I own a 99 disco2 v8 and did not pass my emissions test. I started digging into this problem by reading the rave in the emissions chapter. The p0174 and p0171 codes which in my copy of the rave indicate rich limit exceeded. Does that mean "and it is still lean" so I am giving you code 174 and 171 instead of 172 and 175

I expect codes p0172 and p0175 if it were lean.

Most of the talk on the forums centers around mafs and pre cat o2s. The vehicle runs good at this point no stumbling or hesitation. Checked for vacuum leaks anyhow and of course there is no good place to plug in a vacuum gauge. I can stall out the vehicle with my hand over the intake and I don't hear any whistling noises from hoses.

This all started when the vehicle did have several occasions of stumbling. Seemed to clear itself up. I do not drive the truck often enough maybe or bad gas. Runs good right now but maybe need to drive it more than the 500 miles I have driven it because of the next problem.

I have three not ready conditions (evap, cat, o2s) and laughed when I saw the 17 steps to get the monitors into the ready state. Give me a break. If the 500 miles of over the road and around town driving is not making these monitors ready then they are broke.

If anyone understands why the monitors don't come ready let me know. My simple understanding is most of them have a component that failed but the system is not telling me which component. I am guessing that the P0171 and P0174 have nothing to do with the evap system but maybe they do. No other codes.

 

Make sure your O2's are tight, leaking air can mess up the mixture.


Willie

 

It's on both banks so I would suspect the maf

 

I agree, there is a good chance it will be the MAF. Go drive it really hard, lots of full throttle excelerations from stop lights, try to force it to throw the code that is causing the 2 lean codes, then get back to us.

 

i agree with mike if you dont have any vacume leaks then you have a bad maf sensor

 

Thanks for all your help and suggestions. Are all the codes available for this condition readable with a standard obdII scanner? I was wondering if I should bring it to a friend with an autologic scanner. I assume a test book would see more information but I assumed that all the codes related to emissions and the engine would be available via standard scanned.

Going out to stomp the gas on the truck. Will get back with you.

Again thanks.

 

What do you mean you are going to stomp the gas??
All scanners will give you the fault code numbers, not all will give you an accurate interpertation but there are plenty of places to get the Rover code readings.
So per your codes, you are running lean on both banks, could be a vacuum leak or a MAF.
If it is not running bad, drive it for a bit and see if any additional codes show up that will help you better find the problem.

 

I was experiencing a lot of the same codes plus traany ratios, etc. when I bought mine. This is my first Rover and I was freaking out overanalyzing the issues. I followed suggestions from members on the board and bought a new MAF (around $230 from Atlantic British), reset the codes with a $50 scanner I bought from Autozone, and it has run great w/ no check engine lights for over 1500 miles. I am now a convert to these strange vehicles.

Steve

 

That is why I am waiting to see if his truck throws any additional codes like the 733 or 734, then it is 100% for sure the MAF has failed.

 

Stomp it or wot accelerations. Hope that answers your question marks. Anyhow the truck pretty much acted the same. I started looking at plugs and other items. On the bottom of plug wire 4 guess what I saw? Its cracked. Checked a couple of forums and either 4 or 7 or both. Whats up with the coil and wires. All I see are buy magnacores? The coils wires and plugs were replaced at 75 along with the heads now reads about 105. Certainily the wires are as good as the 75 K plugs wonder why those specific wires failed like others did?

Anyhow will change wires and plugs and see what happens. I did get a code on these last year and thought it was bad gas. I did not last long and then I never saw it again. Is there a chance again that codes are being logged that are not avialable to a simple code reader.
The rave indicates that all P codes are avilable. Are they? I still only have the p0171 and p0174 and the plug wire looks terrible. I will mist tonite and verify arcing.