hogdoghd

Ok, she is my DD with a GMS1 tune and she has been running great except for the every once in a while hiccup at Idle! It's really weird for about a week now when I'm driving home from work, I get to almost the same exact spot and the car starts to sputter and loose boost and then runs fine with no codes!! Then the other day it just started running like **** would not boost and absolutely no power!! It finally threw a P101 code for maf, so I cleaned it to start with but no luck. I changed it out and it ran beautifully that night and morning to work, it even felt more powerful then before!
Then all of a sudden on the way home exact same spot it started acting up again another p101 and some weird a$$ U0073 communication error?? I dont see any boost leaks and when it runs fine it boost great!! This morning when I started the car up when she was going through the normal turbo cycle the car just kept missing / sputtering and boosting and blowing off several times which is weird??? Please help I don't know. I cleared the p101 and U73 it hasn't thrown any since but running like **** no power and wont boost most of the time!!! I know its a lot but I wanted to give as much info as possible!! Thanks in advanced!!

Tommy

68Vette

The code book states: OBD ISO-15765 Communication Bus, Fault Code U0073, Description ISO-15765 Bus Error, Primary Malfunction: Invalid Message received or dual port hardware error: or no communication / Bus off. You might want to take it to the dealer and have them look at the Ignition switch.

umrdyldo

iTrader: (1)

If you are talking about P0101 then you are talking about a boost leak which seems likely from your symptoms.

Check all charge pipes and intercooler for leaks or giant holes.

hogdoghd

Thanks for the replies! I will check again for a boost leak but on my first inspection there were no cracks or holes that I could find!! when it does boost it ramps up to 20-21 psi of boost??? Ill throw it on my lift tonight and check again! The buss communication fault has not come back, so IDK???

ECaulk

iTrader: (6)

Build a proper boost leak tester don't just look at the piping because you cannot see all of the piping or if there is a leak from a connection

umrdyldo

iTrader: (1)

https://www.cobaltss.net/forums/how-...ss-lnf-223319/

hogdoghd

Cool I have the PVC on hand, so tonight looks like a beer drinking night & some boost leak hunting!! Thanks

tuned08ss

So here's a stupid question. Do local shops usually do boost leak test or even know what they are? Is it the same as a smoke test to them? I don't have space in my apartment complex to remove my bumper and check.

umrdyldo

iTrader: (1)

No most shops will have no idea how to do one.

I"m getting ready to make one with a valve stem insert instead of a air compressor hose.

It's not the same as a smoke test either.

tuned08ss

Guess I'll have to find a buddy who'll let me test it at their house.

nismopowerdqg

A smoke machine test utilizes the vacuum/boost system and pressurizes it as high as you want it to go. Easier to spot a leak that way.

hogdoghd

OK I built a leak detector and tested it for leaks!! I started at 15 psi and went all the way to 25 psi!!!!! I sprayed snoop ( soap and water) all over the fittings tubes and innercooler and fittings, tanks and no leak to be found!!! The car is still throwing a p101 (with a new mass air sensor) and now a p106 map sensor abnormal!! I cant figure this stupid car out!! any thoughts????

ECaulk

iTrader: (6)

Did you spray the map sensors and the intake manifold head connection?

Now try removing your bpv and see the condition it is in

hogdoghd

Yes I sprayed the map sensors (both of them), throttle body and no leaks! the bpv is the tanish looking vacuum port with 3 bolts on the turbo, Right????

ECaulk

iTrader: (6)

Yes it is.

hogdoghd

Cool I have a complete spare lnf laying around with turbo!! so Ill just steal it off of my spare!!

Thanks!!

1Shotwonder

With it being a 08 and you stating you do not have any boost leaks I'd check your gms1 connections that where made as they were likely spliced and not the later upgraded jumper harness gms1 package. Also disconnect both upper and lower gms1 sensors and inspect for corrosion if any attempt to clean with dielectric grease (less is more) lmk if you find anything you may want to reduce the crimps if there is any on the harness for the gms1.

umrdyldo

iTrader: (1)

Make sure your MAF sensors is facing the correct way. I just saw someone that did that.

I'd guess you have a MAP sensor issue. Try cleaning the one on top of the manifold and the one in the lower charge pipe.

If P0106 stays then you likely need to replace one or both of the MAP sensors. Or you have a leak around one of them

tomj77

iTrader: (2)

Map sensor leaks are likely, I don't think iv had a charge pipe yet that didn't leak at the map sensor. Those o rings don't hold boost for ****. Best idea, before installing cover oring in silicon and install and let dry over night. After I did that holds 30 psi no leaks at all

hogdoghd

Ok here's an update!! I checked the maf wiring at around 12" away, I cleaned the new maf. I removed both 3 bar map sensors and cleaned and resealed. I replaced the boost control solenoid with one off my spare turbo and checked all boost tubes clamps and so on!!! cleared all of the codes and car ran great for like 4 days then BAM back to the same old bull ****!!!!!!! throwing a p0101 sometimes and a p0106 sometimes Maf & Map!!! I clear the code and runs like brand new for a bit then back to the same pos!!!! ANY THOUGHTS????

umrdyldo

iTrader: (1)

replace your map sensors