Engine Troubleshooting

[conozo]

I have a 88 Sedan DX auto (181,000 miles) with a new weber and pacesetter header. I have two issues. The first one is that once the car is completely warmed up (after 20 minutes of driving) when i am stopped at a light i "believe" i hear a slight engine knock. It goes away after i accelerate past 1500 rpm or if i put it in park/neutral. So it only does it when in drive and not all the time and it also did it before the weber but it wasn't as noticeable. Second issue is that once warmed up the idle will bounce only about 20-30 rpm. Its not much at all but it is noticeable and i thought it was the old carb but its not since it still does it with the weber. But before the weber it was much worse, it would bounce between 100-200 rpm.

Everything else is fine, engine performance is good so i don't know what to look at or where to start. Last question, is there a knock sensor on carb cars?

[2drSE-i]

theres not really a knock sensor on the FI cars either, but to answer your question about the idling, 20-30 RPM is not much, it just surges a little? i wouldnt worry about it unless its surging alot (like it was before). About the knock....not really sure. Are you sure its in the engine? i know my car vibrates quite a bit when sitting in drive.

[2oodoor]

Make sure it is not the pacesetter touching the frame up front, check the whole exhaust too.
The wandering idle sounds like float level or possibly fuel filter restricted. You probably can advance the distributor timing a few degrees with those mods.

Other things could be : the valve lash adjustment, valve timing, and oil pump. Mine would start to give a faint knock after it warmed up, scary sounding, I think the oil pump was leaking internally so pressure would drop, that was solved by replacing all the oil pump o rings (from Honda)

On these valve rockers, you may notice the springs horizontal springs, those keep the rockers on the top of the valve, well some of them are positioned so they may "walk" a little further side to side and My personal thought is those things get a little too much gap in the lash and will make a slapping sound.

[conozo]

the timing is advanced a little. I did replace the filters a while back when i still had the stock carb and no difference was seen. Im not too woried about the idle thing, i just didnt know if it might help troubleshoot the knocking sound.

another note is that when i start the car my oil light is on for a second or two. This wasnt always like this. It used to be that the oil light was only on after starting the car from an oil change, but now it does it every start.

So i will probably replace the o rings on the oil pump. Cause it sounds like its not quite working right from what im thinking. I'm still open to other ideas, solutions.

[2oodoor]

If you never did the oil pump sealing , you can not go wrong by refreshing it.
There are three rubber seals, on mine the one inside the pump had a split in it.
It was really easy, but you have to make all the motions you would if you were replacing the timing belt because you have to remove the lower cover completley out of the way.

[2drSE-i]

how long has it been since an oil change? you may just be a bit low on oil causing the light, mine does this too when ive been 3500 since an oil change (i know im a bastard)

[conozo]

i just had an oil change. But it hasnt made a difference if i just got an oil change or am overdue for one. Im going to replace the gaskets on the oil pump and fix my other small oil leak and see if that helps.

[greentee76]

I had a similar faint knock at idle that was being caused by a leaking vacuum advance diaphram. Idling in nuetral if I took #2 line off the distributer and just plugged it with my thumb the "knock" would go away. Worth checking out. Good luck.