Hey guys I would appreciate any help, long story short I'm a honda/acura girl (please dun hate me) But moved to Hawaii and now get to drive Helga, my dad's 1990 volvo 740gle.

Well recently she started Idling super rough almost dying when I'm driving slow, and she is running really rich. I can't find any vacuum lines off/cracked. I'm going to pull off and clean the 02 sensor....but any other advice would be great!

Well Helga has a relay that we have had problems with before....it's sapose to be mounted against the overflow tank on the passanger side- but ours just sorta sits there. Any how my dad was moving around the wires to it thinking he may have mixed them up and that's why it was running wrong...and it sorta cought fire. One of the wires is totally shot, gonna replace that - but the relay is fine. This relay has caused issues in the past w/ helga not starting as well.

Any how....As far as I can tell it's the Cooling Fan/ Radiator noise relay? Am I totally off here?

Any how could this relay be causing the issues with the rough low rpm idle?

Any help or hints would be great!

Thanks!

I'm Natalie by the way, Helga is my volvo.

 

Does any one know the proper voltage for the 02 sensor??

As far as I know my volvo (1990 740gle) only has the one that is on the cat??

 

Hi Natalie! Yes, there is only the one O2 sensor on the 90 model. Do you know if you have Regina ignition or LH Jetronic? If it isn't turbo it's probably Regina. That relay is called a radio suppression relay but actually controls the fuel injectors. Fix the wire and if the relay is good should be a non-issue. Relays under the hood needed to be mounted with the connectors on the bottom; water can get into the case otherwise and corrode the contacts. To attempt to clean the O2 sensor, heat the cr*p out of it with a propane torch. I've tried cleaning them in the past with only marginal results at best. It could be your air filter, plug wires, d cap, rotor, plugs, MAP sensor (Regina cars don't have an air mass meter), fuel pressure regulator, engine coolant sensor to name some of the usual suspects. The O2 sensor ranges between 0-5 volts.

 

Wow thank you!

I only thought one, but just double checking.

I'm going to check the fuel pressure reg, I know to look for gas on the vacuum side.

That's awesome to know about the relay though! I bet that's what it is...little bastard.

 

Well, the good news is there should be 2 relays side by side mounted on the overflow bracket. The relays are the same type so you can swap 'em to test.
Here's a 90 Regina ignition...note the 2 relays in the back ground and the HEI looking coil in the fore ground above the air inlet tube. Jetronic injection cars have a regular coil.

In extreme cases, it may be necessary to remove/replace a few more parts!!

 

- So we switched them. It wouldn't run at all once we switched them.

- It was running rough before the switch though.

There was quite a bit of corrosion on the connectors, I think somoen said you can order those from volvo? So I'm going to call volvo tomorrow and maybe just order 2 new relays to be safe. Swap em both out. What do they do exactly? I know one does something for the fuel injectors but which one? And what does the other one do?

Thanks!