gmsgltr Posted July 16, 2020 Report Share Posted July 16, 2020 The Short: What voltage should the TPS read at WOT? Because I think I have a problem... 96 850R, manual swapped, NA Throttle Body with 960 Throttle Plate, Manual Throttle Cable. When I did the manual swap (7-8 years ago and probably 7-8k miles) I replaced literally everything with new oem parts... The TPS and throttle cable were replaced... How do I know I have a problem? Aaron (VA5T tuning) can see on my logs that when im WOT my TPS is reading 70% and it should read about 83% when floored. He can obviously re-scale and compensate for this but it's better to get this corrected. I decided after nearly a 2 year hiatus of not touching the car that I am going to look into this... I decided to do this test... both my original TPS and 'new Bosch' TPS measure 3.8V when both the pedal is fully depressed and when the throttle spool is at its stopper at WOT. This guy in the video gets 4.5V all the way open... Do I have two bad TPS devices? When slowly opening the throttle the voltage doesn't jump around, they smoothly increase like I believe it should. What gives? Any advice? Thanks! Greg Link to comment Share on other sites More sharing options...
Oreo931 Posted July 16, 2020 Report Share Posted July 16, 2020 Have you checked whether the TPS have different part numbers for N/A and Turbo throttle bodies? I would assume they are the same, but it can't hurt to check. I'll have to test mine when I get a chance. Link to comment Share on other sites More sharing options...
gmsgltr Posted July 16, 2020 Author Report Share Posted July 16, 2020 wow. no i didnt. but if thats the case then a lot of other people would have this issue with so many of us having turbo cars but NA intake manifolds/TB etc checked its the same TPS for na/t5 etc. for like 10 years of volvo models Link to comment Share on other sites More sharing options...
gdog Posted July 18, 2020 Report Share Posted July 18, 2020 Yes, you should get 4.5v on the signal pin at WOT, or very close to it. Did you verify the throttle plate is going horizontal at WOT? If not, you have a mechanical issue. Are both TPS parts you tested new? This thread is relevant too: http://volvospeed.com/vs_forum/topic/217188-check-your-tps-if-performance-is-sluggish/ Link to comment Share on other sites More sharing options...
gmsgltr Posted August 4, 2020 Author Report Share Posted August 4, 2020 On 7/18/2020 at 6:34 PM, gdog said: Yes, you should get 4.5v on the signal pin at WOT, or very close to it. Did you verify the throttle plate is going horizontal at WOT? If not, you have a mechanical issue. Are both TPS parts you tested new? This thread is relevant too: http://volvospeed.com/vs_forum/topic/217188-check-your-tps-if-performance-is-sluggish/ Sorry I missed your message/help here - The throttle plate goes 99% horizontal. I can tell its not 100% but its damn close. No, both TPS I tested are not new. One is the original Volvo/Bosh unit and the other is a Bosch unit purchased and installed when I did my manual swap 7ish years ago. The 'new' one has maybe 7 years and 3k miles on it... Ill check the link you shared... On 7/18/2020 at 6:34 PM, gdog said: Yes, you should get 4.5v on the signal pin at WOT, or very close to it. Did you verify the throttle plate is going horizontal at WOT? If not, you have a mechanical issue. Are both TPS parts you tested new? This thread is relevant too: http://volvospeed.com/vs_forum/topic/217188-check-your-tps-if-performance-is-sluggish/ Sorry I missed your message/help here - The throttle plate goes 99% horizontal. I can tell its not 100% but its damn close. No, both TPS I tested are not new. One is the original Volvo/Bosh unit and the other is a Bosch unit purchased and installed when I did my manual swap 7ish years ago. The 'new' one has maybe 7 years and 3k miles on it... Ill check the link you shared... lol that is the same video i shared... and i commented in your thread too stating this was 'probably my problem' haha im fine with just buying another tps - the bosch ones arent expensive... i just find it hard to believe its that since mine is barely used. Ill order one today and test it... and should carefully rule out the harness having an issue as well... Link to comment Share on other sites More sharing options...
gmsgltr Posted August 11, 2020 Author Report Share Posted August 11, 2020 got a new bosch TPS in and tested and still only get about 3.8v at full open guess I now need to rule out the harness Link to comment Share on other sites More sharing options...
gdog Posted August 12, 2020 Report Share Posted August 12, 2020 On 8/10/2020 at 5:46 PM, gmsgltr said: got a new bosch TPS in and tested and still only get about 3.8v at full open guess I now need to rule out the harness I assume you're measuring this at the TPS connector between pins 1 (ground: brown w/black tracer wire) and pin 3 (signal: orange w/white tracer wire) at WOT? Make sure you have 5 volts between pins 1 and 2 (5v reference: yellow wire) at TPS connector. If you don't, something's amiss either in your wiring or the ecu itself. Mechanical check: Have a helper hold down the gas pedal WOT while the throttle body cover and boot is off. While they're still holding it, move the throttle bell crank from under the hood; are you able to open the throttle any more? If you can (and you now get 4.5 volts on signal wire) then you either have too much slack in throttle cable, or need a new cable. connector A on ECU and TPS (7/54 in diagram) below: Link to comment Share on other sites More sharing options...
gmsgltr Posted August 12, 2020 Author Report Share Posted August 12, 2020 thank you very much - i will be looking into this tonight Link to comment Share on other sites More sharing options...
