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The mkiv Supra Owners Club

Missfire, black smoke.


Guest Rottweiler

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Guest Rottweiler

I`ve an intermittent problem with my Supra. About a month ago I took the car out and hardly got a mile up the road when it started to missfire badly.It was so bad I hardly made it home.

When I looked round the back the valance and exhaust were black with soot. I took it out again the same day and it ran perfect.

Last weekend it did it again but only for a couple of minutes.Today I`d gone about 4 miles and it did it again. Driving home it was the same and kept trying to stop when I slowed down . It did stop outside the house but started again easily.

Once again the rear valance and exhaust were black and it used nearly a quarter of a tank in 10 milesThis is driving me nuts and now I daren`t take it far in case it packs up altogether.

Can anybody help?

The car is a 1994 non turbo.

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Guest Rottweiler

I`ve got the car booked in for a diagnostic check just to see if there`s anything else wrong as well so it looks as if I`d better start saving.

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If you've got any diagnostic issues your warning light (yellow engine) would be on all the time, on the right side cluster. If it is on you can check for the error code here

 

http://www.mkivsupra.net/vbb/showthread.php?t=35920

 

I suggest you disconnect the battery for 10/20 mins. This resets the ECU and gets rid of any old stored codes. It may also alleviate your symptoms......................

You would be better off cleaning your 02 sensors, disconnect the battery as above, then see what happens.Also, change your spark plugs.

DONT waste your money on a "diagnostic" HTH.

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Duff oxygen sensors wouldn't cause it to misfire, the ECU would just default to a rich mixture, but would run as normal.

 

I would check the plugs, plug leads, distributor and battery terminals first and make sure everything is dry. If the plugs haven't been changed for a while try fitting a new set.

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