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View Full Version : SR20DET boost but no power


Edyz7s
04-18-2018, 11:58 PM
Okay, yes their are threads about this but they all seem to point out to boost leak.
Here the thing with mine. So today I installed a new o2 sensor and knock sensor. The reason for installing o2 sensor is because I have bad gas mileage and hope this would make it better.
And for knock, I never replaced it since I got the motor and when I took out the old one, it was still original.
Inspecting the old knock sensor I found 2 cracks, one small and the other slight bigger. I heard these do go out and usually don't work well if its cracked.

So, starting up the car it started up fine. The only thing i noticed was it was idling a bit higher from a cold start. Usually it goes away when the motor gets hot, but it took awhile this time.

I take it out for a test drive and noticed it was horrible on WOT. Pushing half the throttle i felt it was trying to go but it just did not. I didnt remove as much to install these 2 but everything is in place. I didnt get to torque to spec the knock sensor but I seriously dont know what happened to all my power and clueless whats the cause after these new installations.

S14Serge
04-19-2018, 05:41 AM
Make sure your MAF sensor is good

err
04-19-2018, 07:40 AM
did you remove your intake mani or intercooler pipe when installing these parts? if so check to make sure your coupling are tight. One time i removed my intercooler pipes for repairs and when i put it back together. My car would boost but had no power. did a boost leak test and found out all my coupling were not tight enough and i was leaking air bad. tighten them all and car ran like it was supposed too.

jedi03
04-19-2018, 08:11 AM
turbo spinning up?

Edyz7s
04-19-2018, 10:30 AM
I never touched the MAF before the installations. What are the odds of that going out after?

I didnt remove the intake manifold nor the intercooler couplings to install the knock sensor. I decided to go the hard way and struggle to put it on. I did take off some connections that would be in the way on the side and inside the manifold area. I did connect everything back

The turbo does spool up, cause i here my recirculated BOV go off

Edyz7s
04-19-2018, 11:09 AM
Deiced to unplug the knock sensor plug to the sensor itself and drove around the block, it still did the same thing. Not sure if it was more restrictive, but def. still missing my power...
You guys think i got a fault knock sensor or if I put it on wrong or

oLemurs
04-19-2018, 01:45 PM
maybe you bought the wrong o2 sensor? i know the redtop is skinnier than the blacktop but im not sure if they have the same threads or not.

Edyz7s
04-19-2018, 04:11 PM
Ive always bought the same type (fat) o2 sensor. This is my third time replacing it, 2nd one i think i messed up the wires and revert to original one it came with. I took a test drive with it unplugged and same thing. So that clears out that the o2 is not the problem.
Earlier today i decided to get a new subharness for the knock thinking it could of been that, got a new Wiring Specialties Pro sub harness from a local shop and had to mod it with the old plastic plug to connect with my harness.
Still the same...

Abeo
04-19-2018, 04:15 PM
Did you check for codes?

Definitely sounds like it's pulling timing. I had a bunch of things go on my car (one of them being the knock sensor, and I used ecutalk to see what my timing is doing.

Edyz7s
04-19-2018, 04:21 PM
*sighs*
I got the J4 ecu and Nissan decided to take off the little light that tells you the codes. I also dont have my consult port wired so im litterally on my own, actually been since I got my SR..

Im thinking of reverting back to my old knock sensor if thats the case, despite having 2 cracks on it

Abeo
04-19-2018, 04:27 PM
*sighs*
I got the J4 ecu and Nissan decided to take off the little light that tells you the codes. I also dont have my consult port wired so im litterally on my own, actually been since I got my SR..

Im thinking of reverting back to my old knock sensor if thats the case, despite having 2 cracks on it

Wire up the consult port. EcuTalk give sooo much information that helps with diagnosing this sort of stuff. You can see realtime timing, o2, maf voltage, tps...

Yeah, I'd unplug the o2 sensor first, then try the old knock sensor. I got so tired of scratching my arms from the stock knock sensor location that I temporarily moved it to a bolt on the intake manifold for testing.

Edyz7s
04-19-2018, 11:48 PM
Well i put on my old one back and it runs like how it used too. Guess I did get a defected knock sensor.
I know I still need one because i feel restricted, not as much but you know how you get a feeling for your car

oLemurs
04-20-2018, 11:38 AM
Ive always bought the same type (fat) o2 sensor. This is my third time replacing it, 2nd one i think i messed up the wires and revert to original one it came with. I took a test drive with it unplugged and same thing. So that clears out that the o2 is not the problem.
Earlier today i decided to get a new subharness for the knock thinking it could of been that, got a new Wiring Specialties Pro sub harness from a local shop and had to mod it with the old plastic plug to connect with my harness.
Still the same...

unplug the knock sensor, im pretty sure itll run without one

mr.nismo.
04-26-2018, 11:12 PM
Check your base timing.

Sent from my SM-G955U using Tapatalk

Edyz7s
05-01-2018, 10:32 PM
It was a defective knock sensor because I did ran without it being connected, it would be the same if it was connected.

But I got a new one, ISR was very cool sending me another one no charge, and it runs great again!

The base timing was low. It was around 14 btdc, rasied it up to 17 since I run 91 all the time