1998 Honda Civic

Electrical problem
1998 Honda Civic Manual

The car missfires sometimes, white/grey smoke comes out the exhaust. When I remove the 4th spark plug wire (nearer to the battery side) and put it in it seems fine, when I take out the TPS no smoke or misfire happens, when I put it back in it continues to giveout smoke and misfore.

I have replaced spark plugs but not wire. Bleeded the coolant and replaced. The car has been out of commision for nearly 3 years. A tiny amount of petrol was left in the car. Oil and filter has been changed.

I would appreciate if you or anyone can help as I spent alot already on this car, more and more problems keep appearing.
March 13, 2009.


Do a compression test of the cylinders to see if there is any problem
A bad cylinder would cause the misfiring described.

Mar 16, 2009.
Hello KHLow2008, Thanks for the reply,

Even if I take out the TPS sensor will it indicate cylinder problems when Compression test is done? When TPS is out there is no smoke or misfire(small missfires every minute or so)

I took it to MOT today, it passed everything except emissions, now I dont know if it is the sensor which regulates pertrol or catalyic converter or something else like the distributor.

Does this type of car have oxygen sensors?

In the meantime I will take it tommorrow down a motorway and chuck Redex in to see if it helps.

Bear in mind the car has not been drivin in 3 years and had no previous probs.

Mar 17, 2009.
Sitting for so long can cause things to freeze up and all sorts of problems.

What was the reason for emission failure? Any DTC?

Mar 18, 2009.
Ok I have got it checked out for cylinders and gasket for leakes ect, no probs. So then I changed the throttle body and made a huge improvement on the acceleration and petrol consumption.

The misfiring stopped, very high idle revs came down from 2500 to abt 1500.

Emission failed because of the rich intake of petrol which produces 10 times its normal emmission.

As it stand now, no white smoke, catalyic converter looks okay, cylinders ok, throttle body ok. However still idles high at 1500 revs, it also fluctuates between 1000-2000 revs when its idle or on neutral. As well as petrol consumption. Half tank already gone did only 55 miles and itls only a 1.4i.

If its not mechanical no more could it be electrica?

Mar 25, 2009.
It could still be mechanical. There could be a vacumn leakage. If the throttle body is a used unit, the valve could still be stuck in an open position thus the high rpm.

Try unplugging the IAC connector and reconnecting, noting the rpm change. If none, the IAC could be stuck. Used throttle body sometimes gets stuck.

Remove air iintake hose and cover the lower port, if idlie comes down, the IAC is opening too much.

Mar 26, 2009.