no power, bad mileage, no codes

[ToyTruck]

JUst not sure what to do with this thing. THe truck is a 90 ranger with the 2.3 and Mazda (?) 5-speed. It has ~230K, all original. Recent maintenance includes a full tune up about 8k ago, Oil change about 2k, whole front end of the engine have been rebuilt in the last year (all new belts, new water pump, new alternator, new timing belt, the works). This is my wife's truck, so I don't drive it very often. I suspect that power and mileage have been down for quite some time. Plugs are looking worn with lots of carbon buildup, but not completely fouled. They're black, but not crusty. Wires are still good, at least from a resistance test. THere's a bit of carbo buildup on the body behind the tailpipe.

Where to start? I have no codes to guide me. Computer seems to think everything is A-OK. Any thoughts?

Thanks in advance.

 

[Dave R]

Hmm, normally if your puking out carbon there would be a code, if nothing else for an overrich condition. Is it giving no codes or are you getting the 11,11 system pass code?

If the computer truely thinks that everything is OK, then I'd suggest starting with the basics, checking the timing belt/sprocket timing, igniton timing and cylinder compression.

 

[ToyTruck]

I actually got NO codes at all which, as I've thought about it, makes me think my scan tool may need replacing. Going to check using a friend's scan tool tomorrow.

I know how to check ignition timing, but can it then be adjusted? I don't have a distributor, so nothing to change there. If it should turn out that I have an ignition timing problem, what then?

 

[Dave R]

No, you can't adjust the ignition timing but, that will tell you if the computer has correct control of the engine.

If your getting no codes at all then something is wrong with either your tester or your wiring harness.