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2003 Discovery 2 SE7
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Discussion Starter · #1 ·
Two days deep into replacing the plug wires on my D2 (talk about a nightmare). In my efforts to remove the upper intake manifold to gain access to the back of the motor, I have mangled the SAI piping above the exhaust manifold beyond repair. New ones are expensive, and used ones are seemingly nonexistent (presumably because everyone mangles it). Even if they were cheap, it still makes this engine a royal pain to work on, so I ask the question: is it possible to remove or bypass the SAI entirely?
Probably 10 years ago, when my dad still had his 100-series Land Cruiser, the SAI broke, and instead of spending an absurd amount of money to fix it (I think the Toyota dealer wanted $4,000), he spend about $100 on a little electronic box that got plugged between the harness and the SAI pump that shut off the CEL and tricked the computer into thinking all was well. Is there something similar for the D2, or a different way I could get rid of the SAI?
It seems to me that all I need to do it cap off the holes in the head and trick the computer into thinking the system was working properly. Earlier versions of this engine didn't have an SAI system, so it doesn't seem to be there for anything more than emissions. I'm not concerned about legality - in my state, as long as the truck doesn't throw any codes, you pass no problem, and my dad got his Land Cruiser through emissions with that little box for 6 years or so before the rust got to it.
Anyway, if anyone has any experience with this or any suggestions, I'd love to hear about it. I will probably end up having to buy a new SAI setup, but I figured I'd ask before spending all that money and having to deal with having it always being in the way.
 

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I know it's opposite of your request, but if my pack-rat tendencies haven't let me down, I should have a spare set of SAI tubes in my garage along with an air filter cap.
 

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2000 Land Rover Discovery 2 & 1994 RRC County LWB
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From my understanding you would need a non sai ecu to do this right and this might cause other issues in your Rover. Unless you don’t have safety where you are and they don’t care about a check engine light, you might have to replace that part. I’ve been searching for a way to remove mine without the check engine, but to no avail or at least not a proper way with a delete kit.
 

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Discussion Starter · #4 ·
I know it's opposite of your request, but if my pack-rat tendencies haven't let me down, I should have a spare set of SAI tubes in my garage along with an air filter cap.
Keeping a spare set around is a good idea - it seems Land Rover tasked their engineers with creating the thinnest, most failure-prone tubing possible instead of coming up with a solution that was actually going to hold up if removed. Land Rover never fails to disappoint with comically poor engineering choices. Still love the thing, just wish it was built better than a middle school shop project.

From my understanding you would need a non sai ecu to do this right and this might cause other issues in your Rover. Unless you don’t have safety where you are and they don’t care about a check engine light, you might have to replace that part. I’ve been searching for a way to remove mine without the check engine, but to no avail or at least not a proper way with a delete kit.
Sounds like more trouble than it is worth. Oh well - figured I'd ask. My state has no safety inspections, just emissions testing, which consists of some guy at the local garage plugging a cheap OBD2 scanner in, making sure there are no engine codes, and collecting your $20. If you fail (have the CEL on essentially), you can't renew registration until it passes. That's the only reason keeping me from ripping the whole thing out. If I can't do it without a check engine light, I can't do it at all. Sounds like I will be replacing my SAI tubing. I did manage to salvage some of the important parts of the tubing, so I might try to fabricobble something together before I give in and buy a new set.
 

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Discussion Starter · #5 ·
Since I mangled my SAI tubes and want to drive the truck while I wait for parts or attempt to fabricate something, I decided to attempt to delete the system myself. I unplugged the pump, taped off all of the open vacuum lines, and plugged the holes in the head by cutting the nuts off the SAI pipes, and putting a piece of sheet metal in between the nut and the stud on the head, in the same position as where flange on the pipe would be, sealing it off. It's kind of hard to explain - I'll get pictures up tomorrow, but it essentially makes it function exactly the same as a non-SAI head. Anyway, after doing all of that, and having essentially no SAI left on the motor (except some sealed-off tubing behind the motor and an unplugged pump), and driving the thing over 30 miles, I still have no check engine light, and it runs perfectly (better than before, but that's probably because it has new plugs + wires). I don't get it. Wouldn't having no SAI to speak of throw some sort of light/code?
I'll be driving it like this until a light pops up, and will be sure to update if (more likely when) something happens. In the meantime, I'll get some photos up of what I did.
 
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Discussion Starter · #6 ·
Got a code and associated check engine light. No surprise there - guess it needed a couple key cycles to figure it out. Codes P1415 (Secondary Air Injection System – Malfunction Bank 2 RH (Insufficient SAI flow during passive test)) and C0312 (can't find in the RAVE). I'm not worried about it. So for anyone who doesn't care about a check engine light and wants to get rid of the SAI, here is what I did.

