Safe mode P0171, P0300

Year/Make/Model: 2013 Speed 3
Mileage: 128k
Location: tecksis
Concern: slight rough idle, safe mode while driving
DTC's: (please include descriptions)
Modifications Corksport TIP
ECU/Tuning Software: Stock

Been tracking down the misfire and lean codes for this has been a nightmare.

I have replaced both O2 sensors (they were reading low voltage), fuel injector seals, new OEM mass airflow sensor, rebuilt HPFP with a Corksport kit, new gas cap, replaced the pressure relief valve, new pcv, cleaned the intake valves and have replaced the fuel rail pressure sensor.

Originally it was misfiring with P0300 and P0303. Now it is throwing P0171 and P0300 but they won't stay on.

It keeps putting short term fuel trim at 25% but it reacts normally when on throttle.

My fuel rail pressures are reading slightly low at idle and key on, engine off (20-40 kpa).

When the car doesn't go into safe mode, throttle response and power are good. Seems to go into safe mode more while driving it vs giving it throttle sitting in the driveway.

Pretty much certain there is not a vacuum leak despite the lean code but have not done a smoke test.

So what could it be?

I'm leaning towards the tank fuel pump filter being dirty but I really don't want to drop the tank to replace it if I don't have to because I'm trying to sell the car without doing anything more if possible.

 

could be an air leak man do a boost leak test that's the first thing I check with lean codes. you mentioned stft 25, what's the ltft.

also what are the code descriptions I'm not googling them you used a template that asked you to provide them but did not

 

Ltft are at 0. Stft drops to zero like it should on throttle but when it goes to idle it stumbles and sticks at 25. After stumbling it idles smoothly for the most part with a slught hiccup on occasion.

P0301 is misfire cylinder 1 and P0171 is bank 1 too lean.

 

And for other common questions.

Yes, plugs are gapped properly. Bought a new coil pack and rotated them to make sure it wasn't a bad pack and/or gaps causing the misfure.

Parts cannon has been sequential as I have gone down the most common causes.

I don't have an access port but a decent scanner tool with live data.

Every step has improved the problem little by little. The TIP got replaced because the little plastic piece snapped when I pulled it to clean the EGR valve and pipe. So quickest solution was that.

I've owned the car since new so I know the complete history on it.

The misfire code was originally random cylinders and cylinder 3. Cleaning the valves, egr, replacing intake manifold and throttle body gaskets made it to where it is now which is cylinder 1. It stays as a pending code at this point. I have not been able to do a drive cycle to get rid of it or confirm if will be current.

P0171 Bank 1 too lean is a current code but will go back to pending sometimes after it goes into safe mode.

During this quest, it has thrown a mass air flow circuit code which was fixed by the new one. Also had the shutter valve stuck open code because of that lovely little piece of plastic. Fixed that from the thread on here about it.

When it isn't in safe mode, it runs great. When giving it throttle in neutral, not moving, it feels like when it was a lot newer.

Can usually do an initial moderate pull and it's good until 50ish mph. Then when I lift it starts to do safe mode cycle. I can have the pedal on the floor and it will not respond. While it goes through the flashing CEL phase, that's it. Sometimes it will go back to normal but go back into safe mode under moderate throttle and immediately cut power again.

 

Jiggle the maf wiring while the car is running. It seems like the maf isn't sending a clean signal

 

Did this and it didn't seem to make any difference. Wires look ok as well.

I'll look it over with some daylight and toy with it some more tomorrow.

 

there's also a small ground bear the hpfp single small black wire it's notorious for causing weird issues ensure it's clean and tight.

 

Just cleaned it again (had done it before) and no difference.

Wires in MAF harness look good. Intact and seated.

Stft still stuck at 25 during idle. If you give it gas, it drops like it should. If I very slowly increase RPMs, it will drop to zero around 3700 and then trigger safe mode.

When it goes into safe mode cycle, it cuts stft to zero and it stumbles like it might stall. Stft goes to 25 and it stabilizes and runs a little rough like it has been.

 

Need to do a boost leak test and look for leaks anywhere in the intake tract

 

Well have to build a tester so will probably be a couple days before I can test it.

 

Had a buddy come by for a second set of eyes/ears and while he was here I double checked the MAF harness. It finally did affect it when moving the wires around. It's now throwing the two MAF codes.

It looks like it is the middle wire.

Can I pull the wires and rewire it or should I just buy another one?

 

I would personally just fix it if you have the ability

 

Not the best with wiring but I pulled two pins and the wire that I thought is the issue is definitely a problem (may not be the final solution but definitely needs attention).

Ordered a pig tail from Amazon. Easier for me to solder it in vs. fighting with the pins.

And for anyone else that ever develops this issue, there were no nicks in the wires outside the connector. Rubber grommets looked good too. Pulled the pin and could see the wire was barely holding on in the pin.

 

New harness is installed and made a huge difference. Still throwing a pending lean code. Took a short drive and it ran great until safe mode which took much longer to trigger and went away faster.

Did a boost leak test and no obvious leaks but I think my intercooler may have a slight leak on the bottom side of it. I could feel air a little coming through but it is really windy today so not sure if that's in my head or not.

If it is the intercooler, what's the best way to verify that and then fix it if that's the issue?

 

I doubt it's the intercooler. You should be able to determine that with a physical inspection upon removal

 

Get a 5 gallon bucket with paint/pour lid that you can rig a hose up to. Go to the grocery store and buy 5 lbs of dry ice. Put a bunch in the bucket, add some water and bam, smoke machine.

Car will fail to start/run like shit for a short time after (because no oxygen) so be ready for that.

 

So wasn't the intercooler. One of the throttle body hose clamps was busted but didn't look busted. Replaced it and was still getting the same issue with but slightly less worse.

Stability control light came on so decided to thoroughly go over the brake booster line and it has a leak in the middle.

Hopefully once that's fixed, it will be fully fixed.

 

You have a bunch of leaks then. Time to go over everything with a fine toothed comb

 

This damn car is infuriating.

New brake booster line is installed and made an improvement but still the same issue. Stability control light went off.

Have gone over intake chain mutliple times and can't find any leaks. Had a buddy just look with me for a second set of eyes and same thing.

Fucked with the oil cap and it didn't seem to make much of a difference with it loose or tightened. Car obviously starts to stumble when the cap is lifted.

Have a cheap smoke tester on the way now.

What's the o-ring size on the oil cap? Do you guys think it could be the black evap thing that sits under the intercooler?

 

boost leak test it not just a smoke test