Good Afternoon, I bought this 04 D2 160k of a woman who bought it with her now ex husband. They did some nice upgrades and I’m finding some shady stuff (like removing the check engine light bulb). I have had it about 2 months working on it when I could but PO also removes the cats and added a flow master so I feel like the neighborhood redneck every time I start it, I live in Arkansas so standing out as a redneck is hard to do. I have other Discoveries and have had several in the past. So a couple items I need help with and I appreciate your time.
I replaced front driveshaft u joints with greasable versions and screwed in the zirc in the shaft it’s self and filed with grease. Now it pulsates are certain speeds. It’s almost scary to get over 50 mph. I have drained and filled both diffs and transfer case twice to make sure they are as clean as I can get them.
Also most times but not all the time there is a consistent thump that I can hear and feel through my feet while driving. It gets louder and faster as I speed up, hub issue?
Lastly because this has gotten too long, is the codes that change every time I hook my scanner to the vehicle. I had gotten 11 codes all revolving around misfires, all cylinders. Next morning none of them but it still runs terrible, runs terrible if I clear them runs terrible if I leave them. I have put 4 different brands of double platinum plugs with no change. 2 fill ups with 93 octane no change. My Magnacor wires are here just now so maybe that helps. I can’t shake the feeling that the Secondary Air will have to be put back in as well as the cats before I can do any real diagnosing. Thanks to those of you that made it til the end, and I appreciate your time and info.

Ryan

 

Have you had the driveshaft balanced at a shop after the new u-joint install?

If SAI was removed, they'd need to have either replaced the heads with non-SAI versions or welded shut the SAI ports. Given the missing bulb for the SES light, I'd suspect the latter. You'd also need a computer from a non-SAI Discovery, which would have to be paired to the other systems in the truck as well as the gauge cluster, if you wanted to run without any codes. Note that not all trucks came with SAI originally (mine did not).

Regarding the cats, I think you can get O2 sensor spacers (assuming you don't have emissions in Arkansas) that will fool the sensors into thinking that the cats are present and functional, if you don't want to redo the whole exhaust. Not sure anyone's used them on D2s, but I've heard success stories for other cars that are catless.

 

The heads have been altered with a copper plug like you mentioned, but most if not all of the thicker black plastic tubing is in place and I have a few of the pumps. I think I’m missing some of that stainless tubing but I haven’t looked very hard. Seems much easier to replace all of that than location clusters and having the codes which I don’t like. I like repairing things correctly that’s the joy just making something run is easy.
Cat wise the PO did a poor job of welding the straight pipes in place of the cats and left no bungs for the O2 sensors. So I cut out his garbage and welded in new Pipe and bungs and used the spacers and all is good besides it makes car alarms go off in the Wal mart parking lot. If I cut the flow master out and replaced it with a factory LR mid pipe would that quiet it down where my wife would ride in it? I haven’t decided if I want that just asking.

 

the mid-car silencer will make a moderate reduction in sound levels. I have high flow muffler, and the OEM silencer, and it is not bothersome to drive (but not as quiet as all OEM). Cats also reduce sound when in place (a little)....

Adding the new universal joints with zirks maaaaay have thrown the shaft out of balance (they are usually all placed on same side as much as possible). Did you also replace the centering ball and bush? that could be worn too.....

as for the codes? clearing them does not make the car run better.... Could be any number of things. So are your codes still there with the O2's in place? Have any /some gone away? A bad MAF, intake air leak, engine ground, knock sensor, wire, fuel pressure could all lead to crap running... Check your ECU numbers to see what is in there.... I find it interesting that the PO could even drive it with a stock ECU and no O2 sensors...

Sometimes you have to reset the ECU to base and have it relearn the engine. Does you scanner allow this? Can you see you fuel trims on the scanner? what kind of scan tool?

 

Well the pulling the Intake to replace old wires with magnecor and besides my swapping 5 and 6 it ran great. I just swapped those two and drove it a mile. I will drive it more in the morning. It also quieted it down a lot. Balancing the driveshaft is next. Thank you.