chunks6067 Posted December 18, 2008 Share Posted December 18, 2008 ok so ive had this bad stalling problem (90 AT 4.0) when i test the TPS i get 4.61v where I believe it is supposed to be 5.0v on the other side i am able to adjust it to the proper 4.2 anyone know why its so low on A-D connection i also read a post about dividing the output by the input voltage to get ratio between .825 and .835 (.830 optimum) Link to comment Share on other sites More sharing options...
rworks Posted December 19, 2008 Share Posted December 19, 2008 Check your grounds and clean or replace them if you can. Even after doing that to my '87 I still only get 4.85V. Its a 20 yer old truck, and even new I doubt everyone got exactly 5V. As for the ratio, just get as close to the .830 as you can. Won't be perfect but it should work. Link to comment Share on other sites More sharing options...
chunks6067 Posted December 19, 2008 Author Share Posted December 19, 2008 could that be contributing for my frequent stalls at stop lights and turns or should i be looking at my cps that ive had to change 2x already for a no start right now its currently routed as far away from the exhaust manifold as poss ..or should i be looking at a clogged cat? Link to comment Share on other sites More sharing options...
rworks Posted December 19, 2008 Share Posted December 19, 2008 Not an expert, but I would definitely clean the IAC and throttle body. Gets pretty gunky in there and when I had the almost-stalling problem a good cleaning did the trick. YMMV. Link to comment Share on other sites More sharing options...
chunks6067 Posted December 19, 2008 Author Share Posted December 19, 2008 I cleaned it and the whole TB then i just replaced the IAC after i was convinced it was not working still stalls at every damn light I'm so frustrated ready to sell the damn thing ...drives a man to drinking :beerhead: Link to comment Share on other sites More sharing options...
BLHTAZ Posted December 19, 2008 Share Posted December 19, 2008 That slight difference in voltage I don't believe would cause that type of problem. Sounds like you need to do a fuel pressure test. How long has it been since the fuel filter was replaced? Also...believe it or not...the ground for the fuel pump is back behind the left tail light and you may want to get in there and check to be sure it is clean and rounded good. These trucks are insanely sensitive to having good grounds. Link to comment Share on other sites More sharing options...
chunks6067 Posted December 19, 2008 Author Share Posted December 19, 2008 i replaced the filter last week but today in gonna double and triple check grounds and fuel pressure Link to comment Share on other sites More sharing options...
dakal Posted December 20, 2008 Share Posted December 20, 2008 5.0 volts is ideal, mine is 4.87. if you have 5.0 volts the other voltage should be .08 volts. or 16% of your higher voltage. gave me fits until i set the difference to 16% percent. :thumbsup: Link to comment Share on other sites More sharing options...
chunks6067 Posted December 21, 2008 Author Share Posted December 21, 2008 cool, thats what i did i fixed my problem CPS (3rd one in 2 years) :ack: Link to comment Share on other sites More sharing options...
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