Knock retard without even having a knock sensor?

[shackwrrr]

Well the last few days I have been having some really weird problems, my car will randomly run lean or rich. Well today I pulled out the scan tool, and the fuel pressure tester to check everything over. Fuel pressure it rock steady at idle 62psi(crushed regulator, bad I know)even when running lean. I on the scan tool I went through all the sensors and everything works fine with normal values, except the Knock sensor and the O2 sensor. The O2 sensor circuit has been fubar for a while(stuck at 5 volts all the time)and the car ran normal like that. Now the knock sensor, last time I removed the fuel rail I snapped the top of the sensor off and right now there isnt even one in the manifold, sooo how is the sbec seeing .04+ volts from it? If I give the car any throttle at all it will go active and pull timing.

Now on the lean part, at idle whether lean or running fine the PW is right at 1.8-1.9. What is also weird is that when it goes rich it isnt gradual, The engine will make a dun noise and bog down like the fan kicks on an AC compressor kicking on but neither is happening, It just kinda bogs down and the AFR's shoot right to 14.7 then slowly fades back to lean in the 16's or 18+ and you can feel it and hear it start lean popping. Also when I am driving with my foot lightly on the gas(20-35mph cruse) it goes lean, and if you add some throttle it goes leaner. At WOT there seems to be no problem though, the AFR goes right to about 11.5-8 just like before this was happening so I dont think it is clogged injectors or a bad fuel pump(brand new walbro).

something that I will check and what I think it might be is how well B+ is getting to the injectors, maybe the injector harness connector isn't getting a connection. I think that when the engine bogs and acts like the fan kicks on is because the computer is energizing the alternator which I think is giving normal voltage to the injectors.

Any other thoughts of what it could be. I am here ready with my scan tool, and multimeter. Just figured I would ask since It got dark and too cold to keep diagnosing.

[turbovanman²]

You need to fix the ox sensor, that is why your going lean, computer is trying to lean it out. Disconnect the sensor and it should stablize around .5 volts, if not, your wiring is fubared or the computer and this could be also why the knock sensor is going off when its not there,

[shackwrrr]

In the scan tool, adaptives show +-00, It also does this at warmup before closed loop and also just after ECU reset.

[turbovanman²]

In the scan tool, adaptives show +-00, It also does this at warmup before closed loop and also just after ECU reset.

Its still adjusting for it or its wigging the computer out.

[shackwrrr]

Well I got a little farther today, I checked for voltage drop to the injector harness and that is minimal so the injectors are getting the voltage they want, I cleaned some grounds and they checked out fine. I then hooked up the scan tool again and I disconnected the wiring for the O2 sensor. With the O2 wire not even attached I still get 4.7-5 volts shown on the scan tool, but you are still right about it being related to the O2 sensor. I finally caught the whole lean rich process on the scan tool, when the car is running lean all adaptives are at -29. The feeling of my engine bogging down from a fan kicking on was the computer dropping into open loop. Now I just need to find out if my problems are Harness side or Sbec side. I am worried that it might be harness side because when I had my socketed computer in and I tried phosphate code my check engine light would flash, I didnt know what it was at the time but now I know it was the computer seeing knock without the sensor even there. I did measure voltage at the knock sensor wire and it seems to have some voltage (jumping from 0-.06 volts.

It would be nice just to find another harness, Mine is really bad, the PO "fixed" it many times and most of the wires a very brittle.

[turbovanman²]

That's good and bad news,

I have a wiring harness for sale, see sig,

[shackwrrr]

I have cut the blk-dk grn wire from the O2 to the sbec about 8 in from the sbec itself, I then soldered a wire on that goes to my wideband.

[shackwrrr]

That's good and bad news,

I have a wiring harness for sale, see sig,

I am poor, All I have is that turbo.

[turbovanman²]

I am poor, All I have is that turbo.

No biggie, if you ever need one, I'll probably still have it,


So when did you add the wideband to the ox sensor? If you did, is it still reading 5 volts and if it is, did you set the wb output to the right voltage?

[shackwrrr]

No biggie, if you ever need one, I'll probably still have it,


So when did you add the wideband to the ox sensor? If you did, is it still reading 5 volts and if it is, did you set the wb output to the right voltage?

Ive had the wideband set up for a while now, the PO murdered the wiring on the stock O2 for his flash in your face on the highway pillar pod narrowband gauge, so I just cut the wiring off and wired in the wideband. When I unhooked it today, I checked what voltage it is putting out and it shows close to .6 at 13:1 and when it is running lean it runs around .2, but the computer it still completely completely stupid and sees 5 volts.

I had a job interview on tuesday for a shop, hopefully they give me a call tomorrow like they said.

[turbovanman²]

It did this with another computer didn't it? If so, I would redo the wiring or put another harness in.

Good luck on the job,

[shelbymonster]

do you use the wideband sensor as your o2 sensor for the computer ?

[shackwrrr]

It did this with another computer didn't it? If so, I would redo the wiring or put another harness in.

Good luck on the job,

Yes, the knock sensor part. Rob said he was going to send me a stock cal on a chip to try out in my socketed sbec, so we will see. But the Sbec still has to messed up if it is seeing 5 volts on a wire that literally goes 8 inches out of the 60way and terminates. Maybe the Knock sensor wire is picking up noise without the sensor there, like a floating input without a pulldown resistor. I could try grounding the knock sensor wire.

I would really like to rewire the whole engine with one big deutsch connector, that and separate the engine harness from the body harness.

[shackwrrr]

Today I have been driving it around with with the scan tool hooked up and it seems to be fine. I am going back out in a minute to check the ECM grounds because I think it is getting the better ground through the scan tool. I am am thinking thats what it is because the PW stays the same lean or rich and voltage to the injectors stays the same lean or rich.

Oh and my O2 reads fine now and there are no problems with the knock sensor now.

Edit: my O2 shows .52 volts no matter what, hooked up or not.

[shackwrrr]

Well I followed the ECM ground wire (black with white stripe) from the sbec to the SCI connector, Then from the SCI connector it goes to the front sub harness where I am guessing it connects into the ground that hooks to the head? That harness on mine looks like it sat in the bottom of an oil tanker for a year and was then fed to rabid dogs.

[Aries_Turbo]

the 60 way connector terminals in the harness could be loose where they fit over the pins of the sbec itself.

you have to disassemble the 60 way and tighten up the terminals.

Brian

[shackwrrr]

Now, either I am dumb or this changeover year stuff is messing with me. My knock retard without a knock sensor came back, After I hooked the O2 sensor wire back up, so I watched the voltage on the scan tool, yep, I hooked the O2 sensor up to the knock sensor wire in the harness. But in my defense they are both green with a black strip, just one happens to be dark green that is no longer discernible because of weathering. So tomarrow I will get it all hooked up how its supposed to be and see if that fixes anything.

[shackwrrr]

well here is the 91 shadow diagram and thought they both used SBEC I? it looks like this one has a different pinout than the 90 one. Does anyone have a 90 diagram from a factory manual I can see? Mitchell gets stuff wrong alot.

[shackwrrr]

Well the final diagnosis. is high voltage drop on the PCM ground and that I hooked up the NB sim output of my wideband to the knock sensor input.

[turbovanman²]

Well the final diagnosis. is high voltage drop on the PCM ground and that I hooked up the NB sim output of my wideband to the knock sensor input.

Good on the ground, DOH on the wideband output, lol.