white smoke during idle on a warm engine...

[jdm_rs13]

Car: 1989 Nissan 180SX
Mileage: 138000 kms

Location: Calgary, Alberta, Canada

Mods:
- axle back muffler, decat (stock piping)
- HKS drop-in filter (recently cleaned)
- ground wires (neg to body, neg to alternator, body to cylinder head)
*stock ground wires are still in place (neg to battery holder to intake manifold)

Recent Maintenance:
- 2 mos old Bosch Platinum +4 plugs
- new Bosch 13276 oxygen sensor
- new oil filter
- coolant flush (6 mos ago)
- transmission & differential fluid change (6 mos ago)

Problem:
Started 2 days ago when I was on a stop light, white smoke starts coming out from the exhaust. So, I went to the nearest area I can park my car but it was gone when I got there. Then yesterday, I left my car idling while I went to grab some stuff from a local conveniece store, I came out with the car blowing thick white smoke from the exhaust. It didn't smell like coolant or sweet; it just stunk. So, I turned it off and waited for a couple of minutes before I started the car again. Fortunately, it went away. Then today, it happened on a stop light again. It started blowing white smoke again but it was gone when I got home. It's really wierd.

I checked my oil and it looks clean & at full level. My coolant also looks clean & at full level, including the reservoir. I also check my spark plugs and they're clean but black instead of the normal brownish. By the way, 3 of the plugs had some oil on the tread but all of them had clean electrodes. My idle is at 850 RPM. Vacuum is at 15 In Hg during idle as shown on the boost/vacuum guage. I also noticed when I was driving earlier that my boost is now at 9 psi instead of 8 psi. I am also using 94 octane (with ethanol) gasoline from Mohawk.

Has anybody experienced this or know anything about this? Thanks in advance...

[FRpilot]

sounds like your head gasket is about to go.. this is what happened to my car.. before it started overheating.

[jdm_rs13]

sounds like your head gasket is about to go.. this is what happened to my car.. before it started overheating.
I was hoping it won't come to that... cross my fingers...

An online mechanic at Nico told me to change my plugs to NGK's and that this might be due to inaccurate coolant temperature sensor and AFM readings. I'll try this route first since it's cheaper. I'll also try to change my valve cover gasket and the o rings that goes around the plugs just to make sure.

Anyways, I tried running the car without going on boost and it still gave off white smoke when I was waiting at the stop light. But then again, it was gone when I got home.

[nissan_driver24]

sounds like a blown headgasket

[jdm_rs13]

someone also told me that it might be my PCV valve; it might be letting oil into the intake manifold. So, I followed the service manual on how to check the PCV valve, but the engine always dies everytime I pullout the PCV valve. It states there to take it out while the engine is running 'coz I should hear a hissing sound and a strong vacuum should be felt when finger is placed over the valve inlet. Unfortunately, I couldn't do the test 'coz the engine stalls once I remove the PCV valve. Am I doing it wrong?