Lack of Power

[Supraflymk3]

I just did a Lexus MAFS/550 upgrade over the winter and now when I get going and floor it the turbo spools up real quick to like 12 psi and then it just makes popping noises and the car just doesn't have any power. I think it might be a boost leak but the thing that confuses me is that if I just ease into the throttle it pulls strong and doesn't seem like anything is wrong. Someone told me that my timing might be off but i checked that and its at 10 btdc, the guy told me to try retarding it a little more and that didn't do shit so I have no idea. My check engine light is on with a code 52 knock sensor signal and I know my engine doesn't knock so if anyone has any ideas on that let me know.
So please someone let me know whats going on with both situations or tell me if there both related. Thanks email me at (supraflymkiii@yahoo.com):icon_conf

 

[7MGTEsup]

If you have a code 52 it means something is wrong with your knock sensor or the wiring to it. This also will pull timing to protect your engine from damage (it will boost but you will have no timing advance) it also sounds like your running very rich.

 

[Supraflymk3]

If you have a code 52 it means something is wrong with your knock sensor or the wiring to it. This also will pull timing to protect your engine from damage (it will boost but you will have no timing advance) it also sounds like your running very rich.

how do i know what knock sensor is bad?

 

[johnathan1]

check both for voltage output, and make sure the connectors and wiring to both are good.

 

[Supraflymk3]

i changed both knock sensors with new ones. I forgot to pull the ECU 15 fuse but I took off and it was still the same symptoms. I also noticed that the first Knock Sensor I pulled out had a smaller hex size on it and a different color connector, my thought was that it might be a non-turbo knock sensor. So the next thing I'm going to do is pull the fuse. If that doesn't work I'm going to take my 89 wiring harness and 89 ECU and just replace both. Let me know if theres anything else.

 

[jdub]

i changed both knock sensors with new ones. I forgot to pull the ECU 15 fuse but I took off and it was still the same symptoms. I also noticed that the first Knock Sensor I pulled out had a smaller hex size on it and a different color connector, my thought was that it might be a non-turbo knock sensor. So the next thing I'm going to do is pull the fuse. If that doesn't work I'm going to take my 89 wiring harness and 89 ECU and just replace both. Let me know if theres anything else.

Are you getting a code 34 as well?

Before you replace all that, you might want to take a look at the knock sensor re-wire. Shaeff was selling a kit that made it pretty simple...look here: http://www.supramania.com/forums/showthread.php?t=2943
Don't know if he's still doing it...shoot him a PM.

 

[rakkasan]

i changed both knock sensors with new ones. I forgot to pull the ECU 15 fuse but I took off and it was still the same symptoms. I also noticed that the first Knock Sensor I pulled out had a smaller hex size on it and a different color connector, my thought was that it might be a non-turbo knock sensor. So the next thing I'm going to do is pull the fuse. If that doesn't work I'm going to take my 89 wiring harness and 89 ECU and just replace both. Let me know if theres anything else.

Stop, don't start changing the wiring harness.

First, the knock sensors are all the same (somebody correct me if I'm wrong), so you're fine there. It sounds like to me that you need to do the SOGI rewire. Sheaff sells a great rewire kit here, or you can tackle it yourself

 

[rakkasan]

Are you getting a code 34 as well?

Before you replace all that, you might want to take a look at the knock sensor re-wire. Shaeff was selling a kit that made it pretty simple...look here: http://www.supramania.com/forums/showthread.php?t=2943
Don't know if he's still doing it...shoot him a PM.

Great minds....:icon_bigg

 

[jdub]

Great minds....:icon_bigg

LOL...common sense prevails! :drink1:

BTW...I was gonna say the same thing you did on the straight edge post :icon_bigg

 

[Supraflymk3]

thanks guys. I decided not to put the 89 harness in because I noticed it has fewer plugs other than the ones that go into the ECU. I wasn't sure if having some of them disconnected would effect the performance or if it would even work right. Plus the knock sensor wires on the 89 harness were already fixed but not very good one of them was ripped off.

 

[shaeff]

if your car is a pre '89 then the new '89+ harness probably won't clip into your ECU.

by the way, jdub and rakkasan: thanks for the kind words.

-shaeff

 

[Supraflymk3]

ok i did the knock sensor rewire and now my car runs better than ever thanks everyone for your help

 

[Nick M]

ok i did the knock sensor rewire and now my car runs better than ever thanks everyone for your help

No, that can't be. My car ran fine with code 52. And 52 doesnt do anything

....

 

[Supraflymk3]

....

well something must be wrong with yours because mine was running like shit. Its not randomly just going to run perfect right after i rewire the knock sensors. Give it a couple weeks and yours will run bad because i think mine gradually got worse.

 

[johnathan1]

well something must be wrong with yours because mine was running like shit. Its not randomly just going to run perfect right after i rewire the knock sensors. Give it a couple weeks and yours will run bad because i think mine gradually got worse.

Umm, having an f***ed up ks will make the car run shitty. As far as gradually...I guess it would, if the wire was slowly working it's way loose...

 

[jetjock]

Johnathan, it appears Nick's post went right over his head. At least he was smart enough to fix it. As long as people continue to think of the knock sensors as "dormant" back up devices and not an active part of the ESA system that they are they'll always be those who'll try and run without them.