gmsgltr Posted August 22, 2020 Author Report Share Posted August 22, 2020 On 8/12/2020 at 12:05 AM, gdog said: I assume you're measuring this at the TPS connector between pins 1 (ground: brown w/black tracer wire) and pin 3 (signal: orange w/white tracer wire) at WOT? Yes - this is how I was measuring and got 3.8v on all three TPS's... the original one, a used bosch one, and a brand new bosch one Quote Make sure you have 5 volts between pins 1 and 2 (5v reference: yellow wire) at TPS connector. If you don't, something's amiss either in your wiring or the ecu itself. Just did this - I get 4.77v - So is this it? Now trace the wire and send the ECU to Aaron to double check the ECU? Quote Mechanical check: Have a helper hold down the gas pedal WOT while the throttle body cover and boot is off. While they're still holding it, move the throttle bell crank from under the hood; are you able to open the throttle any more? If you can (and you now get 4.5 volts on signal wire) then you either have too much slack in throttle cable, or need a new cable. connector A on ECU and TPS (7/54 in diagram) below: My issue does not seem mechanical. I don't have any friends so I just set my phone up, recorded and checked it a few times haha. Update: not too telling yet but I followed the wire to the main harness - disturbed the harness along its run and literally right where the front hydraulic engine mount is when pushing the harness around I can get the voltage to jump all over... from nearly 0 to 4.77, but never better than 4.77. My battery would totally start the car fine, but is sitting at 11.66v right now too. Link to comment Share on other sites More sharing options...
gdog Posted August 22, 2020 Report Share Posted August 22, 2020 5 hours ago, gmsgltr said: Update: not too telling yet but I followed the wire to the main harness - disturbed the harness along its run and literally right where the front hydraulic engine mount is when pushing the harness around I can get the voltage to jump all over... from nearly 0 to 4.77, but never better than 4.77. My battery would totally start the car fine, but is sitting at 11.66v right now too. Yep, there's your issue! It (the reference voltage on ecu pin A15) should not move around at all. I'd guess you have at least one smashed wire inside your engine harness at that point. Going to have to open that up and inspect ALL the wires in that area; who knows what else you'll find?! BTW: I just rechecked A15 voltage on my car and on bench flashing setup with another ecu; get just over 5v on both. And it will not move if battery voltage changes a bit; the ecu regulates it to stay at 5v. Check it again after you fix the wiring. Link to comment Share on other sites More sharing options...
gmsgltr Posted August 24, 2020 Author Report Share Posted August 24, 2020 pulled the TPS wiring out... only section not exposed is about a foot leading under the pass. headlight and into the ECU box. The wiring is fine, not a single nick or mark on it from what I have exposed. I measured the voltage again, got 4.77v. Starting to think it is the ECU Link to comment Share on other sites More sharing options...
gdog Posted August 24, 2020 Report Share Posted August 24, 2020 That's weird; I based my last post on yours where you said the voltage disappeared when you disturbed the harness. I'd ohm out all 3 wires between ecu and TPS connector; make sure each is 0 ohms between ecu and tps. One thing that could drop the supply voltage is a partial short to ground (or another circuit) on the A15 wire, so check for that. I meant to mention it before, do you have another ecu to try? It can be stock, to just check the voltage in key RUN position. Link to comment Share on other sites More sharing options...
gmsgltr Posted August 24, 2020 Author Report Share Posted August 24, 2020 I believe the voltage may have dissipated or jumped (but never went above 4.77v) because the back probes got moved around or something. With a second set of hands, I tried it again and I had someone hold the connector and back probes steady while I played with the wiring after I exposed it all and I couldn't get the voltage to move from 4.77v - this is why I'm now thinking it 'could' be the ECU. Great point on another ECU... I did have another ECU. I'll have to find it. I think its a stock auto R ecu but wont matter for key in run position... I was in touch with Aaron already to potentially send mine back for him to test on his bench... and he said the ECU's he had there all measured 5v. I'll ohm out all three wires next. I understand the 'partial short to ground' but how would another circuit drop supply voltage, isnt the A15 wire just the TPS? Could you elaborate a little on that? Thank you for your help on this! Link to comment Share on other sites More sharing options...
gdog Posted August 24, 2020 Report Share Posted August 24, 2020 2 hours ago, gmsgltr said: I'll ohm out all three wires next. I understand the 'partial short to ground' but how would another circuit drop supply voltage, isnt the A15 wire just the TPS? Could you elaborate a little on that? Yes, per the schematic, A15 is 5v supply wire dedicated for TPS use. But it's possible that wire could be shorted to another circuit allowing a partial short circuit to ground. To be specific I'd suggest two tests with, key off, and with TPS connector disconnected, and ecu removed from car: Ohm out A15 at ecu connector to pin 2 on TPS connector. Expect 0 ohms (or darn near) and wiggle the harness at multiple points to verify it doesn't change. The easiest way to do this I've found is to use small paper clips and alligator clip leads to hook up your ohm meter to the ecu and TPS pins. Of course be careful not to bend the connectors! This will free your hands up to agitate the harness. If your meter reads significantly more more than 0 ohms, or the reading changes while you're moving the harness, then there's a high resistance somewhere in that wire, and that's a problem. Assuming test 1 above is fine, then make sure this wire does not have some side short path to ground. This could be a partial short to a ground, or maybe to another circuit allowing an alternate current path to ground. Hook one lead of ohm meter to A15 (or pin 2 on TPS) and other lead to ground. Again jiggle the harness; should always be infinite ohms. You can do the same tests on the A16 wire, but above posts don't indicate a problem there. Link to comment Share on other sites More sharing options...
gmsgltr Posted August 26, 2020 Author Report Share Posted August 26, 2020 Will do this week^ thank you for your continued help! Gonna try another ECU first, also another multi meter for the hell of it... then do what you suggested. Link to comment Share on other sites More sharing options...
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