Timmaay Posted April 11, 2009 Share Posted April 11, 2009 Ok, this is my first time trying to adjust the TPS and through many searches this is the method I followed. Turned key to run position. I have the automatic so I found the square connector with four terminals, put the positve lead of my multimeter into the back of the wire labeled A and the negative to a ground wire on the truck. The meter measured 5.47 volts. It supposed to be around 5 volts but don't know how far off it can be. Anyway, I then put the positve lead into the back of wire B and it measured 4.83. The second number is supposed to be 83% of the first number 5.47x.83=4.54. So it is a bit out of adjustment. I loosen the TPS sensor screws and while watching the meter, moved the sensor until the multimeter read 4.54. When all was said and done I ended up with the first number being 5.46 and the second being 4.52, So very close to spec. But, When I go to start up the truck it takes a couple cranks like usual, starts and then proceeds to idle at ~2000 rpm! I don't have a tach yet so this is just an estimate. What did I do wrong to cause such a high idle? Is the TPS just bad, indicated by the high 5.47? Link to comment Share on other sites More sharing options...
BLHTAZ Posted April 11, 2009 Share Posted April 11, 2009 I don't know where you got the percentage testing method from, but here is the proper TPS testing method from the FSM... viewtopic.php?f=9&t=12260 Your voltage at terminal "B" with A/T and throttle closed should be 4.2 volts. High idle is more typically caused by a problem with the IAC. If you haven't yet, take the throttle body off, remove the TPS & IAC, clean everything REAL good, then reassemble, adjust TPS and fire it up to see what you have. Link to comment Share on other sites More sharing options...
Timmaay Posted April 11, 2009 Author Share Posted April 11, 2009 I will retry it today using that method. Last time I found it hard to get any reading if I didn't put the negative to a good ground. Would this cause a problem? I have already cleaned the IAC real good but not the TPS yet, I will get it all good and clean. The truck was idling at a regular rpm before i messed with the TPS, just had a bit of missfire. And almost wanted to die if I stabbed the throttle. Link to comment Share on other sites More sharing options...
Timmaay Posted April 11, 2009 Author Share Posted April 11, 2009 Well, I cleaned the throttle body and IAC a bit more with some cleaner. Fired and it up and the idle is back to normal. So that's good but not great since it still missing at idle. I didn't mess with the TPS again, I think I'm just going to leave it as is. I have yet to try that mopar combustion chamber cleaner that you recommended BLHTAZ. Are there any other things to try for the rough idle? Link to comment Share on other sites More sharing options...
watchamakalit Posted April 11, 2009 Share Posted April 11, 2009 Need some more info. When was the last tune up? Plugs wires cap rotor fuel filter air filter should all be checked and or replaced before you chaulk it up to a bad sensor. How old is the o2 sensor? How's the compression? There are a lot of things that can cause a misfire (rough idle). The more we know the closer we will get to the problem. Link to comment Share on other sites More sharing options...
Timmaay Posted April 11, 2009 Author Share Posted April 11, 2009 Need some more info. When was the last tune up? Plugs wires cap rotor fuel filter air filter should all be checked and or replaced before you chaulk it up to a bad sensor. How old is the o2 sensor? How's the compression? There are a lot of things that can cause a misfire (rough idle). The more we know the closer we will get to the problem. new plugs, wires, airfilter. Haven't checked the compression yet and I have no idea how old the oxygen sensor is. Thanks for the tips. I will look at some receipts from the previous owner and do a compression test today. Link to comment Share on other sites More sharing options...
BLHTAZ Posted April 12, 2009 Share Posted April 12, 2009 WOW...you must have taken good notes :eek: . I don't recall telling anyone about the combustion chamber cleaner in a long time, although it is some really good stuff. :thumbsup: Link to comment Share on other sites More sharing options...
Timmaay Posted April 13, 2009 Author Share Posted April 13, 2009 WOW...you must have taken good notes :eek: . I don't recall telling anyone about the combustion chamber cleaner in a long time, although it is some really good stuff. :thumbsup: Good memory I guess. 8) Got around to the compression test and all the cylinders are within 5psi of 150. :clapping: And this is without holding the throttle open, because I forgot. Didn't have a chance to dig through the folder of receipts in search of the oxygen sensor age. That's next on the agenda. Link to comment Share on other sites More sharing options...
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