99 WRX Idle Issues and stalling

[jqvp]

Hi Link team

Looking for a 2nd opinion on (sorry to my tuner who is also on here) but I've been dealing with fluctuating idle when the car is warm and sometimes (rarely) stalling. Highway driving and spirited driving everything seems ok.

Some info about the car:

Mechanically sound 99 WRX, standard Ej205 (internals). 

- Bosch 64mm DBW throttle with Link G4X 

- Converted to MAFless (Link IAT, MAP, Lambda)

- Coil on plug conversion to GD

- VF39 turbo

The issues:

- Cold start is fine and seems to behave normally

- Once warm, it starts to idle erratically dipping to 300rpm then going back up to 850rpm.

- Occasionally it stalls only if I come to a complete stop and clutch in. Doesn't matter if I stop suddenly or slowly.

- It randomly went into limp mode once, a DBW calibration seemed to have fixed that (turning car on and off helped me get home).

I've attached my tune and two logs, please let me know if any more info is required or if the links don't work.

Thank you

James

Tune:

https://1drv.ms/u/s!AlUUjgUddC17gZ4O8a1c8ZLBIeSzpQ?e=EAJUBb

Cold start:

https://1drv.ms/u/s!AlUUjgUddC17gZ4PJWmr0PNyE-wteg?e=G16Eq6

Warm start:

https://1drv.ms/u/s!AlUUjgUddC17gZ4Q82KmR7W4zDT6HQ?e=w7lHgp

[Adamw]

The bouncing idle is due to 2 issues.  1) the Integral gain is way too high - currently set to 0.25, more typical for DBW is 0.02 to 0.05.  2) the MAP limit is too low, when it gets close to stalling the MAP goes above 60Kpa so the idle control is disabled.  Set this to 70kpa should do it.  

 

The stalling is due to the base position too low.  Firstly, the top row of your e-throttle target table should have zeros across it.  So fix that first.

You can see in this pic at 72°C an idle position of 2.6% is needed to achieve the target idle speed, but the idle base position table is only commanding a position of 1.4%.  So whenever you enter idle conditions your throttle is already 1% too far closed.

The dashpot settings may need some further work if it still dips too low with the base position table fixed up.  

 

Similar story at 90°C, requires 2.0% to achieve target, but base position is 1.3%.  

 

 

[jqvp]

Thanks Adam! I appreciate the quick response!

Working through your feedback, let me know if I've done it right.

Integral gain reduce to 0.05:

Ethrottle 1 Target top row zero out:

Map Limit increase from 60kpa to 70kpa:

Base position increase from 50 degrees onwards:

Changes made to tune:

https://1drv.ms/u/s!AlUUjgUddC17gZ4TmeLWZw0yzzJqjA?e=UgNLeg

 

Thanks again!

James

[Adamw]

Yep those will be a step in the right direction I would say

[jqvp]

Hi Adam

Uploaded the new tune and it stalls more consistently now.

Copy of tune loaded, maybe I made a mistake.

https://1drv.ms/u/s!AlUUjgUddC17gZ4TmeLWZw0yzzJqjA?e=UgNLeg

Log from cold start with the tune linked above.

https://1drv.ms/u/s!AlUUjgUddC17gZ4VYBApxYFtVyy2fw?e=ZDuWDv

Log from warm start at a petrol station and moving to a parking spot, hunts on idle and stalls.

https://1drv.ms/u/s!AlUUjgUddC17gZ4UIC7UisVNQr9RXg?e=Ej6mAF

Thank you

James

[Adamw]

Idle actuator integral gain is still set to 0.25.

 

[jqvp]

48 minutes ago, Adamw said:

Idle actuator integral gain is still set to 0.25.

 

Hi Adam

I cant find any 0.25 values in my original tune, it was set to 0.145 nonetheless I reduced it to 0.05? Am I missing something or in the wrong line?

Ok I found it, I changed the integral gain in the ethrottle table. I'll revert that other change and updated this idle actuator integral gain!

Fingers crossed

[jqvp]

With the Idle Actuator Integral Gain changed to 0.05 the car would still idle low around 5-600rpm and hunt.

I changed the 'mode' to Open Loop at the suggestion of a friend which seemed to help smooth out idle enough for me to drive home without stalling.

