Hello everyone, thanks in advance for the advice. I bought a NA Volvo 850 2.5 20v, in the test drive the car was flawless, i bought it and started driving it home, after 2h driving, i was going up a hill and the car started shaking a loosing power, i reduce gear and it completely lost all power, after shaking a cloud of unburned gasoline came throught the exahust, then, the engine stop completly and after a few tries it started back up, I got out of the highway and waited for about an hour. After that the car started perfect again and i could drove it for one more hour with no problem. But then I was driving through one more hill, and it happend again but this time there 3 explosions of unburned petrol came out of the exahust. Some told my that the problem maybe caused by the ignition coil gets heat up after a wile driving and it causes the engine to misfire and lose power. If someone can help i will be really thankfull.

 

Do you know the maintenance history on the car? If not, I personally like to do a tune-up on a new used car. On that car would be the distributor, spark plug wires, spark plugs, & filters (air and fuel) to start. Old spark plug wires can cause issues, especially in humid/wet weather. Your car doesn't have an ignition coil that could be overheating or failing. Other things to inspect on a volvo when buying used is the timing belt condition, accessory(alternator) belt condition, & pcv health.

Also, check for any codes stored in the car.

 

Hello, thanks for the answer. The previous owner replaced the spark plugs and spark plugs wires, the wires are NGK and i dont know the spark plugs brand. I was planing on buying some OEM ones. Do think this could be the issue? Im looking also to buy the OEM distributor cap and maybe its necesarie the full distributor.

As you said I am going to do a basic tune-up of the car (Timing belt, pcv sistem, oil change, ...).

 

look at the wires - there's usually a date code on them. Anything over 5 years should be replaced. What I'd do to begin is look at the color of the plugs to see if they are wet fouled. You may also want to check the fuel pressure then check the fuel pump's current draw. BTW, have you noticed if the temp guage was acting oddly? If so, you may have a wonky coolant temp sensor. Last to do is to scan for fault codes. If its a 93-95, there's a diagnostics box on the front passenger side of the engine (check out Volvotips.com on how to use it). If its a 96+ its ODB2 and you need a scanner that can read the older ISO code sets (many do).

 

Hi, thanks for the answer. The temp gauge once it reaches the midle part it did not move a bit. I am going to check the wires, plugs, fuel presssure and pump´s draw, there were no codes on the diagnostics box (its a 95). I will make one post with the results and what i found next week. Have a nice day.

 

That is always caused by plug wires.

I've never seen a bad coil on one of these cars, and they have that extra stuff on the coil, extra electronics, and I honestly don't know what that does. When you go a up a hill, it takes higher voltage to fire, and voltage may seek an escape route other than through the spark plug electrode. You can see where this increasing voltage might reveal a problem with the coil, but I've just not seen one.

Let me just throw in there, for what it's worth, that 850's have the lowest voltage ignition system I've ever seen. Be sure that you get copper plugs and set the gap on them to the tiny gap specified by volvo. Avoid any kind of "long lasting" plug. They can't deal with it.

 

+1 on the copper core plugs, even for the turbos. Also always check the plug gap even for new (if I recall, its .028). I actually had the case where my 95 Turbo developed a misfire even though the wires looked good, I found corrosion under one of the boots on the coil wire. If you've never done a full tune up on an 850, you may want to pop out the air box for easy access to the distributor cap's screws. It can be done w/o doing that but pulling the air box makes it easier. Also check out IPD and FCP for a replacement ignition coil. I know IDP sells a bolt on upgrade replacement for about $125. So do a stage 0 tune up - plugs, wires, rotor, cap and consider upgrading the coil and you should be in good shape.

 

Thanks for the info mates. I am going to buy a new set of oems sparkplugs and wires, distributor cap, rotor and ignition coil just to be save. This is a new car to me I am also going to do the pcv, oil, filters and timing belt with water pump. Anything else I should do?

 

while doing the timing belt, also replace the serpentine belt and inspect/replace any of the serpentine idler wheels. Not all that uncommon for a failed serpentine (aka drive) belt to take out a perfectly good timing belt

 

Okey thanks, I will post the progress soon. Have a nice day.