Our 99 V70 T5M with 49K miles on it has started "surging" when driving the car at 60+mph. It is very subtle and it just feels like you are driving on a windy day. The engine is not misfiring and no codes are stored in the computer. Our dealer here in central Maryland can not figure out what is wrong with it. Any thoughts on the problem?

Thanks,

Rodger

Have your dealer look into VEN for SBs and/or tech-net notes regarding possible software upgrades that "might" address your cars symptom as your complaint sounds like something I've previously read about in there. If nothing is found, ask them if they'd call tech line and see if they have any ideas (assuming that they prehaps didn't already do all that?).

If it's not software related, then I'd guess at a bad MAF sensor (at least worth a try IMHO).

The ETS (Electronic Throttle System) light went off this weekend on a trip and the surging became even more pronounced. Then the next day on the way home it when out. I am guessing the car will now give a code to the dealer's computor and tell them what needs to be fixed. I bet it is a bad sensor. A MAF sensor?

Rodger

I would like to hear what your mechanic does to the car and if the fix works. My 850 (and several other 850 owners posting here) seem to have a similar problem with surging between 30mph and 50mph. Others report fixing this with a new throttle position sensor. I am picking up my new TPS tomarrow.

Probably a bad throttle motor, you'll know soon enough as yes, the Vadis PC is needed to get the codes.

John O wrote:

> If it's not software related, then I'd guess at a bad MAF sensor (at

> least worth a try IMHO).

Thanks for the help. They did replace the ECC Temp sensor and that did not help the surging, but it did stop the recirc on and AC off buttons from flashing on startup. What is a MAF sensor?

Rodger

This may be a dumb idea, but could it be something as simple as an accessory cycling on and off? You're not going to be using the A/C at this time of year in Maryland, but maybe there's something else going on in there? Perhaps something with a worn bearings taking extra power off the engine through the belt? I know this is a long shot, but I suggest it because my 740, (with a far less powerful engine), sometimes "surges" mildly, even with the A/C off. I was told that this is normal because the A/C compressor was not the only thing under there that runs in cycles, but I can't remember what else. (I could have been misinformed here). Does anybody else think something like that could do it?

Tim

I have the same problem with my 850 T5, except the engine does not exactly surge, i.e. there is no increase or decrease in engine revs or any noticable decrease/increase on the speedo but you can sense a slight holding back, this repeats every couple of seconds, its a weird feeling. Still not found out what it is dispite putting the car on a dyno and expensive engine diagnostic equipment, things to check are:- warped brake discs (rotors), ensure traction control is functioning okay. If yours is surging even at idle then it could be something like a faulty temerature sender and hence extra fuel being supplied because the engine management system is receiving incorrect information. Hope this may be of some use.

Regards

Dave Leigh

I have just begun to notice this same condition. '99 V70 - 59,000 miles. Earlier, under warranty, had a more noticable problem with surging while using cruise control at speeds under 60. The dealer put in a module after first trying a software fix. The present problem is different, and I hope it can be fixed.

Dave-

Looks like this is quite a mystery. I don't know about Roger, but what you describe sounds a lot like what I experience with my 740. The revs stay where they should be, but the engine's power seems to fluctuate slightly. (I've never noticed this happening while driving my dad's car, but I don't drive it terribly often). I know for a fact that I do have warped front rotors, (to be fixed in early March), but those cause a rapid pulsation in the steering wheel and the break pedal. I doubt that's the cause of what we're talking about here. Then again, you just never know. As far as I'm concerned, it's just a quirk of my car that I live with because it doesn't cause me much grief. To be honest, I haven't even noticed it happening lately and I've been doing quite a bit of highway driving between school and home (NY to eastern MA). I'd still really like to know why it happens, though. I'll keep thinking about it. Good luck to all in finding an answer.