o2 senor/scan tool ?'s

ok i did my search on 02 sensors.. i am thinking about changing them on my 90 xj..but i swear i had read somewhere that it's not worth it if you have a cracked exhaust manifold cause it may go bad again..is this true? the other question i had was about a scan tool.. have been thinking it would be nice to add to the tool box. any suggestions on where to get them and what kind?? thanks

Changing the O2 sensor with a cracked header should not be a problem - especially since the header cracks downstream of the sensor anyhow. Go ahead.

Scan tools are another issue. The RENIX XJ/MJ (1987-1990) don't talk to just anything. It's a serial data stream out, but some among us are working on tearing it down to make a lower-cost scan tool. Also, the RENIX ECM doesn't store codes, so there's no "Check Engine" light to use, either.

The least expensive (new) scan tool that talks to the RENIX ECM is made by Snap-On, and the MT2500 goes for about $1400 new. Used, look around and see what you can find. MAC Tools also makes one that will work, but I don't recall the model number.

There is also the DRBII (ChryCo OEM) that may or may not be found out there, but that's the one the dealership usually used.

Either way, you're probably in for a search...

5-90

I would say if your sensors bad replace it,your computer will like you for it.As for scanner,I have a snap-on mt-2500 that is useful but still limited in the depth of diagnosing the renix system.If your set on getting one, Ebay is the way to go.I have been patient in bidding at the right time because some items just get over bid.I have added to mine slowly and now cover all makes and models 1983- 2001 for around 900.00 including connectors and cartidges.I know the base unit can be had for 100.00 to 150.00 then just add connectors and cartidges for you vehicle.There is alot of accessories for mt-2500 cause,well my theory,shop mechanics are moving to the newer Modis model that can monitor secondary ignition firing among other things.Oh yeh those things go for $ 4000.00 on ebay,dealer price you could probably buy a new vehicle and then some.