Throttle Position Switch '86 951-long story
01-26-2005, 04:41 PM
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Throttle Position Switch '86 951-long story
Alright I thought I would open this up to people who have had the "pleasure" of messing with this little item.
Ok here is the background. I was having all kinds of lack of throttle response. It would come and go. Sometimes at full boost, sometimes like turbo lag, sometimes like a studdering, you name it. Sometimes it would not come on until I had been driving my car for hours(heat soak issue?..but what) Nothing consistent enough...until later.
So I started with the AFM(Air Flow Meter) Popped the top on mine and saw it had decent grooves worn in the contact strips, so I bent the arms to run on a cleaner area. This seemed to improve my situation...less lag here and there.
But eventually it was back. Sometimes it would not happen at all, sometimes my car would run factory fresh with clean boost and a great power curve.(never did I or my wingman ever see any burned oil out the back end-nice for a 164k mile car)Although on startup sometimes my car does blow condensate with soot that would make an Aboriginal blow artist proud.(6ft on throttle press)
Still believing it to be the AFM I bought one off a 60,000 mile car. Again good for a while....now I am starting to think...clogged catty.(and it still may be part of the problem-see my soot blower comment.
Next was maybe the fuel regulator. I had previously installed a O2 duty cycle meter to start to diagnose this problem. It always tracked slow. But when it would do the studder accelerate, where I would press the throttle and it would bub bub bub like a bad injector(or at least the signal to the injector) and I could not accelerate -then, I would let off the accelerator and it would let me by.
So I bought a 3-bar(why not I am go for more hp anyway)
Plugged in still previous problem. Though my 02 read a lot closer to Stoich.
So next was the O2 sensor. I bought the cheap replacement(see previous post)
Now I can see that my O2/Duty meter tracks real fast. 99% of the issues gone!
And I actually run a little more on the rich side.(which is fine because I am about to free up some air)-after this problem is solved.
Until about a week later. I am cruising along, and go to pass somebody, so I go to shift and BAM I cannot get past this invisible 2k wall, eventually I do(I just kept stabbing the gas until it did), well up comes a stop light. I am stopped at the light(never had a problem with idle) and I try to accelerate and I hit a throttle brick wall at 2k! It absolutely will not go past that, and while this is happening I look at my meter and the duty is working, but the 02 part just disappears. I hit the gas and the meter reads all is working until the 2k wall and then the 02 drops off. So eventually I punch past it and hold second gear(this was at the bottom of a steep hill just to add to the fun) I get home and park it. I try to start it that evening...no go.(the 2k wall) So the next morning I try again(no go the 2k wall) So I think TPS(Throttle position sensor)...I bet you could not wait to get to this
I am sure there are plenty of ways to do this. Please post if you have been successful without spilling profanities
I removed the stock air box top and filter. U-jointed(would have been easier with an air ratchet) the bolt that is under the intake(holds those two metal vacuum lines)so I could move it or push it down. Pulled the intercooler pipe with the banjo bolt.
Obstacles to the bottom screw.
The large intercooler rubber. Those two metal vacuum lines.
Eventually I was able to press down hard enough on the clamped vacuum line(already pulled the blue one off)and get a screw driver threaded between the two hard vacuum tubes and onto the head of the screw(which thankfully for me came out slowly but surely-and no it was not too loose so that the TPS was misaligned) I used a magnet wand to get the screw out of there. Well I replaced the switch and it came time to put that bottom screw in....lots of cussing later it is still not in there. I put the top one in made sure travel was correct on the TPS and am going from there. So far so good!(see clarks garage for a screw replacement idea)-4mm allens
I am sure an "easier" way would have been to simply take the time to undo all the drivers side hoses and intercooler pipe and then unbolt the throttle body and do it from there. Your posts will tell me if this is true. But it looked so simple, how could something like that be so hard!
Bottom line. I am sure that all of the above items contributed to one degree or another to my overall problem. This car has 164000 miles on it and was never properly maintained(until me)
Hope this tale inspired or at least gave you an idea of how not to do it ;P
Thanks for reading.
Ok here is the background. I was having all kinds of lack of throttle response. It would come and go. Sometimes at full boost, sometimes like turbo lag, sometimes like a studdering, you name it. Sometimes it would not come on until I had been driving my car for hours(heat soak issue?..but what) Nothing consistent enough...until later.
So I started with the AFM(Air Flow Meter) Popped the top on mine and saw it had decent grooves worn in the contact strips, so I bent the arms to run on a cleaner area. This seemed to improve my situation...less lag here and there.
But eventually it was back. Sometimes it would not happen at all, sometimes my car would run factory fresh with clean boost and a great power curve.(never did I or my wingman ever see any burned oil out the back end-nice for a 164k mile car)Although on startup sometimes my car does blow condensate with soot that would make an Aboriginal blow artist proud.(6ft on throttle press)
Still believing it to be the AFM I bought one off a 60,000 mile car. Again good for a while....now I am starting to think...clogged catty.(and it still may be part of the problem-see my soot blower comment.
