gmrulz4u Posted July 30, 2003 Report Share Posted July 30, 2003 As of right now, I am under the impression that the TPS on the 2.8/3.1 engines has ONLY 2 purposes: 1) Tells the ECM when the throttle is closed(mostly for idle) 2) Tells the ECM when throttle angle is 70% or greater(so the ECM knows to enter into "Power Enrichment" mode) Is that NOT all it does!!?? I would bet that NO ONE on this board has ever had performance problems, replaced the TPS, and had the problems solved. Can anyone here prove me wrong? I just can't see how a BAD TPS would really cause any major problems? As far as I am concerned, the MAP Sensor on the 2.8/3.1 engines is by far the most important sensor in determining engine load, fuel delivery, etc..etc... Anyone? THANKS GUYS! Quote Link to comment Share on other sites More sharing options...
Vegeta Posted July 31, 2003 Report Share Posted July 31, 2003 How much do you want to put into this bet? Quote Link to comment Share on other sites More sharing options...
gmrulz4u Posted July 31, 2003 Author Report Share Posted July 31, 2003 Well, if we take the statement: "The TPS does NOT control fuel delivery between 1%-69% throttle angle." I will bet my LIFE!! Quote Link to comment Share on other sites More sharing options...
brian89gp Posted July 31, 2003 Report Share Posted July 31, 2003 You die then. The baro is calculated from the airflow/TPS, a bad tps can throw off the baro by a large amount and thusly the fuel; a wrong baro reading can throw the BLM's off by 20% or more, been there done that. It also plays a role in EGR and CCP operation, not to mention the TCC is basically run off the TPS and load calculations. The TPS is also used in a lot of filter coeficients which will throw both spark and fuel off further. Quote Link to comment Share on other sites More sharing options...
gmrulz4u Posted July 31, 2003 Author Report Share Posted July 31, 2003 I don't like to argue, well, maybe I do? But, what you state doesn't make a whole lot of sense...maybe you read that on a website that was referring to a DIFFERENT engine than the SPEED DENSITY 2.8/3.1 engines... First of all, you say "baro is calculated from the airflow/TPS"?? I assume you know that these engines do NOT directly measure airflow, right? Airflow is calculated by the ECM by using the MAP and MAT/IAT. I know the TPS helps calculate BASE PULSE WIDTH, but that's not what I ment when I said: "The TPS does NOT control fuel delivery between 1%-69% throttle angle." I believe you're probably right with regards to the EGR and the CCP though. But my Chilton books says that it only uses inputs from the Coolant Temperature (CTS) sensor, Manifold Air Temperature (MAT) sensor, and Crank Sensor all assist in controlling the current to the EGR valve. So it's not that I don't believe any of what you said, I just would like you to show me where you got this information?? Quote Link to comment Share on other sites More sharing options...
brian89gp Posted July 31, 2003 Report Share Posted July 31, 2003 I don't like to argue, well, maybe I do? But, what you state doesn't make a whole lot of sense...maybe you read that on a website that was referring to a DIFFERENT engine than the SPEED DENSITY 2.8/3.1 engines... well, 3.4 but it is set up almost the same. I was thinking of another ECM that does do a calculation for the baro, the 3.4 does sort of an averaging under certian stipulations (TPS being one of them). Start the car at 5000ft and drive to sea level with a bad TPS with the baro never updating, your fuel will be quite a bit off. The TGP is set up with more of an if/then arrangement. First of all, you say "baro is calculated from the airflow/TPS"?? I assume you know that these engines do NOT directly measure airflow, right? Airflow is calculated by the ECM by using the MAP and MAT/IAT. I forgot about airflow, and yes it is a calculated value. Airflow also HEAVILY relies on TPS and engine RPM, bad TPS and whatever airflow modifies will be skewed. Its not really used much except for idle and some electronics (EGR and IAC) I know the TPS helps calculate BASE PULSE WIDTH, but that's not what I ment when I said: nope, unless I missed something it has nothing to do directly with it except in PE, and even there engine RPM takes precidence. BPW = BPC * MAP * T * A/F * VE * BVC * BLM * DFCO * DE * CLT * TBM "The TPS does NOT control fuel delivery between 1%-69% throttle angle." Not directly, no. But the TPS has enough play in modifier tables to VE that it can cause havoc. So it's not that I don't believe any of what you said, I just would like you to show me where you got this information?? http://www.brian89gp.com/assembly/files/BHAK4257.DIS the baro update is F1E1-F27C And to add, since GM in their infinite wisdom only programmed these ECM's with 3 BLM cells, TPS can throw the fuel off in yet another way. If the TPS is bad it could cause it to stay in decel eleanment too much or not even enter it at all. Since decel and cruise have different fuel needs for the same engine condition, decel in cell 1 will throw the BLM's off which means for the few minutes it takes for them to average back out your car is running too rich/lean. Add to this problem a innacurate baro and the BLM's will start pogo'ing at random. Since TPS plays a role in wether it is considered idle or not, things like stall saver, correct IAC proportioning (witich semi relys on airflow), and even correct idle speed. Quote Link to comment Share on other sites More sharing options...
