diagnosis of codes and sensor readings

[LOCKONS7RA7US]

So in my last post / ramble i was having so wiring or mechanical issues.. still cant make heads or tails of my findings or where to go from here .. so far i popped open the chilton manual and tested every sensor that is related to emissions or related to the codes i pulled when having problems .

TPS- (KOEO)
-4.95v to sensor
-1.14 from ( manual says no more than 0.95 v)
-4.60 ( wide open throttle )
- no skipping going to wide open

Idle air control valve - ( koeo)
resistance - 11.76 ( 7-13 range )
(Koer) dirty test - while engine was running i pulled the connector and it killed the car .

ECT-

cold -69.5 ohms ( ohms off the chart and temps off the chart )

Hot - 4.2 ohms ( middle of chart 3.84-5.37 ohms and 176-158 for temp chart )


MAF- ( new right off the shelf )

wires A , B - 14.41v ( should be no more than 10.5 v )

wires c, d - .68v ( should be in range of 0.34-1.96 v)


IAT -

-51.2 ohms resistance
-48F-52 F outside concrete temp
- engine temp not running and cold 56.1F

so if i am getting over voltage to the MAF and TPS where is the regulated voltage power coming from the PCM >?

 

[1991 sploder]

I would say if it is a first gen those numbers look within specs on those numbers. My question is, how did you get the reading for the IAC if its obd1 without a scanner that is capable did you really take all the readings based off the voltage of the sensors? What type of problem are you having>?

 

[LOCKONS7RA7US]

My question is, how did you get the reading for the IAC if its obd1 without a scanner that is capable did you really take all the readings based off the voltage of the sensors? What type of problem are you having>?

Yes these readings are from a first gen explorer . yes for the IAC I took all the readings based on what the manual said to do for testing that specific sensor for each one.

my main problem i am having is that when the car is warming up it and at temp when i go to put it in reverse the car dies wither is drive , over drive , or reverse and have to put it in park and restart the car , if i put the car in neutral then goin to any other gear it seems to struggle and stay at a low rpm. after driving it for some time its fine.. ran codes and came up with 124 , and 157 . replaced the MAF sensor and still having trouble where it dies when i put it into gear . and so far gone through every sensor and thinking its a wiring problem im going through the harness to see if i have a issue there verses a mechanical one

 

[1991 sploder]

check the vaccum modulator on the transmission ... take the line off that leads to it and check for vacuum pressure I bet your having a leak.

 

[LOCKONS7RA7US]

Would that cause the codes ive been having and ill take a look .. n see what i find..

 

[1991 sploder]

according to my vintage ford code reader book'
124 throttle position sensor above normal voltage.
157 mass air flow sensor fault low voltage.

 

[LOCKONS7RA7US]

Right my dusty code book said the same thing but im trying to see what causes those codes of every sensor i tested normal .

 

[1991 sploder]

Do the throttle posistion sensor mod where u dremmel out the mounting holes on the sensor to adjust it's position check it with the voltmeter or loosen the little bolt on the throttle body that adjusts the throttle position till u get the correct voltage. The Idle air control valve should take over the idle make sure thats working properly too and as far as the maf goes I would just re use the original if possible... what brand did u get? U dont have a clogged air filter do u?

 

[1991 sploder]

so if i am getting over voltage to the MAF and TPS where is the regulated voltage power coming from the PCM >?

Yea its coming directly from the computer from pulse width modulation and those same wires are used there are no return wires they just measure resistance and power the sensors on the voltage from those should read a certain voltage with the sensor disconnected. It doesn't mean low voltage going to the sensors it means below/above normal readings.

 

[LOCKONS7RA7US]

Do the throttle posistion sensor mod where u dremmel out the mounting holes on the sensor to adjust it's position check it with the voltmeter or loosen the little bolt on the throttle body that adjusts the throttle position till u get the correct voltage. The Idle air control valve should take over the idle make sure thats working properly too and as far as the maf goes I would just re use the original if possible... what brand did u get? U dont have a clogged air filter do u?

i might have to try that and see if it works better with my 66mm BBK throttle body . As far as i know the idle air is working properly i have the K&N filter with the stock filter box and thats not clogged . the mass air flow sensor i bought was Blue streak from oreillys