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Hello all. I am having problems with my 2001 Land Rover discovery 2 4.0 liter v8. My head gaskets went out about 2 months ago and I bought a kit and put all new gaskets in the rover. It’s running great but my catalytic converters we’re glowing bright red so I ordered a new full system and installed it. It’s running really good. No misfires, no stumbles, no nothin. The only problem is that my catalytic converters are still glowing red after about 5 minutes of running and I have little power. Can’t go more than 10 mph going up a hill. Read a couple forums saying it might be the coil pack or my engine is running too lean?? How would I adjust the motor so it’s not running lean anymore?? Any suggestions? Been working on it for 2 months no to no luck. Just need some help now.
 

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Hello all. I am having problems with my 2001 Land Rover discovery 2 4.0 liter v8. My head gaskets went out about 2 months ago and I bought a kit and put all new gaskets in the rover. It’s running great but my catalytic converters we’re glowing bright red so I ordered a new full system and installed it. It’s running really good. No misfires, no stumbles, no nothin. The only problem is that my catalytic converters are still glowing red after about 5 minutes of running and I have little power. Can’t go more than 10 mph going up a hill. Read a couple forums saying it might be the coil pack or my engine is running too lean?? How would I adjust the motor so it’s not running lean anymore?? Any suggestions? Been working on it for 2 months no to no luck. Just need some help now.
It could be your cats are plugged. If you live in a non-emissions testing state register your plate there and install a pair of all-flow cats (fake cats). That solves your cats if it's the cats and you don't have to deal with them anymore. P.S. you assume risk of getting caught. I talked to a police officer in Las Vegas (long story) and he said they are giving out allot of tickets to "loud muffler guys" and "straight pipes" I thought it was a Federally enforced thing only. But the officer said they have the authority are doing it because of all the complaints i.e these kids getting a 4 cylinder POS lower it and straight pipe it with a loud muffler when it's beyond obvious a 1999 Toyota turcel doesn't have a V12 engine.

I had engine running rich problems and changed all 4 O2 sensors (BOSCH ONLY) and it solved it. but yours is lean and you didn't mention any codes. If it's your coil packs I don't have any knowledge of coil packs because I always use the most expensive fuels so mine have never needed replacement. If you want to use the lowest octane to "save money" your going to get less MPG and have more problems in the long term on Early model Discoveries.
 

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Discussion Starter #4
I already replaced my cats so it’s definitely not that I don’t think. I will have to try to get some new o2 sensors and see if that helps. No I haven’t had codes read. Planning on doing that tomorrow.
 

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the first $200 worth in parts that you throw at it, probably won't fix it, just like your new cats didn't.

invest in an LR friendly code scanner, it's the first step toward resolution unless you have limitless money to throw limitless parts
 

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It must be setting codes.
Lean could be a vacuum leak (something not sealed properly when heads were done (intake, plenum, vacuum line etc.) firing order mixed up is common as well
Codes are surely the place to start
Report the codes and we will try to help you out.
 

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Discussion Starter #8
Thanks for the help guys, I got an obd scanner and I’m gonna test it tonight. I’ll update you guys when I get that done
 

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not any old OBD scanner will suffice, you'll need one that can communicate and pull codes from the various computers in the car

a great budget tool is the foxwell NT
 

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P1510 - Idle air control (IAC) valve opening coil - circuit malfunction = Wiring, IAC valve

though this fault would not cause hight EGT like on your's, if you used some cheap generic OBD2 reader it can be irrelevant cos the LR protocol is not 100% OBD2 compliant
 

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i was having an issue with my disco and the CEL, i had the code pulled with a generic scanner by the guys at the auto parts store, and it came back as purge valve. replaced the valve, cleared the code, and the light came back promptly.

pulled the code with my foxwell again, and it indicated secondary AIR fault. replaced a hose and all good.

it really boils down to using the right scanner which can interpret your LR correctly.
 

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Discussion Starter #13
I see. Well so far I looked up a wiring diagram for the iac valve and I’m supposed to have 12 volts to both outside pins on the connection and I do not. Im not pulling anything. I’ve been tracing the wire for a couple days now to no luck. I don’t know what’s wrong. I’m also pulling a p1553 code. Read that if the iac valve is not functioning properly it wouldn’t rev past 1100 rpm in gear, which that’s exactly what’s happening. Was thinking the iac valve was busted but then I found that the pin had no power. I’m kind of stuck right now.
 

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I see. Well so far I looked up a wiring diagram for the iac valve and I’m supposed to have 12 volts to both outside pins on the connection and I do not. Im not pulling anything. I’ve been tracing the wire for a couple days now to no luck. I don’t know what’s wrong. I’m also pulling a p1553 code. Read that if the iac valve is not functioning properly it wouldn’t rev past 1100 rpm in gear, which that’s exactly what’s happening. Was thinking the iac valve was busted but then I found that the pin had no power. I’m kind of stuck right now.
What code reader are you using?
 

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I see. Well so far I looked up a wiring diagram for the iac valve and I’m supposed to have 12 volts to both outside pins on the connection and I do not. Im not pulling anything. I’ve been tracing the wire for a couple days now to no luck. I don’t know what’s wrong. I’m also pulling a p1553 code. Read that if the iac valve is not functioning properly it wouldn’t rev past 1100 rpm in gear, which that’s exactly what’s happening. Was thinking the iac valve was busted but then I found that the pin had no power. I’m kind of stuck right now.
1. It's not supposed to have 12V on two pins only on pin 2(brown/orange wire), the others are PWM signals on the earth path

2. In your first post you said that it's running OK just that the CATs are too hot nothing about 1100rpm in gear... though the IACV has nothing to do with that either download this https://www.sugarsync.com/pf/D8700125_05791262_29831# and read what the IACV does if you want to DIY

you was told twice to use a dedicated scanner not generic OBD2 reader so i say again the D2's EMS protocol is not 100% OBD2 compliant , maybe you are chasing ghosts based on that generic OBD2 reader
 

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Glowing cats usually means unburned fuel is reaching them...from running rich. As others have said, get a code reader or have the codes read. I’d suspect the MAF, could try cleaning it but they are consumable, and not too expensive...get a Bosch online for under $100. Depending on the age of the O2 sensors, it wouldn’t hurt to change the upstream pair...avoid no-name sensors. IAC valve won’t cause cats to overheat.
 

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Discussion Starter #18
Thanks guys. I’m going to try to find a good obd reader for it. I fixed the problem with my cats getting hot. That’s not happening anymore but I still have no power. I read what you said about both puns on that iac valve connection not being powered. Thank you. I am going to try to jumper that connection as I can’t find the problem with that. I will update you if it works.
 

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So what was the fix for the cats glowing red hot????
 

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Is your IAC valve buzzing when you turn the ignition key to the 2nd position?
If it is buzzing...Spray clean the MAF sensor, spray clean the throttle body/plate and spray clean the IAC valve and tubing.
Reinstall, clear codes and go for a run. Report back.
 
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