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125k 2007 Volvo V70R- SOLD, 1990 Volvo 760 Turbo
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Discussion Starter · #1 ·
Hi all, I got the turbo out today and it’s getting rebuilt. When I took it to the rebuilder, he was immediately concerned
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he said that this white Is indicative of an extremely lean running engine, and said it could likely be an 02 sensor. Is this the case? There are no engine lights or anything, but I’m becoming increasingly worried that a previous owner just wiped all the codes. Is there a way to check if the 02 sensor is bad? What other things could cause a lean running engine?
 

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They all look like that after 17 years and several hundred thousand


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125k 2007 Volvo V70R- SOLD, 1990 Volvo 760 Turbo
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Discussion Starter · #3 ·

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125k 2007 Volvo V70R- SOLD, 1990 Volvo 760 Turbo
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Discussion Starter · #4 ·
even at 140k?
 

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Uhh yes even at 80k.


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Lean running condition is caused by lack of fuel or abundance of air... or sometimes a combination of the two. Not your issue. The k24 is somewhat of a loose turbo and burns a bit of oil, the white you see is likely evidence of oil burning for years


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Given the choice, I'd believe an O2 sensor over a turbo rebuilder.
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Discussion Starter · #9 ·
alright cool guys! Thanks so much, you guys are a huge help
 

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Discussion Starter · #11 ·
Lol, just realized: this has the original fuel filter. None of the previous 6 owners ever thought to change that…😂
 

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Discussion Starter · #12 ·
Lol, just realized: this has the original fuel filter. None of the previous 6 owners ever thought to change that…😂
Hey guys, so after speaking with my turbo rebuilder and Nick Knight the absolute Volvo turbo genius, they are saying that that white residue means it was running lean. If I get a Vida/Dice port, will it be able to tell me active data so I can see if something is off with my fuel system? I just had the filter replaced, what else would be standard procedure to fix when engine is running lean? I’m sorry, I’m just so extra cautious, I can’t afford an engine swap if something were to go wrong 😂
 

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Get yourself an AFR gauge. Replace the upstream o2 sensor(s) and check your rail pressure. Look for unmetered air(vac leak), faulty PCV​
 

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Also look at LT and ST fuel trims for diagnosis lambda sensor run people in circles looking at voltage, they fluctuate between .9 and 1.0V even when they fail sometimes, pay attention to fuel trims and like above stated AFR.
 

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If the AFR is not right or if the sensor is not behaving properly (e.g., slow or dead) or if the trims go to their limits, the ECU will throw a code.

The AFR is critical for good emissions control so the feds have mandated that the diagnostics be super-comprehensive and accurate. I'd trust the algorithms.
 
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