Off Idle Hesitation Stumble

[Torinate]

Thanks Mike.

There is a great starting point
Much appreciated!

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[Torinate]

Now that the car is away for the winter, I have a little time lol. This is a clip from the log that shows a misfire I believe. I just saw this now, the jump in the AFRs comes at the exact time the torque source 7 goes to 0.

So with that said, did the torque source ending cause the misfire or did the misfire end the torque source? I believe torque source 7 is transmission shift modulation. I have no idea what that means in all of this though. There was no gear change at this point and rpms were in the mid 3000s.

Sorry it's kind of wonky. Timing doesn't look good either.

Anyways, thought i'd post this up for the smart guys to comment thoughts.

I took 3 more good logs as well before I buttoned the car up. I'm really hoping they can pinpoint the misfire issue and especially the off idle hesitation.

Shoot me a PM and I can email the logs. They are still in the csv state as this clip is.

Looking for help for a diagnosis or to point mme in the right direction anyways.

Thanks for looking!!

TIME

RPM

ect

act

IAT2

saftot

FF[ALKY_PCT]

afr_matured

ETC_ACT

MAF_in_lbm_per_min

LOAD_as_a_fraction

vs_IN_MPH

PPS-APP1

PEDAL

tq_source_pid

MAF_Hz

AFR1

AFR2

STFT11

STFT21

LTFT11

LTFT21

VCT1-EXHAUST

VCT1-INTAKE

VCT2_EXHAUST

VCT2_INTAKE

FRP_PSI

FRP_relative_in_PS

Knock

ipsibr_IN_ppm

imrcm_volts

imrc_desired

fpump_dc

gear_cmd

OSS

SSA

SSB

SSC

SSD

SSE

slip_des

slip_act

line_prs_IN_PSI

ANALOG1(V)

ANALOG2(V)

VOLTAGE(V)

ZAFR

ZEGT

ZRPM

ZMAP

ZTPS

ZUSER1

ZUSER2

ZLAMBDA

ZEPCT

ZFUELTMP

5.64​

3015.8​

190.91​

90​

10.8​

0​

80.863​

30.659​

1.427​

40.68​

514.6​

80.5​

7​

8.341​

0.787​

0.779​

1​

1​

1​

1​

16.11​

-21.03​

17.36​

-21.16​

0​

0​

0​

49.899​

3​

1838.8​

53.1​

35.4​

12.2​

0​

0​

1020​

226​

164.8​

0​

0​

14.322​

5.7​

3164.8​

190.91​

90​

11.5​

0​

82.723​

32.001​

1.486​

41.078​

515.2​

80.5​

0​

8.475​

1.235​

0.826​

1​

1​

1​

1​

16.77​

-20.63​

17.29​

-21.29​

0​

0​

0​

49.899​

2​

1869.8​

79.8​

30.5​

12.2​

0​

0​

1020​

257​

165.9​

0​

0​

14.308​

5.76​

3340.3​

190.91​

90​

12​

0​

84.322​

34.934​

1.529​

41.617​

514.8​

80.5​

0​

8.699​

1.235​

0.826​

1​

1​

1​

1​

17.82​

-20.83​

18.08​

-21.29​

-0.25​

0​

0​

49.899​

2​

1886​

79.8​

30.2​

12.2​

0​

0​

1020​

336.5​

176.9​

0​

0​

14.349​

5.82​

3530​

190.91​

90​

11.8​

0​

84.148​

36.916​

1.529​

41.976​

510.2​

80.5​

0​

8.868​

1.219​

0.921​

1​

1​

1​

1​

18.54​

-20.9​

18.21​

-21.22​

-0.25​

0​

0​

49.899​

2​

1904.3​

79.8​

28.7​

12.2​

0​

0​

1020​

344.8​

183​

0​

0​

14.369​

5.88​

3724.8​

190.93​

90​

11.8​

0​

83.26​

39.841​

1.584​

42.282​

509.6​

80​

0​

9.032​

0.9​

0.831​

1​

1​

1​

1​

19​

-20.76​

18.86​

-20.9​

-0.5​

0​

0​

49.899​

2​

1918.8​

79.8​

28.4​

12.2​

0​

0​

1020​

306.5​

186.2​

0​

0​

14.325​

 

[Torinate]

Ok. Only have a sec...

