XJ_Libertad

Well I went in this morning with fingers crossed but it didnt help. I failed my smog check.

1990 XJ 184,000 miles on her.

The guy told me that everything was fine except the HC and the CO. In other words it is running to rich.

The max HC at 15mph is 123 and I was at 128
The max HC at 25pmh is 103 and I was at 121

The max CO at 15mph is .73 and I was at .77
The max CO at 25mph is .93 and i was at .59 so no problem there.

This really is a foreign language to me so I am hoping someone with knowledge can point me in the right direction as to what to do.

The inspector did say that I had the stock cat converter on it and to tap on it and see if I hear anything. If i do I may want to change it even though it passed.

He also said that I may want to run through this tank of gas which is 3/4 full and then fill up with 91 octane and change the fuel filter.

I had put in a bottle of Seafoam with my last fill up of 87 octane. Could this make me run rich?? Or maybe it has been doing its job and busting up all the carbon and that along with an old fuel filter could be making it run rich??

Any help would be greatly appreciated as i only have till the end of February on my temp tags.

AMG

When was the last time you did a tune up? When you did that tune up, what all did you do?

XJ_Libertad

I just bought this Jeep in January and the PO had expired tags on it from 07'. So not sue when the last tune up was done. I know that he had changed the O2 sensor before selling it. I did do the oil change. She runs great and doesn't blow any smoke. Plugs, wires and dizzy cap dont look too old.

AMG

Try checking the spark plugs, and check the timing.

XJ_Libertad

Ok I will go ahead and get a new set of plugs along with the new fuel filter and check the timing. Any suggestions on spark plugs?

AMG

A lot of people say the Champion copper core plugs are the plugs to go with, but I don't know the exact part number for the plugs.

XJ_Libertad

Ok AMG and thank you for the quick responses, I appreciate it.

AMG

No problem, thats why we are here.

je4reyk

Check your o2 sensor and circuit ,even though the po put a new one on dose not rule it out. My 88 was running good,but running gross polluter rich and an o2 sensor took care of it.

XJ_Libertad

How do you check it?

hercman

"I had put in a bottle of Seafoam with my last fill up of 87 octane. Could this make me run rich?? Or maybe it has been doing its job and busting up all the carbon and that along with an old fuel filter could be making it run rich??"

I'd run that tank empty and try with a fresh tank of fuel.

dukie564

^^^ This. Always run a smog test with just fuel in the tank.

Being a 1990 the cat could indeed be clogged or (in my case) completely empty. Your test numbers aren't that far off though.

I'd change out the plugs and the o2 sensor and see how that fairs. BTW you want your jeep to be fully at operating temp before testing. I always suggest going for a "spirited drive" beforehand also - definitely get above highway speed for a few minutes at least.

No use in using 91 octane either - it can actually run dirtier in our engine since it's harder to compress - especially if the engine is not used to it (pcm has not adjusted). Switch back to the normal 87 octane.

ck1

I dont think you got it hot enough...you need to hop on the freeway (and not the 91 during traffic times ) dont know where you are here in marvelous so cal BUT you have to get it hot...drive it for 1/2 hour at 60+ or so beore you go in...I live in Murrieta and have a long hill here on the 15 and before I go in for smog on any of my junk I climb that hill and I have passed every time...GET THAT CAT HOT
hope this helps
Cameron
p.s. Calif smog is a rip off and is over rated...they are slowly and systematicaly trying to get all old cars off the road...I have a 47 Ford with a flat head and received a notice a couple of months ago saying my car was observed smoking heavliy and I need to remove it from the highway...funny it has a new motor in it and doesnt smoke at all AND I havent drivin it since my sons wedding in october..bunch of lyin thieves...brought to you by the same people who say that a Hybrid pollutes less in the carpool lane with one person then sitting in traffic runnin on batteries...go figure!...ok off rant
Cameron

XJ_Libertad

Definitely going to do what you and hercman said and i did go for a "spirited" (lol) drive before pulling into the station but my temp did not go above 185-195. I also plan on changing my T-stat out. Already bought the 195 deg one because I never hit 210 degrees, I think it might have a 180 deg t-stat in her now.

As far as the O2 sensor is there a way to check it or do you just replace it? The one on there is shiny and new.

dukie564

at least take it out and inspect the end. If it's really carboned up definitely replace it. If it's just white/black and the slots are not plugged up at all it's probably ok.

But seriously...it's a $30 part. I'd replace it anyways just to be certain.