Arrrrrrrrrgh!

92 chevy lumina z34 6cyl fwd automatic dohc vinX LQ1 modified 230hp
heres the deal, about once every 7-10 days the car will surge and blow a few puffs of white smoke. once i release the throttle and get back into it, it stops. it does not smoke at all any other time, only when this happens. at first we thought it was the fuel pump. so we replaced the pump and filter, cleaning the tank out in the process. still did it about a week later. mechanic insisted it was the filter, so i put yet another new one on. still does it. cleaned out all the sensors and did an upper intake cleaning. still does it. pressure tests fine, vacuum tests fine, converter and mufflers are new. also had the injectors cleaned. still does it. i simply cannot figure out what is causing this. i was told that the white smoke is a sign for head gasket. but wouldnt that smoke ALL the time? oh, tranny serviced not too far back as well. the problem has been apparent for about six months and i cant think of anything else to replace.
altenator, starter, radiator, a/c, serp belt, converter, muffs, fuel pump/filter all new.
help me please, i have put too much blood, sweat and money into this car. i'd like to finish it...

Head gasket? Maybe. Coolant definitely. Check all coolant areas around intake & exhaust.

couple more q's while im at it. in the center of this pic, there is a valve of some type on the pipe that leads to the thermostat. what is that used for? it is obviously broken. could that be the cause?
next q, the two cables near the top of the pic, they have quite a bit of play in them, is that normal? if not, what is the part called so i can get them fixed/replaced. the one in front has about 1/2 inch of play before it catches the spindle. the back one has about a full inch.
btw, the car hasnt done that since i put a 180 degree thermostat in it. but its only been about two weeks. keeping my fingers crossed.
http://i284.photobucket.com/albums/ll11/DnaProRacing/car003.jpg

The valve is an air bleeder for cooling system, no. Does it have cruise?

yes it has cruise. works fine.

couple more q's while im at it. in the center of this pic, there is a valve of some type on the pipe that leads to the thermostat. what is that used for? it is obviously broken. could that be the cause?
next q, the two cables near the top of the pic, they have quite a bit of play in them, is that normal? if not, what is the part called so i can get them fixed/replaced. the one in front has about 1/2 inch of play before it catches the spindle. the back one has about a full inch.
btw, the car hasnt done that since i put a 180 degree thermostat in it. but its only been about two weeks. keeping my fingers crossed.
http://i284.photobucket.com/albums/ll11/DnaProRacing/car003.jpg


One cable is cruise, the other is downshift. Sorry for taking so long to get back on this but have had family emergency. Did you press. test cooling system? Has it got the inter-cooler turbo on it ?
Some times older engines just need lower temp to run properly, more wear oil does not develop proper pressure or passages may develop partial plug from build-up of varnish. This can result in rise of engine heat/coolant temp & pressure in system, resulting in intermittent leakage around hard spot in gasket.

went and got diagnostics done at pepboys. as much as i trust those guys, they're idiots. none of what they were saying made much sense, the only code I got was the o2. they were saying this seal that seal this sensor that sensor blah blah blah. so i took it to my usual mechanic "an hour away", after inspecting EVERYTHING, all i need is a new o2 sensor. thats it. he explained in detail all the symptoms and they matched what i've been going thru. the only good i got out of the diagnostics is it closed a few wonders about some things i was worried about. block test, vac tests, wiring, etc... Im getting the o2 put in today while im at work, "so nice having a mechanic you trust right next door to work". ;)
now i need to finish the cosmetics. btw, I finally got that dash cover, looks a million times better. thanks for all your help guys. its hard to find good usefull advice that leads you on the right path to finding what is really wrong with these beaters...

Double Arrrrrrrrgh! after putting a new o2 sensor in, it ran great for 2 days. then it started spitting black smoke. was directed to buy a new map sensor. $100 part. screw that I said. tore it apart. couldnt believe the build up that was inside that thing. also found an old vacuum line "that i didnt replace before" had a HUGE crack in it. impatient me went ahead and tackled that while the engine was still hot. burning searing flesh ohhhhh the pain. but i got it done. now i dont chew up half a tank of gas to go to work for 1 day. grrrrr. anywho, put everything back together along with replacing all the vacuum lines and took it for a test drive. more power, more power, loving it. keeping my fingers crossed, lets see if i get past that 2 day mark...
after doing all this to my car for the past year. im down to a few more things before it is finally done.
new carpet: $165
bra: $85
tint windows: $150
jet chip: $157
hard to believe im almost done. its been a long hard journey. but worth it. question is, whats my next project???

First I heard that the o2 sens. could cause coolant in exhaust.

I dont recall saying that. it was a small issue that escalated to a bigger one. a tiny puff of white smoke could have been several things. the black smoke was obviously the clustered map sensor, the loss of power was most likely the vacuum leak. typical lumina issues, several all at once...