1994 850 T-5 burning plugs like crazy - Volvo Forums

winston901 · #1 11-16-2011, 01:56 AM

Hi all!

So I've recently bought myself a 1994 850 T-5 with 214000km, after getting my car roadworthy my mechanic told me to change plugs because they were burnt and was the cause of the spluttering while driving. The only plugs available were Champion platinum's ( cannot remember the number ) and that sorted that. I decided to take the car to ultratune to get it running right and back to manufacturers specs, they changed the champion plugs because they too were burnt after only 1 week! but it ran fine on the 5km drive home, I didn't drive it for 2 days after as I had no need to. When I drove it to work the next time it was fine and running as it should but in the afternoon on the way home all of a sudden while accelerating it started spluttering as it did the first time. Has anyone experienced this problem? If so what was the cause? My best guess is it could be improper spark gap? incorrect fuel mix or pressure too high? ecu fault? sensor fault? something something? I have no idea when it comes to these fandangled fuel injected cars with the computer brains, the only car engine I know is the one in my valiant

Cheers all!

boxpin · #2 11-16-2011, 07:52 AM

Ah, another plug chat. You will find that plug discussions are everywhere. The recommended plug for a 850 Turbo is OEM.

I have tried OEM, Iridiums, champions, Bosch Ps, NGK and I am back to OEM gapped at .026. Yes, I mow through plugs, they last about a month on cheap ones and three months on good ones. Keep in mind, I beat the crap out of mine. Now, are you experiencing this with normal driving or is it sputtering only at high RPM hard acceleration?

rspi · #3 11-16-2011, 10:12 AM

If you have gone through 2 sets of plugs, I would also replace the distributor and wires.

Kiss4aFrog · #4 11-16-2011, 02:50 PM

Do you gap them at .026 to allow them to wear longer or is it to keep the flame from being blown out at high load & RPM ?
Do you have an upgraded coil ?

winston901 · #5 11-17-2011, 04:16 AM

My apologies for spamming the forums with another plug post, my net craps out on me constantly so I only got to view about 2 posts prior to posting. As far as I'm aware the coil has not been upgraded, the spluttering is it's worse under load but is noticeable under normal driving conditions around 2500rpm under and it's fine mostly but now it feels and sounds like it isn't running on all cylinders. I will indeed replace the coil wires and plugs when I can, sounds like a reasonable thing to do. I literally only found out about sp gaping before posting so it's news to me, but something I will do when everything is done. Much appreciated all!

Rickford · #6 11-17-2011, 07:21 AM

Quick question while we're here... On a 94 850 NA what brand exactly is considered to be OEM and what plug number would you recommend? (In Michigan) Thanks!

Kiss4aFrog · #7 11-17-2011, 09:53 AM

I think you need to replace the cap, rotor and wires and see if that takes care of it. When you put the wires on the cap and the coil tower apply silicone dielectric grease to the connection, it's cheap, it's easy. You just need to put some on your finger and smear it around the inside of the boots. It helps seal them so moisture doesn't get in and makes it easier to remove next time. It helps on the plugs too.
Under load the spark is looking for any option to go other than the gap at the plug so it will seek any path it can. You might have enough dirt or moisture someplace between the coil and the plug that it's jumping to ground. It don't need much.

Any chance the mechanic mistook the small center electrode of the platinum plug for being a burnt regular plug?? I can't think of anything that would take a plug out that quick in a stock or near stock engine.

The OEM plug would be listed inside your owners manual and on some vehicles it's listed on the engine or emissions sticker under the hood.

The problem is it's been around 15 years since the engineer specified this exact plug and two main things can happen. The plug is so close to something else it gets "consolidated" or it just flat out gets replaced by something that has better technology (new and improved).

OEM is a hard call because it's a term a lot of people use without knowing what they are referring to.
OEM on my 95 855 turbo is Champion and the original one is no longer available anymore. Even directly from Champion !!

So ... if the dealer isn't selling you a Champion (at least my year) he isn't selling you "OEM" even if he is the dealer. Well, unless he's selling you a Champion plug that was branded "Volvo".
In some cases OEM isn't the best choice because like the military the company chose a manufacturer (OEM manufacturer) that could supply a part for the lowest price and just in time. Cars are sourced from all over the world. If you really want OEM, you have to buy the part from the company that made it for Volvo. I don't know about Volvo service departments but I have supplied parts to dealers for their own brand of vehicle. Always wondered if the customer was informed and if they priced off our part or theirs.

As for plugs. My 2 cents is if you're an average driver I'd go with a non multiple tip platinum or iridium, Champion, Bosch or NGK and that should give you 100K of worry free driving. Myself, I never run a plug that long because they aren't that expensive, mine are fairly easy and it's cheap insurance. I haven't had or come across anyone with a complaint on them from real world average drivers.
If you push your car and spend a lot of time with your pedal close to the floor stick with a standard copper core and inspect them often and don't plan on getting more than 25K.

Always use an "anti-seize" compound on the threads so you don't end up pulling the threads out of the head with the plug.

The reason you get so many choices at an auto parts store is your are being offered every plug from every manufacturer that falls into the safe heat range for the engine (stock). But if you're a grandpa and never use the top two thirds of your tach you might want to go a bit hotter, not that that guy is ever going to ask or if you're foot uses the gas like an on off switch you should go colder. That's where someone who can "read" the color and condition of the plug comes in.

I'm happy with my AC Delco platinums but I am firing them with a hotter coil and that too will make a difference. I have a MSD coil I fabricated a mount for and made up a lead wire.
If I had a bigger turbo and injectors with an improved exhaust I'd be inclined to go with Boxpin and use a copper core at 26 thousands.

boxpin · #8 11-17-2011, 03:06 PM

Quote:

Originally Posted by Kiss4aFrog

Do you gap them at .026 to allow them to wear longer or is it to keep the flame from being blown out at high load & RPM ?
Do you have an upgraded coil ?

Guess this Q was for me. Yes, blow out and I do have an upgraded coil and this is after trying all different types of plugs and gaps over several years.

Kiss4aFrog · #9 11-17-2011, 04:58 PM

Quote:

Originally Posted by boxpin

Guess this Q was for me. Yes, blow out and I do have an upgraded coil and this is after trying all different types of plugs and gaps over several years.

Yes it was.
I'd definitely follow his recommendation then

for an engine that's pushed.
Do you or have you tried indexing your plugs??

But, for a standard engine normal driver you should be able to screw almost anything into it and not have a problem, SHOULD. I don't think plugs are the issue but I'm sitting in the dark out in the middle of Wisconsin so you should take that into consideration.

The other thing is that like Boxpin I have a coil that will put out more voltage and amperage than a stock coil and we don't burn up plugs. A high output coil is like a garden hose with a nozzle on it. It's not that it puts out more voltage all the time, it's that it CAN when it's needed. Most of the time it's putting out the same voltage as a stock (less expensive) coil. Under extreme conditions

it can supply more if more is needed to jump the gap.

If you are running the stock coil I doubt it's burning out the plugs.

Do you know what a burnt standard plug looks like? I've run into a lot of people who have no idea what the iridium or platinum plugs look like new and they think they are burnt out. I ask because it may be what they are telling you but it may not be what's happening.
Best thing is if you can post a picture. I'm sure there are a couple guys here who can "read" the plug for you. If it is burnt out then we're back to the drawing board but I'd do the rest of the secondary first.

Also if you buy a 5-15 dollar plug with the tiny spike electrode DO NOT use a ramp gapper to check and never adjust it with one. If you do you just scraped off 5-15 dollars of platinum or iridium and you have a 1.29 plug

That coating is less than a hair think.