cel throwin codes for every sensor on injector harness

[YoLa]

Before I go ahead and describe my problem, I figure I'll give you guys a background on my five-oh. It's a mass air car with gt40heads/cobra intake/f cam, running rich as heck. I swapped out my a9p for an a9l (cars 5speed) didn't solve my problem. I tried checking the cel codes, but it only works if i ground out the jumper and count blinks for koeo. Won't allow me to run koer or any other method of koeo. Koeo codes are as follows: 51,22,53,54,35,67,85 which appear to be all the sensors on the injector harness. I have checked the wires at the connector to the computer, and 20,40,60 all appear to be good grounds. The TPS reads 5 volts on all 3 wires. I ground out the ACT sensor and it doesn't throw code 64, I'm assuming all my sensors are good, my o2's are less than 8 months old, the computer has been replaced with two known good A9L's. My ECT is brand new. Car was running and driving fine until a few months ago randomly it died out and then became this monster. Now the car floods out when I shut it off whenever I go anywhere, be it the gas station or work. I get stuck pulling spark plugs or waiting a half hour for it to dry up. Any idea how to solve this guys? Vref = 5v, I tried 3 diff tps, cleaned MAF/IAC and TB. with an analog multimeter and using the block for a ground on the tps green wire I read 5v, but with the black wire as a ground I get no reading. With a digital MM, and the green and black wire I read a voltage in between 1-5v and it fluctuates and the block for a ground does the same. I replaced the injector harness with a good harness and still no fix. Thanks guys

 

[jrichker]

What year car? I have the test path that you need, but I need to know the model year. The wiring changed in 91 and again in 94.

That's why it is a good idea to use the sig under the user control panel (User CP) option. It allows you to post your car year & mods, which help greatly when troubleshooting things. No, it is not there for us to snoop and see any "Secrets" you have hidden away under the hood. Be a good stangnetter and update you sig for future reference & don't keep us guessing

 

[YoLa]

sorry, car is an 88 GT w/mass air conversion. Car was running perfect for years after the mass air conversion and months after the HCI swap/nitrous install. I thought I tracked it down to the ground at the drivers side fender apron, where the battery used to be, but that funny connector(black wire with green stripe) on the Mass air harness along with the coil wires and ac clutch connector that connects to the fender apron was providing 10 ohms resistance. Mind you the car starts and runs, just can't set the tps and all the sensors throw my CEL. If I unplug the connector it shuts off my fuel pump, so I have reason to believe its working, but is that enough impedance to cause my problem? Any better ideas? Thanks in advance!

 

[jrichker]

The computer pin 46 signal ground is a critical component: it provides ground for the
MAP/BARO, TPS, ECT, EGR position sensor and ACT. Signal ground is used in many circuits that have
analog inputs to isolate the electrical noise. It is always separate from power ground,
although both may have a common connection origination point. Signal ground usually
has some conditioning that reduces the electrical noise to prevent false readings
The black/white wire (pin 46) is signal ground for the computer. It provides a dedicated
ground for the EGR, Baro, ACT, ECT, & TPS sensors as well as the ground to put the
computer into self test mode. If this ground is bad, none of the sensors mentioned
will work properly. That will severely affect the car's performance. You will have hard starting,
low power and drivability problems. What sometimes happens is that the test connector black/white
wire gets jumpered to power which either burns up the wiring or burns the trace off the
pc board inside the computer. That trace connects pins 46 to pins 40 & 60.
Only an experienced electronics technician can open the computer up & repair the trace if it burns
up and creates an open circuit.

If the ground for the TPS goes bad, the TPS output voltage increases and the idle speed goes up.

Troubleshooting signal ground problems:

Note that all resistance tests must be done with power off. Measuring resistance
with a circuit powered on will give false readings and possibly damage the meter. That means disconnecting either the battery positive or negative cable since there is always some current draw due to the computer and radio circuits.

1.) With the power off, measure the resistance between the computer test ground
(black/white wire) on the self test connector and battery ground. You should see less than 2.0 ohms.

2.) MAP circuit: Check the resistance between the black/white wire on the MAP/BARO sensor
and then the black/white wire on the EGR and the same wire on the TPS. It should be less than 1 ohms.
Higher resistance than 1 ohms indicates a problem with the 10 pin connector or the splice
inside the main harness where the wire from the 10 pin connectors joins the rest of the black/white wire.
Next check the resistance between the black/white wire and the negative battery cable.
It should be less than 2.0 ohms.

3.) Engine mounted sensor circuit: Check the resistance between the black/white wire on the TPS
and battery ground. It should be less than 2.0 ohms. Higher resistance than 2.0 ohms
indicates a problem with the 10 pin connector or the splice inside the main harness where the
wire from the 10 pin connectors joins the rest of the black/white wire.

Repeat the process for the ACT and ECT sensors. Your results should have the same specifications.

 

[YoLa]

Thanks Jric, so I measured some resistances today. first of all, what is really in question on the black/white wire #46, so I tested the white 10pin connector for starters, minimal resistance from one side to the other... .6ohms which is ok, I checked computer test ground to battery ground = 1.6ohms seems fine, white shaker #46sigrtn to batt ground = .6 ohms, EGR to battery ground seemed to be the root of the problem @ 4.34ohms, baro & TPS to battery ground were both 3.73ohms. ACT to battery ground was 1.64ohms and ECT to battery ground was also 1.65ohms. I peeled back some of the harness where the white 10pin meets the main harness and I checked resistances along the wire and I didn't see the problem. I fixed my problem while I had it all apart for the time being, I added a ground to the black/white wire #46 sigrtn I soldered it on and ran it to a nearby grounding bolt changing the resitance in all my sensors and the white 10pin connector down to .5ohms and the car runs like new with NO CEL whatsoever. I would still like to correct this problem without leaving the hack job on there. Thanks for your advice

 

[YoLa]

any thoughts?