Strange TPS values when engine is running - Miata Turbo Forum -Boost cars, acquire cats.

Welcome to   Members

MEGAsquirt A place to collectively sort out this megasquirt gizmo

LinkBack Thread Tools
Old 01-15-2011, 04:40 PM   #1
Junior Member
Thread Starter
Join Date: Sep 2009
Posts: 65
Total Cats: 0
Default Strange TPS values when engine is running

I put a dial for my TPS on my tunerstudio dashboard today because I wasn't convinced my TPS is giving correct values.

Calibrated TPS.

Ignition on but engine off. Throttle closed 0%, Throttle Open 101%

Engine on. Throttle closed 10%, Throttle Open -22%???

Why would my TPS work fine with the engine off but as soon as it's running the values are all weird?
jerrah is offline   Reply With Quote
Old 01-15-2011, 06:00 PM   #2
Boost Czar

iTrader: (60)
Braineack's Avatar
Join Date: May 2005
Location: Chantilly, VA
Posts: 69,641
Total Cats: 1,355

do you have a vtps?
Braineack is offline   Reply With Quote
Old 01-15-2011, 06:39 PM   #3
Junior Member
Thread Starter
Join Date: Sep 2009
Posts: 65
Total Cats: 0


Tps & throttle body off a nb8. I can get full range values between 0-100% when engine isn't running.
jerrah is offline   Reply With Quote
Old 01-15-2011, 08:30 PM   #4
Hittin' Boost & Cones
iTrader: (2)
240_to_miata's Avatar
Join Date: May 2007
Location: Cromwell, Connecticut
Posts: 2,555
Total Cats: 10

I think I had my TPS signal walking on me when I was experiencing bad grounds...or maybe a loss of the 5v ref signal. Check both of these.
240_to_miata is offline   Reply With Quote
Old 03-21-2011, 12:41 AM   #5
Junior Member
Join Date: Jun 2007
Posts: 411
Total Cats: 0

OK I seem to be having this issue too. I have a 3 wire vTPS off a 1.6 automatic, Wiring is correct.

Calibrating in TS is no problem. Ignition on, engine off, TPS sweeps from 0-100% without any issue, as seen here.

Engine on, signal is a bit jumpy and goes from a low of -30 to about 50-60% max. Checked calibration of zero throttle in TS, no change in value.

I measured the voltages at the wires with the engine off and on.

5v reference: engine off zero throttle: 4.96 engine off full throttle 4.97
engine on zero throttle: 4.96 engine on full throttle 5.00
TPS signal: engine off zero throttle: 0.65 engine off full throttle 1.99
engine on zero throttle: 0.65 engine on full throttle 1.20

Why do I have a drop in voltage at the TPS signal wire when the car is on?

Can anyone guide me on the steps I need to do? I did try running a new wire for the TPS signal and ran it straight to the 2L pin. Same thing.
Is it a ground issue? If so, how do I track it down?

Thanks MT

Last edited by Greg G; 03-21-2011 at 12:58 AM.
Greg G is offline   Reply With Quote

Related Topics
Thread Thread Starter Forum Replies Last Post
FS/FT: 03.5 Mazdaspeed Protege leatherface24 Cars for sale/trade 15 10-16-2015 11:35 AM
MS PNP requires reading and following directions??? satisfied MEGAsquirt 141 10-06-2015 10:44 AM
00/99 IAC into 92 wiring harness AdoboMiata MEGAsquirt 4 09-22-2015 02:32 AM
VE values too low? compuw22c MEGAsquirt 4 09-12-2015 07:42 PM
ME221 Now has Autotune and Long Term Fuel Trim Tables Motorsport-Electronics ECUs and Tuning 0 09-05-2015 08:02 AM

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

All times are GMT -4. The time now is 11:00 AM.