I posted this in the Prelude forum, but only got one bite.
So I'm posting in Tech to see if any of you can help...

Symptom: Engine doesn't like to idle, very rough and will stall off most of the time.

Background: Rebuilt the motor after I spun a rod bearing.
Parts used for rebuild:
Standard overbore JDM Honda type-s pistons and rings
RS Machine did the bore and hone
Eagle rods, clutchmaster aluminum flywheel, honda bearings

Motor fired right up and ran great for 1000 miles, then it started stalling at idle.
It has gotten progressively worse (idling) and now I am at over 20k miles

I did a compression and 100psi TDC leak down test
Compression: 230, 150, 220, 190
Leak Down (%): 44, 70, 50, 70
During leak down it sounded like the air was going to the crankcase, not the intake or exhaust

Crazy numbers i know...
it runs fine when I'm motoring along, but not at idle and at initial tip in it mostly hesitates
It doesn't smoke, doesn't burn oil or coolant, the coolant and oil aren't mixing, the coolant system didn't get pressurized from the leak down test.

What do you think is causing the leak down that is causeing the poor idle?
Are the two not related?
Thanks!

 

Compression: 230, 150, 220, 190

Danger Will Robinson.... Danger!!!

When one cylinder is less than 70% of it's neighbors you have an issue.
Your leakdown numbers are a little scary as well. If I were you I'd be thinking about a teardown.

 

I know there are serious issues, just looking for a diagnosis from the results of the test and the symptoms.
And wondering why the car runs at all (knock on wood).
Anyone???

 

Well, there are a number of things that could be wrong... my initial guess would be rings and/or head gasket. There could certainly be other problems though, depending on all the things that were/were not done during your rebuild.

 

Thats the thing,
if it were the rings, there would be smoke? Considering the 70% leak down combinded with low compression numbers.
If it was the head gasket, with an open deck H22, wouldn't there be oil/coolant mixing? the coolent system being pressurized? white smoke?

It ran fine for approx 1,000 miles then, all of a sudden idle problems.

A tear down or new(used) motor will be needed, But this is just odd.

 

Smoke == not necessarily
The rings on my DSM were toast when I rebuilt the engine, only smoke you would ever see was a brief spurt on high boost, and only if you had been driving for a while without hitting significant boost levels.

Oil/coolant == Not necessarily
depends where the leak is

Bottom line is, I'd guess there are actually MULTIPLE problems with the car, and only a teardown will remedy them. If you had this engine built by someone, don't let them touch it again. If you did the build, you might want to find someone to help you with it when you redo things.