Sounds like you are on the same path I was on. I hope yours is less expensive. In my case I think the wires were a problem because of my own carelessness during the head gasket job.

If you have a code reader or can get one post your codes. This forum is the best place in the world to get help with land Rover engine problems... It has helped me immensely.

I've gotten pretty good at replacing the coils. But I haven't been able to replace them with the intake on as some others claim; there just isn't enough space to pull them out. With the intelligence off I still have to remove the plug wires to get my coils in place.

I've decided to leave my typos unless they are curse words because it is so entertaining to read what my phone does. I meant intake, not intelligence. Keep intelligence on.

 

We must be related. I like being under my truck, too and though I wear a suit for work I am MUCH more comfortable in overalls. Thanks! I got my 24mm on it but I could only turn it a hair and then couldn't get back on it with either the box or open ends, even though twisting the wrench every possible way. I saw a cheap set of the crowfoot wrenches at HF and will pick them up. I think it will take the crow foot wrench plus my jointed ratchet. I really like the ratcheting wrenches but I have not seen one that big in any of the stores I frequent. Reminds me of the TORTURE of removing and tightening the driver side o2 sensor (with o2 tool and ratchet). But, has to be done.

 

For sure!

 

The plan tonight is to remove the crossmember and drop the exhaust from the front flanges back to the Y pipe. Of course I have to start it without pipes for a few seconds to irritate the neighbors (as if they weren't already irritated with me) and be sure replacing the cats is necessary (though I am pretty sure, with the rattling coming directly from the driver side cat, and the several other symptoms/causes that line up).

On my DII the pipes entering and leaving the cats is not straight from front to back, and the passenger side cat is skinny and tall (instead of round). That should provide a challenge. Last time I used a muffler shop (on my old Mercedes), they used a flexible pipe, so I will probably have to go get a couple of those, but I have to look at the body mounts (exhaust mounts, I mean) first to be sure the weight of the exhaust won't be placed on anything flexible.

And I will admit that it is remotely possible that if it runs fine without the cats I may limp up to the muffler shop to let them figure it out.

I am hopeful this will finally resolve all misfire problems. Will report.

For anyone curious, the side out I referred to previously essentially involves removing the rear resonator, using a 90 degree bend, and exiting the exhaust through a new hole in the rear, driver, quarter panel with a black, metal ring around it. I just like the look (have seen it on youtube and elsewhere) as opposed to my droopy rear resonator, and the main muffler does most of the work anyway. Assuming I do the work instead of the muffler shop, I will document it in another thread.

EDIT: I have to throw another observation in that convinced me that the cats are an issue. I was idling the truck in the driveway just to see if it would throw any codes. It was idling very poorly, then getting better, the poorly. As it warmed up, I was standing next to it and the engine was bogging down to almost stop and I heard a slight hiss then exhaust sound. Almost as if I loosened a bolt at the flange. Then engine sprang to life at that exact moment and idled fine after that (with exhaust sound). It stands to reason that the pressure from the clogged driver side cat caused the exhaust to find a path through the gasket at the flange. Of course I turned it off to prevent burning the gasket or (further) damaging the engine. That is a pretty sure sign.

I finally did get a code, P1129 (o2 sensors transposed). I had to splice one connector because the one on my harness got stepped on, and I may not have a good splice. But can anyone tell me if the front o2 sensors have a left and right? If so, that's news to me, but I can't think of any other reason why that code would even exist.

 

The O2 sensors themselves are no different left to right. The front and rear are different.

Now the O2 sensor plugs on the harness have to be on the correct side. Example: You can not have the RH bank sensor plugged into the LH plug on the harness.

1) Make sure you don't have the LH and RH plugs on the harness crossed over

2)When you spliced the new plug in are you sure you spliced the correct wires together? (neg. to neg. / + to +.)

 

I'm sure the harness is correct let to right because my old harness still has all of the plastic covering intact and the o2 cable doesn't reach very far. I think the wiring of the plug splice is at fault. Unfortunately I am always working in the dark with lights that don't do the job. Also, the harness that came with engine 2 is a little different than my original harness (engine 1), which is in the truck.

It really has to be the splice. I'll figure that one out for sure.

In the interest of full disclosure I made ready to drop the front exhaust and disconnected it from the manifold and muffler, but two bolts on the crossmemeber would not budge and rounded off a bit. I usually forge ahead and tried a few things (socket and a hammer, different wrenches, vice grips, and halfway into getting rid of one with a small grinder) , but after so many consecutive nights I decided that was a sign I needed to take a break. And I am.

Best to you. I'll be back at it tomorrow... Probably.

 

I should add I am sure the harness made a difference and pretty sure the splice is weak. When I started it with the harness the o2 codes disappeared. When I dropped the exhaust down a little the front passenger o2 went offline, and that's where the splice is. I got some better electrical connectors and will double check the wiring when I can see a little better. My flashlight (pen light) is so covered with antifreeze and oil I think it is poisoning me when I have to use both hands.

 

I know about the "poisoning" all to well. LOL.... It didn't take to long before I invested in one of these "head lights" and never looked back. I love it.

 

I've got one of those but it is incompatible with my baseball cap with the LEDs in the bill. Remember, I live out in the woods of East Texas... I have to represent. Haha. Sadly, the bill doesn't allow me to glide under my oily, broken, Rover without hitting snags. That's when the headlamp or the aforementioned poisonous pen/mouth light come into play.

 

Mine is fixed. Did it in about 7 minutes.

DiscoMike has been in the hospital and called me today. I was detailing the problems and then things I had done to resolve all of the crap I have been dealing with (specifically, any throttle kills the RPMs). He said "It's your Mass Air Flow Sensor." Are you sure, I asked? "Yes. Don't you have a friend with a Rover like yours? Swap them out." That's it. Definitive. Conversation done.

So I got off the phone and told my wife "he said it is the MAF." She didn't know what I was talking about, but I continued nonetheless, "it can't be the MAF because it was working before I did the head gasket, and worked a little while after, and... oh crap."

Couldn't wait for my friend to get here...

I took my MAF off, sprayed it with some of the MAF sensor cleaner, sprayed the contacts on the cable and the MAF connector with electronic cleaner and put a little dielectric grease on them, put it all back together, and my two weeks of misery ended. Amazing. No misfires. All back to normal.

Almost...

As soon as it heated up (about 3 miles form the house), I heard a rattling sound and the SES came on... 1,3,5 and 7 all misfiring. It was running badly so I turned around. That's the catalytic converter for sure. Trip to the muffler shop in the morning and I'll be done.

DiscoMike is a mad genius. I am an idiot because I didn't check the MAF before.

I'll follow up with how it goes with new cats but I am 99 percent sure all of this boiled down to a tiny little wire that looks useless but means everything to the engine: the MAF.

So, in summary so far, I had lots of misfires and o2 codes, difficulty starting, and negative acceleration. I was in the unique position of having a bad wiring harness (made bad by me, most likely) and that had to be replaced. All of my misfires were the death of my cats and o2 sensors (again, my fault), and I spent at least a week messing with my rover almost every night, in the cold, when all I had to do was clean my MAF. I think it is absurd that a dirty MAF could literally strand you, and that goes to show the negative side of computer controlled engines. I'm ordering a new one tonight as a spare.