EFI tuning and computer and sensor wiring questions for the EFI guys

[cobravin]

or engineers
my car is running very rich when you lay into it, on the dyno it quickly drops off the chart into the 9's (air/fuel)and didn't come up until 4800 rpm when it just barely broke 10 to 1

the dyno guy believes the chip burned by ford chips.com may be off and suggested i get a copy of the map so he can tweak it instead of doing a complete re burn, i needed the mail order (4 position sct chip)in order for the car to run because of the 90mm lmaf meter

the phone number i had for them no longer works and i have heard that he is now a co owner of SCT chips, so since no one will call me back when i call SCT and leave messages for Jerry?,i cannot obtain the chips map so will probably need to have it re dyno'ed and re burned but just wanted to make sure there was no other reason the car was running rich before i go through the hassle

i get codes 42 and 92, hego voltage high(rich)

while checking some things with the multimeter i noticed some problems or things that I'm not sure are right, does anyone see anything obviously wrong???

MAF METER TESTING,(new Ford 90mm lightning)new pigtail soldered in, key on and black multimeter probe grounded

red wire(conn A)has 12.11 volts and continuity to pins 37 and 57(all continuity checks done with key off computer disconnected)

black wire has no cont to grd or to any wire in the computer pins ( i hard wired a ground to the maf in hopes it was my problem but it still ran rich with no change)

tan wire (conn C),( goes to pin 9 from computer)has 5.77 volts, this wire also has good continuity to pin 9

blue wire (conn D),( goes to pin 50)has .01 volts and good continuity to pin 50

***with one probe into connector A of the MAF(red) and the other in either side 02 sensor connector (not 02 itself)12v wires i am getting 426 ohms of resistance when running a continuity check (both plugs disconnected)should i have any resistance on that wire???

***below has some results that seem odd also when testing the 02 SENSORS

there is good continuity from both o2 heater ground to pins 16,19,20,40,49,60 of the computer

left 02 heater ground to right has good continuit

**there is 28 ohms of resistance between 02 heater ground and 02 heater 12v( key off unplugged)

02 VOLTAGE CHECKS WITH KEY ON
**from either 02 heater grounds to the 02 heater pos i get 12.19 volts

**from the 02 signal wires (pins 29 and 43)
to 02 heater ground or frame i get .01 volts
but to the 02 pos wire i get 5.53 volts???

TPS TESTING
with key off i show .05v between blk(46)and red(26)
with key on i show 5.02v on the same wires

with key on i show 98v between blk and grn(46 and 47) goes up to full open with no gaps or flat spots(new ford tps)

**IAC TESTING key on
from red wire to tan i get 11.93v
from red wire to frame ground i get 12.13v
from tan to frame i get .19v???
* i also don't notice much if any change when disconnecting the iac when running

** also i read somewhere to check continuity between pin 46 and pins 40 and 60 at the eec harness, these are the results with the meter on the continuity setting
40-60 good continuity
46-40 NO continuity
46-60 NO continuity
i have good continuity from pin 46 to the act, ect and vip test plug
this is with computer and sensors unplugged, should i repeat the test with the sensors plugged back in??

engine is 5.0 converted to mass air
vortech v1-sc supercharger stock pulleys, bosch 117 bypass, home made 4" powerpipe
ford gt40 y303 aluminum heads
stock cam with 1.7 roller rockers
90 mm lightning maf meter
42 lb injectors no fmu
walbro 286? fuel pump(the big one)
new ford fuel pressure reg 40 lbs unplugged drops to 35 plugged in, my new holley broke and was spitting fuel out
70mm bbk throttle body with new ford tps
explorer intake no egr or smog or cats
new(reman) a9l computer with SCT 4 position chip burned for my setup by fordchips.com

any suggestions or further testing i should do, besides put a carb on it thanks guys.......Vinny


i have checked for vacuum leaks with ether with no change in rpm

 

[jrichker]

TPS TESTING
with key off i show .05v between blk(46)and red(26)
with key on i show 5.02v on the same wires

You are reading the VREF voltage.
Try this... Currently there is some dispute about setting it at .99 volts being worth the effort, but anything less is probably OK. All you need is less than 1.0 volt at idle and more than 4.25 at Wide Open Throttle (WOT). You'll need a Digital Voltmeter (DVM) to do the job.

The Orange/White wire is the VREF 5 volts from the computer. You use the Dark Green/Lt green wire (TPS signal) and the Black/White wire (TPS ground) to set the TPS. Use a pair of safety pins to probe the TPS connector from the rear of the connector. You may find it a little difficult to make a good connection, but keep trying. Put the safety pins in the Dark Green/Lt green wire and Black/White wire. Make sure the ignition switch is in the Run position but the engine isn't running.

Here’s a TPS tip I got from NoGo50

When you installed the sensor make sure you place it on the peg right and then tighten it down properly. Loosen the back screw a tiny bit so the sensor can pivot and loosen the front screw enough so you can move it just a little in very small increments. I wouldn’t try to adjust it using marks. Set it at .97v-.99v, the closer to .99v the better.

(copied from MustangMax, Glendale AZ)

1. Always adjust the TPS and Idle with the engine at operating temp. Dive it around for a bit if you can and get it nice and warm.

