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CRAracer05 ~ 94 Talon TSI

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
You've got something weird going on that's beyond my understanding. Remember that ecmlink's suggestion on how to use coasting fc offset is a rule-of-thumb. You can increase or decrease to your setup's needs.
This is always my luck, I get hit with the weird issues. I'm going to try swapping out the TPS if I have one in the rare event that once it gets hot, that its going to a dead short and passing 5V directly back to the ECU. That's the only way I can see it going 5V (100%) throttle at idle, other than some internal ECU fault.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
You've got something weird going on that's beyond my understanding. Remember that ecmlink's suggestion on how to use coasting fc offset is a rule-of-thumb. You can increase or decrease to your setup's needs.
Ok so after some reading and also making the adjustments you suggested I think I'm good now. This is a long log but its from cold all the way up to temp fans on and back down again. I only saw two quick spikes in the idle and the ECU quickly corrected itself. After reading Adjust Your TPS! I learned that you can get closed throttle issues by using the TPS Adjust feature as you create a dead zone in the TPS position/voltage as the TPS is not mechanically preloaded at 0.63V output. So I zeroed the TPS Adjust out and and set the scale to 100%. Once I did this I then manually readjusted the TPS to get 0.63V at close with software adjustment. Time will tell if this fix holds, but the car has never idled this good since I built it.
 

Attachments

  • log.2021.10.04-03 fixed idle.elg
    457.4 KB · Views: 3

Vegas Smith

Proven Member
4,675
2,484
Dec 2, 2002
Houston, Texas
Looks much better. You probably unknowingly didn't complete the TPS adjust. You still may have some wiring issues. As you can see at 631 and 842 seconds there is blip in the tps/map readings which are both 5v sensors. I wonder if you have a 5v wire issue or possible a sensor ground issue? You can also see the the tps voltage just flatly drop towards the end of the log and sat at .57v for no reason. Your idle switch starts randomly activating as well due to the weird tps stuff going on. You may want to test your 5v wire on the tps and see what you find. While this stuff is small it is important to get figured out before you try and tune the car.

Also, I suspect your wideband isn't setup correctly. Your switchpoint is 2.49v but the ecmlink site suggests a value of 3.12v for the wideband you picked in the ecu tab. Make sure this is sorted out.
 
Last edited:

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
Looks much better. You probably unknowingly didn't complete the TPS adjust. You still may have some wiring issues. As you can see at 631 and 842 seconds there is blip in the tps/map readings which are both 5v sensors. I wonder if you have a 5v wire issue or possible a sensor ground issue? You can also see the the tps voltage just flatly drop towards the end of the log and sat at .57v for no reason. Your idle switch starts randomly activating as well due to the weird tps stuff going on. You may want to test your 5v wire on the tps and see what you find. While this stuff is small it is important to get figured out before you try and tune the car.

Also, I suspect your wideband isn't setup correctly. Your switchpoint is 2.49v but the ecmlink site suggests a value of 3.12v for the wideband you picked in the ecu tab. Make sure this is sorted out.
Ok looking at it now I see the MAP also went to 5V with the TPS like your saying. The TPS adjust was another setting leftover from the previous tune. I can test the 5V wire at the TPS, but as you see in the log it is only spiking briefly so It's going to be hard to trouble shoot without a consistent and constant issue. Do you know of any common fault areas for the 5V sensor circuits, or where the sensor ground wires come from? I would think if the 5V supply was bad it drop voltage not spike to 5V, unless there is short from the 5V supply wire to the ECU sensor input wire but then again that wouldn't cause both sensors to spike to 5V at the same time.

I will also play with the AEM WB, I believe at one point it was set at 3.12V but it wouldn't log the displayed values.
 