Any other suggested changes?

Tune with Open loop active:

https://1drv.ms/u/s!AlUUjgUddC17gZ4TmeLWZw0yzzJqjA?e=OUPBW5

Log with Open Loop

https://1drv.ms/u/s!AlUUjgUddC17gZ4TmeLWZw0yzzJqjA?e=ihVs54

[Adamw]

Can you give us a log in closed loop and a copy of the tune.

[jqvp]

Hi Adam

Copy of the current state of tune. Spent 2 hours with the tuner trying to iron this out, just when we think its fine, it starts hunting again or idling really high. The revs also hang for "too long" when coming to a stop.

I've managed to log with this current tune and captured some of the stalling around 3x when coming to a stop. It wouldn't start back up without me holding up the revs. Then towards the end of the log it idled just fine. 

Copy of Tune:

https://1drv.ms/u/s!AlUUjgUddC17gZ4aLWaFtfVGO_qOiw?e=fIGdQC

Copy of log with 3 or more stalls - conditions: heavy traffic, more stop start, pretty hot, no aircon on. 

https://1drv.ms/u/s!AlUUjgUddC17gZ4btfVAn1EGG_mTwA?e=w5YWiS

Copy of log with no stalls with exactly same tune - log starts off with me spraying water in the engine bay trying to find an air leak - no soap suds formed around hoses/throttle body. Conditions: light traffic, much cooler, aircon on a bit of rev hang but did not hunt at idle when stopped.

https://1drv.ms/u/s!AlUUjgUddC17gZ4c5D3QEVx5HbzqfQ?e=h9Sfh2

Thank you

James

[Adamw]

The idle control mostly looks like it is doing the right things now.  

I suspect your stall issue is possibly fuel related.  Your normal warm idle injector PW is about 0.75-0.9ms in areas of the log where it is idling well.  In all the places the engine stalled the PW dropped down under 0.5ms just on entry to idle - in a couple of places as low as 0.3ms.  I suspect some of your injectors may not even open down at that sort of PW.  In some cases that very short PW was due to reaching very high vacuum in overrun, in others it was the CLL pulling fuel out the whole way down towards idle.  

Try the changes in orange below to see if that improves the stalling problem.

The rev hang is due to excessive offset and base position.  For normal warm idle your TP sits at about 1.7%. In the places with the rev hangs the throttle is sitting at 3.6%.  It looks like the base position for 80°C and above needs to come down to about 1.8%, possibly some of the offsets need to come down a bit too.  

But, lets not change to much at once, try the changes for the stalling issue first before messing with the hang. 

[jqvp]

Thank you Adam!

I've made those 5 changes and will try it out tomorrow, will report back.

James

[jqvp]

I made those changes and had no stalls yesterday, however I forgot to save the logs!

I managed to do a short log whilst parking my car in the garage.

https://1drv.ms/u/s!AlUUjgUddC17gZ4eZd_t1neVasG5dQ?e=nPPBdB

James

[jqvp]

^{Hey Adam}

^{Thank you for the help so far! I've been driving the car without much issue aside from the rev hang but as you said, I dont want to change too many things till the idle is sorted. It seems it is, I'll start doing longer drives with logs.}

^{However I've had another problem appear. I've gotten fault code 76 twice now - once was prior to the above changes and the second was today. (I don't think it's related but just stating the facts)}

^{I've done the TPS Calibration each time after clearing the fault codes, there were minimal changes made to the voltages each time like 0.02v difference.}

^{Can you spot anything obvious with why it might be triggering the fault code and going into limp mode? Both times that it happened it was right after taking off from a traffic light and attempting to accelerate as I normally would.} 

^{Second question, because the problem is so intermittent, how would I best try to catch it on a log?}

^{Copy of my base map:}

^{https://1drv.ms/u/s!AlUUjgUddC17gZ4gmXGRSvynd5SX3Q?e=jpihZi}

[jqvp]

Hi @Adamw

Whilst not the same circumstances, I was moving my car in the car park and when I turned it off after parking the tracking error happened again.

I've attached the log below, any ideas?

It looks to have given me the error when the I turned the car off... but is it normal for my TPS sub to be zero %? Everytime I've gotten code 76 it's been within the first 10 minutes of driving the car...

