Trooper BLACK SMOKE/ACCERATION

[need2see]

I have a 1993 Trooper Isuzu - bought @ 138k - now at 142k
Started having a major power loss and burning fuel. It is running very rich. A good mechanic friend said the Egr valave was stuck and the plugs were bad. Oil was getting into the plugs.

He replaced the plugs with NGK, and cleaner out the EGR valve. Disconnected the battery and everything seemed fine for a week. I was also told the valve gasket needed to be replaced.

When the Check Engine light came on, I went to a localforeign car repair shop who said the codes were mis-firing and EGR valve.

Then problem got worse. When I stumped on the pedal I would lose power for 3-4 seconds until it grabbed a burst of speed. When it did a huge bloom of black smoke would exhaust. (it could be a great get-away car if it had some power)LOL

I replaced the plugs again with Denso which seemed to work fine on a 10 mile trip. That evening went to movies and the truck had a steady flow of black smoke, idle rough at some stops- almost to the point of stall. Plus I am buring fuel very quickly - I get about 40 miles per quarter tank.

This morning (maybe because of daylight) the smoke is either very light or occassional at best. However, at high RPM's there would be a good cloud of black smoke, once every 30 second with no apparent lack of power. the lack of power is only when it is in gear.

The oil was changed about 3 weeks ago, along with the air filter. The oil smells slightly like gas and the air filter looks brand new.

As a new Isuzu owner - learning all my tools again, this is driving me nuts.
Do I need a new EGR valve? Can I re-clean the old because maybe the ports it sits on weren't cleaned? If so, how?

The O2 sensor light has been on since i bought it. Which i hear is common @ 90k miles. Would replacement stop the car from running rich? I never ran rich until the EGR valve was unstuck. (or fixed - LOL)

Is it possible I did not tighten the plugs well enough that more oil reached the cylinder - buring more smoke?


Thank you for any help you can provide. This is my only vechicle now - and work isn't in walking distance. - I need HELP!

[Ramblin Fever]

HAS the O2 sensor in fact been replaced??

If not, this could be your issue for sure.

[trooperbc]

the egr may need attention, but it is not causing the symptoms you describe. yes the O2 sensor could. the O2 light btw only indicates your truck has gone 90,000 miles; it is a reminder, not a diagnositic component. you get it to turn off by swithching a small screw on the back of the instrument cluster from one hole to another (or remove the bulb so you don't have to do it again in 90k). your first step is to replace the O2 sensor and first check the wiring and connectors.

another possisbility is leaking injectors and/or a fuel pressure regulator putting out too much pressure (unlikely), or leaking ( possible). but first the O2 sensor.

the oil and plugs. it's possible he's talking about oil that has seeped past the spark plug tube *seals* in the valve cover and shorted out the plug-ignitionwireconnector. this is common. you fix it by replacing those seals when you replace the valve cover gasket and/or you get the 'new' spark plug ignition wire set that has connectors that are larger in diameter with built in ridges which are designed spefically to keep that oil away from the plugs.

the shorting out and resultant missing will also result in possible gasoline in the crankcase.

btw, buring oil will create 'blue' smoke. burning coolant or water, white smoke. excessive fuel, black smoke.

//bc

[need2see]

Thnak you - I appreciate your help.

no it hasn't been replaced.
Do you think I need a specific brand of O2 sensor? I hear Isuzu's are very particular.

I will follow up all on your advice
Thanks again.