Volvo 850 strange boost problem

Jaumme · Post by **Jaumme** » 15 Jul 2019, 11:14

My '93 volvo 850 t5 is doing some weird things when i go full throttle, it boost ok till 3/4 of the white lane on the boost gauge and then the boost comes down to the half of the white lane till 5000 rpm, at 5k rpm it goes like 3/4 again, is that normal? or what i shoud look for? the car seems to pull ok but when it reach 5k rpm you can feel it pulling more till 5500.

Jaumme · Post by **Jaumme** » 15 Jul 2019, 11:15

i tested all i know the tcv is ok and the bypass valve is ok, the wastegate actuator is also ok, all teh vacuum tubes are perfect, there are no leaks in the intake, fuel pressure regulator and pump hold the correct pressure( its new) and everything seems to be ok so i dont know what to look for. The car has 75k kilometers,

Post by **matthew1** » 15 Jul 2019, 11:28

It could be a collapsing hose. What's the condition of these? Also, on my 850 T5, the large hose on the intake manifold would slip off its mounting point to the manifold.

Jaumme · Post by **Jaumme** » 15 Jul 2019, 11:47

all the hoses are tight and strong thats not the problem, ithink its more about electronics

Post by **Clemens** » 15 Jul 2019, 14:15

i have a similar condition on my 94 T5 M. I got used to it since I couldn't find the source...

Jaumme · Post by **Jaumme** » 16 Jul 2019, 11:03

LOL i noticed now the volbo and pronlem in the tittle lmao i was too assleep yesterday.
Ok getting in the topic again i recorded a video for you to see the problem.
maybe the tps has something to do here?

Jaumme · Post by **Jaumme** » 16 Jul 2019, 12:56

i checked the TPS with an ohmmeter and here are the results, I think something is f*cked there, but i need anyone to confirm

Post by **erikv11** » 16 Jul 2019, 13:19

That does look like a dead spot in the sensor. However I understood there are two "right" ways to test the TPS:

(1) ignition on, back probe the connector, test voltage
(2) remove TPS, connect to the TPS leads, test resistance

Looks like you are doing ignition on, back probe, test resistance. What are the voltage numbers in the setup you have, does it also peak and drop (presumably), or rise steadily?

viewtopic.php?t=47868

Jaumme · Post by **Jaumme** » 16 Jul 2019, 13:43

i unpluged the tps and conected aligator pliers to the pin 1 and 3 then tested resistance

Post by **erikv11** » 16 Jul 2019, 16:26

According to the link I posted, you need to use the center pin and one of the outside pins, not pins 1 and 3.