Clogged poppet

[needlenose]

Is it possible for a clogged poppet to cause a low speed vibration but not throw a misfire code? I believe my engine might be slightly missing at low speed. It seems to clear up at about 1200 rpm. I'm also getting a raw smelling exhaust at idle. The only code thrown was a TPS code.

I've replaced the cap/rotor/wires/plugs.

 

[Justin S]

Might wanna check compression, if all tune up stuff is good, might have a weak cylinder

 

[needlenose]

Thanks for the input. I ran the numbers:

1. 185
2. 180
3. 180
4. 170
5. 185
6. 170
7. 180
8. 170

It does it with the belt off as well, so it can't be anything accessory related. It also seems to be slightly intermittent; not continuous. My research seems to indicate that anything TC or flexplate related would make a noise. This doesn't make any noise at all. Just a slight shuddering at 1000-1200RPM that comes and goes.

I heard tell that the distributors go bad and cause shuddering and misfire codes? What's weird is I have no misfire codes. It starts immediately, everytime. There is no real "cranking time".

 

[kennythewelder]

Your compression looks ok. As for a clogged poppet, well, with ethanol in gas these days, dirty poppet valves are a good possibility. A co worker of mine has a 95 with a 4.3L He fabed up a hho generator. I think he used 10 plates inside of it, and it was to much for his alt to keep up with, but he ran it for 3 days. The difference in the way the truck ran before he installed the hho and he removed it 3 days later, was night and day. His generator was cooking the water off into a mist, and that was piped into the intake. This had a cleaning effect on the fuel system. He said his truck never ran so smooth. The point is, it would not hurt anything to clean out your poppet valves with a pressurized fuel injection cleaning system. They screw into the fuel line at the test port valve. If you don't know about hho generators, here is the youtube page. https://www.youtube.com/results?search_query=hho+generator