Persistent DTCs/Rampant limp mode

Tyler Young

Tyler Young

The road to hell is paved with tread tracks
Greenie N00B Member
Greenie Member
So since my last post i have bought a computer, downloaded free VT and logged data from the last 2 days. Below are screenshots of an example or 2 of what I've been dealing with along with a few descriptions.

first half is idle, then a short drive across the parking lot. This is what my pcm looks like in limp mode
RED-intake manifold PSI
BLUE-boost PSI
GREEN-MAP voltage
PURPLE-wastegate duty cycle

Just prior to this log I was stuck in Kroger parking lot for about an hour because p0069 MAP/BARO correlation, p0245 wastegate solenoid low would come up every time I cleared my codes
 

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  • LIMP_MODE_IDLE--500' R-MAP_PSI B-BOOST_PSI G-MAP_V P-WSTGT.png
    LIMP_MODE_IDLE--500' R-MAP_PSI B-BOOST_PSI G-MAP_V P-WSTGT.png
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Not too familiar with this problem, but might want to log intake manifold pressure and barometric pressure in VT with the key on and engine off. This is the only time manifold pressure and barometric pressure would be expected to correlate, so log the condition.

The P0245 is pretty clear cut, it means continuity is lost to the solenoid. It could be an intermittent wiring/connector issue, a failed solenoid, or bad PCM (very unlikely).
 
-FAULTSTART-BARO_MAP_IM-PSI.png LIGHT BLUE-ambient baro
DARK BLUE-MAP voltage
RED-intake manifold PSI
This was taken the other day at idle after it started in limp mode. Only difference is when I cleared the codes it started back up correctly on the next try...

The baro reading is kinda throwing me off though. Granted it doesn't fluctuate more than .2 but, in my mind the ambient baro should stay constant so long as I'm not changing altitude or anything... idk
 
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Ok so I couldn't get it to fault but this is .csv as a positive start (sample)

This is an example of a good idle and some rev (test)

example of ignition (halfoff)

On another note. What are y'all using to view .csv? sorry, new computer so I'm still downloading software
 

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I just use excel and freeze the top row to view .csv files.

The barometric pressure jumping around is normal, the sensor just has very low resolution.

There is something wrong with your MAP sensor. I think the issue might be a bad MAP calibration or the MAP is bad. The PO may have unloaded the tune and left a modified map sensor on, you should check the part number.

There is likely a flag that sets the DTC when the difference between barometric pressure and IM absolute pressure is different by more than a certain amount with KOEO.

In your "test idle rev" log, the MAP sensor is pegged at an absolute pressure of 9.5 which does not make sense, it should drop closer to 4 to 6 psi (absolute) at idle. (either that or you have a huge vacuum leak)

The purpose of the flag is likely just a safety check, since the baro pressure and abs pressure are used to calculate the boost pressure. You can probably get rid of the limp mode by disabling p0069 in versatune. DO NOT go into boost if you do this, there is a reason it triggers limp mode. If your MAP sensor calibration is bad then the boost targeting will not know what is doing.

Edit:
Try sticking to a single thread when you are trying to get help. It makes it much easier for others to follow the problem.

I guarantee the problem is your tune after reading your other thread. The PO had a CS 3.5 bar sensor, you replaced it with another 3.5 bar sensor. The sensor isn't reading correctly because the PO uninstalled the tune before selling the car. Now that you have Versatune you can fix this by entering the MAP sensor scalar values to an OEM map and flashing the car.

Scalar A = 210
Scalar B = 0.35
Offset = 4.26

Post a consolidated list of the mods you've found on the car, it will help us see if you need any other corrections to the tune.
 
