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My TPS reads correct at idle (2-18, 0 ohm; 3-18, open circuit) but does not read correctly at WOT (2-18, open circuit; 3-18, open circuit).

If I remove the TPS, I can get the correct reading at WOT (2-18 open and 3-18 0 ohm).

I have tried to adjust the TPS while on the throttle body but cannot adjust enough for the WOT.

Question,
1. Can I adjust the Throttle body for additional travel to satisfy the TPS?

2. Does it really matter if the WOT is not reading correctly as I do not drive the car at WOT in any gear?
 

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check the linkage, those plastic peices at the end can get really sloppy.. if you have a pick and pull near by,, find a mbz diesel look at the linkage.. steel end peices, best yet, those end peices will fit on the alfa linkage( threaded rods ), get all 4 of them done at one time, also check that round ball at the firewallit's on a bushing, can/ well go badd/ sloppy.. heres a few photos, of what i did..in the morning.i will post photos of the mbz diesel parts. i have a few extra.
 

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with all these parts on my car.. motor movement.. not an issue( paul sprell motor munts, and a polly tranny mount( i do not have a alfa tranny.. it's a t5 now) throttle responce is very. very good, and my throttle pos. sender, works perfectly
 

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2. Does it really matter if the WOT is not reading correctly as I do not drive the car at WOT in any gear?
I think the problem we need to address, is why aren't you ever driving at WOT in any gear? Shouldn't you be driving a Geo Metro? :p
 

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. the wot on this switch comes on at 75-80% throttle..sorry 3 am here, cannot sleep..how i set up mine..closed throttle tremianls.3-15 set this one first.. just as a cheat( worked well for me put 1 bussness card between the throttle stop and the throttle body) set the the tps so it read ' infinity ' on 3-18.. now always check the throttle to make shure it is fully open, take off the air tubes, reach to the throttle shaft, oped it up ALL the way, look inside the throttle body. is it FULLY open?if so check termainals 2-18, this now should read ' infinity ' now have a freind/ wife/ son/ daughter/mistress( don't get caught with the latter:):) ) have them plant the trottle all the way down,peek inside the throttle body.. FULLY open? if not adjust the pedal throttle stop to make this part work..as a extra cheat, you can open the wot switch body if you need to to adjust the inners for ware, or find a bmw or any L-jet car, pull the swtich off one of those car.., most of them work the same way.. part no's might be a wee bit diff..
 

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one more thing, if you do go to your local ' pick nd pull ' bring your volt meter.. a throttle body( valve) switch , and a throttle position petentiometer look the same works diff inside..a volt meter will tell you the diff.. the later will show a continuousy varying signal.. the former will show only 2 infinity contacts on at closed throttle and one at open throttle.. but agian CHECK THOSE LINKAGE ENDS, SLOPPY ENDS WILL NOT HELP YOU AT ALL..:)
 

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1. Can I adjust the Throttle body for additional travel to satisfy the TPS?
Don't do it.
What you describe is more than likely related to a linkage rod problem.
You can't tweak the TB to open any more than it opens to begin with anyway. It only offers adjustment for how far it closes and that should never be tampered unless you know exactly what you are doing as guessing and fiddling will only make things worse on the ECU and related while improving nothing.

2. Does it really matter if the WOT is not reading correctly as I do not drive the car at WOT in any gear?
2 parts.

Part 1: Yes it matters as it also triggers the ECU to run a little fatter fuel mix and in open loop.
If you've an electronic VVT it triggers that also.
(without all that going on, you're potentially running stupid lean when you least want to do it)

Part 2: The 'WOT' switch should engage at around 57~59 degrees travel.
ie: not right at the WOT point (90 degrees) but slightly beyond half travel.

Again, that points most toward incorrect linkage adjustment.
ie: if the TB doesn't open enough due to incorrect linkage, the TPS is never gonna switch anyway, and as you say it does function when off the TB its prolly fair to assume that it is indeed a functional TPS.
You could try it against a protractor while it's off the throttle body if you wanted to confirm the angles more closely. From the point at which the idle switch is just active (as in even a tiny deflection toward the open throttle direction will cause it to switch off) lay the protractor w/zero at that point and read the degrees of angle that the high travel switch engages at.
If it ticks at around 60 degrees it's linkage. Though anything less than 89 degrees (the max the TB can move regardless) would still imply the linkage is wrong and not letting the TB move enough to even engage a 'wide' TPS let alone reach full throttle.

Its a switchbox rig with a circut closing at zero TB deflection and a switch closing at 57+ degrees TB deflection while 'middle travel' is no switch engagement, it's not a progressive sweeper/potentiometer, so 'switch on' is 'switch on'.
(not to say its impossible for the high or low end switch to fail in a way that doesn't let it activate in the right range, but the odds of that are REAL slim with outright failure being the more common defect)

But as Antony asked: Why aren't you ever using full throttle?
Granted you don't need to be there all the time, but in the grander scheme of things, it can actually help things in an Italian Tune~Up kind of way if done periodically.

Engines that are meant to to spool need to spool occasionally or they load up with carbon and junk and stuff and start to run like **** until said carbon and stuff and junk gets blown out. (these are not American V8's that cruise at 2000rpm all day)

*Simular premis: you wouldn't try to cut your lawn with the lawnmower set to 'idle' would you?
 

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.. tifosi.. tifosi........ you wake up.( 4 hours diff. time zone from here ). first thing that you do ...is go to the alfa romeo bb...man you are ADDICTED!!!
 

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i am now going to try to sleep...
 

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Discussion Starter #14
Thank you for all of the replies. Some additional data points....
1. Throttle linkage may be out of adjustment but for reference, it has never been messed with (at least back as far as 1986!)
2. I understand that theTPS only has 'on-off' type values. My TPS does not show continuity between 3-18 unless at the very end of travel.
3. Metal rod ends sound good. I'll take a look next time I'm at the yard.


4.
 

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Discussion Starter #15
There is a throttle stop on the floor behind the pedal. Is that mis-adjusted?
My inability to have the throttle body activate the switch is with the throttle linkage disconnected at the throttle body in an effort to eliminate variables.
 

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I should have a used TPS laying about that I could send you for testing purposes.
 
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