Thunder ECU erratic TPS

[Ernie]

Hey, I am having a couple of issues with the tune and can't figure it out:

First thing, I'm getting erratic TPS signal (DBW setup) at speeds from 2 to about 10-12 kph when the car is warmed up. Changes in TPS causes acceleration enrichment to kick in, which causes the car to jerk/surge. Trying to chase this down but feeling a bit stumped. TPS is rock solid in every other driving situation including idle. Could this be wiring, electrical noise, ecu? Changing the throttle body did not help.

Secondly, idle speed control seems to be ignoring speed lockout in closed loop mode. Closed loop works to about 8 kph even though speed lockout is set to 2 kph. However, idle ignition control stops working at speeds above 2 kph. Can these to functions interfere with one another?

Thirdly, unrelated but something I noticed and is worth mentioning. Randomly getting Lambda error 4, either on Lambda 1 or Lambda 2 but never on both and sometimes on neither. Also, this happens on two Thunder ecus on two different cars.

Low speed log start at around 25:30 min file time

Log:

https://drive.google.com/open?id=1Smp37nyfwA_Vemwsli1j43NFW8skae7k

G4+ Thunder 1uzfe v1.1483.pclr

[Apex Speed Tech]

Hi There,

Share your map so I can see more, but one place to start is to ask yourself why TP (main) and (sub) don't mirror more precisely.

1. No evidence the ECU is asking the throttle to move around like this.  You're not in idle mode (Status is "Hold - Speed", ISC Trip & offset are both flat, and e-throttle 1 target (%) is flat)

2. TP(Sub) doesn't move as much as TP(Main).  That could be a smoking gun. 

3. E-Throttle 1 Motor DC (%) mirrors TP Sub much better than Main.

Is there a way, mechanically, your TP1 sensor has backlash or other installation issues?

 

[Adamw]

I would be suspicious of the wiring, as Neel says when it starts to play up you have an offset between TP main & sub.  At the beginning of the log they match up pretty well.  The 5V output on the ECU is logged stable at 5.00V so the first thing I would suspect is a worn track in the sensor but if you have already changed that then I would be taking a close look for a high resistance connection somewhere.  

[Ernie]

On 3/16/2020 at 11:30 PM, Apex Speed Tech said:

Hi There,

Share your map so I can see more, but one place to start is to ask yourself why TP (main) and (sub) don't mirror more precisely.

1. No evidence the ECU is asking the throttle to move around like this.  You're not in idle mode (Status is "Hold - Speed", ISC Trip & offset are both flat, and e-throttle 1 target (%) is flat)

2. TP(Sub) doesn't move as much as TP(Main).  That could be a smoking gun. 

3. E-Throttle 1 Motor DC (%) mirrors TP Sub much better than Main.

Is there a way, mechanically, your TP1 sensor has backlash or other installation issues?

Map is attached to the original post. I can add a drive link if it's not working.
I haven't touched the throttle body in any way. I'm using 2003 350z tb, they both have some free play but I assume it's normal. They both work on standard 350z's.

On 3/17/2020 at 9:35 AM, Adamw said:

I would be suspicious of the wiring, as Neel says when it starts to play up you have an offset between TP main & sub.  At the beginning of the log they match up pretty well.  The 5V output on the ECU is logged stable at 5.00V so the first thing I would suspect is a worn track in the sensor but if you have already changed that then I would be taking a close look for a high resistance connection somewhere.  

Thanks, I will check the wiring first chance I get. I am not sure how much I can nitpick the log but in some instances the TP main voltage does not change while TP main % does.

Any ideas on the other two issues?

[Adamw]

16 hours ago, Ernie said:

I am not sure how much I can nitpick the log but in some instances the TP main voltage does not change while TP main % does.

Can you give me an area in the log to see an example - everywhere I look the voltage seems to match the reported TP.

 

16 hours ago, Ernie said:

Any ideas on the other two issues?

The speed lockout thing seems weird, I see what you mean, it seems to be turning off somewhere around 7.9kmh rather than the 3 that is set in the map you attached - is it possible that setting was different when the log was taken?  Last time I tested this function it seemed to work correctly.   You could also try changing the speed lockout to driven wheel speed just to see if there is anything odd going on there.

The lambda error 4 seems to be caused by a sudden drop in battery voltage (The log shows it dropped from about 14.1V to 11.9V, but potentially it dropped lower and just wasnt captured due to the logging rate).  No fans or AC turn on at that point so it would suggest possibly a bad connection?

 

 

Edit, added this comment later:  Looking at the funny drops in battery voltage, that seems to happen in the same areas that the TP starts to play up.  I would be suspecting maybe something like a lose ground connection?  If there is a lazy main ground connection you could potentially get ground current travelling through the sensor ground instead which could be what we are seeing on the TP sensors...

[Ernie]

Hey Adam, sorry for the late reply. The reported TP vs. TP volt difference is at around 29:52 mark but again, not sure how much to nitpick since the time stamp differences are in miliseconds.

For the speed lockout, I did not change the lockout speed. It is the same whether I use driven on non-driven wheel speed. Perhaps I should try setting the non-driven wheel speed not as an average of both wheels but try to use a single wheel speed sensor?

The voltage drop corresponds to me almost stalling, rpm was 297 at the point where the voltage dropped to 11.92 V. I did scrape the exhaust a few moments later and the lambdas did reset for some reason. But the lambda error 4 happens randomly after lambdas are powered on. This has happened on two different ecus on two different cars. Perhaps I am doing something fundamentally wrong with the wiring? Wire gauge, etc.? The error does not trigger the CEL. PS. I though the the lambda error for low voltage is 26.

[remski2]

Here is what I noticed.

Your accel enrichment is kicking in at very low TP delta.

Increase your deadband so it stops from happening.

Your TP seems to be relatively stable at idle where the accel is not kicking in.

Start with 0.8 % and see if that helps.. 

[Adamw]

17 hours ago, Ernie said:

The voltage drop corresponds to me almost stalling, rpm was 297 at the point where the voltage dropped to 11.92 V.

It seems a bit unusual to drop to 11.9V just due to low RPM? or is it a tiny battery? Even if the alternator was not charging I would expect a normal car battery to hold ~12.7V for some time.  There are some other areas towards the end of the log where batt voltage spikes low - admittedly at slightly lower RPM than normal idle but it seems a bit odd to me. 

 

17 hours ago, Ernie said:

The reported TP vs. TP volt difference is at around 29:52 mark but again, not sure how much to nitpick since the time stamp differences are in miliseconds.

Yeah, I think that is just due to logging/aliasing/sample rate affects, if I plot them on a similar scale they seem to follow a similar trend mostly within about two hundredths of a volt. 

 

Still, the only logical explanation that I can fit to what you are seeing is a bad connection or a failing TPS.