Vegas Smith

Proven Member
4,675
2,484
Dec 2, 2002
Houston, Texas
@steve Maybe Steve can help

I believe the sensor ground is in the ecu? It's not like a chassis ground. You're right that the increase in voltage might indicate a ground-out or something. Maybe jiggle the map/tps wires while logging and see if you can recreate the spike. The 5v source on the ecu supplies all the 5v sensors so if it has an issue I would suspect all 5v sensors would be affected which is what we're seeing.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
@steve Maybe Steve can help

I believe the sensor ground is in the ecu? It's not like a chassis ground. You're right that the increase in voltage might indicate a ground-out or something. Maybe jiggle the map/tps wires while logging and see if you can recreate the spike. The 5v source on the ecu supplies all the 5v sensors so if it has an issue I would suspect all 5v sensors would be affected which is what we're seeing.
I did a bunch of research today, and believe what I'm seeing is a loss of the 5V sensor ground circuit. I'm wondering if there is a junction point somewhere where the grounds from each sensor come together and go back to the ECU. The TPS & MAP (former air flow sensor connections) both share the the same sensor ground from what I see in the service manual. Looks like C-66 [ECMlink calls it C-61] connector pins 17 & 24 Green/Black wires with what looks like several junction points without connectors. Does anyone know where any of these junction points are before I have to cut harnesses open?
 

Attachments

  • 1991 Laser_Talon Volume 2 of 2.pdf
    151.4 KB · Views: 1
  • 1GECUPinout.pdf
    128.1 KB · Views: 0

iugrad92turbo

Supporting Member
12,729
712
May 22, 2007
Kalamazoo, Michigan
The green and black sensor grounds attact to then cts, tps and maf sensor.They all end up at two grounds on the ecu pins. Ive done more than enough wire harness jobs so i know it.too well.
 

steve

DSM Wiseman
13,911
962
Feb 3, 2002
Boulder, Colorado
Yes, stock TPS.
OK, and the connector still has the metal retaining clip?
I find it interesting that from the logs it only happens for a short interval and not right out of the box.
It is acting like the sensor ground connection is intermittent but if it was near the ECU you would see spikes with the TPS, ECT, MAF, IAT, and Baro signals at the same time. Because it just a short spike it's not a blown sensor ground inside the ECU but this doesn't rule out the ECU just make other causes more likely.

Can you just log you slowing pressing the throttle without the engine running?
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
The green and black sensor grounds attact to then cts, tps and maf sensor.They all end up at two grounds on the ecu pins. Ive done more than enough wire harness jobs so i know it.too well.
This I know, I was more interested in where the intermediate junction points are located in the harness?
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
OK, and the connector still has the metal retaining clip?
I find it interesting that from the logs it only happens for a short interval and not right out of the box.
It is acting like the sensor ground connection is intermittent but if it was near the ECU you would see spikes with the TPS, ECT, MAF, IAT, and Baro signals at the same time. Because it just a short spike it's not a blown sensor ground inside the ECU but this doesn't rule out the ECU just make other causes more likely.

Can you just log you slowing pressing the throttle without the engine running?
No retaining clip, I was zip-tieing it before on my previous build. I had thought about ordering a connector kit and changing out all the connectors that are cracked or missing wire clips.

I have a feeling that I'm losing the sensor ground at one of the intermediate junctions inside the harness because I'm not spiking all of the sensors on the circuit just some of them.

I will log the TPS car not running.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
If I were to guess I would say you tapped the 5v tps source for your map sensor and that's why we're seeing both have issues.
I'm running the ECMlink direct cable to the MAF connector for speed density. Nothing is spliced on the original engine harness. The sensor outputs going to 5V tells me the sensor ground circuit is the issue otherwise it would be going to 0V with the 5V supply dropping out. If the 5V supply was shorted it would also drop.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
Here is the TPS log without the car running. Its hard to do it smooth as the S90 has a much heavier spring than stock.
 

