TPS wiring

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 11:12 am

Hey everyone,
Background: I've had a boost controller come into my possession, and need to wire it up to my car using tps and rpm. Problem is, the car doesnt have a variable tps, on the rubbish one. Car is currently running a link g1, and as far as i can see, the tuning is done off the o2 sensor and the map sensor, but is still hooked up to the rubbish tps to run idle.

Research: So, after many an internet search ive come across one of the 6 pin bmw ones which bolt on. These things come with WOT switch, idle switch, and then the vtps. Everyone wires them up and only uses the tps (because its all they want) and leaves the rest blank. I need both, the switch for the idle etc to talk to the ECU and the variable to talk to the boost controller.

Method: AND FINALLY, can i just bridge off the 5V from the idle/WOT switch and feed that into the Vtps, run the other side to ground, and that will give me a varing signal on the final pins output?

Post Script: One day, i will get myself a better ECU, and will switch it all out for a 1.8 TB and TPS, but for now $30 and some wiring is better than $1000.

Thanks in advance, and any help is as always, very much appreciated.

marcellarius · Post by **marcellarius** » Mon Mar 07, 2016 1:39 pm

No, it won't work.

Assuming it's wired up the same as the OEM, the ECU provides a 5V feed, but this is a pull-down input: when the switch closes it connects to ground which 'pulls down' the voltage to 0, which the computer can then detect. Inside the ECU there is a resistor that only allows a tiny current to flow through the switch.

If you hook up the pot, it will allow current to flow which could be enough to pull down the idle/WOT input.

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 5:51 pm

Alright, so I can wire up the wot and idle as per oem. Can a jerry rig something that feeds a signal like a tps. I don't need anything to go to or from the ecu, only the boost controller. Being that it's a potentiometer, could I run 12v (or a lesser 5v) to it, and it would give me the voltage change I require?

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 6:03 pm

Ok new plan. Wire up new tps's fixed portion of tps as per oem. Wire in a 12v-5v converter from old cellphone charger, and feed into the variable part of the tps. One output signal to the boost controller, other output ground.

I think that's gonna do it.

marcellarius · Post by **marcellarius** » Mon Mar 07, 2016 6:10 pm

Can you take a 5 volt reference from the ECU though? Other sensors/potentiometers will need a solid 5V feed.

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 6:14 pm

Yea I assume I can, the more I research, it looks like I can just wire it up directly to the ecu's 5v and when it's not at wot or idle, it will just output a linear voltage depending on position (to the fourth pin) which won't be fed back to the ecu, so it shouldn't care.

siren676 · Post by **siren676** » Mon Mar 07, 2016 6:33 pm

Just use the links analogue output to control a boost solenoid, no need to make stuff more complicated, also make sure the ecu has been tuned properly for higher boost otherwise it can/will blow up.

The car will be running off rpm vs map sensor reading, in this mode the tps is used to tell the ecu whether you are accelerating or not to add a little more fuel. The o2 sensor is only used to maintain correct afr's at idle

For the love of god do not mess with stuff you dont know about, its not like a stock ecu where it can adapt slightly to a couple of mods.

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 6:52 pm

Car is tuned for high boost, I'm just replacing the manual boost controller with a electronic one.

I've just been down to check voltages and it is definately running a fixed tps.

siren676 · Post by **siren676** » Mon Mar 07, 2016 6:58 pm

It is just rpm vs map, I have 2 of these ecu's and that is all they need to run

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 7:06 pm

Well that's good to know then.

The external controller will have better control of the boost levels than the ecu though? As it builds its own maps that can be fine tuned to keep optimal boost pressures. It's a hks evc6.

siren676 · Post by **siren676** » Mon Mar 07, 2016 7:24 pm

A boost controller only does that, it controls a solenoid which determines the boost level(It should not be messing with the map at all), the link has a proper boost control function inbuilt, it just has to be set up and wired correctly

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 7:40 pm

Yea I know it doesn't mess with the map sensor. I see the boost controller being far easier to setup than the extra gear in the ecu at this stage. Mainly because I don't need to get into the ecu.

siren676 · Post by **siren676** » Mon Mar 07, 2016 7:45 pm

Its your car dude, just note that the boost controller may increase boost to areas that havent been tuned yet and blow your motor up, but hey its not my car do what you want.

If it were my car i'd leave it alone or take it to a tuner and do it properly.

Papamoeziz · Post by **Papamoeziz** » Mon Mar 07, 2016 8:07 pm

Thanks for all the info, and I do understand your concerns, and do value the input. I'm just trying to weigh up the pros and cons of both options. And I know NOTHING about early link gear.

I'm the kind of guy who likes doing things myself, and will always prefer to learn firsthand. I have tuned a couple of motors in the past (bike motors on a G3) And I'm yet to grenade a motor (first time for everything though!)

So in saying all that, wouldn't have a serial link cable I could borrow?

siren676 · Post by **siren676** » Mon Mar 07, 2016 8:21 pm

Not at the moment, its kinda permanently installed in one of my cars as i mess with it so much

. I got it from HiTech motorsport in Drury and it was pretty cheap from memory

2low2c · Post by **2low2c** » Mon Mar 07, 2016 9:29 pm

what g1 do you have is it miata link or is it a lem wire in because there's a big difference in the way they operate.

