so my '95 960 is greedy. 13mpg generally, and while my driving is a touch spirited, it is by no means aggressive. I've tried weeks of gentle driving, keeping the tach around 1500 (when OD kicks in at around 40mph) and I got a whopping 15mpg.

So I'm (probably) running rich. My exhaust smells a bit, and the engine is a little noisy - kind of like a diesel truck engine (my motor does not diesel).

I thought that might just be motor mounts going, but it doesn't vibrate the vehicle or anything, it's just a rumbley noisy motor. Injector cleaner should make it use more fuel, not less, right? so that won't solve my problem - any ideas? I never stall or anything - if anything, I idle a bit high (sometimes as much as 1000rpm idle).

NEED ADVICE! (it's the stock i6 Bosch motor, whatever is standard in american imported Swedish built 960s)

Oh, and I'm cheap - I use 87 - would 93 get me a whole 10mpg more? (supposed to be 25/18 right? I do mostly highway miles, and the ones that aren't are around 40mph which should be the peak of fuel efficiency... right?)

HELP! (and thanks!)

 

Sounds like you have a ton of carbon buildup first of all. You need to clean the carbon out of the top of the motor. A free (but dangerous if you aren't careful) way to do that is to get a windex bottle, and fill it with clean tap water. Remove the intake boot, leaving the throttle body open to air (You MUST leave the idle control valve plumbed and plugged in - or else the engine either won't run, or wiill overrev and explode). What you're doing is lightly misting water into the throttle body with the windex bottle, keeping your hand on the throttle to keep the rev's around ~4k rpm's. I wouldn't spray directly at the TB, I'd spray it above the TB, and let it get drawn down in by the vacuum. What you're essentially doing is steam-cleaning the top end of the engine, and works just as well as any top-end chemical cleaner.

Why would you have lots of carbon you might ask? Because you're a self-admitted cheapass depriving your engine of the proper anti-knock rating. What happens is that your engine is tuned from the factory for minimum 91 octane. Running 87 allows the engine to spark knock under load, and when the knock sensors hear knock, the ecu pulls timing, causing reduced power, reduced mileage, etc. Also with this comes carbon buildup, because you aren't burning fuel anywhere near as efficiently.

You could have other issues, but this one sticks out, especially since you say the engine makes alot of noise. Sounds like spark knock to me. I would follow my advise above, and then see how it drives with proper fuel and a good cleaning. Drive it hard, VERY hard, give it lots of load with 93 octane fuel. Get it nice and hot, it's called 'an italian tune-up'. Works well for also removing carbon. You could be having a coolant temp sensor issue. Do you have any codes (CEL on??)?

 

Wow, thanks for the fast advice! I'll do that tomorrow (or asap)

No CEL, but I do have a wonky trans that I have another thread regarding that has died... sometimes the trans gets stuck in W mode, but the arrow in the dash flashes and my E and S lights flash back and forth (even though I keep it in E all the time).

I'll do the Italian cleaning on my German engine in my Swedish car, then I'll run some 93 with some octane booster perhaps - is this better than taking the throttle body off and cleaning the plates by hand?

Also, I'm not the original owner, so I have no idea what the previous owner did (I've had it almost a year now) as it was purchased from a police impound auction in Philadelphia (haha). I guess the carbon builds up in the head, not the throttle body (the accelerator does not feel gummy or sticky at all - smooth all the way to the floor) so I'll do it the described way.

Anything to do after that to get things even better? I'd love to get 30mpg in this beast ;-)

 

I wouldn't waste your money in octane booster, regular 93 will be fine. Cleaning the carbon in the combustion chambers though via the water misting is going to do what you need. Doubt you'll ever get 30, best I've ever gotten in mine is 21.4 mpg.

 

wait, firstly, is it safe to be spraying water directly into the manifold like that? (or indirectly, whatever) isn't the block made of iron....?

and if I'm doing a genuine Italian tune up, like the Ferrari's of old, should I want to replace the plugs/wires/dist first? No clue when the last time plugs were replaced - I guess I've been itching to get under the hood of something anyway, so might as well spend a bill or so and get a decent spark going, and gapped right first, right?

What is the proper gap for this engine btw?

 

Actually, the block is made of aluminum alloy in these vehicles. And you aren't spraying water directly into the intake manifold, as I said, you want to spray it OVER - atomized water mist. The water will boil instantly in the combustion chambers, there is no fear of rust, lol, it will disappear out the exhaust instantly. On bare metal, gas will rust something faster than water will, so....


And as far as plugs, might as well. There are no wires, since it's COP - just boots. My boots were in great shape, but they're cheap if you want to replace them. Gap is .024"-.028". I recommend NGK copper plugs, BKR6E - same plug my BMW uses P/N 6962, available everywhere, only a couple bucks each.

 

And fwiw - if you blow up your motor it's not my fault :P Just throwing that out there, hahahahaha. Liability reasons, you know. I've done this on MANY engines and have never had an issue. Never tried it on this car, but I just had the head off it 15k ago soo...

 

ok not worried about the rust then (I'm used to hondas with iron blocks and aluminum heads! eep!) and when you say to spray it over the "boot" are you talking about the box that holds the filter? or do I open the front of the manifold?

Also, never opened the valve cover, so I didn't know there were no wires - what are these "boots" to which you refer? (there's no haynes manual! Whaddya expect?!?)