Looking at one of the logs for the off idle stumble. Typically how long should it take the car to react after stepping on the gas to moving? I see where pedal % goes from 0 to a positive number (when I step on the gas) and then the VS in MPH doesn't move for 0.4 seconds. Sometimes it's right away (thinking no hesitation then) but others are the .4 second delay. This must be what i'm feeling. That brief period where I step on the gas and then the car decides to go. It feels like a LOT longer in the car... Now to figure out why...

 

[K4fxd]

Is the delay off idle or while the car is moving?

 

[Torinate]

Right off idle. Car has not started to move yet.

Like a delay box lol. Only sometimes though…. Pedal position and mph are beside each other in the log and you can see the pedal move but no change in speed for this period.​

 

[brianbr]

Have you tried re flashing your tune just for s&g's?

 

[Torinate]

Have you tried re flashing your tune just for s&g's?

great idea! No. I never did. I’ll try that in the spring though!

 

[Torinate]

Thanks for the help already…



But no further ahead yet. So, this is what I plan to do late winter / early spring before the car really comes out. I will have a few questions as well, so looking for more direction.



Car continued to have the idle miss (popping at idle and misfire counts on ForScan). The off idle hesitation has not changed or if anything, gotten worse. Step on the gas and expect to move but there’s the delay and then go. Long enough to be felt by anyone in the care – even my wife who knows nothing about cars but was able to diagnose my car as having something wrong with it.



I have logged with my nGauge as well using ForScan real time. Is there a better device or way to see what’s actually going on? I’ve used the typical PIDs that Lund says to datalog with, but I’m told there’s too many to get an accurate reading. I can likely make a custom datalog file to use – but what is most crucial to diagnosing these issues. I believe there to be 2 separate issues…



First plan is to start with another compression test. Last one early summer was fine, but for peace of mind, I’ll start there.



Next will be to pull the injectors again. Is there a fuse that I can use to stop the fuel pump from firing? This way the fuel lines should be completely empty and I won’t have to relieve pressure etc. Last time I just disconnected the injectors so they would spray but the lines and rails were still full. I think this time I’m going to pay more attention to the actual injector harness and wires to see if there’s anything going on with the wires. I know they’re tight in there and could rub maybe? Has anyone had issues with DW95 injectors? I used a cheaper injector cleaner last time and didn’t see anything. I wonder if sending them to someone to be professionally cleaned and flowed would make a difference? They could also check for any leakage that the unit I used wasn’t really able to (or at least I couldn’t figure that part out).



Plugs are brand new – maybe 500 miles now. I’ll have a look at those again as well. The old ones looked great. I moved the coils around last time but that didn’t seem to make any difference at all, so I’ve tentatively ruled those out.



I’m not going to do another smoke test. I’ve done 3 now and the last one was over an hour. Vacuum hasn’t changed at all.



TB is new (Soler Performance) but was doing this before the change with the stock TB. Maybe not to the extent it is doing it now. Anyone have a stock 15-17 TB that is known to work without issue? May be worth trying it if nothing works.



MAF has been cleaned x 2 with MAF cleaner. No change.



Here’s a few items I want to rule out – but not sure how to go about it. Evap Purge Valve. Any way to check / test this? Would this cause either of the issues?



Next is the VCT solenoids. Someone commented they may be a bit delayed but wondered if the log had too many signals and couldn’t keep up. How are these diagnosed / tested? Would this cause one of my issues?



O2 sensors and cats. How can I check my O2s to see if there is an issue?



