Resolved 1G Car stuttering under boost after air can removal

[91Bomb]

Removed air can yesterday and did a couple pulls in 3rd, 4th, + 5th gears with no problems. Then I started getting bad stuttering that SEEMS like boost leaks but I didn't have any problems before removing air can. I'm boosting at 15 lbs with cheap/free mods. Oh yeah it then started stuttering at evn 1 lb boost or higher. Tonight it seemed like it would hold close to 10 lbs before stuttering and low boost/ normal driving car is good and so is idle.

Actually I got some logs tonight and should MAP afr be around 14.0 steady? My logger is showing from 8's up to over 20
Logger didn't show any trouble codes.

 

[Absit]

MAP afr

What?

 

[91Bomb]

MAP reading is 8.1-20.4 afr (logged using mmcd)

I'm not sure what it's supposed to read but I thought it should be around 14 for stoichotomy.

 

[Absit]

A MAP Sensor is supposed to read the manifold's absolute pressure, generally in PSI here in the United States.
Your AFRs should be ~14.7:1 when you're at idle and cruise, and between 10 and 12:1 in open loop.

 

[91Bomb]

A MAP Sensor is supposed to read the manifold's absolute pressure, generally in PSI here in the United States.
Your AFRs should be ~14.7:1 when you're at idle and cruise, and between 10 and 12:1 in open loop.

On my mmcd it says MAP and on a log readings are fluctuationing ranging from 8.0 -20.2 afr while driving

(ed - mmcd past version 1.4 has sensor listed that don't exist on DSM's and will display random values based on whatever is stored at the memory location the "sensor" is mapped to.)

 

[Absit]

How's your ECU look?

 

[Colt4G63 also]

Is your MAF still plugged in?

 

[91Bomb]

I never unplugged the MAF and I've double checked everything around where I was working when removing air can.

Please feel free to ask questions concerning my logs because I don't know much about what everthing should read (btw anyone have a link explaining this stuff?)

Car runs great except into boost. No trouble codes or stored codes.

 

[Absit]

Have you done an actual boost leak test?

 

[91Bomb]

Have you done an actual boost leak test?

No I haven't. I tried doing a boost leak last year with BLT connected at the turbo inlet. After hours of fooling around spraying soapy water I couldn't figure anything out. Put everthing back together and no more boost leak

 

[Absit]

Do another one, properly.

 

[91Bomb]

Do another one, properly.

I guess I'm going to have try and boost leak test. Is putting BLT at turbo inlet a good place or should I go about it another way? Any tips are apprecited.

Can you tell me what the proper way to check the turbo for shaft play or any other problems while I have access to the inlet side.

What about those logs? Is there anything I can look at to tell me anything? Keep in mind I know next to nothing on what's normal or not. Anyone have a good link explaining datalogging btw?

 

[Absit]

You can compare load to boost, but unless you know what you're looking at it's not super helpful. Put the boost leak tester on the compressor housing inlet. Check for shaft play by wiggling the compressor.

 

[91Bomb]

You can compare load to boost, but unless you know what you're looking at it's not super helpful. Put the boost leak tester on the compressor housing inlet. Check for shaft play by wiggling the compressor.

How much play is too much? up/down back/forth?

 

[Absit]

Without going down there and measuring - if it feels wrong, it is.

 

[gofer]

How do I make/buy/use/troubleshoot my boost leak tester

 

[91Bomb]

Ok my boost leak tester holds 20 lbs

So I'm going to leak test this weekend. I'm planning on attaching BLT to turbo inlet. Other than leaks at obvious places like TB, intake hoses/connections, i/c, where else could you get bad leaks? Intake manifold gasket? ?Turbo seals?

I guess I could test at 2 different places like 1 test from turbo inlet to just before bov and then from bov on upstream, right?


*UPDATE

Today I put the boost tester at turbo inlet and sealed the hose that comes off i/c and discovered a huge leak from a vacuum hose that's between the boost controller + wastegate. Put a new a vacuum line in there and solved problem. 1st boost leak fix for me

 

[91Bomb]

Took the car out tonight and still got the same problem

I got an exhaust leak somwhere up near the front of the car that has been getting louder lately so maybe that's causing the problem? I've had exhaust leaks in the past which never caused any so not sure..

Is it common for 1g bov's to go bad and cause boost leak type problems? I'll have to test that and also pressurize the intake after I/C since test from turbo through I/C went good today after fixing a vacuum line. Didn't notice any shaft play on 14b turbo tho.

I have a logger like mentioned so is there anything to look for concerning a possible bad sensor? Car breaks up real bad but only under boost..

 

[91Bomb]

SEMI- RESOLVED


My throttle body was leaking at one of the shaft o-rings. Replaced that and major leak at BISS Now I'm going to replace all 7 gaskets + o-rings on TB and then see if I'm good..

No boost leaks from turbo inlet through intercooler tho

 

[ssicb]

DSMtuners save another noob!