Thread: D2 V8s are great

Sounds like a good pick up DaveA. Well done. You didn't mention the viscous cooling fan hub. It may be loosing efficiency at 150 thou and need replacing.

Originally Posted by Grumbles

Sounds like a good pick up DaveA. Well done. You didn't mention the viscous cooling fan hub. It may be loosing efficiency at 150 thou and need replacing.

Good point!

I've just ordered one from Rover Parts Plus. I'll get my mechanic to fit this whilst he's replacing the two faulty O2 sensors.

Dave, couple of things
-the penrite 10w-40 everyday oil is ideal... make sure you change it regularly as with all other brands
- the engine has 2 oxygens sensors...each is screwed into the exhaust just shy of the catalytic converter. Chnging them is a 5 min job. Once changed, the "adaptive values" in the engine management ecu software should be reset to zero. You can do this yourself if you have the app Torque Pro on an android phone. You will also need a bluetooth dongle plugged into the obdll port which is in the passenger side footwell up under the rhs of the glove box. If your mechanic fits the oxygen sensors, make sure they reset these values...

Originally Posted by Hoges

You can do this yourself if you have the app Torque Pro on an android phone. ..

ok,, what should it read if working correctly?
or,
will resetting them again do any harm?

Originally Posted by DaveA1963

I've been recommended Penrite 10W40 engine oil.... Is this a good choice?

As Hoges says,,

the thing to remember is the RV8 has flat tappetts,, so needs added ZINC,, Most of the Penrite range has this,, but not all brands of oil do----

Originally Posted by Pedro_The_Swift

ok,, what should it read if working correctly?
or,
will resetting them again do any harm?

(I) If everything is working correctly, the fuel Trim should be 1.0

(2) No, you are just resetting the values to the ECU firmware default values

Reasons:
The engine management system (EMS) ECU has a 'fuel map" in its firmware which adjusts the Air Fuel Ratio either side of a theoretical optimum of 14.6 (or 14.7) which represents the air/fuel mix for complete combustion of petrol. This ratio is often denoted by the Greek letter "lambda" and has a value of 1. The EMS adjusts the air/fuel mix depending on a range of external factors...air intake temperature, airflow through the MAF, fuel temperature, throttle opening, rpm, engine load, road speed, spark advance, and residual oxygen in the exhaust stream (from O2 sensors). Depending on demands, the ECU constantly changes the air/fuel ratio by altering the timing and duration of the fuel injection pulse on each cylinder.

for a fixed set of conditions, the timing and duration of the EFI pulse is determined from a database in the firmware. When the system goes "closed loop" the EFI pulse values for particular conditions may change as determined by the feedback from the O2 sensor... in which case, new values corresponding to actual conditions are added to the database. The default database values are "trimmed" accordingly. These new values are called the 'adaptive values' based on feedback from the O2 sensor as to how efficiently the fuel is being burned. As the system gets more data, it is continually comparing with known values and adapting the new data accordingly. On paper it is represented by a series of large three dimensional spreadsheets

Sometimes, you need a richer mix for sustained periods...e.g starting on cold mornings, sudden acceleration for overtaking... in which case the system will go "open loop" and use the predetermined values, and then drop back into closed loop for more efficient driving...

when you fit new injectors, a new MAF, a new O sensor etc they may have slightly different characteristics (due to manufacturing tolerances) which affect the burn ratio. So the system has to "learn" these new characteristics and make new changes...that's why you 'reset' the values back to the default values and let the system gradually allocate new values to achieve optimal burn ...


The android app Torque gives you the immediate/short term and long term fuel trim values. under normal circumstances they should not vary from 1 by more than 1 or 2 %. If they rise above 1 say to 8 or 9 it means the ECU senses there is a leak somewhere in the air intake and is supplying more fuel to try and compensate. If they drop below 1 significantly then there's probably a blockage somewhere causing a rich mixture. So the ECU reduces fuel flow accordingly. A faulty MAF, air temp sensor or fuel tem sensor can cause problems in this regard. These changes are flagged by the O2 sensor, which is why it's central to a properly operating system.

There's quite a lot of this stuff in the P38 forum about 6-12m ago with screen shots of the Torque app showing suss air/fuel ratios...
sorry for the long post
hope this makes sense...

What a Truly Awesome Post!

I have just learnt SO much about how EFI works!

Thank you Sir!

You're welcome DaveA...flattery will get you...everywhere!

FWIW: there are some very good explanations on the net on how all this stuff works... I find it interesting so I read up on it so I could maintain the P38..

If you can get a firm grasp on the underlying principles, then the rest is just different approaches to the same outcome (Ford vs Holden vs MB vs Audi etc). That's why in solving a generic problem you can sometimes find the answer on another forum...e.g. problems with a particular O sensor which may be used by a dozen different car companies. some clues to LR engine problems in the late 90s and early 2000s can be found on BMW forums...

SWMBO says I have too much time on my hands...but hell...a man needs a hobby