high rpm (all story)

[toto]

Hello. I am owner of a Disco year 1994 3.9V8 manual. This car was upgraded by the previous owner with chip to 200hp without catalytic converter. 10 months ago the engine was destroyed completely. Recently I decided to put it on the road again. I bought a Disco year 1995 3.9V8 manual, that worked fine, I took out only the engine and the catalytic converter and I put them on the old one believing that my old car would now work jut fine like the old times. Now the problem is this: Without having changed the transfer box or the gear box I get high RPM with low miles (I calculate the miles always with the GPS as it is more accurate than the speedometer and thus the size of the wheels is irrelevant). With my car’s old engine I got 60m/h+ with 2.500RPM while with the new one I get 57m/h with 3.000 RPM. The (new) engine accelerates easily till 4.500+RPM with 5th gear (I didn’t try harder). I thought maybe the RPM meter doesn’t work properly but the high petrol consumption and the vibration feeling made me reject this theory. What do you think might happen if I changed the ECU? Do you have another suggestion? Also, how can I check if the Lamda (Oxygen) Sensor works or not? Any serious advice is welcome and urgently needed. :(

[toto]

I forgot to mention that since I changed the engine, I changed the clutch as well (is there a chance that my problem is bad placement of the clutch?). I have used the alternator from the new car.

[Bull Bar Cowboy]

You have done nothing that will alter the gearing, therefore either the clutch is slipping or the rev counter is reading incorrectly ……………….

As you have changed the alternator, it is probably the revcounter reading that is wrong. The rev counter is fed from the alternator, but it must have the correct size pulley to read correctly. Compare the pulley sizes of the old and new alternators ……… if they are different (and I suspect they are – the new one is probably smaller) , then change the pulleys …………..

Ian