Hi all, after a little advice. My car was running great until a few weeks ago when the Engine management light came on while moving through traffic slowly. I took it to the garage and was told Inlet Manifolds need replacement as its comon but in checking the codes the light went off.

It stayed off for about 50 miles, and I used for local driving over a number of short trips but yesterday the light came on again, in similar traffic situation. This time I got a family friend to borrow a reader from work and the code was P0175 System Too Rich (Bank 2). Checked everything else and no errors displayed. Hes cleared the codes and did a quick road trip and all values seemed fine.

Car runs fine even with the EML on. I would have thought inlet manifold problems would cause too lean results? Would a good first place to start be replacing the MAF sensor.

(FYI, not sure if it shows in the Sig, but the car is a 2005 4.2 Supercharged Range Rover)

Thanks for any advice

Hi,
Ill think between the SC and cilinderhead in the inletmanifold there is overpressure.
There is the SC for right?
Maybe the rubber gaskets?
Piet

Outlet pipe of the SC. Chech the rubber connections.
And maybe the coolers around the inlet manifold on the cylinderhead?
Or one of the CO sensors in the exhaust.

Inlet manyfold

Click image to enlarge

thanks for the information and images. what Im confused with, is why, given the code is running too Rich, it could be a gasket or seal and why it happened when it does.

I would have assumed if it was a gasket/seal, they would go when under heavy acceleration, especially since I did drive it under heavy acceleration between the original reset and when the error reoocurred rather than idling and moving through slow traffic? Also wouldn't they show a running too lean code for too much air?

Not sure where to start now. Is it easy to get to the inlet manifold and supercharger outlet pipes?

Yep, easy. Just pull up the top engine cover. The alu body in the middle is the SC. On both sides you see the rubbers.
Numbers 2 in the drawing. Maybe you can hear the leak?
If one is leaking over there the air pressed in the engine is less on one side and with the the same amount of fuel the mixture is richer than.
But you can also try to disconnect one of the OC sensors at the time, and look wat happend.

Ah great, Ill take a look when the weather clears! Thanks

So while we had good weather, Ive checked those seals and they seem fine. I had a check of all the pipework and everything seems fine. No Engine Light is on yet so cant read any problems.

I did check the battery and its only reading 12.0v so put that on charge but cant see that being the problem or the fault wouldn't happen 10-15 mins into driving surely?

While checking the seals, I took the oppertunity to take a look at the air filter and MAF and did notice a lump of dust covering the MAF. Remove and cleaned the sensor while I was at it anyway and the car seemed a bit more responsive when I took it up the road to test.

Ive also read on another site a can of BK44 fuel cleaner can help, and given Ive done 105k, don't think it would hurt so that can go in tomorrow before I fill up. Ill let you know how it goes over the next week or so and if it comes on, compare battery voltage and check the O2 sensors. Thanks

If you have a boost leak the car will run rich, as the maf will measure air that doesn’t make it into the cylinders and add fuel for the calculated volume which obviously will be off and the car will run rich.

Makes sense and the possibility the problem is at the Manifolds exists by that logic, I just wondered why the EML would come on when in traffic, after about 50 miles and not while under heavy acceleration or high speeds or not straight away.

ok, so the light has returned after 150 miles or so and its picked up rich running on Bank 2 again. It came on while sat in traffic and getting warm so presuming it is the manifold suggested thats warped slightly under the heat.

Its raised a couple of questions, firstly I notice the car has Air Intake Manifolds that are quite smaller and the larger main inlet manifolds. Presume I need to get them all off and fit all new gaskets? Which do I need to get refaced though?!

how easy are they to get off? Just trying to determine if its something I can do with a friend or best leaving to the garage if its a PITA?

Also, are all the manifolds the same on the 4.2S/Cs? I ask, as I presume I'll need to get them refaced, but thinking it may be easiest to buy a set off ebay, then send them to get refaced so the job can all be done in one go?

Anything else worth changing while the inlet manifolds are off?

Thanks for any advice as always

anyone able to help?