TPS voltage won't go below ~190 - 2003-04 Mach 1 Registry Owners Club

HamMach1 · 07-17-2019, 09:38 PM

Changed the IAC valve and the TPS today.

Removed old TPS, installed new one, started car up, held a rev at about 1800 rpm. Actually decided to research the TPS and learned it needed adjusting. Plugged in SCT, saw the TPS voltage was floating around 190 and no matter how much I rotated it (which is barely any obviously), it wouldn't change much by +/- 5.

Then I think I broke the new TPS by putting a load on it (opening the thottle body a little), thinking maybe that's how it was supposed to be done, only to basically destroy that little internal measuring doohickey once I released tension, as it now holds little tension and only read something like 1.20 lol... and maybe that little *snap* sort of noise I heard was telling. Put old TPS back on, still read around the 190 or so.

Could it be something with the throttle body? Could the SCT be that far off?

Oops, this is the mentioned doohickey:

hotford · 07-18-2019, 12:51 AM

Voltage at idle should be close to 1.0 Volts

HamMach1 · 07-18-2019, 10:52 AM

Quote:

Originally Posted by hotford

Voltage at idle should be close to 1.0 Volts

I'll have to try again today. Maybe I read the scanner wrong. I'll snap some photos.

HamMach1 · 07-18-2019, 06:40 PM

Something tells me this isn't good lol. This is the old one. The new one flashes back and forth between 1.00 and .75, so I think it's busted, as I don't think it's actually getting a read at all. I found a Motorcraft TPS online that I'm going to try in a few days. My RPM still stuck at about 1800 RPM and was rising so it's all sorts of messed up.

bigtrain · 07-20-2019, 08:38 AM

Is it a oem throttle body

HamMach1 · 07-24-2019, 07:05 PM

Quote:

Originally Posted by bigtrain

Is it a oem throttle body

Yep. Tried a second TPS. Throttle reads 1 and then flashes .75 and back to 1 and back to .75, whether the TPS is plugged in or not.

Possible wiring? No idea how I could have ruined everything just by replacing the IAC and TPS lol

rich1 · 07-27-2019, 02:18 PM

This sounds like a bad ground in the wiring . Check engine and PCM wiring harness for proper grounding. Use wiring Diagram for Pinpoint check on PCM outlet plug to see if 1.0 volt is present

HamMach1 · 07-28-2019, 07:37 PM

Quote:

Originally Posted by rich1

This sounds like a bad ground in the wiring . Check engine and PCM wiring harness for proper grounding. Use wiring Diagram for Pinpoint check on PCM outlet plug to see if 1.0 volt is present

Thanks Rich. I'll look into that

07-17-2019, 09:38 PM	#1
HamMach1 A.D.D. FTL Join Date: Oct 2006 Location: Jacksonville, FL Posts: 3,017	TPS voltage won't go below ~190 Changed the IAC valve and the TPS today. Removed old TPS, installed new one, started car up, held a rev at about 1800 rpm. Actually decided to research the TPS and learned it needed adjusting. Plugged in SCT, saw the TPS voltage was floating around 190 and no matter how much I rotated it (which is barely any obviously), it wouldn't change much by +/- 5. Then I think I broke the new TPS by putting a load on it (opening the thottle body a little), thinking maybe that's how it was supposed to be done, only to basically destroy that little internal measuring doohickey once I released tension, as it now holds little tension and only read something like 1.20 lol... and maybe that little snap sort of noise I heard was telling. Put old TPS back on, still read around the 190 or so. Could it be something with the throttle body? Could the SCT be that far off? Oops, this is the mentioned doohickey:

07-18-2019, 12:51 AM	#2
hotford Registered User Join Date: Jan 2005 Location: Durham/Canada Posts: 236	Re: TPS voltage won't go below ~190 Voltage at idle should be close to 1.0 Volts __________________ 1982 GT 2003 Mach 1 2003 Marauder 2011 Shelby GT 500

07-18-2019, 06:40 PM	#4
HamMach1 A.D.D. FTL Join Date: Oct 2006 Location: Jacksonville, FL Posts: 3,017	Re: TPS voltage won't go below ~190 Something tells me this isn't good lol. This is the old one. The new one flashes back and forth between 1.00 and .75, so I think it's busted, as I don't think it's actually getting a read at all. I found a Motorcraft TPS online that I'm going to try in a few days. My RPM still stuck at about 1800 RPM and was rising so it's all sorts of messed up. Last edited by HamMach1; 07-18-2019 at 07:01 PM.

07-20-2019, 08:38 AM	#5
bigtrain Registered User Join Date: Aug 2011 Location: Absecon,NJ Posts: 225	Re: TPS voltage won't go below ~190 Is it a oem throttle body __________________ 04-DSG, K&N air intake, bbk 65mm throttle body, SLP loudmouths, pypes x pipe, intake spacer, cobra intake cams,AM short throw shifter, ssbc rotors hawk hps pads,plasti-dip black rims and badges (for now), next mod- suspension

07-27-2019, 02:18 PM	#7
rich1 AUTOMACHTIC Join Date: Oct 2007 Location: RTP/ N.C. Posts: 4,813	Re: TPS voltage won't go below ~190 This sounds like a bad ground in the wiring . Check engine and PCM wiring harness for proper grounding. Use wiring Diagram for Pinpoint check on PCM outlet plug to see if 1.0 volt is present __________________ UPGRADES...Tokico Illuminas Borla SS Catback , Steeda Underdrives , Strut Brace , HPM Lower K Brace , L /C Arms , U /C Arms , HPM PanHard Bar, K&N FRPK 2, GOODYEAR GT1 , MRT- H-Pipe , JLT VaporTraps , SLP-12'" Tips! , FRPP Shorty 1 5/8 Headers , Brembo D/S & PBR D/S Rotors ,FRPP Alum.DS ,Roys 3/8 Spacer , SVT Focus 255 pump SCTsw Chip PRO-DYNOjet NA 300.01hp /315tq (Auto) ,Innovate W/B ,Compucar Wet Kit (90jet) + Heater and E Gauge * 360 hp/385tq 12.5 -1/4 @112

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)

Thread Tools
Show Printable Version Email this Page
Display Modes
Linear Mode Switch to Hybrid Mode Switch to Threaded Mode