Switched over to gen3 electronics, boost gauge is dead now

lalojamesliz1

New member
So I installed the gen3 efi on my gen3 engine and it fires up and drives great but my stock boost gauge isn't reading at all now???? 
I'm using a berk gen2 to gen3 patch harness. 
While I'm cruising the AFR's jump from 14.7 down to 14 back and forth and when I build boost, my afr's go down to 12.5 with roughly 80% of my gas pedal down and 10.0 - 10.5 at WOT
It runs great besides the afr's bouncing around a little. 
Any ideas on how to get my stock boost gauge to read properly?
I want to turn up the boost now since I have the st205 ecu running the show now but I don't want to ruin my engine because of this

I tried my gen2 map sensor and it also doesn't make the gauge work.
The PO had the CEL bulb removed because it doesn't light up so I can't check for codes. I need to figure out (again) how to open it up so i can fix that bulb so I can check for codes
 

lalojamesliz1

New member
The PO took out the bulb and bulb holder for the CEL light. I just pulled the bulb/holder from the cruise control since the P.O. also removed that system.....
I'm getting code 52 and the usual code 54 since im using a st205 ecu. I know code 52 is for the knock sensor but I've been up to 7psi and 5000 rpm since I got the car on my little test drives around where I live and I haven't had any driving issues so I don't think it's in limp mode.
Any ideas?
 

lalojamesliz1

New member
I just looked and my knock sensor isn't plugged in. To make things worse, I don t see the damn wire/plug for it! 
I see a plug/wire for what I think was the tvis but that's it in that area. I'm tempted to connect my antilag vacuum thingy since it has a similar plug but something would probably go wrong  (yes, I gotz that homo engine  )
Anyone anyone know where the knock sensor wire comes out of the main harness? I'll look for now
 

underscore

Well-known member
Ah that'll do it, I'm not sure if LHD is different but on my RC it looked like it came from the main run of wires that crosses over the intake manifold. If you can't find it a junkyard 5SFE should have the same plug and shielded wire, that's what I used for troubleshooting before rebuilding it right from the pin in the plug to the ECU with new wire.
 

lalojamesliz1

New member
I had my car on stands looking from the bottom. Only oil leak evidence. I'm going to look from the top now. .
I got this car back cheap but man it had a bunch of small issues.
I'll check by the injectors.
Thanks underscore
 

underscore

Well-known member
No problem, best of luck finding it as it's hard to have a good look around back there (especially if it turns out to be missing). Worst case jam your hand in there with an old camera or phone and blindly take a bunch of pictures to see if you can spot it in one of them.
 

lalojamesliz1

New member
Found the wire. It comes down right next to the tvis wire. Only thing is someone cut it and it's only a few inches out from the harness and it'll be hard to strip and connect a new wire too.
Since its shielded, could I use any wire connector to connect another shielded wire with the knock sensor plug?
Also, anyone know what other car would have the same connection for the knock sensor? The sensor plug looks like a square happy face with horns lol I'm sure it's a gen3 knock sensor
Since I have to remove the st205 intercooler, I might as well do a compression test. I have some new bkr7e plugs go install and I ordered some new oem plug wires from twosrus not knowing they are closed for 4 more days. :doh:
 

lalojamesliz1

New member
underscore":2acmdvpp said:
No problem, best of luck finding it as it's hard to have a good look around back there (especially if it turns out to be missing). Worst case jam your hand in there with an old camera or phone and blindly take a bunch of pictures to see if you can spot it in one of them.

I like doing that with my phone also. Either with pictures or videos :D
 

underscore

Well-known member
Does it look like this?

5S2298_2__ra_p.jpg


That's the sensor from a 5SFE, it was the same in my RC.

You could try attaching a replacement plug and piece of wire to the cut wire, only the part of the wire in the main harness was shielded so I'm assuming noise from there to the plug isn't an issue. It'd be worth a shot if you don't want to deal with running a new wire.
 

lalojamesliz1

New member
To be honest I'm not 100% sure since I only saw it from the side. It looks similar though.
I was just thinking, since the wire is already out of the harness and is not far away... what about soldering a wire to the sensor blade connector (the metal part inside the plug just to be sure) and them soldering that wire to the cut end :shrug:

I think I'll try that before I order it from a guy tomorrow. I found a guy that could sell me the pigtail

I'm also working on the st205 ecu code 54 fix right now lol
Lots of little things but I'm finishing up the list I have for now :)
 

underscore

Well-known member
You could do that, I'd try crimping a female spade connector on the end of a wire instead of soldering directly to the sensor, that way if it doesn't work you don't have to try to clean up the sensor.
 

lalojamesliz1

New member
The diy code 54 harness worked with my ecu :D :twisted: I was about to buy a mr2 ecu for $220 too.....
Now to take care of that knock sensor wire.
 

lalojamesliz1

New member
underscore":2llmskf6 said:
Does it look like this?

5S2298_2__ra_p.jpg


That's the sensor from a 5SFE, it was the same in my RC.

You could try attaching a replacement plug and piece of wire to the cut wire, only the part of the wire in the main harness was shielded so I'm assuming noise from there to the plug isn't an issue. It'd be worth a shot if you don't want to deal with running a new wire.

Yup that's the same connection. I took out my knock sensor earlier today so I can test it (might as well so I can rule that out) and it matches the one in the picture you posted. I think it was a 27mm deep socket and I used my 18" breaker bar that made it easy. The antilag vacuum thingy was in the way but it wasn't a big deal with the socket extension to pass it

I'll use rockauto to check what other common cars have that same KS connector so when I hit the junkyard I'll have more options on what cars to hit.
 

lalojamesliz1

New member
On the boost gauge situation..... it's working fine :doh:
It's just like Bryan from BERK told me after we talked it over for a little bit. The guage is looking for a different voltage and yesterday when I was boosting, it would start reading so that showed me it's working fine. My bad :doh:
 
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