Friday I took the 1988 244GL B230F for the test. This is after replacing the air filter, air box T-stat, pre-heat tube (they look for it), the fresh air hose (old one had a 1/16 x 1/2 inch hole), the oil trap, flame trap, the PCV hoses, and the cat-back exhaust system (from anothe car).

It tested too high on one, too low on another, thank goodness the test guy is a buddy and we weren't hooked into the state computer. He said "Dirty Burn" another mech there said "not enuf air".

The ignition wires, distributor cap & rotor, Bosch W7RDC spark plugs and Fuel Pressure Regrulator, are all about 6 months old. In Feb we ran 2 cans of Techron through the fuel system in 70mph highway driving (long trip).

It has a sort of random hiccup, even after all those new parts. Huuuuuuum pum huuuuuuuuuuuum pum pum huuuum pum huuuuuuuum, pumitypum, and so on. Idle speed or 2400 RPM, same hiccup. Not apparently tied to a specific cylinder.

I feel stumped, and have a visceral revulsion to paying anyone to do anything before I have run out of fixes.

Before investing in

1) a BG Induction Cleaning ($130)
2) a new ambient temp. sender ($35 Volvo)
3) a new O2 sensor ($179 Volvo)
4) new timing belt (it is due soon)
5) getting the injectors cleaned
6) checking to see if it has a burned valve somewhere,
7) taking it to my Volvo guy (Nils Nilssen, his real name!)

I would like some ideas of what sort of thing could cause the problem?

Your input will be greatly appreciated.

Thanks in advance,

Bob

:>)