Next was maybe the fuel regulator. I had previously installed a O2 duty cycle meter to start to diagnose this problem. It always tracked slow. But when it would do the studder accelerate, where I would press the throttle and it would bub bub bub like a bad injector(or at least the signal to the injector) and I could not accelerate -then, I would let off the accelerator and it would let me by.
So I bought a 3-bar(why not I am go for more hp anyway)
Plugged in still previous problem. Though my 02 read a lot closer to Stoich.
So next was the O2 sensor. I bought the cheap replacement(see previous post)
Now I can see that my O2/Duty meter tracks real fast. 99% of the issues gone!
And I actually run a little more on the rich side.(which is fine because I am about to free up some air)-after this problem is solved.
Until about a week later. I am cruising along, and go to pass somebody, so I go to shift and BAM I cannot get past this invisible 2k wall, eventually I do(I just kept stabbing the gas until it did), well up comes a stop light. I am stopped at the light(never had a problem with idle) and I try to accelerate and I hit a throttle brick wall at 2k! It absolutely will not go past that, and while this is happening I look at my meter and the duty is working, but the 02 part just disappears. I hit the gas and the meter reads all is working until the 2k wall and then the 02 drops off. So eventually I punch past it and hold second gear(this was at the bottom of a steep hill just to add to the fun) I get home and park it. I try to start it that evening...no go.(the 2k wall) So the next morning I try again(no go the 2k wall) So I think TPS(Throttle position sensor)...I bet you could not wait to get to this
I am sure there are plenty of ways to do this. Please post if you have been successful without spilling profanities
I removed the stock air box top and filter. U-jointed(would have been easier with an air ratchet) the bolt that is under the intake(holds those two metal vacuum lines)so I could move it or push it down. Pulled the intercooler pipe with the banjo bolt.
Obstacles to the bottom screw.
The large intercooler rubber. Those two metal vacuum lines.
Eventually I was able to press down hard enough on the clamped vacuum line(already pulled the blue one off)and get a screw driver threaded between the two hard vacuum tubes and onto the head of the screw(which thankfully for me came out slowly but surely-and no it was not too loose so that the TPS was misaligned) I used a magnet wand to get the screw out of there. Well I replaced the switch and it came time to put that bottom screw in....lots of cussing later it is still not in there. I put the top one in made sure travel was correct on the TPS and am going from there. So far so good!(see clarks garage for a screw replacement idea)-4mm allens
I am sure an "easier" way would have been to simply take the time to undo all the drivers side hoses and intercooler pipe and then unbolt the throttle body and do it from there. Your posts will tell me if this is true. But it looked so simple, how could something like that be so hard!
Bottom line. I am sure that all of the above items contributed to one degree or another to my overall problem. This car has 164000 miles on it and was never properly maintained(until me)
Hope this tale inspired or at least gave you an idea of how not to do it ;P
Thanks for reading.
01-26-2005, 06:10 PM
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Looking at that TPS it just seemed like it would be so easy, I mean two little screws..how hard could it be?
Oh yeah....German Over-engineering.
Oh yeah....German Over-engineering.
01-27-2005, 10:46 AM
#6
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Originally Posted by theedge
I think I just took my throttle body off as well, four hex bolts, 7MM I think?
Looking to take the throttle out in my S2 to replace the TPS. Any advice appreciated. Clarks' just says "remove throttle body," so I guess it can't be too tough.
01-27-2005, 11:29 AM
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Just an update.
The TPS I replaced it with was from a lower mileage car.
The engine was on a pallet, so it was much easier to just undo the four throttle body bolts and....did I say easy.
The throttle body came off without a hitch. and so did the bottom "mission impossible" screw, but for some in-human reason the top screw would not budge-despite PB blaster and all kinds of gripping from the side.
Finally I had enough and busted out mr dremel. I flattened a side in hopes to get better grip. This worked and after the first turn the scew came out like butter. Who Knows. It just shows plan for the worse and be pleasantly surprised when it goes smoothly!...oh yeah all this on an "hour" lunch break
The TPS I replaced it with was from a lower mileage car.
The engine was on a pallet, so it was much easier to just undo the four throttle body bolts and....did I say easy.
The throttle body came off without a hitch. and so did the bottom "mission impossible" screw, but for some in-human reason the top screw would not budge-despite PB blaster and all kinds of gripping from the side.
Finally I had enough and busted out mr dremel. I flattened a side in hopes to get better grip. This worked and after the first turn the scew came out like butter. Who Knows. It just shows plan for the worse and be pleasantly surprised when it goes smoothly!...oh yeah all this on an "hour" lunch break
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09-14-2006, 01:26 PM
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09-14-2006, 01:32 PM
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Originally Posted by 7thStranger
Don't feel bad on the S you have to remove the intake manifold to remove the throttle body, to remove the switch.
09-14-2006, 03:50 PM
#11
I had pretty much exactly the same problem that Bruce writes up on his site. I had a high/fluctuating idle but thought the TPS was set correctly because I could hear it click. Well, when I tested it at the idle position I was getting an intermittent connection. I went into the TPS, bent the arm slightly to get better switch contact and now it works great. Just because you hear a click at the idle position does not always mean the idle switch is making contact.