Beyond these things, what else is there to check? I’m open to all ideas. I’m open to a new tune as well, if that what it takes. Ultimately, the goal this spring is to get rid of the misfires and off idle hesitation. I didn’t even get to the track last summer for fear of having a misfire under full boost at high rpm for fear of popping the motor.



So the questions… What’s the best way to datalog for this? Best device or program? Anyone have a 15-17 TB that is known to work? What fuel pump fuse to pull? Evap and VCT – how to check / diagnose?



Honestly, frustrated here. So if you have ideas post up!



Thanks again!



Sorry for the lengthy update…

 

[engineermike]

Do you have vcmscanner? You can get a really fast data rate and see what component is causing the delay.

 

[K4fxd]

Here’s a few items I want to rule out – but not sure how to go about it. Evap Purge Valve. Any way to check / test this? Would this cause either of the issues?

Easiest way to eliminate it is to cap it off. I don't remember seeing any fueling issues, but I do look at a lot of logs.

 

[Torinate]

Do you have vcmscanner? You can get a really fast data rate and see what component is causing the delay.

No VCM scanner. I’ll look into that for sure. The delay was told to me that it was likely from logging so many signals. But not positive. Would an actual delay of the VCT solenoids cause the miss or hesitation? I’m wondering if an actual VCM delay or a data logging issue.

Easiest way to eliminate it is to cap it off. I don't remember seeing any fueling issues, but I do look at a lot of logs.

Cap off the Evap as a way to see if it makes a difference? Would this throw a code then? Unfortunately ?, It hasn’t thrown any codes and nothing stored. No bread crumbs on what to look for or where to start. Hasn’t even thrown a misfire code but they are evident with Forscan.

I don’t believe I have a fueling issue. Lambda appears great throughout. Bank 2 short term fuel trims are higher than bank 1. They are very similar to initial fuel trims when logging for the tune. This is part throttle and cruising. Under WOT the fuel trims are perfect. But, would a leaky injector or a few cause the misfires and idle pops?

 

[K4fxd]

I don’t believe I have a fueling issue. Lambda appears great throughout. Bank 2 short term fuel trims are higher than bank 1. They are very similar to initial fuel trims when logging for the tune. This is part throttle and cruising. Under WOT the fuel trims are perfect. But, would a leaky injector or a few cause the misfires and idle pops?

I think your fueling is fine. Yes a leaky injector could cause all kinds of strange things.

The delay was told to me that it was likely from logging so many signals.

The logging of so many channels will delay the reporting of the parameters. It will not cause the car to delay.

IE; The intake cam might look like it is not moving until .5 seconds after it should on part of the log and it moves when it should in another.

Is it really being late? or is the scanner not catching it due to to many PID's being logged?

 

[Torinate]

I think your fueling is fine. Yes a leaky injector could cause all kinds of strange things.

The logging of so many channels will delay the reporting of the parameters. It will not cause the car to delay.

IE; The intake cam might look like it is not moving until .5 seconds after it should on part of the log and it moves when it should in another.

Is it really being late? or is the scanner not catching it due to to many PID's being logged?

Yes exactly what I was trying to say lol. If the cam has a delay, it would affect driveability. If the logging is delayed, it would not affect driveability BUT may make it appear there is a delay and skew the log.
Ok. Looking at the VCM scanner stuff. I’ll need an MPV it appears. Any suggestions?

 

[MCS]

But no further ahead yet. So, this is what I plan to do late winter / early spring before the car really comes out. ......

Damn Todd, that sucks! I read through it and by page 2 I think my eyes were starting to glaze over. I hope you get her back in fighting form. These changes all took place after our trip to Mustang Day? She seemed to run fine then!

 

[engineermike]

The pcm commands the cams to move, then measures the actual location. Tb angle, fuel, and spark are all a function of actual cam position not commanded, so slow responding cams don’t generally cause bad drivability unless the calibration is bad. I’ve actually electronically locked my cams at various positions and you’d be surprised how little difference it makes at anything but idle and wot.

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