tab/tad issues... need help!
02-19-2015, 08:20 PM
#1
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tab/tad issues... need help!
Ok guys here is what i got goin on... got a 94 5.0 i have had a missfire for a while juat at low rpm like 1000 to 1500 and a horrble lack of power and fuel mpg... so i decided to replace all my vac lines with rubber.. well i did and i notice from wwhat diagrams i have seen that the tab/tad were crossed so i switched thwm back... now the truck has a horrible rattle comming from the engine somewhere.... so i swapped back and it went away but still having power loss problems and rpm stumble! Any help would be much appreciated
02-19-2015, 08:43 PM
#4
First off, pull your codes - there may be some in the computer even if your CEL isn't on. Sean's got a sticky up at the top of the page on how to do that.
Then there are a few tests you can do that would help narrow things down. Fuel pressure test. Compression test - dry and wet. Vacuum test. You can use a multi meter to test your TPS and a few other other sensors. And you can check ohms resistance on your spark plug wires.Clean and re-gap your plugs (or just replace them if they're old)
If you have a timing light, trying it on each wire will tell you if there's an electrical misfire. If current isn't going through a spark plug wire to ground, the light won't flash.
Then there are a few tests you can do that would help narrow things down. Fuel pressure test. Compression test - dry and wet. Vacuum test. You can use a multi meter to test your TPS and a few other other sensors. And you can check ohms resistance on your spark plug wires.Clean and re-gap your plugs (or just replace them if they're old)
If you have a timing light, trying it on each wire will tell you if there's an electrical misfire. If current isn't going through a spark plug wire to ground, the light won't flash.
02-19-2015, 09:03 PM
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Well i pulled the codes and only one i got was 121 tps....and fuel pressure is good and compression... also i have checked the vacuum and it seems to be spot on... i just dont know what te deal is with those tab/tad controls that made it knock
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02-20-2015, 07:50 PM
#8
Pretty sure it's the black wire - should show about .9 to .96 volts closed then rise steadily up to about 5 volts WOT then fall steadily as you close the throttle.
Meter on volts dc.
I don't remember which color probe goes to the black wire or whether the other probe goes to pos or neg.
Sounds like I need a refresher too. I have it somewhere, I can try to look it up if you can't find it. (but maybe somebody else will jump in and clarify that one)
Another thing I read is that if it passes that test, try tapping it gently with a screwdriver handle as you open and close the throttle - similar to a bumpy road, I guess.
Meter on volts dc.
I don't remember which color probe goes to the black wire or whether the other probe goes to pos or neg.
Sounds like I need a refresher too. I have it somewhere, I can try to look it up if you can't find it. (but maybe somebody else will jump in and clarify that one)
Another thing I read is that if it passes that test, try tapping it gently with a screwdriver handle as you open and close the throttle - similar to a bumpy road, I guess.
02-20-2015, 09:34 PM
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Haha yeah ill give it a whirl... also i got the secondary air situation figured out its all good to go... maybe this tps deal is my problem... i sure hope so or im sending this pos down the road !