And I'll go with those NGKs - I like NGK platinum for my cars, usually, though - any reason to go with copper instead? (that's why I'm used to paying $14 per plug on my civic hahaha - NEVER have a bad spark though!)

 

For the first statement - please re-read my first post. Secondly - the coils have boots on the bottom of them where they contact the spark plug, like a regular plug wire. And coppers - they simply work. No issues with platinum plugs, and if the coppers can easily lite the 600+ hp bmw's my friends shop builds and uses them in, they're plenty for this car.

 

I just don't know what an "intake boot" is - different jargon than I'm used to, sorry :-/ if you mean the filter box, should I take the filter out when doing this? or do you mean the entire plastic assembly leading up to the intake manifold? (thanks, and sorry - excuse my ignorance?)

You're awesome, btw.

 

Ahh, my bad, sorry. By intake boot I'm referring to the rubber boot that attaches tot he throttle body. Remove this from the throttle body, but as I said - keep the ICV plumbed still (you'll see what I mean when you go to do it). You can't pass liquids thru the MAF sensor.

 

OMG ok I know what you're talking about :doh:

I was sincerely concerned about putting that high of a humidity air through the regular intake haha - so it basically I should clean the throttle body while it's still on the car, and only with water (instead of carb cleaner or whatever) so it can go through the cylinders as well.

Would any kind of solvent work better than water? (or are they all flammable? I don't want to burn my face off - I like my face, even if my mother in law doesn't....)

 

some one on the honda forum I use recommends a fuel additive "Seafoam" for use with hondas (2 accords and a civic I had) for carbon buildup, and it seems that it might clean the throttle body and the engine at the same time...

Ever use anything like this?

 

The throttle body isn't your concern, it's the carbon buildup inside the engine. Water works just as good for this as Seafoam does.If it bothers you this much, grab a nice clean shop towel and wipe off the throttle butterfly

 

seafoam is supposed to be put directly through the throttlebody the same as your method with water, no? (and put through the fuel lines as well, I suppose...)

 

Was having a thought (since I can't really find my way around this engine bay sans haynes manual, etc)

What do we think about oil additives and fuel additives for engine cleaning? Would those work as well? Or do I need to buy the real shop manual?

 

For the 5th time, if you're having spark knock and poor fuel economy, your problem IS INSIDE THE COMBUSTION CHAMBER. If you don't want to use my method, use seafoam, or tear the motor down and send the head and pistons to the machineshop to get hot tanked to get the carbon off them.

 

ok, ok - I never said I don't want to use your method -I was all set to do it today, and was going to do a tune up at the same time (turned out not to have a big enough torx driver to open the valve cover) and I found that I had no idea where the vacuum for the throttle is - I found the throttle by having someone push the accelerator down and saw the cable move under the hard plastic cover, but I don't know where to put the water - those moving plates, are they the throttle body? (looks different than throttle bodies I've had in the past) if not, where is it? I'm used to it being covered by a rubber thing like on CV joints...

I'm all game for whatever needs to be done, doing plugs, headlights, and changing the coolant, so I'm already in there (and finding a leek in the PS system...) as well as trying to see if the AC needs to be hooked up or just charged (for defogging) I just don't know where half of this stuff is, due to lack of documentation - are any of those software manuals (the downloadable ones) any good?

And how do I know if it's a spark knock or a valve tap? (or are they the same thing...) I mean there's no misfires ever, just a rumbly truck engine - made me wonder if I had a bad coil somewhere, but I dont' have a timing light to check the individual coils (I *will* have a large enough torx driver tomorrow though, haha)

And thank you, kendogg, for your advice in this matter - I really really do appreciate it, I'm not trying to be a pain, really, I just am a true volvo n00b -_-'

Thank you again!!

 

See the big rubber intake boot that takes up a majority of the picture? Remove that as I sated above. Start the car, hold the throttle open and keep the rev's above 3k RPM's. Lightly mist water above the throttle body. This isn't rocket science. Not trying to be rude, but if you haven't found any of this now with the fairly detailed instructions I've given, I'm not sure if you should be attempting any of this.

Now, as you've pointed out, a misfire COULD be possible - but that'll usually throw a misfire code CEL, or at the very least a rich mixture code. To verify, just unbolt and remove the coils one at a time while it's running and see how the rpm's change - you'll notice the drop in rpm's as each cylinder dies. If one doesn't, then you're missing something there. However, with the symptoms you've stated, I don't believe that to be the case.

 

Thank you kindly for the image - funny you mention rocket science, my father is a rocket scientist (mechanical engineer specializing in fluid dynamics), my grandfather was a mechanical engineer (weapons R&D for army post WWII), and I'm a mechanical engineer myself (civilian contractor for the us govt) - I suppose mechanical engineer != mechanic heh

Anyway, worst thing that happens is I completely destroy the car and have to pay 1000 for another just like it, meh. (unless the worst that could happen is something that would kill me, lol...or destroy the universe :-/ uh oh...)

So I'll remove the entire intake up to the manifold simply to bypass the MAF, and basically get water into the engine through it's intake and keep the rpms high enough so the water boils up the grime.

Warm up the car first, or ok to do it cold? (I prefer to do plugs when it's cold so I don't burn myself lol... but I can do the plugs another day)

You are the best, and deserve some credit here - too bad this isn't like some other forums I frequent for software troubleshooting (I'm usually the one giving the advice not taking it!....you know what I mean) in which people get "points" of some sort to gain seniority, or trust, or whatever - you'd get my vote!

I'll let you know how this turns out :-)