Running Lean and P0170

[Riceburning101]

Alright here is the deal. I am having trouble with cold starts. It turns right over just fine and starts but then usually stalls maybe 20 seconds later. Usually happen 5 times until engine gets warm. Now here is the fun part. I am running super lean. At idle its hit or miss where the a/fr at any where from 13-full lean. Cruising I am seeing 16:1-full lean and bogs like a S.O.B. on accelerating when I hit boost only running wastegate pressure on a 16g so 10ish psi. On boost its still hit or miss on a/fr again anywhere from 13-full lean. Finally, after limping home finally get a CEL for p0170 and obviously missing rear o2 sensor where my WB is. So after that Bible length story I have tested the CTS resistant it solid and within specs. I only need to test the connector its self. As far as I can see the wires look fine. So I swapped out fuel rail, injectors, and fpr that changed nothing (all stock fuel setup ie 450s etc.). So I tested the air temp sensor on the maf. I got 3.8 ohms only problem is its 35 ish degrees here and 3.8 ohms should be for like 50ish degrees. Also I ran the car without the maf and it seemed to idle smoother. Plug the maf back in while idling and it starts to bog and give it gas makes it bog.

So basically can a maf with a faulty temp sensor cause my lean/bog issues and cause the hard starts? Also for testing the CTS connector whats the resistant specs or how do you test the CTS connector. Also I know the P0170 is usually the front o2 but I want to say its only maybe 5 months old and was a Bosch direct fit.

Sorry for the long post but thanks in advance for any help or insight.

 

[delta448]

P0170 is a fuel trim malfunction, not O2 sensor. It means the ECU has adjusted the fuel trims as much as it is able (IIRC, 12.5% in either direction) and the O2 sensor is still telling it that it isn't enough.

You have to figure out why there isn't enough fuel being injected. This could be due to pump failure, kinked fuel lines, clogged fuel filter, improper global injector settings in the ECU, failed FPR, FPR vac/boost reference issues, CTS issues, MAS issues...

I'd check the MAS first since that seems directly related to your problem. Yes it can do that.

 

[primo513]

like delta said at the end, take a look at the mas. make sure the connector is clean and not corroded at the connection on either end. also take a look into the intake to make sure the sensor isn't dirty either. Ive seen extreme idle/stalls come from a mas thats dirty as hell.

 

[Riceburning101]

Well I messed with the MAS this morning and plugged my obdi scanner in. Before I for i even started the car the IAT was at 60 real temps were 25-30. I watched the IAT from the scanner all day it never got close to the outdoor temps. Luckily there is another DSM guy near by and we are swapping MAS's tonight. I am got a new fuel filter that will be on tonight. Eliminating some options. Also I was watching the lbs/min for the MAS at idle its saying roughly .350-.425 lbs/min I don't know if that is normal or not but just something I noticed.

It was the MAS. Plugged in the other one and all problems solved.