Contour Enthusiasts Group Archives Forums Modifications General Mods TPS Adjustment mod... has anyone done this?

Case in point- a 300 hp car that does not hit peak power until 6000 rpm will feel slower off the line than a 200 hp car that hits peak hp ar 3500 rpm. this is why those damn mininvans feel soo quick 0 15 mph

Haha, exactly! Why have to put your foot to the floor to feel a little power? Why not have your throttle a little more touchy and responsive and make a little more power under less pressure? If I get a chance today, I am going to do it, so if I get it done, I will post the results.

You keep saying that, but have said nothing to prove or back up you statement.

Your thinking of/comparing OBD-II to OBD-I, like the system this mod was originally done on, is completely incorrect.

It will be tuned out for the exact reasons I gave. It alters the amount of fuel at part throttle settings (Not WOT!) and therefore will effect both short & long term fuel trim by causing the engine to run richer. When the PCM see's this is will eventually pull out this extra fuel trim and you will be back to square one.
This is a known fact.

Also once the TPS reaches a specific throttle percentage the PCM thinks it's at WOT. It DOES NOT care if it's 92% or 93% or 94% (which would be a tenth or a few hundreths of a volt apart) All it see's is WOT and acts accordingly based on the air flow data from the Mass Air and "preprogrammed" tables in the PCM.
Therefore this mod will NOT effect WOT.

Please state your proof and explanations as to why OBD-II would suddenly change from it's normal programming procedures.

I would also like OBD-II data over a long term test as well since I can tell you from personal experience it will be tuned out...

BTW - a recent magazine did the same mod on an LS1 Camaro and the results agree with me. I will see if I can find it for you...
It showed an initial throttle tip in increase in fuel (we are talking a split second) and then the PCM compensated for it and acted normally.
They even dyno tested the mod! It did show and initial increase in power for the split second and them flatlined to a "pre-mod" dyno run level.

NO change at WOT! (not that there would or should be)

They also talked about the PCM (OBD-II) compensating for it in the long run.

If you want better throttle response:
Optimize your throttle body.
Elongate (oval) the top and body side a little.
Both will give you much better results and they will always be there.

I'm now really confused. I thought this mod was for part throttle settings only. What did I miss?

You didn't miss a thing. It will only affect part throttle.

However thanks to OBD-II it will be a temporary effect at best.

There you guys go again, letting facts and reality get in the way of perception and feelings.

Don't discourage this. They will do it and be convinced the car is faster and will be happy. It doesn't matter that is doesn't really work! :p

For better throttle response, adjust the linkage to open the throttle plate further, sooner. GM has been doing this for years. 1/2 throttle on the pedal gives you 3/4 throttle on the throttle body.
Makes the car seem faster cause of better "response" at part throttle, where most "normal" people drive. Car isn't faster but it "Feels" faster.

Well, I think I'll try it and if it doesn't do anything I'll put it back. I'll post any findings. After all, it is something else to try and the info will be good for the others.

If you don't like the idea, then don't do it. Like I said, with my experiences it works good and throttle response is increased. I have done this trick on many different cars with both OBD-II and OBD-I as you call it and they have all had the same effect.

I do NOT want to argue about it, like I said, I asked a question... didn't think someone would actually be upset for a question. I never made ANY claims of significant power increases or anything, so don't ask me to show documented proof because nothing you have said so far can be proved either. It's too bad that your magazine article and articles that I have read and personal experience varies so much. It isn't like I am suggesting something that has never been done before, this little trick is used ALL OF THE TIME, and still is on current cars.

Like another person in this post said... they noticed it right away and it felt great... that's all. What about that do you not believe? On the OBD-II cars that I have done this on, it has NEVER gone back and been "tuned out" back to normal because no matter what you think... and depending on your "long term results", I did this trick on a Land Rover Discovery Series II over a year ago and it still feels the same... in fact about 6 months after we did the trick, we put it back to stock spec to see if it was noticeable and sure enough, it was. We put it right back and it was just how it had been for the last 6 months and still is over a year. His OBD-II never did anything to counter it... it CAN'T, just as the rest of the cars containing OBD-II and OBD-I.

The TPS is the ONLY sensor that tells the computer how much you are depressing the throttle body, so there would be no other sensor to counter this.

If you don't like the idea of this, then just don't do it... don't discourage it... it's 100% reversible, and if it doesn't do anything, you can put it right back where it was to begin with.

I don't understand how or why you ever took this personally and got so defensive about it, but that's your prerogative... a simple question to end up in an argument?... I hate to have to return the attitude and argument as it has been put on me, so I am sorry for this post taking a turn... the info is here... if you want to try it, then go for it, if not, then don't... you can always put it back to normal anyway.

Don't take it personally Don. Demon's just getting a good discussion going ... I never took anything he said as being "argumentive" in tone just "thought-provoking". I think written words tend to be construed generally in a negative tone, when if the person was there talking to ya face-to-face it would no problem ... just gotta imagine a smiling face talking back to ya (like this: ) ,and we'd have a lot less banter back and forth here on CEG. Anyways... enough of that ... let's find that voltage boys! If I was more electrically proficient I'd have tried this already - may still give it a try and experiment with voltage anyways ... .

The voltage level is .98 no more than that to set the tps sensor. This will benefit from the the start until full throttle then it feels the same. It only helps on takeoff and midrange. This adjustment is worth it when you combine with high flow exhaust system. Let me know what you guys think after trying this mod.