'04 XC70 misfire, sluggish acceleration; no codes

[Not Boxy]

Good afternoon!

Car has 100K; trouble started at 90K back in February. Misfire in 3rd and 4th gear. Sluggish acceleration. Car performs better when gas is punched. *Very* intermittent soft "surging" and hesitation when shifting. Eventual transmission problems. All service, general maintenance, fuel induction/filters/plugs/engine mounts/control arms/belts/etc. meticulously replaced for life of car.

Replaced all (5) coils. Transmission started hard shifting with minor "clunk" (hope that's descriptive enough!) New valve body and rebuilt transmission. Trans builder very, very reputable. Did dealer reset of transmission, replaced valve sensor and replaced fuel filter.

Sadly, car *still* has misfire/sluggish acceleration, and shifting problems. I *almost* want to guess that the "learning" part of the transmission has failed. Is that possible? I've been to the dealer, etc. and everyone is stumped. Luckily, I have an extended warranty. I adore this car and dearly want it to hit 200K. Any clues?

[RockitShip]

Pull plugs, note condition (and then possibly replace, but note condition for each... write down if you have to).
Check and/or replace all vacuum lines.
Also, get car scanned for codes, etc., from Autozone/volvo dealer/indie, whatever.
You could also briefly disconnect the MAFS, and see if it changes condition.

Report back.

[Not Boxy]

Hello Rockit - thank you very much. Plugs were replaced last year; but will follow advice. Am working with a dealership - no codes; very frustrating - and will follow through with MAF and vacuum lines. They've scheduled me for this Tuesday.

Btw, I don't mean to sound too eccentric - but as several after market parts (lower control arms/rotors) have failed ver-y quickly in this car, I wonder if it could be the same with plugs.

[Not Boxy]

Just reporting back. Still f*cked (pardon - but this has been going on since February) on the misfire/sluggish acceleration. Replaced plugs with Volvo plugs, replaced left CV axle. Had wheels balanced.

Still getting shudder/misfire in 3rd or 4th gear.
Still getting sluggish acceleration.

Lower control arms (replaced) are going back in for an adjustment. (Which should solve giant shudder at idle.)

I am reporting back; but am losing hope. :mad:

No codes; still no codes.

[Astro14]

Well...I am really not sure how to advise you on this...you bring up several disparate, unrelated issues...how did you draw the conclusions in this thread?

So...Lower control arms will have nothing, repeat, nothing to do with shaking at idle...they have to do with handling and safety. If they needed to be done, they needed to be done (they're common at abou this age). Bad motor mounts might cause the feel of shaking when they allow more vibration to be transmitted to the frame - you need to have them checked as well, they fail in about 100K.

CV joints/axle has nothing to do with acceleration or idle...it will click in turns when it starts to wear out, and you want to replace it before it fails and you're stranded.

If there are no codes, then the engine is not "missing". That's when a cylinder fails to fire....and it leads to a very rough running engine. If you've got 2 cylinders misfiring, it won't run at all....and if you've got a misfire, it often starts under load (most difficult for plugs to fire) and eventually get worse (misfire at idle). Sometimes, it just starts and happens under all conditions. Replacing the plugs or coils can fix a miss, but why did you replace parts that were not conclusively failing? A guess?

Sluggish acceleration, poor response, the symptoms you describe have little to do with the transmission. It is more likely that you have a failing throttle body (common on earlier models, not on yours) or your Mass Air Flow meter (MAF) is dirty or failed. The MAF generally won't throw a code...and it's easy to clean yourself.

First, go get a can of MAF cleaner (NOT carb cleaner, get the right stuff...). follow the directions in the resources thread and clean it. with 100k on the car, I know it's going to be dirty (yes, I've done this to our XC, yes it was dirty, yes it ran much better afterwards and the cleaner is only $7 at your local parts store...well worth doing...)

Next, you say that the "learning" part of the trans rebuild failed. I doubt that. More likely that it was never done. You need VADIS to put the car in adapt mode...doubt that the rebuilder could actually accomplish that. See the valve body replacement notes in the resources section, go to the end, read through the notes. The adapt procedure is complex. I would recommend that you simply take it to the dealer, have them do the drive cycle.

And stop guessing...just because other cars have had a problem, doesn't mean that your car has that same particular problem. Bad diagnosis leads to wasted time, money and effort....and leaves you frustrated. The car will get to 200K, but keep in mind that while doing all the preventive (scheduled) maintenance will help it last, it does not preclude component failure (unscheduled maintenance)....it will need occasional repair in addition to being maintained.

[Not Boxy]

Hi Astro,

The reason all these nice things keep getting replaced is because they are under warranty, and the dealership likes to replace everything they can get their (billing) paws on and say "we fixed it!"

I'll read through the trans notes. But after rebuild, the dealership reset it for me. I'll show them to the builder (it's a friend of mine's shop - Volvo won't rebuild) perhaps there's something he missed. It's an Asian Warner that he's worked on before in other cars, but it's always good to check.

I mentioned the MAF ten days ago... *perhaps* they didn't check it; just found (yet another) part they could replace and charge my warranty company for.

