Recently bought myself a 89 xr4x4, fairly good nick, but having a bad engine problem.

Drive it fine, u till the revs get to about 4000 rpm, and it goes all hesitant, feel like it's hitting a brick wall! rev counter goes spazzy then lift off and it's fine again.

So first things first we did a service, oil plugs leads rota cap rota arm, still did it, so did the led diagnostic check, came up with 25, throttle position sensor and 31 ecu. Ecu we put down to a superchip, so we changed the tps, still did it. Have now changed thermostat and thermostat sensor, still doing it, what other problem could it be? Sounds electrical due to the rev counter but this is costing a small torture at the moment!

Thanks!




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I had a similar problem with my 2.8 XR4x4 and turned out to be a dieing fuel pump. maybe check your fuel filter and then pump.