Hey everybody, This thread has been amazingly helpful on several issues that i have had since i bought my disco last year, and i like to thank you all. but now i have one that stumps the heck out of me, so ive joined to ask for help. Ive been looking around this thread for a while and i can't seem to find any help related exactly to the problems i am having. If anyone can help me please let me know

I have a 2003 Discovery hse with 110,000 miles. i have been having the problem of running rich, extremely rich. Black tip exhaust. I get about 6 miles to gallon and cannot figure out why. The odd thing is that the engine is throwing absolutely no codes/light up at all. Ive replaced the plugs, wires, o2 sensors, engine coolant temp sensor,(just did thursday 12) I even had the ECU replaced. Since i am getting no codes at all and im just lost absolutely. Thank you again for your help. also im not seeing any leaks besides oil.lol

 

Here are some ideas. Sounds like you may have a couple of things that add up to the problem, but none of them on their own is enough to toss a code for that single item.

1. By no codes, do you mean that check engine light does not come on, or do you have your own scanner (a code reader that can also read live data)? Engine light could be burned out/painted over/removed.

2. If you have access to a scanner, are data points related to fuel and temperature (a.) reasonable [coolant temp actually warms up, etc.], and (b.) not "frozen" [values should change, not be steady and constant - O2s should change - if they did not change, why would they be monitored in the first place]? One temp sensor is the IAT, part of the MAF, shows how cold air is, should change.

3. Oil separator in passenger side valve cover - pull off vac line to plenum and remove separator and clean. Can impact vacuum system.

4. Throttle body and MAF sensor clean with CRC or similar solvent made for the purpose. MAF should be cleaned when stone cold.

5. Air filter. Air intake clogged with trash.

6. If coolant temp sensor was replaced, does the heat gauge work (come up to 9:00 position on warm up)?

7. SeaFoam or BG44K induction cleaning. And some in the tank to deal with injectors. But all injectors being stuck partially open is not logical.

8. Timing (advance) should also change on your scanner.

 

Tire condition and pressures can also affect your fuel economy. It wont cause you to run rich, but wont help the situation of you are already running like crap

 

Also, think of it this way - you are running rich, with no codes, because the ECU thinks whatever set of information it is acting on is correct. So if something like your thermostat is stuck open (or removed, if you just bought it and PO had a HG problem), and truck does not warm up, the ECU is still sending more gas because it thinks you moved to Nome, Alaska. The data reading scanner can tell you a lot of things, and sometimes you have to look for what is out of place.

 

thanks for your replies, and help

in relation to 1. i do not have a scanner, i am going Monday to have the engine scanned and get a definitive answer. The engine light does work and is still installed. At vehicle start up it goes light on then goes off.

2 and 4. I remember reading that cleaning the MAF can damage it. should i just buy another one and have it installed. Is it possible to change the IAT without messing with the MAF entirely . Or should i just get a new MAF and put it on.

5. Air filter is new i will clean out air intake tho.

6.the heat gauge does move to correct position.

7.8.3. im am just lost. im not very literate when it comes to land rovers or engines. all i know is just from fixing what i have to so far. what would Seafoam do and im sure i can find a link to administer it

i get what your saying about it running open. i just wish there was a code i could go off of. thanks again for the advice if you have more or know any other option please let me know

Dgi thanks for the advice i do try to keep the air pressure right i found that the hard way lol.