I have a 1999 VR4 which has a huge cough after about 2 seconds of full accelleration. It just dies for a 1/2 second and then kicks back in again? Mitsi dealer says ??? no fault codes showing so can't fix it!! Someone has suggested an overboost problem but does anyone else have any idea where to start on this one??
Ashdann,
My Australian 4G63T Starion had the same problem. It turned out to be a hole in the diaphram of the vacuum advance on the distributor. Under turbo boost it was forcing air/fuel mixture through the hole and into the distributor cap. This would then explode in the cap and unsettle the timing sensor in the distributor for a second or two (causing the huge bang/cough). Very embarrassing when overtaking. From memory the VR4 is also a turbo with a distributor. Replace the vacuum advance unit.
TDM
Wow! All of our 4G63 motors are distributorless ignitions. The ECU controls advance based on airflow. I think all of the "modern" VR4's are V6 motors aren't they?
The 4G63 VR4 cars in the U.S.A. are rare and have a cult following.
He has an earlier version of the same engine. It has been around for a while. It's like saying "my 305 yadda, yadda".
To original poster: It sounds like fuel cut. It should feel like hitting a brick wall under full boost. What kind of boost are you running? Are you running bigger turbos? I would check the vacuum line going to the waste gate acuators, if you're stock.
My Mitsubishi Cordia Turbo does the same thing. Could be the same problem as yours so I'm interested to know if you solve the problem.
Are we checking for leaks or blockages?
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