There *is* a misfire - even the service manager has felt it (at dealership.)

Okay: (2) more clues:
1). It definitely works worse in damp/rainy weather. More shudder/ heavier vibration at idle (which goes away when it's put in park)
2). My tach is jumping on deacceleration (sp) - very slightly - mostly in the (2) lowest gears.

Btw - I did have a bad shudder when I first bought it, in idle. They replaced the top engine mount, and it went away. :confused:

[Astro14]

Not Boxy - we're talking past each other here because your understanding of words like "shudder" "misfire" "reset" is different from mine. You also failed to mention that the dealer was doing all this work under a warranty.

Let's start with the trans - a rebuilt trans has to be adapted to the car. This requires the TCM to be placed in adapt mode by VADIS, then the car has to be DRIVEN while in adapt mode, so that the computer can measure the shift parameters and set the operating values for the 3 major solenoids (and 5 shift solenoids) in the trans valve body. It's not a "reset". Without this complete procedure, including about 45 minutes of driving the car - the trans will NOT shift correctly.

Shudder at idle. While Webster's may define it as vibration, (or quaking in fear) - in a car, it usually means a short, rough feeling in the driveline, usually as a result of faulty transmission shifting. So, a rough idle can be caused by 2 things. 1st is the engine runing poorly, or 2nd, the engine mounts, which are designed to absorb vibration, are worn out, and the engine is sitting on the subframe and transmitting more vibration to the passenger compartment...if they replaced the mounts, then it was likely the latter.

Poor running, including shift bump, rough idle and the other things you describe. This can have a multitude of causes. The MAF is common, and can cause the symptoms you describe. If you have not cleaned the MAF yourself, then this isn't a DIY discussion (cleaning the MAF requires a screwdriver and a can of cleaner...)

You're going to have to work with the dealer. But when you go to the dealer, or any mechanic, it's like going to the doctor - stick to the symptoms and let them make the diagnosis. Don't tell them how to fix it, tell them how the car is operating. You wouldn't walk into the doctor and say, "I have Hashimoto's Thyroiditis" which requires specific chemical and antigen tests to determine. You walk in and say, "I feel tired, I am gaining weight, I feel run down" and let him refer you to the endocrinologist, who performs the blood tests and concludes that you have Hashimoto's...

[Not Boxy]

Dear Astro,

You are WONDERFUL. Thank you *so* much. I've been wrangling with the dealership since February, and, I suspect, a slightly drunk master tech. ;)
Anyway, thank you for the VADIS, DRIVEN thing. The dealership didn't catch on to that, and certainly didn't tell me, and I will bring it to their attention.

At Firestone yesterday, they discovered the bearings in the control arms were shot. Not sure if bearings are part of the '04 XC70 control arms, but I will do my research before heading back to the dealership for them to fix it (as they replaced them recently.) I also have (2) (rear?) engine mounts to replace, apparently...

I will check on the MAF. I had an air filter replaced (not sure if it's the same thing - all these damn engines look like Japanese lunch boxes - I have some vintage 60's Volvos - B18's and B20's- and can *at least* identify the parts!) by a non Volvo part; perhaps it was the MAF. Anyway, I am on it.

The "surging" in the gas line(?) has become very apparent the past few days. Hopefully, they can figure it out. :rolleyes:

I can't thank you enough. I've definitely fallen through the cracks in resolving these few issues... as a female, all of these things ("I dunno... it, you know: like, kinda surges when I hit third gear sorta") are particularly frustrating to get resolved, especially with no codes!

I'll let you know how it goes. Hope you and yours are safe and happy... [thumbup]
not boxy

[Willy]

I had an air filter replaced (not sure if it's the same thing -
The M(ass) A(ir) F(low) sensor sites right behind the inlet air filter housing.
The sensor itself is secured in the housing by 5-point security torx screws.
Willy

[Ars Gladius]

For the location of the MAF sensor see first two attached images.

As Willy mentioned, you will need a special screwdriver, a T-25 5-Point Tamper Proof Torx driver (Regular Torx and Tamper Proof Torx have 6-points). These are not commonly available, but your dealer will have the correct tools, however they will want to do it.

If you want to DYI, it may be easier to remove the housing instead of just the sensor, see third to fifth attached images.

[Not Boxy]

Thanks very much, Gladius/Willy.
Poor little thing is going into the shop (again) later this week.

I am so nuts about this car (it reminds me of my old 245) and want to keep it on the road for another 100K.

Thank you all again for your time, effort, and consideration. It is greatly appreciated.

[ironmike]

Thanks very much, Gladius/Willy.
Poor little thing is going into the shop (again) later this week.

I am so nuts about this car (it reminds me of my old 245) and want to keep it on the road for another 100K.

Thank you all again for your time, effort, and consideration. It is greatly appreciated.

Well?

[Allen]

Bad fuel/water.

[Astro14]

If you want to replace the MAF, then I would just order it here: http://www.fcpeuro.com/products/volvo-air-mass-meter-c70-s60-s80-v70-xc70-xc90-0280218088

No fancy tools needed, and it's half of what you would pay at the dealer...simple...