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Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 3:51 pm
by jetspeedz
Not sure what is going on, I suspect it is fuel related just based on the fact the injector pulse and duty go to zero as soon as this problem occurs.

Driving on the freeway on the way to work, all of a sudden i feel like I have no power, no throttle, car is still on the check engine light comes on and than after about 10 seconds it goes off and car is back to normal. It did this to me once so i brought my laptop to datalog hoping the check engine code would show something but nothing, even in this attached datalog there is no CEL code which is upsetting.

I see even when the CEL comes on at about 08:17 the Fuel pump is showing as on, but the injector is at zero. Since the CEL is not throwing a code it leads me to believe it is related to something which is not monitored like PGM-FI main relay possibly? but if that was bad i would suspect the Fuel sensor radio button would go off and it does not indicating the fuel pump is working.

Any suggestions to dig into looking at anything specific is appreciated since it is intermittent and only has happened 2 times now its not easy to track down.
Datalog-200129-000.s3d
datalog 08:17 is when it occurs
(3.6 MiB) Downloaded 22 times
thanks

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 3:52 pm
by Spunkster
post the calibration that this datalog was made with.

In the datalog are you referring to the area between 8:15 and 8:25?

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 3:59 pm
by jetspeedz
I don't have the calibration with me but I will post it when I get home.

Yes it is between 08:17 and 08:23, does anything pop out to you?

I'm curious why no code was thrown but the CEL came on during that time. Wish there was some code to help me track down the issue. The calibration has not changed in years and it was running fine all this time. It just started.

Any feedback is highly appreciated

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 4:13 pm
by jetspeedz
Spunkster wrote:
Wed Jan 29, 2020 3:52 pm
post the calibration that this datalog was made with.

In the datalog are you referring to the area between 8:15 and 8:25?
I could not wait, i ran to the car and pulled it off the laptop. Here it is.

Any feedback? Why didn't the CEL throw a code in S300?
Tune v9.0.skl
Calibration File
(42.63 KiB) Downloaded 13 times

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 4:53 pm
by Spunkster
When this happens you can see your MAP pressure go into boost and stay there and it is boost cutting.

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 6:45 pm
by jetspeedz
Spunkster wrote:
Wed Jan 29, 2020 4:53 pm
When this happens you can see your MAP pressure go into boost and stay there and it is boost cutting.
It does not go into boost, what you see in the datalog is exactly what happens on the physical gauge as well. When this occurs it is not on boost at all, just cruising speed on the freeway.

Any suggestions of where to even look?

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Wed Jan 29, 2020 8:03 pm
by dluder
I'm on my phone so I can't view datalog. Does this just randomly cut off? It could be faulty ignition switch.

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 4:28 am
by DaX
jetspeedz wrote:
Wed Jan 29, 2020 6:45 pm
Spunkster wrote:
Wed Jan 29, 2020 4:53 pm
When this happens you can see your MAP pressure go into boost and stay there and it is boost cutting.
It does not go into boost, what you see in the datalog is exactly what happens on the physical gauge as well. When this occurs it is not on boost at all, just cruising speed on the freeway.

Any suggestions of where to even look?
The log definitely shows you getting way into boost and based on your calibration, you hit boost cut. Now, you many not have physically gone into boost, but that's what the MAP is telling the ECU. What MAP are you using? Do you have a spare you can try swapping in?

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 9:33 am
by jetspeedz
dluder wrote:
Wed Jan 29, 2020 8:03 pm
I'm on my phone so I can't view datalog. Does this just randomly cut off? It could be faulty ignition switch.
It is very random, no way to replicate it. I was going to turn the car on and move wires to see if its possible a lose wire with all the vibration but thats not very scientific.

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 9:37 am
by jetspeedz
DaX wrote:
Thu Jan 30, 2020 4:28 am
jetspeedz wrote:
Wed Jan 29, 2020 6:45 pm
Spunkster wrote:
Wed Jan 29, 2020 4:53 pm
When this happens you can see your MAP pressure go into boost and stay there and it is boost cutting.
It does not go into boost, what you see in the datalog is exactly what happens on the physical gauge as well. When this occurs it is not on boost at all, just cruising speed on the freeway.

Any suggestions of where to even look?
The log definitely shows you getting way into boost and based on your calibration, you hit boost cut. Now, you many not have physically gone into boost, but that's what the MAP is telling the ECU. What MAP are you using? Do you have a spare you can try swapping in?
You are awesome, I did not even bother to look at the boost drop down where you can see the PWM raising, but as you can also see the boost graph is completely flat but the PWM jumps up to 35% which like you said would indicate a boost cut issue with the MAP sensor.

I'm using a 3 or 4 BAR map sensor Omni i believe ill have to check when i get to the car. I don't have a spare MAP sensor and it is very intermittent so it is hard to nail down what is causing the map sensor to go wonky like this. I was hoping the CEL would throw a code but it does not.

I also did a quick test last night on the way home, i let off the throttle and inject pulse and duty dropped to zero so i don't think my initial suspicion it is a fuel problem is correct.

Question, if the map sensor is acting up, and it hits the boost cut when I'm physically not boosting, why do you get the sensation the car has no power, does the boost cut kill the injectors?

Thanks for the feedback leaves me going down a different path now.

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 9:38 am
by jetspeedz
It happened this morning again but it was instant for maybe a full second and full power was restored. Datalog attached.
Thursday Datalog-200130-000.s3d
Datalog Thursday
(2.9 MiB) Downloaded 14 times

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 9:42 am
by jetspeedz
I just reviewed the datalog from this morning and same thing PWM jumps to 37% despite I'm not physically on boost at all.

What would cause a MAP to behave in this manner, can't be a vacuum leak, I'm leaning towards electrical maybe poor contact or wire harness issue?

Anything to look at in particular in the actual tune, i don't think anything is wrong it has been running fine for years.

Any reason why the CEL does not actually throw a code?

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 9:44 am
by jetspeedz
Spunkster wrote:
Wed Jan 29, 2020 4:53 pm
When this happens you can see your MAP pressure go into boost and stay there and it is boost cutting.
I understand what you are saying now, but as you can see the Boost is at 0%, i'm not physically boosting, its the MAP PWM that jumps to 37%.

Why would the CEL not throw a code?
Do you think this is a faulty MAP sensor or wiring issue.

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 10:14 am
by jetspeedz
I feel like a bonehead, i keep thinking the Gear bar is MAP but MAP is at the bottom and I can see what you guys see when you say you are in boost. I can assure you I was not in boost physically.

What would cause the MAP to behave this way, a wiring issue or a bad MAP sensor in your opinion?

Re: Help - Car cuts off Check engine light but no Code? (log added)

Posted: Thu Jan 30, 2020 10:30 am
by jetspeedz
This is a general question when setting new start and end time is there any way to see the full log or do you have to always close it and open it again?