2. When you probe the leads of the TPS, do not use an engine ground, put the ground probe into the lead of the TPS. You should be connecting both meter probes to the TPS and not one to the TPS and the other to ground.

3. Always reset the computer whenever you adjust the TPS or clean/change any sensors. I just pull the battery lead for 10 minutes.

4. Check the procedure for your year, on my 90 I have to turn the idle screw until it just touches the tab, then insert a .010 feeler gauge and give it about one more turn. Then you adjust the TPS voltage to .98v, reset the computer. Start it up, if the idle is to low then turn the screw in until it is just right, then readjust the TPS voltage to .98v and reset the computer and start it up. The key is to adjust the TPS voltage and reset the computer whenever the idle screw is changed.

** also i read somewhere to check continuity between pin 46 and pins 40 and 60 at the eec harness, these are the results with the meter on the continuity setting
40-60 good continuity
46-40 NO continuity
46-60 NO continuity
i have good continuity from pin 46 to the act, ect and vip test plug
this is with computer and sensors unplugged, should i repeat the test with the sensors plugged back in??

You are missing the signal ground (pin 46) for all the sensors. The odds are that you cannot dump the codes either. Your MAP, ECT, ACT, TPS & EGR sensors are probably not working correctly. 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.
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 1.5 ohm. Next check the resistance between the black/white wire and the negative battery cablet. It should be less than 1.5 ohms.

O2 sensor wiring...
The following is a Quote from Charles O. Probst, Ford fuel Injection & Electronic Engine control:
"When the mixture is lean, the exhaust gas has oxygen, about the same amount as the ambient air. So the sensor will generate less than 400 Millivolts. Remember lean = less voltage.

When the mixture is rich, there's less oxygen in the exhaust than in the ambient air , so voltage is generated between the two sides of the tip. The voltage is greater than 600 millivolts. Remember rich = more voltage.

Here's a tip: the newer the sensor, the more the voltage changes, swinging from as low as 0.1 volt to as much as 0.9 volt. As an oxygen sensor ages, the voltage changes get smaller and slower - the voltage change lags behind the change in exhaust gas oxygen.

Because the oxygen sensor generates its own voltage, never apply voltage and never measure resistance of the sensor circuit. To measure voltage signals, use an analog voltmeter with a high input impedance, at least 10 megohms. Remember, a digital voltmeter will average a changing voltage." End Quote

Measuring the O2 sensor voltage at the computer will give you a good idea of how well they are working. You'll have to pull the passenger side kick panel off to gain access to the computer connector. Remove the plastic wiring cover to get to the back side of the wiring. Use a safety pin or paper clip to probe the connections from the rear. The computer pins are 29 (LH O2 with a dark green/pink wire) and 43 (RH O2 with a dark blue/pink wire). Use the ground next to the computer to ground the voltmeter.

Most of the common multimeters have a resistance scale. Be sure the O2 sensors are disconnected and measure the resistance from the O2 sensor body harness to the pins on the computer.

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. Do not attempt to measure the resistance of the O2 sensors, it may damage them.

The O2 sensor ground (orange wire with a ring terminal on it) is in the wiring harness for the fuel injection wiring. I grounded mine to one of the intake manifold bolts

 

[cobravin]

You are reading the VREF voltage.

***i was hoping you would respond, thanks, as far as the tps i was just posting the measurements to see if anything was screwy with the numbers, i have set the voltage and iac idle many times, i was just hoping someone would notice some voltages or resistances that were out of line with regards to the sig rtn


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 1.5 ohm. Next check the resistance between the black/white wire and the negative battery cablet. It should be less than 1.5 ohms.

***i repeated this test below with the computer hooked back up and back probing 46 and got different results but i don't know what it tells me, below is the first test, and below that is the last


also i read somewhere to check continuity between pin 46 and pins 40 and 60 at the eec harness, these are the results with the meter on the continuity setting
40-60 good continuity
46-40 NO continuity
46-60 NO continuity
46-batt neg = NO cont
i have good continuity from pin 46 to the act, ect tps bap and vip test plug
this is with computer and sensors unplugged, should i repeat the test with the sensors plugged back in??

****re tested with the computer hooked up but power off
40-60 = still good
46-40 = now good continuity
46-60 = now good cont.
46 to bat neg = now good cont.

i also have good continuity between all the signal wires of the sensors, act ect tps bap self test plug BUT NOT TO BATT GROUND, IS THIS NORMAL??? this is with the computer unplugged


O2 sensor wiring...

***i will put new 02 sensors in and backprobe the wires at the computer but do these tests i did with regards to the 02 sensors mean anything??

there is good continuity from both o2 heater ground to pins 16,19,20,40,49,60 of the computer

left 02 heater ground to right has good continuit

**there is 28 ohms of resistance between 02 heater ground and 02 heater 12v( key off unplugged)

02 VOLTAGE CHECKS WITH KEY ON
**from either 02 heater grounds to the 02 heater pos i get 12.19 volts

**from the 02 signal wires (pins 29 and 43)
to 02 heater ground or frame i get .01 volts
but to the 02 pos wire i get 5.53 volts???