Before I get any grief for deleting cats, just want to say to please save it because I'm not going back. I also put spark plug non-foulers on it, so I should not have a code for the rear O2 sensors Now for the problem, I'm getting these codes 1170 and 1173 which the Rave manual says:

P1170 Downstream fuel trim malfunction (bank 1) Front sensor aged - rear HO

rich RH bank (NAS and EU-3 only)

I have also recently seafoamed the intake. Could the front O2 sensors be bad from the seafoam or does this have anything to do with the cat delete, or maybe a vacuum leak? Thanks

 

Unless you are getting codes for the rear cats you are fine there.
Yes a vacuum leak can cause the front O2's to throw codes.
Yes the Seafoam can also cause O2 codes, have you cleared the codes and they came back or have you not tried that yet?
Doubtful the Seafoam ruined the O2's though.

 

Yea, it's come back twice and I even doubled up the spark plug non foulers, so the rears are are way out of the exhaust mix. I noticed my intake tube to throttle body has no clamp, and I can pull it off pretty easily. That would be my first guess, but I didn't get these codes until I deleted the cats and seafoamed it, so I don't know.

 

I'm betting its the Seafoam.
I've never done it but I have heard of some people having problems.
How much air gap is there around the rear O2's?
If there is not enough gap around them they will throw codes.

 

They have the same amount of gap as you would by doing a regular non fouler mod. I just added one more non fouler to make it longer, and more away from the exhaust. Overall, it the sensor is about 3 inches away from the exhaust stream, but the non foulers should still allow some exhaust to to get to them.

 

I'm out of idea's, I'll think about it though.

 

It looks like Bosch has outsmarted you... the codes you are getting are DOWNSTREAM codes... which means that the computer doesn't like the ratio between the upstream sensors and the downstream sensors, so it thinks the upstream are bad.

 

Jafir, I was wondering about that because the wording from RAVE very loosely suggests that. Now what? Has the non-fouler trick worked previously on these? I've already done more than the usual non-fouler trick. Do the rear sensors have to sense some exhaust, or can they just be out in the open air and pass? BTW, I haven't had the truck long, but my mileage is poor 9-11mpg with 60-70% city. I'm going to try and clean the PCV later today because it also stumbled once at a stop light (nearly shutting off) without codes.

 

Usually people have problems with deleted cats and o2 in open air. You have made some changes that you clearly state your not going back. Most changes people make affect fuel consumption in a negative way and that's exactly what you are doing. So don't expect your fuel to get much better, also driving habits have alot to do with it, loud exhaust and such usually don't match up with grandma's driving habits. You want better fuel mileage get a Honda.

You could try all the normal tune up stuff on mikes list. Always run premium fuel blah blah blah the disco does not care its a thirsty thirsty monster. 87 octane will use more fuel go less miles 93 still use lots of fuel get few more mile better for fuel management system.

 

Perhaps your front o2 sensors really are bad then, if your MPG is low. They are pretty cheap, you can get the fronts, oem bosch, from amazon for around $50 or $60 each.