gmrulz4u Posted July 31, 2003 Author Report Share Posted July 31, 2003 Yeah I know, I totally understand what you are saying, and I appreciate you clarifying some things for me:) I know what you mean with the RETARDED idea of using 3 BLM cells!!?? What the fuck is that!!?? I remember thinking that my ECM was screwed when I kept scanning it and never seeing cell numbers other than "0", "1" and "2"! I kept reading everywhere online that ECM's use 16 cells, so I just assumed mind was messed...but of course I was wrong, and instead learned how stupid GM was when developing these ECM's... I guess I should have just made this thread something like "who had a problem, changed the TPS, and had the problem fixed?". Because I don't really care how the TPS effects fuel delivery, I just wanted SOMEONE to say that they have replaced a performance problem by replacing the TPS. I have searched this ENTIRE board for "tps", read every single thread, and found NONE that indicated this. I did the same thing over at 60degreev6.com, v6z24.com, beretta.net, etc...etc...it's like NO ONE has ever had a TPS problem!!?? I mean a lot of people have replaced their TPS in an attempt to "fix" their problem, but it has never actually cured anything. This is just another peice of evidence that, to me, shows just how UN-important the TPS really is... I know every sensor means SOMETHING to the ECM, and effects performance in SOME way, but the TPS is so low on the "Sensor Importance" chart that it seems like it's NEVER been the culprit when diagnosing engine performance problems etc... Quote Link to comment Share on other sites More sharing options...
Vegeta Posted July 31, 2003 Report Share Posted July 31, 2003 Damn, I step away for a bit and all this goes on. I don't think there has ever been a real in depth discussion of the TPS...cause generally no one cares. A scan tool will tell you if its working or not and from there you replace it or keep it. Quote Link to comment Share on other sites More sharing options...
brian89gp Posted July 31, 2003 Report Share Posted July 31, 2003 I know of one person who had horrible problems with multiple bad TPS's, also had to re-scale it in the end to get it working 'ok'. Damn, I step away for a bit and all this goes on. I don't think there has ever been a real in depth discussion of the TPS...cause generally no one cares. A scan tool will tell you if its working or not and from there you replace it or keep it. I'm bored Quote Link to comment Share on other sites More sharing options...
Whiskey River Posted July 31, 2003 Report Share Posted July 31, 2003 I guess I should have just made this thread something like "who had a problem, changed the TPS, and had the problem fixed?". Because I don't really care how the TPS effects fuel delivery, I just wanted SOMEONE to say that they have replaced a performance problem by replacing the TPS. I mean a lot of people have replaced their TPS in an attempt to "fix" their problem, but it has never actually cured anything. This is just another peice of evidence that, to me, shows just how UN-important the TPS really is... Well, here is my experience with the TPS. My 92 3.1L was experiencing a hesitation when taking off and it was stumbling when going down the interstate using the cruise. Turned out that the TPS had a bad spot in it and was giving readings of 0 volts. Once I replaced the TPS, I experienced no more hesitation or stumbling. Quote Link to comment Share on other sites More sharing options...
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