I have a 99 S80 T6 with about 37K Miles on it. Recently, when I floor the accelerator pedal and during this Wide Open Throttle (WOT) position, the car initially responds beautifully, the initial sensation is that the car is pulling forward very strongly then within 4-5 seconds and above 4000 RPMs seems to back down a bit, then surges up again etc. This fluctuation in power happens every 4-5 seconds as long as the car is in WOT. Although the car is very fast, the solid pinning you to the seat sensation at WOT throughout the power band is fading....now I get that initial kick in the pants followed, like I said, with a type of surging sensation every 4-5 seconds....it just doesn't pull strongly and continuously with the gas pedal floored as it used to when it was newer, if you know what I mean.

I've got a K&N filter installed, Denso Iridium Plugs...everything's working, the air filter is clean, am running Mobil 1 Trisyn in the crankcase and have had the car for a while....I use premium fuel..there's no water in the tank, I used injector cleaner, which didn't help. The car is a gem and still under warranty.

What do you guys think is happening? Is my inline fuel filter clogged or clogging? Is there a fuel filter inside the gas tank too on the intake tube that I may need to change? Are the wastegates on the turbos screwed up or in need of adjustment? Are the turbo pipes leaking boost pressure? Can I tweak anything? Anyway, if this surging has happened to anyone with an S80 what was the solution. Sorry for all the questions, but please...I would really appreciate your input out there. Thanks.

We had a similar acceleration problem on our 99. We found that the pedal ground connector was corroded. Since replacing it the problem has gone away. You may want to check that.

Vince,

I've had the same problem on my 99 S80 T6 since it was new. The dealer tried MAF & software updates. I tried new plugs. It still surges so I live with it for now.

Charlie

Actually, I had not had an opportunity to get to WOT in my 1999 S80 T6 until I was passing some trucks on a back road a couple of weeks ago. I did experience the surging you spoke of. My fuel filter is almost new.

I recently cleaned the Throttle Body to fix an idle surging/cold idle problem. My throttle response under moderate to hard acceleration (not quite WOT) has improved noticably since cleaning the TB. Next chance I have to try WOT, I'll report back.

As for the software, I have had a great deal of difficulty trying to find out from the dealer if my s/w is all up to date. When I ask, they say "Yeah, it's fine, you're all up to date", but somehow, I don't have much confidence that they really checked.

Usually cured by software. Take it to your dealer. If SW doesn't cure it, then it'll probably need a MAF sensor, also common.

Gary ahd Keefus:

Thanks guys. I appreciate the input. I'll post again after the problem is found. By the way Gary, the MAF sensor is brand new (less than a week)...the dealer changed it 'cause the old one threw a code out and illuminated the Check Engine light. It surged with the old one as it does with the new one. But I'll let the dealer check it out, clean the throttle body like keefus suggested and update the software and I'll report back to the forum once it's cured.
Thanks,
Vince

Take it back because that's what's called a "comeback". They were suppose to fix the problem, replaced a part yet obviously didn't solve your initial problem.
It's been said that cleaning the throttle unit can help in some circumstances (usually idle related) but those throttle units are not easily removed/re-installed on a T-6 and they're also known to be problematic as well.
If SW and/or cleaning the throttle unit doesn't help, a new throttle unit may also be in order.

Interested in comments regarding surging at idle and replacing throttle body. Just encountered problem on 2001 2.9. At 49K, had slight problem and dealer did software download. Now at 58K out of warranty, surging has returned with vengeance. Dealer charged $200 for diagnosis and cleaning: "Should take care of it". I didn't even make it home before "Service Engine System" came on. So I returned to Dealer who said "Well, we have to try cleaning before we talk about replacing unit--which will be an additional $830, but I can work with you a little bit." I said #$!!!!*XXX. Dealer checking with Volvo but doubts company willing to cover replacement of throttle body despite first complaint made under warranty.

1. Gary in your post you said throttle bodies "are also known to be problematic": how can I substantiate that in argument with Volvo of America?
2. Any other ideas on getting VoA to help?
3. How expensive should replacement be? (Since you guys are talking about cleaning throttle unit yourselves without removing it from car, I guess I got hosed worse than I thought this morning. I figured $200 was worth it if it would solve the problem.)
4. Is it true throttle body cannot be replaced by non-dealer because it must be 'programmed' after installation?

Any Help will be appreciated.

Gerry--the frustrated in Indiana one

I posted a procedure on Bay 13 recently in FWD Maintenance for cleaning an S80 T6 TB without removing the TB itself, worked great for me. Check it out at www.volvospeed.com.

Thanks again guys. You're the best. I'll clean the throttle body as per keefus before I take it back to the dealer. (Thanks for the link, by the way.) I don't want the dealer telling me that they have to clean the throttle body at that time, when it really needs a throttle body replacement, as per Gary's theory. These service guys at Gold Coast Volvo in Pompano Beach Florida are very nice and courteous but aren't the brightest service people I've ever encountered.....they don't even know how to rotate tires properly, however, when I do get back my car from service, it's usually shiny and clean....but still not working right or done wrong...HAHAHAHAHA. Last time I took the car in for a tire balance and rotation, a bad MAF sensor and the famous clunking noise up front...the car was there for 5 days. I got the car back and only the balance and the MAF had been changed. Everything else was either not done, not found or basically my imagination according to them. It's always a battle with these people.

I'll let you guys know. Thanks again.
Vince

Hi Vince,
I seem to have the same problem as you do. When i go WOT the kickdown comes on strong and after 2 seconds the car stops pulling (about 4000rpm) and after a couple seconds I feel it picks up again. I also have a new MAF so when I have the chance I'll take my car to the dealer and see what they can do with the software. I'll let you know what happens

Cheers

Alex

I have good news about the surging engine at WOT. I went for my 144,000 kilometer checkup yesterday and I explained to the technician how my car was outputting uneven power when i go WOT (wide open throttle). He scratched his head a little and remembered about a software download about eneven torque on heavy accleration for the S80. If I remember its download number 527.

I took the car out for a highway ride last night, all I can say is... YEEEEEEE-HAAAAA!!! I totally forgot how much this car can whoop ass! It feels and drives like new. I hope this software download will do the same for you.

Recently had similar problem w/ a 2000 S80, only at idle. The first time they replaced the MAF. Two weeks later problem started again, it would occur when blower unit was on. Symptom was that idle was too low. The paperwork they gave me says they performed a software download per Tech Note 28-35. Description is UPGRADE ECM BP, FP Number 8691303-5. Occurred at 39k miles.
This seems to have resolved the problem. /c