Ok, I have a 91 xj limited 4.0 auto. 162k. Saturday I'll be replacing the fuel filter, egr valve, plugs, wires, air filter and an oil change.

I failed echeck last week, hence the changing of the egr valve. I was 715 ppm over the max for ohio nox standards. Anything else I need to check/change?

 

o2 sensors at 162k if they're still original...

 

**There isn't an EGR valve on a 91. Last year for that on the XJ was 1990.

**X2 on oxygen sensors if they are original. Replace both of them if you're going to keep the vehicle with NTK brand sensors.

**No mention of your plans to replace distributor cap and rotor. No tuneup is complete without replacing these items. Use Champion copper plugs gapped to .035; gotta verify gap.....never trust gap out of the box!

Good luck and enjoy your XJ!

 

To add to the above, do yourself a favor and spend a couple bucks on an oil filter. Mopar, Purolator, WIX, CarQuest Blue, and NAPA Gold are good choices. FRAM, STP, and Quaker State are not.

While you're in there make sure to inspect the vacuum hose that runs from the throttle body to the gizmo on the firewall above the engine. The MAP sensor's hose has a tendency to become brittle and cause rich running.

 

Thanks for the input. I wasn't 100% sure on the egr valve. I thought there was only one o2 sensor and it's one the down pipe. I'll deff change the cap and rotor as well.

 

Can't hurt to do a drain and fill on the transmission while you're at it.

 

Thanks for the input dudes! I'm hoping to keep this below $175. And how's the sea foam down the brake booster vac line work? I heard that was good to do too.

 

I've never messed with seafoam. I did use some BG 44k when I got mine to clean the injectors. It seems actually well regarded but even that might be bogus.

Also, if you're going to use any of this crap like seafoam or BG, I'd do it before replacing the plugs & o2 sensors.

 

Will do for sure haha. What's bg 44k? Can I get it at advance/autozone?

 

Oops. you're right. Your year (91) XJ only has 1 oxygen sensor. Use NTK though; that is the brand sensor that your XJ came with off the factory line.

 

Ok sweet. Will that make my maint reqd light go off?

 

As far as Seafoam goes, just follow the directions on the can. It'll tell you how to dribble it in.

 

91 has no EGR valve.
Cap and rotor and make sure your intake manifold bolts aren't loose.

 

Lol that's what we all hope but the reality of it....... Lol if you are wanting to do the whole shebang, you're going to be spending more. Now if you want to split it up in to smaller cheaper(at the moment) projects. I'd do:
1st part. Bosch O2 sensors and a oil change(rotella/napa gold filter)
2nd part. Either spend coin on a full tranny drain(not flush) and new fluid or do the slower drain and fill(search) if you do drain and fill for the second part, also replace cap and rotor.
3rd part. Continue drain and fill(if you go that route) seafoam or water treatment through intake, new spark plugs(champion coppers) and wires.
4th part. Ditto drain and fill, change out axle fluids and transfer case fluids. drain and flush radiator, clean heater core if you're getting cold air.
That's what I'd do to spread out the cost and ease ability

 

Free and easy, check tire pressure.... Lol