VK EST Problem

[RayRay07]

When accelerating in the VK, the engine is missing and backriring.
i think it has something to do with the EST sensor/s, when the car is backfiring the EST light in dash is off and and after giving it an airleak by unplugging the EST sensor, it runs normal when the light is on. what does the EST sensor do and its purpose? Could it be faulty? What other things could be causing it? ive got no idea about the electrics of the engine. also i have the new little black coil, the bosch one, could that be a problem?
thanks

[Tom_1569]

The EST is electronic spark timing, it uses all those unreliable sensors to tell the dizzy when to make spark. Suprisingly it runs at all when you think about it lol. Nah I have the EST still in mine, and once nutted out its not a bad system. I would be against T (from oldholden) in scrapping it, and only scrap it for a blue HEI as a last resort.
Have you tried to get the codes from the comupter? If you dont know how to do this, let me know and ill right it up tonight when im home.
When the light is on, it should run like ****. The light is to indicate their is something wrong within the EST system (most of the time its actually the sensors stuffed rather then them sensor detecting something wrong lol). The EST system will activate limp mode when it indicates something wrong, and as far as i know is the only time the light should come except whilst cranking. When limp mode is activated it retards the timing so much that it sound like its running on 1 or 2 cylinders. It runs like **** and is really hard to drive, aswell as uses a heap of petrol (dont drive in limp mode unless you have to).
Also when you replaced the coil, did you get the one for EST or for a HEI as the HEI one is different, i dont know how much difference this will make if at all.

[RayRay07]

ok, its coming abit clearer to me now, as for the codes from the computer i havn't a idea. ive done all i can do within my knowledge of the engine. if thats how the EST light in supposed to work then theres definetly something wrong with my engine, because its the total opposite, when it starts it runs like**** and when the light randomly comes on it will run perfectly fine. If you are able to show me how to get the codes from the computer, it would be greatly appreciated mate.
thanks

[Tom_1569]

ok, its coming abit clearer to me now, as for the codes from the computer i havn't a idea. ive done all i can do within my knowledge of the engine. if thats how the EST light in supposed to work then theres definetly something wrong with my engine, because its the total opposite, when it starts it runs like**** and when the light randomly comes on it will run perfectly fine. If you are able to show me how to get the codes from the computer, it would be greatly appreciated mate.
thanks

Yeah sounds like something not right, actually new thought where are you? i have a spare EST computer you could try. I cant work out which sensor would **** the light up, so maybe try your computer, otherwise id says its wiring.
To get the codes you need a small wire, even an opened up coat hanger should do the trick. With the car off, have a look at the rear of the engine (closest to firewall) near the rocker cover their will be a wiring loom and then their will be one wire sticking out with a rectangular end on it. Put some wire or coat hanger down that, and earth it to the brake booster (most convenient spot) then jump in and turn the car to on (dont start or crank it) The est light should flash and your air con thermo should be running. I cant remember how to read the codes off the top of my head but it work by a series of flashes of the EST light. If you have time go see if its going to flash. If its not going to flash then theirs no point me looking up the codes tonight. If its not flashing you are really at a dead end, but start by replacing the computer, checking wiring and earths. Then look at sensors that can cause similar problems.

[RayRay07]

just went out and tried it, the aircon thermo was working but no flashing of the EST light. so i suppose i should try a different computer then right? I'm in bundy mate.
thanks

[Tom_1569]

just went out and tried it, the aircon thermo was working but no flashing of the EST light. so i suppose i should try a different computer then right? I'm in bundy mate.
thanks

Yeah id start with trying a WORKING computer, you should be able to pick one up for no more then 20-30 bux. And your just a few thousand k's from my house if you wanna try mine :P

Also when i had my last fault and i tryed doing fault tests, the fan would come on but no flashes also. Next time the light comes on, try and do the test again. Ill check in the manual when i get home but you should be able to leave the car running (in limp mode light on) and wire it up and get results. I know sometime when you turn the car off it clears the fault code it really isnt the smartest system, but isnt to bad when everything is working properly.

[RayRay07]

thanks for all your input mate, greatly appreciated, my mates dad runs the council depot down here and theres a couple vk's in there so im going there tommorow to borrow one of the computers, i'll get back to you on how it all goes, if i need the codes or not.
thanks alot

[RayRay07]

Problem fixed, turns out it was a combination of faulty computer and faulty temp sensor. car's runnin good again