Im stumped, Wisemen...I could use some advice

[jpbrazill]

I have a 91, I am throwing 2 check engine codes, but I cant seem to solve the problem because they turn on and then turn off. As Im driving the light will come on randomly and then turn off randomly. The two codes are fuel injector connector and knock sensor.

All my connections are good, and I have done a boost leak test. No boost leaks. I replaced the resistor, and ecu, cleaned all connections to injectors, and knock sensor. Is this a typical problem if the light comes on and goes off randomly?

Also, after 10psi, the car falls on its face, but boost will still reach 20psi. Unfortunatly, my buddy has my logger and moved....so Im with out logs. Does this appear to be a faulty injector? or knock sensor? I have done every search to see if anyone has ran across this problem, and I found nothing. Wisemen, show me the ways!!! Thanks!

J.P.

 

[Boosted90GST]

well the codes arn't lieing to you... my guess is both.. check all the connection clips on the injector harness and see if everythings okay.. have you ever changed your knock sensor befor? is this the original 1? if so then it's just shitting out on you and it's time for a new one

 

[steve]

The error codes are stored as long as you don't reset the ECU.
Without you pulling the codes we are just pulling stuff out of our backsides.

Steve

 

[jpbrazill]

The error codes are stored as long as you don't reset the ECU.
Without you pulling the codes we are just pulling stuff out of our backsides.

Steve

I did reset the ecu. The battery was disconneted for a day. Still throws both...and very randomly.

 

[scottsee]

Have you tryed a diffrent ECU?

 

[steve]

Still throws both...and very randomly.

Then you shouldn't have any problem reading them out. What are they?

Steve

 

[jpbrazill]

Have you tryed a diffrent ECU?

Yes, same thing.

 

[jpbrazill]

Then you shouldn't have any problem reading them out. What are they?

Steve

I dont have a problem reading them. I had posted that the two codes were "injector" and "knock sensor" codes 31 and 41. I am having trouble fixing the problem. After changing the following:

ECU, injector resistor, CAS, MAF, I still throw the two codes. I cleaned my injector connections, along with the knock sensor connection. The light still appears on/off in total randomness....(technical term)...nothing worked.

I still get to about 10 psi really strong, and then after 10, it falls on its face...but will still hit 20psi (where my boost is set for pump gas). I had also stated that my buddy ran off with my logger, so I dont have any logs for you guys...sorry. Still stumped.

J.P.

 

[44pirate]

Make sure you have the knock sensor plugged into the right harness connection. There are two back there and they look similar and you can connect it into the wrong one. I've done it, had same issues as you.

 

[olmytsi]

Did you try replacing the knock sensor?

 

[jpbrazill]

Did you try replacing the knock sensor?

Not yet, cant find one locally. I just wanted to see if anyone else had ran accross these issues. I didnt know if it was uncommen for a knock sensor to cause these problems.

J.P.

 

[scottsee]

Not yet, cant find one locally. I just wanted to see if anyone else had ran accross these issues. I didnt know if it was uncommen for a knock sensor to cause these problems.

J.P.

I'm sorry, call me old fasion but if your getting an CEL about your knock sensor why would you not think it wasn't causing it? or want to change it?

 

[steve]

I dont have a problem reading them. I had posted that the two codes were "injector" and "knock sensor" codes 31 and 41. I am having trouble fixing the problem. After changing the following:

ECU, injector resistor, CAS, MAF, I still throw the two codes. I cleaned my injector connections, along with the knock sensor connection. The light still appears on/off in total randomness....(technical term)...nothing worked.

I'm sorry I don't know how I missed that.

The others have suggested replacing the knock sensor and that's good advice. They are cheaper to order online from JNZ or Rockville. It would also be a good idea to check yours to see if the black sealant is breaking down and make sure nothing has damaged the wires.

The 41 code usually seems to be caused by bad injector wiring or a bad injector.
Have you identified which cylinder is causing the problem.
Too bad you don't have your datalogger it makes that much easier.
Does the problem happen randomly all the time or only after the car gets hot?

Steve

 

[jpbrazill]

I'm sorry, call me old fasion but if your getting an CEL about your knock sensor why would you not think it wasn't causing it? or want to change it?

I have thought about changing it, as stated, I havent found one locally. I just didnt know if the CEL for both codes is normally, or commenly due to the knock sensor. Also, when a sensor goes bad, doesnt the code normally appear all the time? I dont know much about knock sensors, so I figured I would ask. Thanks though, I will try and find one.

J.P.

 

[2fast4]

What did you do before this started happening? Back tracking might help to sort it out.

I might be off but check battery/alternator output test, esp amperage(not sure what the amp? 400cca?). Also the batt terminals. This seems very unrelated issue with inj/knock sensor. You definately need logger of some sort. Dirty injector?

 

[44pirate]

I have thought about changing it, as stated, I havent found one locally. I just didnt know if the CEL for both codes is normally, or commenly due to the knock sensor. Also, when a sensor goes bad, doesnt the code normally appear all the time? I dont know much about knock sensors, so I figured I would ask. Thanks though, I will try and find one.

J.P.

If the knock sensor is not connected the CEL will come and go. The ECU will default to 9 knock count and pull timing all the time. That has been my experience. Did you check the Knock Sensor connection??????

 

[Rick@AP]

Check the plug at the ECU and the wires.

Also, check for corrosion on the wires and make sure your recieving a strong signal at the ECU.

 

[jpbrazill]

What did you do before this started happening? Back tracking might help to sort it out.

I might be off but check battery/alternator output test, esp amperage(not sure what the amp? 400cca?). Also the batt terminals. This seems very unrelated issue with inj/knock sensor. You definately need logger of some sort. Dirty injector?

Battery is good, Alternator is good. I have an orbital battery, 770cca. As far as the injectors go, I will be sending them to be cleaned, flow tested, etc. I still dont know if this will fix the problem, but it wont hurt to try. Thanks

 

[jpbrazill]

If the knock sensor is not connected the CEL will come and go. The ECU will default to 9 knock count and pull timing all the time. That has been my experience. Did you check the Knock Sensor connection??????

Yes...I did. Nothing changed, but Im still trying to find a new one. Thanks!
J.P.