my car had a little engine vibration when car is cold, it was like when i start my car in the morning, the engine vibrates a little bit, and when i drive, the engine is not that smooth as usual, it still has power, but the car just feel like hesitate when i am on gas. after drive for like 20 minutes, and shows three bar on my thermostat, the car become compeletly normal, just wondering if anyone had experience on this tho? thanks for help.

also i noticed my thermostat is not very stable, sometime it drop for one bar and goes back soon.

ps: i had a vortech supercharger

i am going to change the spark plug to ngk 7173 tomorrow, hope that ll help

 

Sounds like engine misfires.

could be as simple as needing new plugs like you mentioned.

 

wait............so you HAD a vortech supercharger? why is it not on the car anymore? and how does it feel to drive a car without that after having that kinda power?? or are you still FI?

 

thanks ya@inlinepro , i ll put 7173s on once they arrive, it really sounds like misfire tho

and yes i am still withe the vortech supercharger, and the car still have power even have little vibration, after the car completely warmed up, the car is very smooth and with a lot of power

 

i have a slight misfire too i believe. sounds like we have similar symptoms, i too am vortech SC, but i changed my plugs about a week ago and the problem still exists. At idle the car kinda of hick-ups, rpms hold steady with no fluctuation, there is a bit of a very muffled thump, and the car has a mild vibration. I've also noticed it around the 3k-4k rpm range under light acceleration. no signs of any problems in open loop, accelration is very smooth and linear. but with mild, closed loop acceleration, it is not smooth and there are slight lurches occasioanly. i figured it was misfire, but im not sure since i've changed plugs. no CEL. any ideas?

 

yep, sounds like we are really similar tho...do you thing that we should probably go do a fuel service to clearn up the fuel system, i guess it could also be some dirty injector problem tho.

 

btw, what spark plug are you using right now? i ll try ngk 7173, which is one step colder than stock ones, hope that ll help, dam

 

i did switch to the ngk 7173, the problem did not get better or worse after this. oddly mine does not show any signs of a problem when it is cold and warming up. The problem only seems to happen when my car is at 14.7 a/f as indicated by my a/f gauge. During warm up and acceleration in open loop, no problems.

 

oh. not happy to hear that, but anyway, i ll switch to 7173 first.

i ll probably take it to some shop anf figure that out, cause it really bothers me. i ll let you know after

 

No check engine lights at all?