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Discussion Starter #1
the history of my problems goes as follows.

I have a 2001 hyundai lantra
The cam belt went about a year ago, so i decided to replace it. realised i had 8 bent valves so instead of replacing them i got a 2nd hand motor off a 1999 lantra, after pulling my motor out and gearbox off i found out the flywheel wasn't fitting on.... after a thousand and a half calls i found out the size of the crank was changed after 1999, so after changing my flywheel i managed to bolt on the gearbox....

i dropped the motor in and plugged her up, after alot of pissing around with the fuel i got her firing, this is where my problem is

it fires up ok, idles awesome right up to 1000rpm.... but as soon as it gets one rev above that the whole tone changes and the motor starts chugging like its wanting to cut out..... the revs just jump up and down and the rev counter looks like a yo yo just bouncing up and down.... and it just does that no matter how far down the accelerator goes.... but the weird thing is as soon as i lighten up on the pedal and it goes back down to 1000rpm it settles down and runs like a dream again

i have changed injectors, plugs,leads, power pack, all belts, re set timing, intake manifold. throttle body, cleaned out air intake components,

i guessed it might have a vacuum issue so changed the rocker cover and still no change

i have also changed the slave cylinder and master cylinder but that was because of a whole diff issue
i have run out of any other ideas apart from it being an electrical issue so if anyone has any help to give i would love the input

cheers
 

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There must be some codes stored in the ecu after all that misfiring. Can you get them read and see what the car thinks is wrong? Could be throttle position sensor, camshaft sensor etc. Maybe you can swap these over from your old motor?
 

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So you dropped in a '99 motor into a 2001? I'm surprised it works at all. The electronics are all different. How did you get all those sensor wires and harnesses to connect up?
 

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Discussion Starter #4
the only difference between a 1999 dohc 2ltr motor and a 2001 dohc 2ltr motor is very slight.... apart from making the crank on the later model lighter by decreasing the diameter of the crank size and modifying pistons to fit, and the intake manifold being slightly different.... the actual block is pretty much the same.... it has the same sensors on the block its self so it wasnt hard leaving the 2001 accessories in and bolting them to the 1999, which meant most wiring was still compatible
 

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I see.

In the US the '99 motor is not compatible with the '01. I think there is a lot of differences with the sensors.

In your case, I'd still expect that you have some sort of electrical incompatibility. Did you scan for trouble codes?
 

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Discussion Starter #6
ok guys thanks for all the feedback..... the problem was the crank sensor.... but not the sensor itself, it was the human that put it in..... i had a mate helping me, a self confessed mechanic (im sure we all have one of them) and when we first changed motors he realised there was no crank sensor on this one so he swapped it over off the old motor.....as all block heads know.. u plug it in and bolt it up so i didnt think i had to check it.... after your feedback i decided to check it and soon as i touched it, it fell out. so this whole time it wasnt plugged in or bolted up..... so moral to the story is it was my fault for not rechecking his work but now the motor runs like i dream.... cant wait to finish the body kit and get her back on the road..... thanks for the steer in the right direction guys.... saved the rest of the hair on my head :liebe011: :banana:
 
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