Bad MAP Sensor

[jmorri15]

Im have a GVR4 running Speed Density with a HKS VPC and all of a sudden i started having a weird problem with my car smoking after i get off the boost. I replaced my O2 sesnsor. did a compression test 150,160,160,150. checked for boost leaks. It only ever does after i boost and then get off the gas(to shift or just to slow down) So i think ive finally figured out what is causing the smoke. I think my map sensor isnt responding quickly enough and its keeping my car super rich for a few seconds. well anyways id like some input if anyone else has ever seen a problem like this. well here are the videos.
video 1
Video 2
the whole time its smoking it af gauge is reading really rich.

 

[shane90gsx]

Um that smoke looked blue. It was a bit far away when you let off. the map sensor may be bad causing the black puff. But it looked like blue smoke after that. (both very little black and mostly all blue). You can have leaky valve guides or seals and still have ok compression. I think its your head hommie

 

[jmorri15]

i was thinking that but it has no smoke any other time. i can hold boost and it doesnt smoke and its only when it changed from low boost to high or high boost to low does it act weird

 

[99gst_racer]

the whole time its smoking it af gauge is reading really rich.

So, it pegs rich when it starts smoking after you let off the throttle?
What are you measuring your AFR's with?

Do you have the ability to datalog your MAP sensors output to verify that it's reading properly?

 

[shane90gsx]

So, it pegs rich when it starts smoking after you let off the throttle?
What are you measuring your AFR's with?

Do you have the ability to datalog your MAP sensors output to verify that it's reading properly?

Thats a good questions...besides the point here but doesn't it go rich when you let of the gas all the time anyway? I know when i "blip the throttle" or like you punch it and let off the car dips rich then adjusts. Is your car just staying rich for an extended period of time?

 

[jmorri15]

yes. it stays pegged for a few seconds, it varys sometimes it 1 second sometimes its 10. but its been getting constantly worse. all i have for af is just a narrow band hooked to my o2 sensor. i wish i was running link but right now i have a keydiver chip and no data logger. so i have no input besides seeing my gauge stay pegged and the smoke. my goal was to get link last month but i got a ticket so that set me back most of the money i wouldve used.

 

[99gst_racer]

Your narrowband gauge isn't accurate enough to be useful for anything. Our cars spike full lean on deceleration. Check your lower intercooler pipe to see if it's inside walls are covered in oil.

 

[jmorri15]

my af guage is staying super rich on deceleration
as far as the oil i pulled both pipes off the intercooler to see what was in them. there was a very small amount of oil on the intake side. and the turbo side had maybe 2 thimble fulls of oil at most. oh i dont have a catch can the hose is still coming off my valve cover into the intake. hers a pic of the same intercooler setup i have.

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EDIT: deceleration after boost
oh and i have a gm 3bar sensor coming in(it should be here tomorrow), so thats gonna be my test. if it fixes the problem im good.


How bout a bad turbo seal. would the af gauge see burning oil as running rich?

 

[jmorri15]

Update. the map sensor fixed the stutter but i still have smoke so it has to be the turbo seals as well

 

[georgiaboy]

Yes, the blue smoke is oil in the exhaust. This can be cause by a number of things, but *could* be the valve seals, valve guides, or turbo thrust bearing. Take your car up to about 40-45 MPH in second gear then let off to where the engine goes into a high-vacuum condition. Watch behind you when you crack the throttle again to see if you see much blue smoke. If it is your valve guides or valve seals, the vacuum from the cylinder is actually pulling the oil down the valve stem past the valve seal and guide and causing you to burn oil (this is where the blue smoke is coming from) when you get back into it.
Pull a plug and rotate your crank until you can see the top of the piston with a flashlight. Is your piston clean at 12 o'clock and 6 o'clock? This means your rings are on the way out.
If your piston is the same color all over the top and the decel test didn't yeild anything, your problem may be your thrust bearing in your turbo. In boost it will push the turbine (shaft) assembly toward the turbine side and seal the oil from getting out, but in vacuum the turbine shaft thrusts toward the compressor housing and may allow oil to bypass. Then you see blue smoke.........

I hope this helps, man!

-Les

To the OP, nice car BTW!

-Les

 

[98blackeclipse]

I had the same problem in my 2g. I at first thought my motor was bad because I was running it the day befor without oil. The next day I noticed it would blow some smoke when I shifted or when I down shift it to slow me down. Everyime that happens it would throw plenty of smoke. It just got worse from there. It got to the point to where it would smoke when I was a at a stoplight. I then decided to take it to a mechanic and did a compression test and it flew with high numbers. The mechanic told me my rings were ok and that the head was most likely be ok too. We then decided to take the turbo out and there you go that was the problem it hade so much shaft play in and out and up and down it was ridiculus. It turns out I was running the turbo at 20psi and didn't know it. After I upgraded to a 14b it stoped blowing smoke. The bad turbo is most likely your problem.