92411


92410


I unplugged the SAI pump (you can just remove it - it is serving no purpose right now. I kept the pump, its associated tubing, and the crossover tube behind the motor in the truck for when I go back to SAI), and taped off all of the open vacuum lines from where the valve was next to the head (see top picture). To seal off the holes in the head where those thin tubes attach, I cut a circular piece of sheet metal and placed it between the nut (which I cut off from the SAI pipes I mangled) and the stud in the motor (see bottom pic). It runs and drives quite well like this, you just have a check engine light. If there weren't emissions testing in my state, I would keep it like this and remove all of the other stuff (pump and crossover tube). It makes the engine so much easier to work on, and costs no money, as you don't have to swap to non-SAI heads or anything if you do it like I did.
I will be switching back to SAI at some point unfortunately because of emissions testing in my state, but this is an economical way to get rid of the SAI if you don't care about a CEL and live where there isn't emissions testing.
 

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Discussion Starter · #7 ·
Also, does anyone know how the computer knows that the SAI isn't working? Is it just looking for resistance across the pump leads or something else simple like this? Could I just solder a resistor between the two pump leads and get rid of the CEL, like you can do for an airbag light? There isn't anything electrical to the system besides the pump as far as I can tell. I'd love to be able to figure out how to get rid of the system for good with no CEL.
 

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Noooo! I was holding my breath trying not to jynx this! I really wanted it to work, I want mine out so bad and that crappy pump noise at start up sounds like a blow dryer under the hood. As far as I know it is off of resistance but I’m not entirely sure how you’d go about tricking it, but you’d be a baller if you found out how and sold us simpletons a kit to delete ours :ROFLMAO:

Now I’ve heard it’s technically illegal to remove and honestly I can’t see anyone giving a $#!% about it, but if you came across a stickler, you could get fined from my understanding. IMO the juice is worth the squeeze:LOL:

Read this, it looks like the guy kind of found a way to trick it and when you can’t you can just clear the codes, but for the most part it seems his doesn’t come on unless there’s specific circumstances.
 

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Discussion Starter · #9 ·
Noooo! I was holding my breath trying not to jynx this! I really wanted it to work, I want mine out so bad and that crappy pump noise at start up sounds like a blow dryer under the hood. As far as I know it is off of resistance but I’m not entirely sure how you’d go about tricking it, but you’d be a baller if you found out how and sold us simpletons a kit to delete ours :ROFLMAO:

Now I’ve heard it’s technically illegal to remove and honestly I can’t see anyone giving a $#!% about it, but if you came across a stickler, you could get fined from my understanding. IMO the juice is worth the squeeze:LOL:

Read this, it looks like the guy kind of found a way to trick it and when you can’t you can just clear the codes, but for the most part it seems his doesn’t come on unless there’s specific circumstances.
You and me both. I hate this system with a passion. The pump sounds like a woefully imbalanced, nuclear-powered hairdryer on steroids - you could wake people up in a different county with that thing. As for the legality of it, technically "emissions equipment tampering" is punishable by a decently large fine ($2,500 federal on top of whatever your state charges), but that assumes someone finds about about what you did and reports it to the feds and/or local gov't. Like you said, I don't think anyone would care, assuming they found it at all. I like those odds - certainly worth the slight risk IMO.

Thanks for the thread. Sounds like I have some messing around to do with my truck to see if I can get this light off for good. For now, I'll try clearing the codes and see if they come back - one of the posters in that thread said he drove his truck over 500 miles, and the light didn't come back unless he pulled the battery (which in my experience also resets the emissions drive cycle counter).
 
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Discussion Starter · #10 ·
Cleared the code, and the check engine light came back on at the next cold start - no real surprise there. Doing some research, it seems as though actuation of the SAI system is determined by the main coolant temp sensor, not the secondary one (only there to tell if the thermostat sticks?), so messing with it is out of the picture. If I can't keep the system from attempting to turn itself on, I have to figure out how to keep it from sensing that something is amiss. I would think this has something to do with that vacuum control valve mounted to the right side of the intake, as there isn't any other electronics on the system from what I can tell. It looks like this valve is what controls the actuation of the larger SAI valves that connect the pump with the exhaust. I wonder what happens if I clear the codes and unplug this valve (capping all open vacuum lines of course)? Looks like I'll be doing some more experimentation, as well as research on how the system senses something is amiss in order to try to trick it.
 

