engine back firing? Help please! Urgent!!
 

hi guys,

I've got some problems with this D15 engine. Hope you can give me some help here.

The engine seems to be backfiring into the intake at high revs. The throttle body makes a fluttery sound once the engine revs up. It seems the engine is forcing air backwards into the intake manifold.

I checked the ignition timing, it 's spot on. No traces of blown head gasket, no smoke comming out of the exhaust either.

Valvetrain looks in good condition too. But compression test yield 190psi for piston 2, 3 and 4 but piston 1 only yields 160psi.

Could it be that the number 1 valves are damaged and not sealing properly? At idling, from the rear of the exhaust muffler, i can hear a faint shhhhhh sound.

Just want to know what can cause this syndrome of engine forcing air back out of the throttle body?

THe engine is totally lost of power too.

Re:engine back firing?
 

Buy a D16Z6, turbo it, blow it up and start all over again!

Re:engine back firing?
 

this is just a friend's car for normal everyday driving. It's not running right and i'm trying to sort it out for him.

as for turbo fun, i've got a built up Endyne/Eagle combo ZC DOHC waiting for turbo once it's finished running in.

Re:engine back firing? Help please! Urgent!!
 

sounds like a bad valve seal or a broken valve. Do a leak down test.

Set #1 @ TDC COMPRESSION STROKE and pressurize the cyl w/ air, feel the TB (should be wide open) and you should feel air coming out if u have a bad intake valve.

Re:engine back firing? Help please! Urgent!!
 

thanks crx88si,

I'll do that later tonight. I'll let you know the outcome.

Re:engine back firing? Help please! Urgent!!
 

No problem.

A leakdown test is really good for figuring out why a compression check is low.

Bubbling coolant = Head gasket
Air coming out exhaust = bad exhaust valve
Air out of TB = bad intake valve
Air out of oil fill = bad rings

Incase you don't know, TDC Compression stroke can be found by checking to see if the Rotor is pointing at the #1 spark plug wire. (under the cap).

Re:engine back firing? Help please! Urgent!!
 

it suck when you try everything and you cant figure it out. good luck

Re:engine back firing? Help please! Urgent!!
 

sounds like either ring lands or a valve... does it run on 4 clys or does it miss/stumble or run with a dead miss?