hey there everyone!!! And Tech, PLEASE HELP!!!! I was hoping to get some help with my emission. I've got a 1995 850 2.4L non-turbo. I went for emission testing, and failed the NOx. This leads me to believe that it's the EGR system. I tested the EGR with a vacuum, and it seemed to be working fine, as when I put a vacuum on it while the car was idling, it started to stall. I cleaned out the EGR anyway, and made sure that there were absolutely no blockages in the tube. I tested it while the car was running with a vacuum and at idle. the more I pulled the vacuum, the more the car wanted to die, so it's working. I tested the solenoid modulator controller with a vacuum hooked up to it. I took it for a drive, and what I got was very little vacuum when excellerating and decellerating (0 to 3Hgs). the only time I got the vacuum up to 8Hgs or so was when I was traveling at a constant speed, but it had to be very constant, otherwise it dropped to 3 to 5Hgs VERY QUICKLY, and took a considerable time to get back up to 8Hg. Is the EGR solenoid my problem? Or is it working properly, and I should be checking something else?

Thanks!

Ed

 

NOx is usually blamed on to the catalytic convertor and crankcase ventilation System (PCV in volvos). To check the health of your PCV system, just pull the engine oil dipstick out with engine running and hot. If you see any kind of white steam like thingy blowing out, then your can needs a PCV job done. There are many threads here about how to do it and all I can tell is that if you are a little do it urselfer, then the job is not that hard to do. Also, this can save you $$$$ in future that you will have to spend on fixing leaking seals if the PCV is not taken care of - Ofcourse if its needed.

 

when you retest the car......run the car for ~30minutes before you go to get it tested. Cars burn cleaner when they are at normal operating temps......

 

It sometimes helps to take it on the highway and beat on it a little also.

 

Soleniod possible. I have seen cars to many weird things. I have seen cars fail due to needing an oil change!! You say really yes it failed and we changed the oil and tested again within 2 hours not touching anything else and it passed.

 

Good to know....Thanks

 

Okay all, My flame trap system (PCV valve system) had already been cleaned, and was working fine. I had a catalytic convertor change about 8 months ago, but the car does burn oil, so I wasn't sure if that was part of the problem, in that I ruined it, but it was working with the HC and CO, so I thought it may have been okay. FYI; I was getting a periodic 422 code, and I couldn't figure out why. The plugs distributor, rotor, air filter, and wires were about 8 months old also (maybe 10,000 miles). I had just changed the oil from 10W-30 sythetic to 10W40 non-synthetic and added a bottle of Lucas Oil treatment (really thick stuff supposedly to help with the burning oil, and blowby). Now this was the state of the car when I first took it, and it failed with just the NOx. I had replaced the plugs, rotor, distributor, air filter and wires, and put HEAT in the 87 octane fuel and retested. I then failed the HC and the NOx, but not the CO. I then took the intake hose off, cleaned the intake (which wasnt that dirty, as it was cleaned about 8 months ago), but what I did do was take off the vacuum adapter on top of the intake manifold. From there, you can see the hole for the EGR valve. I then hooked up a vacuum gun to the EGR, and with some carb cleaner, I began to clean it in the open and closed position, and operate it with the vacuum gun. I then took compressed air, and with the EGR open, I blew out all whatever I could down the pipe, and into the exhaust. Earlier in the week I had a half tank of 87 octane, and filled the rest with 93 octane. I did this knowing that if my EGR system didn't work any better, that the higher octane would lower the temp of combustion due to a higher flash point of the 93, and make the engine run cooler to help reduce the NOx emissions. FYI; you do not want to have a full tank of gas when you take the emissions test, as excess gas fumes in the tank get run through the charcol canister, and into the engine to get burned off, and could create more HC fumes. So again yesterday, when I was all done, I took it to the emissions test, and I passed. I think that it was a case of the tube being slightly restricted, but not blocked. I was working, but not at full potential. I believe that cleaning the EGR in the open position, and blowing compressed air through the hole opened it up. And since I change the oil, I have had no more codes, and it's been 2 weeks. I usually got the code once a week. Hope this helps someone else. And Thanks everyone!!!!

 

Glad that it passed and you are back in bussiness...