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Love the description :-) Posted by RS [Email]  (#15)  [Profile/Gallery]
(more from RS) on Mon, 9 Aug 2004 18:10:29
In Reply to: 1990 900s engine with tachycardia, Tony, Mon, 9 Aug 2004 17:31:03 Members do not see ads below this line. - Help Keep This Site Online - Signup |
A few questions. Some of them may seem off-the-wall, but they could lead us to a decent diagnosis.
Does the high engine speed occur at idle or does it take on a life of it's own when you're driving?
What are the conditions of the spark plugs? Clean white porcelains? Tan porcelains? Any excess wear on the electrodes?
If you're in a situation where you can stop and pull one of the plugs when you stop it after it's been racing, smell for gas on the plug.
Have you checked the connector to the NTC sensor (on the intake manifold flange between the runners for 2 & 3)? Sometimes, if the contacts in the connector are dirty, it can feed incorrect info to the ECU.
Have you cleaned the AIC valve? That's the silver unit next to the thermostat. It has two hoses going to it. Try cleaning that with carb cleaner first. You'll probably get a lot of black crud out of it. Sometimes they stick, but they usually don't stick in an open position like yours appears to do. Also, check the hoses, especially the lower one, for cracks and oil damage.
Does the Check Engine light go on when this happens?
After you stop the engine when it goes into hyperdrive, pull the plug on the AMM and see if it starts up.
Do the gas pedal or the throttle cable bind?
Is the chain on the cruise control actuator binding on anything or is it tight?
When you open and close the throttle by hand does it seem to bind on anything and does it ever stop short of the stop screw on the throttle body?
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If all of the things above don't show anything unusual, it might be possible that you have an intermittent problem with with the throttle position sensor. You'll want to check to see if it clicks just as you approach the throttle-closed position and that you have electrical continuity between pins 1 & 2 on the sensor when the throttle is closed.
posted by 66.167.50...
, Mon, 9 Aug 2004 18:10:29 <-- Viewing This Message, Wed, 11 Aug 2004 16:52:31
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