sensor failures

[dan_chandler]

I have a 92 bronco xlt 5.8l. I have checked codes and tested sensors as I go when I replace a sensor within a couple days another problem arises and a different sensor tests bad. Ive replaced iac valve o2 sensor tps ect all due to codes and a follow up test of the sensor. I got the truck in february and at the time I was gettin 12 mpg average around town within a month it dropped to 9 at that point I changed plugs wires cap rotor o2 sensor still no change recent cold snap brought up new issues. Starts up great but idles up to 1500 if I wait around 2 to 3 minutes it will come down to my usual 750 but since this all started it now idles in gear automatic around 1000 and doesnt want to shift till 3500 and cruises around 2500 at 35 mph I can pat the gas sometimes and it will then upshift but starts back up at the next stop light. After driving for about 20 min I park the truck and the idle jumps to 2500 under no load. Sometimes after that I can shut it off let it sit for about 5 min and then it will idle perfect and shift perfect. Engine codes currently koeo 327, 328 which has to do with egr position sensor cannot get koer test to activate. My question is will changing that sensor effect my idle situation the ohms reading I get of the sensor itself is 15000 ohms the reference signal on the plug is 5 volts.

Thanks for reading I know its a lot of info but I really nead help it is my only means of transport right now

[96EB5.8]

I doubt the EGR code is the problem. first ck for vac leaks [hoses gaskets ...] then ck the TPS for correct operation/adjustment and for IAC mounted correctly. IF those are ok ck the MAP sensor[can be tested for hertz but easier to just replace with a borrowed or new one].

[JKossarides]

You need to figure out why you can't perform KOER self dynamic test, make sure the Ford Code Reader batteries are fresh or it won't trigger the computer properly, incomplete or failed test results.

What transmission are you running, AOD or E4OD, C6....?

You can pull and clean the IAC using throttle body cleaner but only in the bottom valve part to remove any built up carbon inside and it will improve idle.

Most TPS sold today are "plug & play" with no "adjustment slots" using a multimeter for adjusting voltage setting, the setting is automatic when reconnected, make sure the "tangs" little plastic bumps inside the spring loaded ring in the center engage the end of the TB shaft otheriwse it's like being in neutral.

Check thru the emissions sytem for possible vacuum leaks in the lines or hoses.....it doesn't take much...


Good Luck ~

[dan_chandler]

Sorry e4od new idle air control valve new tps plug and play unit no adjustment and vacuum holds around 12 with vacuum pump. Thank you for replying and your help

[dan_chandler]

I went through and checked all my sensors again tps that I replaced last month was getting 5 volts but sending nothing back out from closed to wide open throttle. I warranty replaced it and now it idles great and shifts right on time.

[96EB5.8]

Sometimes just because it is new does not mean it is good. GLad to hear you found it.

[JKossarides]

What was the end result as to why you can't pull fault codes for KOER self dynamic test.....?

Thanks ~

[96EB5.8]

OBD 1 codes are ok for some things but sometimes are useless for drivability problems. They either are not present or for something unrelated to the actual problem, as in this case. On SD systems it almost always comes down to tp, maf, spark or fuel. Most of these on OBD1 are not code friendly. I am a ford senior master tech[tech for 20yrs] and I specialize in gas drivability