Attachments

  • log.2021.10.08-05 TPS no run.elg
    16.1 KB · Views: 1

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
I changed out my ISC o-ring today and did a boost leak test. I think this leak was bigger than I thought because now I can blow the tester off the turbo and the system will hold pressure for minutes. I also swapped out the TPS sensor out with a spare I had laying around and readjusted it. I also readjusted the BISS to idle around ISC position of 32. Then I went for a drive tonight with narrowband sim off as it was idling at 14.7 ish without sim and 17ish with sim after idle testing. I did get my AEM WB all adjusted and logging close to my actual gauge readings (as fast as I can look between the two) so I'm not sure if that is bad injector settings or what causing the narrowband sim to be off even though it pulses correctly. Overall it was running well besides fuel tuning being way lean if trying to get close to boost. . After the log, I came home to check everything over and back out again I raised the global fuel to be safe and was able to go back out and build boost at 10:1 just to make sure I could build boost for the tuning session. After cruising home the Front O2 quit cycling and was stuck at 0V causing me to run in open loop at a light. So I thought I was good to take it to get the tune done but now I'm not sure if something is wrong or the tune just needs to be fixed. Should I just turn the narrowband sim back on and let them fix the tune? Do I need a new factory O2 sensor?
 

Attachments

  • log.2021.10.10-05 first drive.elg
    543.7 KB · Views: 0
  • log.2021.10.10-06.elg
    37.6 KB · Views: 0

Vegas Smith

Proven Member
4,675
2,484
Dec 2, 2002
Houston, Texas
I changed out my ISC o-ring today and did a boost leak test. I think this leak was bigger than I thought because now I can blow the tester off the turbo and the system will hold pressure for minutes. I also swapped out the TPS sensor out with a spare I had laying around and readjusted it. I also readjusted the BISS to idle around ISC position of 32. Then I went for a drive tonight with narrowband sim off as it was idling at 14.7 ish without sim and 17ish with sim after idle testing. I did get my AEM WB all adjusted and logging close to my actual gauge readings (as fast as I can look between the two) so I'm not sure if that is bad injector settings or what causing the narrowband sim to be off even though it pulses correctly. Overall it was running well besides fuel tuning being way lean if trying to get close to boost. . After the log, I came home to check everything over and back out again I raised the global fuel to be safe and was able to go back out and build boost at 10:1 just to make sure I could build boost for the tuning session. After cruising home the Front O2 quit cycling and was stuck at 0V causing me to run in open loop at a light. So I thought I was good to take it to get the tune done but now I'm not sure if something is wrong or the tune just needs to be fixed. Should I just turn the narrowband sim back on and let them fix the tune? Do I need a new factory O2 sensor?
When the switchpoint is incorrect the car will run richer or leaner based on what direction the switchpoint is off by. That's likely why you're seeing that difference in sim vs non-sim AFR. Not sure what is going on with the front o2 but I wouldn't let that affect your dyno tune. They can just turn on sim. Also, TPG tuning I'm sure knows what they're doing so they can provide further direction on the switchpiint issue. One last thing, ground the wideband at the ecu chassis ground near the passenger's left foot. That will give you most accurate ecu/wideband reading.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
When the switchpoint is incorrect the car will run richer or leaner based on what direction the switchpoint is off by. That's likely why you're seeing that difference in sim vs non-sim AFR. Not sure what is going on with the front o2 but I wouldn't let that affect your dyno tune. They can just turn on sim. Also, TPG tuning I'm sure knows what they're doing so they can provide further direction on the switchpiint issue. One last thing, ground the wideband at the ecu chassis ground near the passenger's left foot. That will give you most accurate ecu/wideband reading.
Well that makes me feel better, I was just trying to make sure everything is solid for them and all they need to do is the tuning. You guys have all really helped, the car has never idled so good. It still needs a little work on stalling coming to a stop light or sign but even that is better than before. I believe I'm grounded to the right side of the center console steel where the ecu and radio mounts right now.
 

craracer05

Supporting Member
325
51
Sep 29, 2005
Warren, Ohio
Nice. Be thankful you have such a competent tuner that’s local. What are you going to stop at power-wise or are you telling him to max it out?
Right now I'm leaving it at 520whp on E85, I' planning to build a new short block over winter and I will take it back in the spring. He said there is a lot left but it's not worth breaking a rod right now.
 
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