Faintly blinking CEL no codes

jfley · Post by **jfley** » 12 Nov 2011, 18:22

Ok Everyone, I think we have a good one here!

My 189K 1996 850GLT NA started some funky stalling bit with no warning....I would be tooling right along and blub, blub and stall....set the CEL.... This could happen almost anywhere, but mostly after a little traffic.

Sooo.... I did the usual, clean out the flame trap,throttle body and butterfly valve, check wires cap, roter, plugs, fuel pressure on the rail, and looked everywhere for leaks in all vac hoses. I was getting a number of codes...0171,0172, 440, and 455....

after reteiving the codes, as you might imagine I tackled one at a time.....EVAP first, replaced the VAC hose from the manifold to the purge valve ( which I tried to clean out, carefully usung a vacumm cleaning device). 455 was gone after that..

0172 was next....two new HO2S, and an ECT, as well as hoses and T-Stat, and AF.......stalled again.......used electronics spray cleaner and cleaned the MAF.....I understand the test that says its OK is to disconnect it and if the car stalls its bad.....car kept running

Checked the hot air valve on the air box and even after the car was running for some time the cold side never opened...I have it rigged to be open to cold at all times.......so far so good......although my expectations are not high, however now all the codes are gone and my CEL blinks on ever so slightly and never stays on, but sometimes burns bright , then faint again , some times it goes out and then on again, all intermittent.....never sets a code.....what the...???

I AM STUMPED.....any one have thoughts???

Post by **misha** » 12 Nov 2011, 19:10

Usually...(always)when CEL is flashing it means that the engine is misfiring.

About p0172 code...almost always it's because of the vacuum leak.It's the vacuum elbow which is located at the left side of the intake manifold when you look towards the engine.It's hidden between alternator,power steering & intake manifold.

On the code scanner,THAT vacuum leak always shows that o2 sensors are bad,even if they are brand new.

Supposing that you have one....how is your air pump & air pump check valve(sas valve)?

You also mentioned that you installed new spark plugs.Are they oem Volvo plugs?If they are not then check the gap on your new plugs,maybe you just need to re-gap them correctly.

My suspect for flashing CEL would be unproperly gapped new spark plugs.

About o2 sensors....are you saying that you replaced them?ALL sensors in these cars MUST be OEM Volvo or OEM Bosch,not GENERIC Bosch.

If you installed generic/universal o2 sensors,you wasted your money because you'll need oem ones.

But...i would check spark plugs gap first.

jfley · Post by **jfley** » 12 Nov 2011, 19:51

Thanks Misha!..I did use bosch replacements on the O2s....but checking the plugs once again is a good step...funny thing, they are platinums, and read somewhere else tonight I should take them out and go with OEMs ???

The elbow under the manifold had been previously replaced found that issue a while ago on the car my wife drives (Same as this one only white)......I can hear the SAS air pump working but I am not sure where the check valve is ??? does it have the purple hard plastic vacuum line in it and sit just above the exhaust manifold heat shield?

Post by **jreed** » 13 Nov 2011, 05:08

Yes, that sounds like the SAS check valve.

jfley · Post by **jfley** » 13 Nov 2011, 06:41

Ok, Now is it a serviceable part as in can it be taken apart and "cleaned" etc....or is it a part that just needs to be replaced?

Thanks....

Oh And I'll have all of the plugs out and regapped today....lets see if the flickering light goes away!

jfley · Post by **jfley** » 13 Nov 2011, 16:50

Plugs out ...regapped.... not off by much if at all......but the car CEL is flickering even less and it goes really well....it's been a while since I had this kind of get up and go......Tomorrow I'll recheck the rotor and cap.....Looking better every day.

Thanks everyone!

Anything on the SAS Valve ????

Post by **misha** » 14 Nov 2011, 09:43

Something just felt on my mind...

What light is flashing?
-service light?
-check engine(or lambda light for european market vehicles)?
-orange arrow?

Did you checked the codes?

jfley · Post by **jfley** » 14 Nov 2011, 15:35

Hey Misha....Check Engine is the faintly blinking/flickering....sometimes not at all...no orange arrow ....had the cluster out for the odometer gear fix a couple of months ago , think I broke the service light...

Still no codes at all....drove it to and from work today...and I just touch the gas and takes off....no sign of the stalling yet...

Post by **misha** » 15 Nov 2011, 14:58

jfley wrote:...Check Engine is the faintly blinking/flickering....sometimes not at all...

When CEL is blinking,engine is misfiring...that's for sure.

The only question is why it's misfiring?

Usual culprits are unpropriate spark plugs,wires,cap,rotor & ignition coil.

Engine can also misfire when the one of the cylinders are dead.But if that is the case you would be aware of that,i guess.Spark plug on that cylinder would be fouled with oil.

One of the suspects can be a bad SAS valve.When it goes bad it lets the water from condensation in air pump and then later,air pump push that water into the engine,or engine suck that water from air pump.That's one of the reason why the CEL is blinking.I know that because my CEL did the same.The difference is that my CEL didn't blink all the time.....it would do that ocasionally,almost never.

Check the air filter after a few miles after the cold start-up.Drive it a few miles and then check it,it may be wet.

If that's the case,then SAS valve is the culprit.

I just plugged mine a few years ago because it was badly detoriated,and few months ago when i replaced exhaust flexible pipe,i removed it completelly.I plugged the the hole where it was and i'm preparing for SAS delete process.I just want to investigate all potential problems(if they exists)before i do it.

jfley · Post by **jfley** » 18 Nov 2011, 14:53

Misha, that sounds like what is happening ....nearly exactly......I'll check the air filter tomorrow....its going be a cold night and it will be a good test for the whole system......by the way the CEL came on yesterday strong and set a P0455 code again......guess I am looking to the evap canister now too.....

Thanks again!