Will Wilton

Engine problems at 4000 revs

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Have 1999 is 200,vgc, 70,000 genuine miles..when I hit 4000 recs (overtaking ext) when vvti  usually comes in,it acts as if rev limiter (6000 recs) is cutting in?!

Have cleaned vvti filter,and solenoid,and carb..still doing.

Thought also maf sensor but told dosnt have one..only map sensor..any ideas?

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VVTi doesn't really come in at a certain point, it is variable so you don't notice it. The ACIS system does kick in around that engine speed so that is probably a good area to investigate. Possibly the VSV isn't operating, or there is an air leak in the pipework.

When you say it is as if a rev limiter is cutting in, do you mean it actually cuts in/out or is it that power is lost so it cannot accelerate?

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Hello Colin,thank you for replying.

Will take a look at the ACIS system (when stops raining..lol),check pipes ext..please educate me further..VSV?

It accelerates to 4000 revs,but no further,losing power untill below 4000 recs.

Thanks for taking time to answer..;)

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Vacuum Switching Valve. It's basically a small solenoid that allows a vacuum feed to pass through it. The output is attached to the ACIS actuator. Potentially the actuator could be leaking air, so when the VSV opens you have a air leak into the intake which causes a problem for the MAP, or the actual ACIS valve isn't opening correctly and disrupts the airflow into the engine.

This is the test procedure in the workshop manual. You don't need to use vacuum gauges, you can normal see the actuator arm moving when you rev the engine. Or join the input and output of the VSV pipes together and clamp - you can then open/close the ACIS at will, bypassing the VSV.

 

 

Screen Shot 2018-01-24 at 16.49.55.png

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Are there any lights on on the dash?

Limp mode can do this. Knock sensor problems for example, can cause limp mode to kick in. It is normally accompanied by the Check engine lamp though.


Sent from my Iphone using Tapatalk Pro

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Sorry I also you have said it could be the front pre-cats in the exhaust which have been known to break up on the IS200 and block the exhaust.

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