Do I need a new throttle position sensor?

A bit of history first. Ive had a "slow down 5-8" light. Was so bad after driving it for 5mins it would shut the car off. So I pulled every plug apart and used Contact Lube on all connectors. This made the "slow down 5-8" light almost disappear. With a 2-3hour drive it would come on but slowing down would turn it off and never it would shut the engine off. It never came on at full gas, only when going fast and then slow.

So I swaped the MAF from right to left and left to right, my cable would not reach to do a cable swap. I drove the car till I got the same "slow down 5-8" light again.

Returned and swaped the "Throttle Position Sensors", went for a long drive(right after first test) and no lights came on at all............Also I drive the car as hard as I could, droping gears on high rpms and trying everything to get the "slow down 5-8"(or 1-4) to come on and nothing........... just to add something in, when I used contact lube on everything I also put some inside the throttle position sensors. So Im thinking that I might have a temp-o-mental throttle position sensors. What do you think?

Also Id like to add that when hot, out of some random maddess it idles bad sometimes. So I was looking at the idle adjustment screew and thought I might have a play with to see if I can improve it a little and knowing that any change on one side must be made perfect for the other to keep it in balance I noticed that the 5-8 side has a lot more thread on it compared the 1-4. Check out the pic's. So if I adjust this and do a turn on each? or screw them all in and come out the same?


Thanks
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Perhaps, but read this first. I had the exact same issues, thoroughly cleaned the TPS, and havn't had a SINGLE problem since January-- and the power increase was substantial.

http://ferrarichat.com/forum/showthread.php?t=174841

Edit: The hot problem is also linked to a problematic TPS. Mine would stall and idle rough too, so I'd hold off on screwing with the screws.

 

yup. Screw them in and then back them both out the same amount to aid your rough hot idle condition. If your idle settles above 1100 RPMs, then you've backed them out too far, but err toward "too far" rather than too little. You want 1000 RPM idle, but 1050 is OK, too.

 

Why I was guessing these in the first place was when I first put contact lube on everything it did make a huge improvement. Infact it was this thread you have posted that made me do it(thanks!). Im going to take the TPS off now, have a feel(which I didnt do before I just lubed them). Go for a run see the difference and then I will re-screw the screws all the way in and evenly out. Aiming for 1000RPM - thanks No Doubt!

thanks for all your help, this forum site is amazing!

 

The "Slow Down" lights indicate overheating catalytic converters, which should have nothing to do with Throttle Position Sensors or "idle adjustment screws". You shouldn't have to adjust those screws unless someone has been randomly messing with them.

Have you swapped the exhaust temperature ECU's from left to right? These are what trigger the "Slow Down" lights. If you are getting the light for the 5/8 bank, and you switch the ECU's, and then get the light for the 1/4 bank, then it's clear that the problem is a faulty ECU, which is very common. If you still get the "Slow Down" light on the 5.8 bank after swapping the ECU's, then you need to do some checking to see if your converters are actually overheating - they can get very, very hot and cause serious damage if you ignore a genuine warning!

 

I think your onto something Miltonian because what I have done today was:

Took the TPS's off, cleaned them went for a run. Last about 2 hours before 5-8 came on.

Car cooled down.

Adjusted the Idle adjustment. I found the 5-8 was max in, letting almost no air in. The 1-4 was 3.5 turns out. I set them both to 3.5 turns and the thing idles perfect at 1000rpm. After a while the 5-8 came on again.

while the car was warm I

swaped the cables of the O2 sensors, so the 5-8 was now pluged into the 1-4 and the 1-4 is pluged into the 5-8. but check this out. The Slow down lights came on straight away and 1 bank was shut down. However the same light would come on(5-8), which I think is strange. While I swaped it I couldnt even drive to the road from my garage.

Went back and swaped it like normal, car ran fine but after a while(15mins of hard driving) 5-8 came on.

Swaped 02 Sensors again to make sure it wasnt a fluke that they worked so badly swaped, same story, still 5-8 came on with 1 bank shut down and couldnt make it to the road.

Swaped back to normal and car run fine for 15mins and then 5-8 came on.

What I dont get is, why when I swap it the 1-4 doesnt come on(maybe bad exhaust temperature ECU, if so, why did it come on so quick with one side and not the other)?

got any ideas why?

Tomorrow I will swap the exhaust temperature ECU's like you said Miltnian and I will see what happens.......... 1am now and Im falling asleep.........

Thanks heaps for all your effort with this.

 

Swap the exhaust temperature ECU's. I'll bet the warning light will switch over to the opposite side after you do it.

Not to insult your intelligence, but do you know where the exhaust temp ECU's are located? It should only take a few minutes to swap them side to side.

When these go bad, they can give a false signal at any time, whether the engine is hot or cold. Part of their function is to shut down the Motronic ECU for the appropriate bank of cylinders, so that excessive unburned fuel does not cause the catalytic converter to continue to overheat.

 

no offense taken at all, I believe there number 37:

http://www.ricambiamerica.com/article_info.php?articles_id=214

 

Good catch Milt. I misread the original post. Slow Down is certainly not the same as CEL.

I stand corrected.

 

Are you really talking about O2 sensors connectors??? Swapping O2 sensors is not good at all ... your engine ECUs are then trying to correct the mixture on one bank looking to the exhaust gas of the other bank !!!!! The mixture correction process will diverge and will lead to maximum rich or maximum lean correction on each bank and may prevent you to drive the car.
In you case, what must be swapped are (as already said) the cats ECU in a first attempt, then the thermocouples in a second step if nothing change, then have a look to your cats and your mixture.