Papamoeziz · Post by **Papamoeziz** » Tue Mar 08, 2016 7:51 pm

It has the miatalink map sensor, but when I pulled off the kick plate it has the maz16b chip, not a flyin Miata one. So I'd say it's a link.

2low2c · Post by **2low2c** » Tue Mar 08, 2016 9:24 pm

ok it's g1 miata link you can't tune it on a laptop you can only adjust it with a hand controller, also the internal boost control doesn't work. if i was you i would use a different boost controller like a greedy that doesn't need a tps signal .or just use a boost tap.

Papamoeziz · Post by **Papamoeziz** » Tue Mar 08, 2016 11:39 pm

Sweet, thanks for the info. I think I will try the hks one and the throttle body mods. I have a mate who has a portable O2 sensor, so I can shove it up the bum at my next track day and see how bad it is.

Side note, I thought if you had data log lab you could tune the miatalink g1's?

2low2c · Post by **2low2c** » Wed Mar 09, 2016 8:00 am

only if you have a fm chip.

2low2c · Post by **2low2c** » Wed Mar 09, 2016 4:56 pm

hey Papamoeziz i see in one of your other posts that you said your car is an 1800 is there an adapter between the throttle body and the manifold?

Papamoeziz · Post by **Papamoeziz** » Wed Mar 09, 2016 5:27 pm

Hey 2low, yea it's got a massive chunk of ally (30ish mm thick). I do want a 1800, it would help my pipe work.

Papamoeziz · Post by **Papamoeziz** » Wed May 11, 2016 9:52 pm

Alright! She's been a little while since asking all these questions and figured I should update the progress. Here is what I did.

1. Pulled off the 1600 tps/trottle body and adapter plate. I needed to in order to get the feed from the intercooler up from under the sway bar ( it was a shitty over the rAd system, and was a MESS.

2. Threw on an 1800tps off a vvti or whatever car. New problem, no wot or idle switches.

3. Went and got an E30 BMW tps (6pin) (and tb) to wire up. New problem. It fits a stock 1600 Tb shaft, not an 1800 one.

4. Luckily I'm an engineer, so during a break from design I jumped on a lathe (and mill) at work and turned down an adapter stalk. This was probably the most difficult part to get it all centre, true, and clocked to the right degree. Not only that, but the BMW tb opens backwards :/

5. Adapter built to mount the tps to the 1800 tb also. So now at wot it hits the BMW idle switch, and at idle, it hits the BMW wot switch. Problem, wot on the BMW is probably 5-10 degrees in length, so won't be getting enrichment for AGES. Time to mod the tps

6. Pulled open the BMW tps, to find the wot a lot like other idle tps's. Unlike the actual idle which was a direct press contact, the wot was a metal bar running on the shaft with a rib when it hit wot (or idle in this case). Solution. Bend the bar to open sooner.

7. Put it all back together, adjust the tps to the Tb as per instructions, so at idle (closed) it's on, just open its off.

8. Wiring the switches was easy, as I just pulled the original tps apart to see what wire did what, and joined to the corresponding on the new tps. The variable tps was a little more fiddly as I had to wire in a 5v source (from a car charger, 12v to5v adapter wired into where the radio was (because racecar)) and run it to and from the tps, and then the final feed wire to the boost controller along with a tach feed from behind the gauge cluster.

And all done! Now some might ask about the tps voltages, it runs from just over 1v to just over 5v. The beauty of this boost controller that it sets the tps auto magically after a few pulls, as well as measuring the boost level that wastegate opens. After that you're free to setup 2 boost levels and a scatter boost (which I have no need for so didn't wire up) and fine tune the setup.

I started by winding it up to 10psi, and it is AMAZING the change in response of the turbo. The wastegate not open if the turbo spools too quickly (flow vs oriface in a shitty boost tap) and seems to have way more control over the wastegate. I have also changed the entire plumbing and reclocked,rebuilt the turbo so it could also be due to some of that but WOW.

As you can see in the picture (ok, so I can't upload on an iPad) I have .3psi of overshoot currently which I'm happy with as I want to borrow a friends O2 meter before I go winding the boost up further and fine tuning .I also need to look at making sure the spark can hold up.

All in all, a massive success (so far). Thanks to the guys above for the advice and knowledge as it has steered me in the right direction.

Papamoeziz · Post by **Papamoeziz** » Sun May 15, 2016 2:59 pm

Ok, so have been mucking round with the car today hoping to go have a play with the Hamilton car club and have come across a bit of a weird one. Car idles nicely, but as I feed on the gas it will climb Happily to about 2600rpm and then starts to hunt terribly. If I continue to slowly increas throttle the hunting picks up pace until I pass around 2900,3000 rpm and is then happy all the way up.

I have checked the tps resistance values with it disconnected as I open it, and it all works/does what it's meant to do, and voltages when it's plugged in and they all seem to line up also.

I do not get these problems when I run the car with the tps unplugged. It happily does its thing with no hunting surging.

Any ideas?

Papamoeziz · Post by **Papamoeziz** » Tue May 17, 2016 9:06 pm

Update: sorted it. Went through a method of elimination and realised it was my wiring. The bmw's use the ground wound about the tps to shield it, which I assume then goes to ground somewhere and that's what I did, so the ecu in the car wasn't getting the current draw. God know why it did it at 2600rpm, but once I'd stopped the ground being able to ground elsewhere and forcing it to ground through the ecu, all problems went away, and she is running like a CHAMP!

TPS wiring

TPS wiring

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