[RainyS60R]

Anyone else experience an occaisional backfire while shifting?

This is odd problem #2 for my car. For the past 5-10K miles or so, I have been hearing a muffled backfire-like sound while shifting. It doesn't happen all the time, maybe 5 to 10 times in a typical day (~50 miles). The dealer, as expected, pleads ignorance every time I broach the subject. There is no fault code to accompany the noise and I haven't noticed any other performance issues related to this. They said they updated the software on the car, but the problem continues.

The backfire doesn't appear to be RPM or temperature dependent. It's completely random and seems to have to do with the load being removed from the engine.

Any ideas?

- Tryg

 

[R Kelly]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

It's not a backfire (which is detonation in the engine).

The "pop" is unburned fuel exiting the tailpipe and combusting when it comes in contact with oxygen. Normal for our cars, especially under moderate-strong acceleration.

Be happy yours does it, some people have a hard time getting the "pop".

 

[RainyS60R]

Re: Anyone else experience an occaisional backfire while shifting? ("R" Kelly)

Hmmm.... unburned fuel exiting through the exaust system. Are you sure that's a good thing? Won't my cat, sensors, etc suffer damage as a result? I don't have to be racing the engine to hear the pop. It has no common cause so far as I can tell.

Don't get me wrong. I'm all for personality, but at over $40K this does strike me as a tad unrefined. The "R" does stand for refinement, right?

- Tryg

 

[R Kelly]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

Quote, originally posted by RainyS60R »

It has no common cause so far as I can tell.

Depending on how quickly I shift and get back on the gas, I can control whether I get pops or not. Try varying your shift technique.

Do any GT owners get pops?

 

[willyjp]

Re: Anyone else experience an occaisional backfire while shifting? ("R" Kelly)

My V70R MT started doing it noticeably at about 5k mi.. Before that I'd read about it on this forum and wondered what people were talking about.

It is MUCH more noticeable (and sporty) during warm up. On winter mornings I start cold, back out of my garage and pretty much coast down hill about 750' to the paved road. I stop, get out to pick up my newspaper off the driveway and then usually pull out smartly with about 1/2 throttle
but shift up to 2nd. rather short (3000-3500rpm ). This never fails to produce some very noticeable popping and burbling from the exhaust. http://********************/smile/emthup.gif Ditto on the 2 to 3 shift, but above that either it doesn't happen or I don't hear it.

I really kind of like it. Reminds me of several old British cars I have known (Jags and Healys--I think SU dashpots had characteristics that tended to produce that rich surge on sudden throttle closing, but I'm not sure if that's the explanation). It's much less likely once I'm fully warmed up, but if I try, I can often produce it by using a lot of throttle but shifting up at mid-range revs rather than winding it out.

Definitely adds a sporty touch to the car. Now if it also had an atomizer that sprayed out the aroma of hot Castrol R!! But I guess that'd be too much like the old days!!!

 

[Johann]

Re: Anyone else experience an occaisional backfire while shifting? (willyjp)

The V70R had a "Pop", the S60R more a "Pang". Funny thing with the S60R is that when cold it pangs in sync with the shifter. During a 2nd-->3rd gear shift I can hear a pang when the shifter goes out the 2nd gear slot and again hear a pang when it goes in the 3rd gear slot.

 

[e1618978]

Re: Anyone else experience an occaisional backfire while shifting? (Johann)

I liked the pop initially, now I am tired of it. Hopefully the 6spd GT does not have a shift pattern that causes it.

 

[Needsdecaf]

Re: Anyone else experience an occaisional backfire while shifting? ("R" Kelly)

Quote, originally posted by "R" Kelly »

Do any GT owners get pops?

I have heard it once or twice in 8,000 miles of ownership. Only when driving really hard.

 

[LTA]

Re: Anyone else experience an occaisional backfire while shifting? ("R" Kelly)

Quote, originally posted by "R" Kelly »

It's not a backfire (which is detonation in the engine). The "pop" is unburned fuel exiting the tailpipe and combusting when it comes in contact with oxygen. Normal for our cars, especially under moderate-strong acceleration. Be happy yours does it, some people have a hard time getting the "pop".

"R" Kelly,

Most people I know (lay-people and auto mechanics) don't call detonation "backfire", they call it "ping". Those same people DO use the term "backfire" for the pop sound coming from exhaust (which you could say is detonation in the exhaust system somewhere).

