Hesitant Rover Disco II

[SPODONAHUE]

Greetings all!
I have a 1999 Disco II, about 107k miles and in the past month I have had this feeling that when going from full stop to about 20mph or so there was some serious hesitation in the Rover. The inital feeling is that you step down on the gas, the RPM climbs, flattens out (so does the power) and then a split second later boom back to where it should be. All this happens in about 3 seconds or less, and is random --I cannot get the problem to repeat on demand. About 4 months ago I went through a major string of bad luck with the dealer (Land Rover Portland Grrrrrr... bought it “certified” at 38K, but that's a whole n'other story) and have been going to an independent Rover mechanic ever since. In the month of July '05 I had ALL the O2 sensors replaced (twice, yep 8 total), a full head gasket job, new plugs, new wires, new ignition coil, new Mass Air Flow Sensor, new drive belts, new Throttle Heater Plate, breaks, and a new battery. The Rover was running pretty good up until the last few weeks, and with the head job I'm pretty sure that I'm "carbon build-up free". This evening I had the same hesitation in the Rover and heard a faint "click" then boom off to full power though there is a slight feeling of underpower-ness when on an incline that was not there before. With the Rover doing the hesitation I'm the one now doing the hesitation and not jumping out into traffic as I used to.
Before I go back an bleed at the mechanic again I'd like to have a better understanding of what others think. I'm not a mechanic, just an Architect.
Cheers,

 

[tuxigezu]

Hi

I have a 10 year old disco with 99000km. It is a 300tdi. I must say that it has quite a bit of hesitation as well. I believe that it is reaonable to see a change in performance from 38k miles to 107k miles. The vehicle is significantly older . 107k miles multiplyed by 1.6 is 170000 kms this is nothing to sneeze at.

There are many reasons why it could hesitate. Eg engine tuning . Gearbox drive train backlash,auto transmission oil level, dirty fuel filter, dirty air filter,dirty injectors, dirty fuel, poor performing fuel pump and the list goes on.

I am a mechanincal tech and I usually service my own cars. As a general rule start with the cheap things first.(fuel and air filters) Get a friend to help you if you are not sure. I have a great deal of faith in both the vehicle and the engineering behind it. It pays to narrow down the symptoms yourself before going to your mechanic and handing over your cheque book. The mechanic does not have a crystal ball and will do the same thing narrowing down the symptoms. If you are not sure you really have a problem sometimes it is better to wait until the fault becomes self evident. Its your money. Be very pointed about questioning the mechanic. "How do you know my O2 sensor is playing up, have you done the diagnostic to find out?"

Best regards

Tuzigezu.

 

[SPODONAHUE]

Thanks for the info, the day after your post the check engine light came on. I took the Rover into my mechanic to pull the codes (2 codes can't remember what they were) and it came back "running rich". It was suggested that, after all the work ($) I had done (see earlier post), I should start with the basics. We pulled all the air filters, replaced them with new ones, and re-set the log for codes. I just got back from putting about 600 miles on the Rover with no codes. My question is this, will the Rover "re-code" if it is still running rich or will the current level of O2-to-fuel mixture have to exceed the previous level for it to code again?