My car "surges" at 60mpg

redslvr67 · Post by **redslvr67** » 22 Oct 2009, 20:35

Was looking for help with my car surging. When I am cruising at 60mph my rpm's go up 200-300 rpm and then drops back to normal about every 2-3 seconds. It only does this when I am at 60mph. Can anyone help me figure this out. Thanks in advance

Post by **dcarlson12** » 23 Oct 2009, 11:36

Hope others chime in if they think otherwise, but sounds like ETM going bad to me. i.e. bad spot on the potentiometer

Post by **mvsuzr** » 01 Nov 2009, 21:03

I agree.

Check out Don's ETM Room on this forum.

Excellent info.

I had idle/surge problems, replaced my ETM with an XeModex unit, no problems since then.

gunner · Post by **gunner** » 08 Feb 2010, 11:11

I have this problem as well , where can this part be had? would you have part#

Post by **vegasjetskier** » 08 Feb 2010, 11:21

gunner wrote:I have this problem as well , where can this part be had? would you have part#

See this thread: https://www.matthewsvolvosite.com/forums ... =12&t=5694

You also might want to look through the "Don's ETM Room" forum.

Post by **vegasjetskier** » 08 Feb 2010, 11:23

redslvr67 wrote:Was looking for help with my car surging. When I am cruising at 60mph my rpm's go up 200-300 rpm and then drops back to normal about every 2-3 seconds. It only does this when I am at 60mph. Can anyone help me figure this out. Thanks in advance

In addition to the ETM, I suspect that the torque converter might be unlocking and then locking up again. Have you changed the transmission fluid and filter?

mlanctot · Post by **mlanctot** » 24 May 2010, 16:35

Very interesting post. Just last week my S80T6 has developed a similar situation. Cruising at 60 an occasional 200 to 300 RPM surge or flutter. Talked to a friend how rebuilt the tranny and he said it sounds like transmission is unlocking during normal use. If I go above 60 does not appear. Going to clean the ETM, its time and monitor.

So what happened with the above thread?

Post by **boosted5cyl** » 25 May 2010, 06:46

Unlikely to be the ETM, typically the torque converter should be locked up at 60. Therefore if the ETM is causing a fluctuation of 300RPM, you should also see a relational change in roadspeed. I have noticed that the lockup is a little higher on the S80 than what I'm used to though.

People are too quick to jump on the ETM bandwagon for the S80 to be honest, I think it messes up troubleshooting jumping to that conclusion almost every time something peformance/motor related crops up. Ask yourself, "if its not the ETM, what could it be?" I not denying that the ETM isnt a common issue, but the amount of times its gets blamed when its not the issue is pretty high.

mlanctot · Post by **mlanctot** » 27 May 2010, 05:13

I agree to a point, the ETM needed to be cleaned any ways. I have found that the ETM for my car needs cleaning twice a year. I travel about 25K/yr.
A funny thing happened yesterday. I had a job in NYC, about 2.5 hrs away. It was extremely hot in CT about 95 but the A/C was short cycling and figured it needed to have the shims in the clutch adjusted. Drove there and back WITHOUT A/C. The tranny performed fine, no surge at all. I'm wondering if leaving the A/C off effected the tranny performance. In other words, without the electrical drain on the system effecting voltage fluctuations. I should note that my transmission was rebuilt last year. The shop I used I've known for 20 years and has an awesome reputation. Well last night I fixed the A/C and shall monitor how the car performs going forward.

joncott63 · Post by **joncott63** » 01 Jan 2013, 13:05

I read through the posts on this and didn't find that anyone cured the problem. Any more information out there on this issue? I was having an erratic throttle response when the engine was cold and just starting out and thought the two might be related. Cleaning the throttle body cured that the irregular throttle when cold but not the 60 mph surge, so evidently they weren't related. I'm thinking of having the tranny fluid and filter replaced. Any info would be appreciated.
Thanks!