Copy of current base map and log below, let me know if they don't work and I can put them on the google drive instead..

James

PC Datalog - 2022-11-26 11;26;51 pm Tracking error.llgx

26.11.22 Starting.pclx

[jqvp]

As I read other threads, I can see TPS Sub is barely moving and not matching the ethrottle target (which I assume it should?) 

Would this point to a wiring issue?

[Adamw]

Yep, you've def got something wrong with TPS sub, it appears to be working - the voltage changes when you move the throttle, but your TPS sub closed voltage is set to 0.91 V and the ANV4 is moving between 0.7 & 0.9V, hence it shows zero all the time.   TPS closed voltage was set at 0.63V in your screenshot a couple of posts up so either something have changed there or it was never stored after calibration or something.

[jqvp]

12 hours ago, Adamw said:

Yep, you've def got something wrong with TPS sub, it appears to be working - the voltage changes when you move the throttle, but your TPS sub closed voltage is set to 0.91 V and the ANV4 is moving between 0.7 & 0.9V, hence it shows zero all the time.   TPS closed voltage was set at 0.63V in your screenshot a couple of posts up so either something have changed there or it was never stored after calibration or something.

Thanks Adam, I'll try the calibration procedure again and store to ecu.

Does it make a difference calibrating when cold or warm?

[Adamw]

21 hours ago, jqvp said:

Does it make a difference calibrating when cold or warm?

It shouldnt do if everything is in good condition.  

[jqvp]

Hey Adam

I've done another ethrottle calibration and also updated the fault delay to 2 seconds to try to prevent it randomly going into limp mode whilst I'm driving in traffic. 

Did a 30 minute drive with random stabs of throttle to try to replicate the error but it didn't happen.

It appears the TPS Main and Sub track quite well, though there was one point where it was very 9%+ different. The throttle body is a brand new Bosch unit, all wiring was professionally done. Not sure how to explain this random variance - is anything sticking out as being incorrect or anything I can change to prevent it?

Also at some point which I'm not sure if its in the log is I got the following error "fuel calculation clamped at its minimum value" but the car didn't stall or anything. When I looked again at the laptop the error was gone...

 

PC Datalog - 2022-12-4 8;45;15 pm.llgx 27.11.22 Starting.pclx

[Adamw]

You still have an issue with the throttle in that log, at time point 10:12 the TPS sub started drifting away from TPS main, it was only moments away from faulting when it suddenly come right on its own.  Given it is a new throttle and Bosch stuff is generally of good quality, I would be leaning more towards it being a bad connection somewhere.

 

On 12/4/2022 at 11:42 PM, jqvp said:

Also at some point which I'm not sure if its in the log is I got the following error "fuel calculation clamped at its minimum value" but the car didn't stall or anything. When I looked again at the laptop the error was gone...

This is not an error, this is just telling the tuner that he is commanding a PW shorter than what you have set for the minimum effective PW, so you cant make it any leaner at that point.

[jqvp]

Thanks Adam!

Looks like I'll need to take it back to the tuner to diagnose then if its not something that can fixed tune wise.

[jqvp]

Took some time to tackle this issue, bypassed the body/interior wiring harness altogether and directly wired the throttle body to the ECU with shielded wire.

My battery has been relocated to the boot and the positive runs through the same hole as the engine harness so I'm thinking there might've been signal interference. Question: Should there be nothing in TPS Error Accumulator if everything is working fine? If so, then I'm thinking that maybe I have a grounding issue and signal interference?

Copy of tune:

19.02.23 updated wiring.pclx

Copy of log:

PC Datalog - 2023-02-19 4;07;04 pm post wiring upgrade with some rev hang.llgx

Drive notes:

- Just cruised around and didn't notice anything strange aside from high idle/rev hang when at a stop, this happens frequently but will change from light to light. 850rpm at one and then 1500rpm at the next. 

- It looks like I was moments away from getting Fault code 76 again and then it came good...

 

[Adamw]

Yeah looks like you still have the same problem.  

[jqvp]

So should there be nothing logged in TPS Error Accumulator if everything is working correctly? 

I'm guessing it may be a grounding issue due to phenolic manifold spacers, the ECU grounds off the top of the intake manifold.