On my 1990 Volv DL 240, I had Bosch Platinum plugs for 3 months. My engine really ran bad so I replaced them with the Bosh Super plugs and it runs smoother now. But when I start my car it will try to die for a sec and I have to give it gas so it won't. The check engine light also comes on but goes off as soon as I give it gas to revive it. This only happens once with every time I start it, after that it keeps going without dieing. My mech. said using the Bosch Platnium Super plugs could of messed up the oxygen sensor. I see that they're pretty expensive so I wanted to check and make sure before I buy a new one(gonna try and put it on myself). Does this sound like the oxygen sensor?

 

Volvo uses and recommends NGK plugs, Bosch Platinums are known for bad performance in some cars. They might have harmed the OS.

 

Could be. If you have never replaced it then it may be time anyway. The thing about the Spark plugs is very common. With most 80's and early 90's euro cars the electrical systems were designed to run on standard spark plugs. Changing this can have very negative effect on your electrical, fuel management and or emissions system. If the system isn't operating as intended it will constantly be trying to compensate. Sometimes that means a more rich or lean fuel mixture or in the case of my MB 3.2, the wrong plugs finished off a weakened coil.

Anyhow, the replacement of an o2 sensor should be considered regular maintenance and if you are doing it yourself be prepared for the old one to be seized. If it is then you will have to heat it up with propane torch (get it red hot) then cool it with water quickly. If you do that 2 or 3 times the little bugger will most likely come right off.

just be aware that this may or may not fix the stalling thing but is a good guess.

 

I thought Volvo 240's originially used Bosch Super spark plugs? Volvo actually recommends NKG instead?

Wow, is the oxeygen sensor that hard to get off? I don't have a torch.

 

Not too hard unless rusted, but I would check for trouble codes first. The cars shipped with plain ole copper core plugs, nothing fancy. I'm using Bosch WR7DC, no problems.

 

Not all the time. It depends on where it is located how hot it has gotten and how long it has been on there. Sometimes the sensor comes right off. I just have not had it that easy usually. Don't let it intimidate you though, it's not that hard.

 

Forgot to mention if you don't have a torch get some good rust penetrating oil and soak it with it. Then tap it with a hammer for a 20 seconds then put more penetrating oil on it. The vibration lets the oil work into every little crevice. Then use a big cheater bar slid over the end of you wrench to improve your torque. Often that's all it needs.

 

Strangely, today the stalling did not happen when starting- through out the hole day.

I was told the Bosch Super Plus was pregapped and I didn't need to gap them, so I didn't. Is this ok?

 

Yes, you are fine not gapping them. Electrical systems are alot more uniform these days so gapping is quickly becoming a thing of the past