Think about it, it make sense, the sound comes from the "back" and sometimes you'll even see "fire", hence the term "backfire", no?

Yeah, it just symantecs but let get it right.

LTA

 

[Wayne T5]

Re: Anyone else experience an occaisional backfire while shifting? (LTA)

I learned to drive stick on a Jimmy C-3500 dump truck that would backfire when it wasn't tuned right and when you would let off the gas very quickly before shifting. The truck actually had a spark arrestor in the exhaust tip that eventually got blown out from too much backfiring. I used to love looking in the side view mirror to see the flame...

In our R's I actually think it was designed to do this, lol.

 

[geoguy]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

My car makes these pops (someone called them "fuel puffs") mostly when cold, during the first mile or so of driving. I can usually prevent them by not quickly releasing the gas pedal when shifting.

I don't like them . . . seems undignified for an otherwise classy car, & I'm sure they don't do the exhaust system any good. Engine cylinders were designed to contain that type of explosion . . . cat & exhaust were not.

Dealer says they "are a trait of the R", but I think it is simply a poor design that is admitting a too-rich fuel mixture at the wrong time.

- Mark

 

[Johann]

Re: Anyone else experience an occaisional backfire while shifting? (LTA)

A backfire is when mixture ignites "back" into the intake manifold, outside the cylinder.
Often part or the whole manifold will come off..

 

[JARMO]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

It's a fuel-puff (coz of a too rich mixture and it ignites in the exhaust...no harm to any parts it causes so don't worry).

Mine "puff's " even if I floor in neutral, lift it rapidly and then floor it again http://********************/smile/emlove.gif (but I never complained of the hp

) .... and during driving and shifting it sounds like a "double shotgun" thus "BANG-BANG"

 

[kr900]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

My '04 V70R consistently does the same thing, usually noticed only on the 1-2 shift.

After reading on swedespeed and talking to the dealer (Sandberg) I've learned that it is considered a "feature" of the R rather than a flaw.

 

[Mash]

Re: Anyone else experience an occaisional backfire while shifting? (kr900)

I get the POP every time I shift at higher rpm's/ I LOVE IT!!!!!!

 

[Mash]

Re: Anyone else experience an occaisional backfire while shifting? (geoguy)

LTA... you will find out soon enough that KELLY knows what he is talking about. To correct him the way you did and be wrong at the same time will only delay you from getting help from us in the future. Be more diplomatic with your approach and responses The end result will be much more helpfull for you. These guys have helped me a ton......as for guys that want to correct the experts in this forum.....well......they don't get that much help. IMHO http://********************/smile/emthup.gif

 

[JCviggen]

Yeah, doesnt harm anything. Sort of surprising they do it even on the stock exhaust, but turbo cars have a tendency to.

Other volvos can do it too

 

[willyjp]

Re: (JCviggen)

A little popping off on throttle closure was the rule with carburettors (and maybe especially with SU's as I said above) including Volvo 4's. Those who started driving since emission controls, fuel injection and lean,lean,lean running aren't used to it.

But if lean, clean burning is not an issue, it still happens. I noticed the AMLMS Audi's were shooting flames out their side pipes back past their rear wheels while braking for the chicane at the end of the main straight when I saw them run in Portland a couple of years ago.

 

[lm2lg]

Re: Anyone else experience an occaisional backfire while shifting? ("R" Kelly)

Quote, originally posted by "R" Kelly »

Do any GT owners get pops?

i can get my car to do it if i shift at 6200 to 7000 rpm's when i let off the gas in when shifting, but it wont do it by its self

 

[SilverS60RNYC]

Re: Anyone else experience an occaisional backfire while shifting? (RainyS60R)

Quote, originally posted by RainyS60R »

Hmmm.... unburned fuel exiting through the exaust system. Are you sure that's a good thing? Won't my cat, sensors, etc suffer damage as a result? I don't have to be racing the engine to hear the pop. It has no common cause so far as I can tell. Don't get me wrong. I'm all for personality, but at over $40K this does strike me as a tad unrefined. The "R" does stand for refinement, right? - Tryg

volvo came out with a statement to dealers that this was a feature programmed into the ecu to increase the sporty nature of the car. or something like that...
which sounds more like to me
"Its a feature, not a bug"

either way, its normal.