I'm sure my issues have been discussed in this forum before. I have a 2000 S-70 w/120K miles.I am the original owner.

1) Since almost new, the transmission has done odd things like hesitating several seconds before engaging from P or N, and then jerking firmly into gear; downshifting automatically when the car slows down; fumbling for the right gear when you slow down and accelerate again. Over time, I've had fluid flushed, new software allegedly installed, fluid flushed again, and new software allegedly installed again. It still behaves as I've described.Are there any other steps I should be taking?

2) The engine knocks. Old-fashioned ignition pinging sound. Sounds likerolling dice, especially when hot and under load. This has been going on for 10's of thousands of miles -- car's been maintained according to the book; dealer just shrugs, but agrees, it'sknocking. I only use premium gas. Knock sensor has been replaced, to no avail. Any thoughts?

 

I am not very good on Auto Trannys, so I wont even act like I know that answer. But on the second part, the knocking issue. That is usually due to an ignition, or fuelproblem, of some sort. It may be something directly in the ignition itself, or a sensor of somesort not giving correct data input to ECU, causing incorrect ignition timing. Like the Knock sensor for example, when it detects the pinging, it's response is to retard ignition timing. Does the car ever just stall out on you?? Who did your last timing belt replacement?? Oxygen sensors, MAF sensor, just taking long shots too. All these sensors help to adjust fuel levels in the engine.

 

Just a thought... you said it knocks when it gets hot. Might wanna try some heavier oil. I am in texas where it gets very hot and i run 20w 50 in my s70.

 

Kibbys got a good point, heat. Excessive engine operating temp will cause precombustion as well. So your cooling system, and oil selection are very important factors as well. Has anyone tried putting a lower temp thermostat just for experiment?

 

thanx jsj! [sm=icon_rock.gif] See not all girls are clueless when it comes to cars! HAHA!

 

Hey Gibby, Woman or Man, great call either way!! I like looking dumb, it's a very natural feeling for me. lol

 

well i had the same problem with my firebird (RIP)BUTwas fixed with heavier weight oil and performance thermostat.

 

Poor firebird. Yeah, that Texas heat is brutal. I wouldn't be affraid of 20 50 and a 160 thermo myself down there. With an oil and tranny cooler as well. Maybe upgrade to a 3 row radiator as well. But then again I get pretty O.C.D. on my vehicles. lol But by god it wouldnt overheat then!! lol That 110 summer heat is unreal.

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it sounds to me like theremay bea commonality between the tranny and engine.
heat.
what system helps BOTH the tranny AND engine remove heat?
the cooling system.
im willing to bet that the tranny fluid was burned when it was changed.was it brownish red?smelled weird?
im willing to bet that at least one of the times it was replaced it was,indeed burnt.
as far as the ping,if your CERTAIN your using the correct heat range AND part number,id DEFINATLY look to the cooling system.the cooling system cools the plugs too.
make darn sure your using the correct plug.a plug that runs too hot will DEFINATLY pre-det {ping} a performance engine,{high comp. ratio/boost pressure}ESPECIALLY under a load.
when u have the cooling system flushed,that dosent mean put the garden hose in radiator and see water come out.
u have to do that in ADDITION to removing the block plug and draining the block.
then a "radiator cleaner" needs to be used.u can buy it at the parts stores.volvo uses a really good one.
u pour it into the radiator and fill it up with water the rest of the way,and u run the car and it cleans all the films,oils and any rust scale that may be present and RESTORES the cooling system to maximum efficency.
they also have one thats for "neglected cooling systems", if u have NEVER had the engine coolant changed/flushed.
u can open the overflow tank,if the coolant is brown,that is REALLY ,REALLY bad.
even if it looks ok ,it{decent color to it}can still be not cooling your car properly.
the tranny uses coolant to cool it as well.
also maybe ur thermostat is opening too late.maybe there is some residue/film {from not proper flushing} on it and it not functioning properly.or maybe it just needs to be replaced.
on a side note,i suggest that you do NOT put whateever oil u may THINK u can put in your car.
there is a temperature range with which all oils work in a particular application{car}.
it VARIES from CAR to CAR.there is REASON why a manufacture list in the owners manualwhat oils u SHOULD use at CERTAIN temperatures.when u start putting in oils tat arent listed u
adding 20w-50 is just stupid.moronic actually.hows that firebird running now?whats that?its at "pull-a-part" salvage yard?hm... IMAGINE THAT.
That is only treating the SYMPTOM,NOT the PROBLEM anyway.
anyway u have a chance u could spin a bearing cap or NOT protect ur engine under certain conditions{film strength,tearing,etc.. is affected when u alter the oil}.
one last thing to consider.
When u use a different weight of oil,the amount of suplhurs/phosphates change.go to mobil1 website they have a chart to show you,if interested.
this has a DIRECT realationship with valve jobs,etc..that is,ull likely need one after running 20-50 for a year or so.again,hows that firebird running now?
as a matter of fact,i have a 1999 s70 t5 and 20w-50 is NOT even listed as a usable oil for ANY temperature ranges.
people think they can just put whatever oil in their car they want and they are smarter and know more than a manufacturer who has spentMILLIONS of dollars researching and "tweaking" to find out the BEST oil for the CONDITIONS.those people end up BUYING another car.
this is key,the BEST oil for YOUR operating conditions.
one last thing,i live in oklahoma,where the tempaerature FREQUENTLY get just as hot in texas.
i have ALWAYS used the correct oil{as defined in owners manual},on ALL my cars.
i STILL am driving my 1993 mazda protege AFTER 16 YEARS of continuous service ,WITHOUT replacing anything except the front strutsand two lower ball joints.but then again,i DO NOT substitute my oil when i see fit.
same with the volvo.
so in closing,i would really try the chemical cooling system flush{its made and is safe on aluminum and metal radiators/engines blocks.}
i have used it for YEARS with amazing success.
oh ,i almost forgot,u may have carbon build up that causing the engine knock.
again,volvo {at least here} has a kik butt cleaner that cleans all that carbon build up that a charm.wynn's also makes a kik butt cleaner.