I had a haltech tps for a long period of time but have always had issues with inconsistant readings. With the accel wizard open and the car not running, i get varying readings of 0 %/s to 19.7 %/s. The moment the car is running, its all over the place up to over 150%/s at time. This is all without me touching the pedal. This is obviously kicking the accel enrichment on and makes the car buck and / or run lean.

I thought the tps was bad, replaced it with a OEM hyundai tps (had a d shaft so i went with it). Seems to be a narrower range than the haltech tps but i have getting the same problem with the readings. the car is also immedately running worse, even with the tps calibrated...

Im figuring im getting some interference from the other wires in the system since all of the wires are ran through the same place in the firewall and i do not have shielding or shielded wire.

Any other thoughts? I have looks at my grounds several times, the voltage is constant to the TPS when the car is off. Ill have to check with it running.

i have been trying to figure this is out for at least a month and its rather fustrating.

 

as far as grounds go i have heard that if too many things are ground to the same area that can see increase EMI problems.

 

free bump for the best avatar I´ve ever seen

 

ALL sensor grounds must return to the same place the MS unit itself grounds at the very least. Multiple grounding points can be bad and is not good practice - this leads to ground loops, voltage offsets and the like. You'd be surprised to see how much "ground" can vary depending on where you measure and under various battery and alternator loads.

 

Do you see noise on any of the other sensors?

I'm thinking something like a loose battery ground, bad alternator, bad coil ignitor, etc.

 

Have you checked that you're getting consistent 5V at the TPS sensor when the car's on (not necessarily running), and what the resistance is from the TPS sensor plug to where everything is grounded?

 

ill pull various measurements and post them. I do know that when the car has power, but not running there is a constant 4.87 volts to the tps.

 

+1 for the ground issues. When I build my own harness, I always run the sensor grounds back to the MS. That's better even than running them to the same ground point as the MS.

Ken

 

how did you manage to connect several wires to one, effectively?

 

I use a small terminal block right at the MS. Each terminal segment can hold 2 or more incoming wires. I daisychain 2 adjacent segments with a small "U" shaped wire connecting the segments; this gives sufficient room for securing all sensor grounds w/ 20g wire. The whole idea is that the sensors and the microprocessor ADCs "see" the exact same ground. There are a bunch of ground pins available on the DB-37 as well. I use one ground pin for a power ground wire to ground and another pin just to collect the sensor grounds. This way the significant current that flows during injector actuation is isolated to the power ground wire/pin. The sensor grounds flow very little current and always see what ground is on the PCB - which is the goal here. If you're interested Bruce Bowling videoed a very nice presentation on grounding practices including the hows and whys. I'm no electronics whiz but the concept became crystal clear after seeing him explain this very important concept. He specifically speaks to the multiple ground wire issue, it's quite interesting. Lemme know and I'll track down the link.

 

When ever I use a stand alone EMS with a FC (especially the s4, no full range TPS) I always install a GM TPS sensor (95 Cavalier TPS is $16 and the plug is $15 at Auto Zone). Most people just use S5 TPS's, but that is still a 20 year old part. I have made and installed 6 of these so for and they work great, plus it beats paying $430 for a NEW Mazda TPS at last check.

Here you can see the S4 TPS is not making contact at any point past 20% throttle


Nut remove and outer are removed and an adapter that I make installed onto shaft end.


New TPS bracket installed.


GM TPS installed.


The back side of new TPS slides over my new shaft end attachment.

 

I just have the TPS connected as an on-off switch for idle speed control and overrun fuel cut, and I use EAE + a little bit of MAPdot AE for accel enrichment.

Ken

 

For me this is an inexpensive way to get a full throttle TPS.

 

I use no TPS at all, the EAE and MAPdot AE covers everything for me. Of course, I don't need idle speed control or other civilized touches....