testing my tps and the ohms are jumping around ... could it be bad?

C

cecil bass

Member
Joined
Aug 27, 2012
I just pulled my tps so I could test it . I checked the ohms to see if they rise while pushing the lever up they go from 1.50 ohms to 5.8 ohms at the highest but before the lever gets pressed the whole way the numbers start to go down so when I depress the lever all the way down the reading is 5.30 ohms if I let up on lever the numbers go up ....... Does this mean its bad? I would of went to auto zone to test it but they said they can't...... Any info would be helpful!
 
dont ohm it..
key on read the center wire with a voltmeter (push an open paperclip in from the backside of connector)
should be .40-.44 at rest and should increase steadily as you increase blade angle , full open should read 4.5v-4.9 v

better yet get a scanmaster and you can see the TPS voltage
 
I just reinstalled the tps and tried to adjust it with the scan master it just reads 00 tried screwing it all the way out to reset it no matter how I adjust the darn thing it just stays at 00 what do you think is wrong???
 
cecil bass said:
I just reinstalled the tps and tried to adjust it with the scan master it just reads 00 tried screwing it all the way out to reset it no matter how I adjust the darn thing it just stays at 00 what do you think is wrong???
Click to expand...

Are you trying to adjust the tps or the iac? If it's the tps you need to loosen the 2 screws slightly that hold it in place and watch the reading on the scanmaster to set it at .42 to .44 with the key on engine off then tighten the 2 screws down snug so it can't move but don't over tighten them to the point of doing damage to the sensor.
 
whitehot1 said:
Are you trying to adjust the tps or the iac? If it's the tps you need to loosen the 2 screws slightly that hold it in place and watch the reading on the scanmaster to set it at .42 to .44 with the key on engine off then tighten the 2 screws down snug so it can't move but don't over tighten them to the point of doing damage to the sensor.
Click to expand...
I can adjust the tps fine .... Dont we first adjust the IAC on driver side of TB but when i try it just stays at 00 when I turn the screw. So does that point to a bad IAC sensor? Before this started happening it was at 23.
 
cecil bass said:
I can adjust the tps fine .... Dont we first adjust the IAC on driver side of TB but when i try it just stays at 00 when I turn the screw. So does that point to a bad IAC sensor? Before this started happening it was at 23.
Click to expand...

I didn't realize you were resetting the iac. Yes the iac is set first then adjust the tps. It is possible to have the iac so far out of adjustment that it will read 00 no matter how many times you turn the idle air adjustment screw. When the iac is set properly there should be approx. 1 to 1 1/2 threads of the adjustment screw protruding through the throttle body.

Here is a link to help adjust the iac and also how to clean it and the throttle body.

http://www.vortexbuicks-etc.com/basics.htm#IAC (Idle Air Control) Adjustment
 
I adjusted the IAC to 23 turned the car off restarted and the IAC is at 00 again ... The car is idling up and down very fast ..... So should I replace it or could there be something else causing this???
 
Start looking at all lines .pcv. I use a smoke machine. Do you have scanmaster? The Iac at zero means the ecm cant control idle.The iac is a controlled vacuum leak to idle the car. When there is a leak the numbers should drop fast and iac will close. like stated above set the screw 1 to 1 1/2 threads showing through throttle body. If numbers are still zero I would start looking for vacuum leaks. Has any work been done to the car lately? Did you have iac plugged in and unscrewd from throttle body? The plunger should have shot out.Make sure there is nothing in Iac bore, dirt, carbon. Good luck
 
The only thing I have done presently was change the coil and module if it was a vacuum leak wouldn't it do this all the time ? most of the time the car runs perfect just out the blue it will start to act up it might do it for a mile or so then it goes back to running perfect....... I'm confused! So I can blow smoke into the vac system to show leaks?
 
The smoke machine pushes smoke into vacuum system. It would do it all the time if you had a vacuum leak. Take out pcv and see if its sticking. If it is sticking open it could cause some problems. be careful not to break the rubber grommit. Do you have a vacuum brake set up? Do you have any codes stored? Pull module plug and make sure all the pins are good . Does the iac go back to normal at times or does it stay at zero?
I will check back later have to go to work. good luck
 
cecil bass said:
I adjusted the IAC to 23 turned the car off restarted and the IAC is at 00 again ... The car is idling up and down very fast ..... So should I replace it or could there be something else causing this???
Click to expand...

What does the scanmaster show now for the TPS. When you are making adjustments to the iac be sure the TPS is set to around .38 and it doesn't go past .46 while getting the iac adjusted correctly. When making the adjustments to the iac idle air control screw only turn it in small increments like 1/8 to 1/4 turn at a time and give it some time before adjusting it again, take your time when doing this don't rush it and you will get it right. Make sure the engine is fully warmed up to normal operating temps before starting the adjustments and turn the engine off and restart it after each adjustment. If there are no other problems like vacuum leaks or bad sensors you should be able to get the iac and TPS set correctly. If the iac and TPS are the originals i would replace them with BWD brands, but thats just me i don't have faith in 27 + year old parts mechanical or electrical.

Here is a link for resetting the iac.

http://www.gnttype.org/techarea/faq/IACreset.html
 
cecil bass said:
Is there a guide for measuring vacuum at different place in the vac system to check for leaks?
Click to expand...

Get a PVC plumbing end cap that will tighten down in place of the MAF. Drill and mount an air valve on it, pop the rocker shafts off and pressurize the entire induction tract with about 25 or 30PSI.

Squirt down with your favorite soapy/watery mixture and look for bubbles.

Then say holy #*(@^$ at all the oddball leaks you find that make no sense whatsoever. :)
 
Basically you're removing the MAF and plugging the pipe up with an air inlet. When you remove the rocker shafts it causes all the intake valves to be closed. When you fill the engine up with 'boost', you'll have pressure on the compressor side of the turbo, the intercooler, the plenum, intake gaskets , EGR system, and all the hoses and connections in the loop.
 
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