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Cleared the code, and the check engine light came back on at the next cold start - no real surprise there. Doing some research, it seems as though actuation of the SAI system is determined by the main coolant temp sensor, not the secondary one (only there to tell if the thermostat sticks?), so messing with it is out of the picture. If I can't keep the system from attempting to turn itself on, I have to figure out how to keep it from sensing that something is amiss. I would think this has something to do with that vacuum control valve mounted to the right side of the intake, as there isn't any other electronics on the system from what I can tell. It looks like this valve is what controls the actuation of the larger SAI valves that connect the pump with the exhaust. I wonder what happens if I clear the codes and unplug this valve (capping all open vacuum lines of course)? Looks like I'll be doing some more experimentation, as well as research on how the system senses something is amiss in order to try to trick it.
Make one giant vacuum loop by linking it all together, it’s too stupid to figure out what’s happened :p
 

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Discussion Starter · #12 ·
Make one giant vacuum loop by linking it all together, it’s too stupid to figure out what’s happened :p
Lol that was my thought too. Unfortunately, at least in my prior experience, confusing the computer usually results in it vomiting out a CEL. I'll try it anyway though - why not right? If that doesn't work, I'll keep trying other things. Hopefully something works.
 

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Discussion Starter · #13 ·
Alright, you are never going to believe this. I tried unplugging the vacuum control valve on the side of the intake and clearing the codes a few weeks ago - CEL came back at the next start. So I kind of gave up, and since emissions testing isn't due on the truck for at least another year, I decided to just deal with looking at the light while waiting until the last minute to do anything about it. So anyway, after work today, I fire the thing up, and the CEL is GONE! No more lights on the dash. I haven't done anything differently, cleared anything, or changed anything. It just went out by itself. I have no idea why this would happen, but it's gone, and I still have no SAI installed to speak of. I haven't checked to see if there are any stored codes, but I highly doubt it considering there is no light. Super weird. I might bite the bullet and pay the $20 to go through emissions early just to see if it will pass or not - I'm too curious. It makes no sense whatsoever, and I'm super baffled, but the light is gone. I'll let you know if it comes back, and I'll scan the computer to see if there are any stored codes in the system.
 

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Can you see the CEL at ignition self test ?
 
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Discussion Starter · #15 ·
Can you see the CEL at ignition self test ?
Yup! CEL comes on at self test when the ignition is turned on. It goes out once the truck is started. So the bulb isn't burned out or anything. Everything seems to be working properly. The light hasn't come back after three driving cycles since it first went out yesterday, either. Very strange.
 

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Discussion Starter · #16 ·
Photos of the CEL, just to make sure I'm not missing something.
Ignition on, right before starting the truck:
92511

After starting the truck:
92512


That was a cold start at 33 degrees ambient. At these temperatures, the system certainly should have kicked the SAI system on, but the CEL remains off.

The more I dig into this, the stranger it seems. Scanned the computer today with my Foxwell NT630Plus. Here's what it spit out:
92510


When the CEL was on before, two codes showed up under the "Pending Trouble Codes" section - P1415 (SAI related error - only this one bank for some reason, not both) and C0312 (not a clue what this means - can't find it anywhere). This was before, with the CEL on.

Now, after the CEL turned itself off, the unknown C0312 is gone, and under the Pending section, P1415 shows up, as does a new unknown code - C0712. However, this time, yet another unknown code - C0313 - showed up under "Stored Codes" (BTW, if anyone knows what these C codes mean, I'd love to know). And yet there is no more check engine light. I am super confused at this point. The codes are all still there, more or less (3 total, but main screen only shows 1?). Why isn't the light still on?

Stored trouble codes:
92513


Pending trouble codes:
92514
 

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Is this rover still running ok with no sai? I need to fix a head gasket and am thinking of replacing the heads with non sai heads...

Thanks
 

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Discussion Starter · #19 ·
Yeah it’s been running exactly the same with no SAI. Just have an intermittent check engine light - it comes and goes seemingly for no reason (on most of the time, but will shut off for a week or so and come back). I forgot to put the SAI tube behind the engine back in last time I had the intake out, so I took the pump completely out as well. I’ll have to put everything back in once it comes time for emissions testing (unless I can figure out a way to trick the system). As long as your state doesn’t do emissions testing (and you don’t plan to sell it to someone in a state that does), by all means go with non-SAI heads. I would personally do what I did and cap off a set of SAI heads in case you ever want to sell it for whatever reason (most states have some sort of emissions testing, so it will greatly expand your possible list of buyers), but if you don’t care or plan to keep it forever, then go for it.
 

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I don't have emissions testing where I live. I have a few non sai parts cars. I was thinking of pulling the ecm and swapping them. Have you tried swapping the ecm? Here's a picture of the vehicle I'm working on...
92773
 
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