrreilly wrote:I just replaced the upper engine stabalizer bushing.
And also the lower front engine mount (under crankshaft).

Just like mrreilly, my upper and front mounts are good.