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dude this is great. ok so what i've discovered so far.
Threadstone TR8 FMIC
TurboSmart BOV(VTA)
CS 3.5 BAR MAP
Radium PCV baffle plate "limp dick" hose that i assume use to be connected to an OCC
ported intake manifold with PCV plugged/ VTCS delete
EGR delete
EMUSA k0422 turbocharger with stock downpipe
HTP 3" CAI turbo inlet with AEM filter
i suspect that the fuel pump internals have been swapped A. because there is a ziptie around the bottom metal line that leads to the rail and B. on other data logs i have registered up on the high end of 1900 psi. C. i'm throwing codes for system too rich(thankfully not lean) and with the 3" inlet if the internals were stock it should be lean.. right? as for everything else, i believe it's stock. but as i have only had this thing for about a year now, i'm just stumbling onto all this stuff.

here's the tricky part though. when i replaced the MAP i replaced it with the same spec that was existing. the vaccum leak i did have went away for a period of about a month and then came back.. my dash shows that i have a leak but in my data logs it shows i'm operating under the correct amount of vaccum. based off the limp mode logs makes me think it's more of an electrical fault coupled with a stock tune on aftermarket parts.. i mean the wiring harness is half covered in electrical tape so PO reworked it some. what do you think?
 
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God thats a mess lol. IDK how you've been driving the car like this for a year...

If the intake is larger than stock then you would expect to throw a lean code without a tune because the MAF calibration will be off. Make sure you have the OEM MAF sensor installed. There are differently calibrated MAF sensors for Mazda L engines depending on if the engine is turbocharged or not and the parts stores don't know or care which one they sell you.

Everything is pretty suspect. There's no way you'll get anywhere with diagnosis without having sensors that are reading correctly.

IMO you just need a customized OTS basemap from Freektune for the 3" intake and MAP sensor just to continue diagnosing. Either that or pickup the full version of versatuner so you can make corrections.


In the meantime you can gather more data to see how far off everything really is. Log these parameters in versatune:
upload_2020-8-3_22-22-42.png

upload_2020-8-3_22-22-47.png
Get an idle log, slow 2nd gear acceleration from 2k to 6k rpm (no boost), and maybe a part throttle boost log. Also a WOT log if you have been doing WOT on the map thats already on the car.

You can't tell whether or not you have the HPFP internals without taking them out.
 
so wot studders after about 60% throttle so i try to stay outta that honestly. I've done a few pulls but it scares the hell outta me cuz it feels like a timing issue at that point(i dont think my timings off but just feels like that at wot) as far as logs I'll see what I've got so far and upload some csv
 
Tyler Young said:
here's the tricky part though. when i replaced the MAP i replaced it with the same spec that was existing. the vaccum leak i did have went away for a period of about a month and then came back.. my dash shows that i have a leak but in my data logs it shows i'm operating under the correct amount of vaccum. based off the limp mode logs makes me think it's more of an electrical fault coupled with a stock tune on aftermarket parts.. i mean the wiring harness is half covered in electrical tape so PO reworked it some. what do you think?
Click to expand...

I wouldn't call -4.8 psi the correct amount of vacuum, unless you have more logs to share.
upload_2020-8-3_22-26-7.png

I don't think its an electrical issue.
 
is it not? to be honest man, I'm new to all this tuning stuff. I've always worked on older less tech reliant cars. but I'm no quitter and i love this car

but no, around -5 is pretty consistent
 
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you ready for some weird shit?..

idle

2nd gear low accel top at 6k

I've got a 4th gear WOT log but VT support needs to get back to me bc i wasn't able to view it

none of those logs were taken in limp mode..
 

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You need to do the following now before you hurt the motor.
Confirm that the correct MAF sensor is installed
Confirm that you have upgraded fuel pump internals
Install a base tune that is calibrated for the 3" intake and upgraded map sensor
 
ok, so I think it's about time for an update. I have confirmed that I have AutoTech HPFP internals, I have not, until about an hour ago, modified the scalars and multipliers... leading me to believe that the tune is the main issue. Haven't had a chance to flash it yet though
 
Ok so I realize this thread is old but I figured y'all would like to know I got my speed back up n running. The CS MAP was faulty and caused the vacuum leak and limp mode so I've replaced it with a bosch 3 bar. I've got a base MAFcal and am currently fine tuning it. Thanks for the help guys fr. Much love
 
Glad you figured it out and are running again!
If you haven't done so already please contact corksport so that they're aware of the issue.
 
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