steve said:

Perhaps you have said but I've forgotten, what year and car did you pull the harness from?
There is some 1990 info in https://www.dsmtuners.com/threads/t...l-wiring-harness.412841/page-2#post-152709711 and some comparisons to later harnesses.

Click to expand...

Im actually not sure, I didnt pull it my self. It does have the separate closed idle switch/cable (which is not on the billet throttle I installed) how else can I tell?

Ok So I got it to run continuously (just barely) last night, but not well. I checked and the White/sensor wire coming from the TPS did seem to show .5v now at the ECU plug but I'm not sure if it's reading it now or not.

So after I got it started, I adjusted the idle screw to open the throttle more, and doing that it kind of ran (the TPS voltage was showing .68v at that setting) it was weird though, the RPM would climb a few hundred, then it would come down and almost die, and the engine would slowly recover/adjust, and the cycle would repeat and it would be missing a lot.

BUT, When I would first start the engine (even after it died) it would run ok for the first 8-10 sec, then almost die and I'd have to hit the throttle, where the RPMs would increase, but also be missing.

However! I found this wire was cut: (coming from the MAF)


Also I will install the O2 and see if that does anything.

1G Turbo MAF pinout from the FSM.

Pin 1 Green/White ECU Pin 6 (ECU MAF reset) (ECU Pin 14 on 1990)
Pin 2 Green/Blue ECU pin 10 (MAF Airflow)
Pin 3 Red MPI Relay pin 4/5 (MPI Switched Battery)
Pin 4 Green/Red ECU pin 23 (ECU +5v Sensor Power)
Pin 5 NC
Pin 6 Green/Black ECU pin 24 (ECU Sensor Ground)
Pin 7 Green/Yellow ECU Pin 16 (Barometric Pressure)
Pin 8 Green/Orange ECU Pin 8 (Intake Air Temp)

The NA MAF doesn't have a MAF Reset input. It's pinout is:

Pin 1 Green/Blue ECU pin 10 (MAF Airflow)
Pin 2 Red MPI Relay pin 4/5 (MPI Switched Battery)
Pin 3 Green/Red ECU pin 23 (ECU +5v Sensor Power)
Pin 4 Green/Black ECU pin 24 (ECU Sensor Ground)
Pin 5 Green/Yellow ECU Pin 16 (Barometric Pressure)
Pin 6 Green/Orange ECU Pin 8 (Intake Air Temp)

well I hooked up the the cut Maf wire, and put in the O2 sensor, with zero change.

So I can now get it to stay running but not well. What is is that happens at "start" because it kind of seems to run ok for the firstr 8-10sec Then starts hunting and missing, and if I give it gas, it almost dies then "catches up"

Also, I put a probe at the ECU plug for the TPS contact. while running it is getting proper volatage at the contact at least. (I dont know if the ECU is reading)
However this last time, with the car running I used the spare TPS and plugged it in, in my hand and turned it it and saw both the V change and the engine did increase in speed. so it sound like the ECU is seeing it.

Right now after the car starts and it starts missing the A/F is bouncing around 16.5+/-

So the TPS works fine when it's loose but fails when it's mounted to the TB?
It looks pretty tight under there, any possible physical issues causing the TPS to fail?

well, I dont know, TPS sorta seems to be working now. Heres a couple videos of the car running (plugged the TPS on the TB back in) +Probe at the ECU, Neg at battery. (no chance, that is grounding or completing the circuit? )

sorry the vids arent great, but you can see the multimeter on the left, and when you hear the car stumble, that is when Im cracking the throttle. but you see the TPS .V going up. It was running lean 16.5-17

Second video, I upped the FP to 58 or so, that definitely helped, but still lean 15.5, but it did help it run better, and lessned the stumble when I cracked the throttle

I can see you have a V2 DSMLink, can you post a log so we can see what it's seeing and what you have things set to.
I wouldn't be cranking on the fuel pressure but instead changing the injector global and deadtime to get the AFR's where you want them.

Which actual MAF did you wind up with.

steve said:

I can see you have a V2 DSMLink, can you post a log so we can see what it's seeing and what you have things set to.
I wouldn't be cranking on the fuel pressure but instead changing the injector global and deadtime to get the AFR's where you want them.

Which actual MAF did you wind up with.

Click to expand...

It's a 2g MAF.
I just turned up the FP just because it was the quickest way to see if it did anything, while it was running.

Well, thats the other main problem. as soon as the car starts the ECMLink software freezes. I've tried both a tablet (MS surface) and a laptop. (can I start another thread on that since its related to ECMLink, more than this project?)

I previously "reset" all the settings; here's some pics of where its currently in ECMLink

I'm just getting my project running and I have a stand alone temp sensor just in front of the TB. Now in my previous set up there was no MAF. My intake temps were, at idle/start up just above ambient (80F*) and normally didn't get too much higher except for heat soak. But after installing the 1g ECU with 2G MAF, My intake temps were showing near 120 just after start (haven't driven the car yet) and I started to wonder if the temp sensor was bad, but after shutting the car off, the temp would start dropping immediately.

Is it the MAF that's heating the air that much?

Isn't this just the measuring spot difference?
Don't you have an intercooler? If so, pre intercooler v.s. post intercooler.

Is this still the old Porsche you swapped the DSM ECU into?
Are we talking about the exact same sensor in the same location by the TB?
How were you measuring the temp both times?

There isn't anything in the 2G MAF that normally would heat up. The airflow measurement is done by ultrasonic counting of the vortices generated in the airflow not by measuring the cooling effect on a heated wire like a GM MAF. The two other sensors in the MAF are IAT and absolute barometric pressure and neither should be heating the air.

So I trimmed all the excess wiring and unneeded connectors and reconnected everything....almost, apparently, cause now no start.
Right now I see #24 the black with green, not connected coming off the ECU, where does that connect?