Well it started yesterday, car stumbles and feels like its going to stall out under normal acceleration.

It almost feels like a major intercooler hose leak, but the hoses are solid (i checked)

I pulled the plugs and found that they where pretty blacked up (black suite) which usually indicates an overly rich condition of some sort. I figured with the winter gas (still 93oct) and the one range colder than stock (br8eix) that i was simply not getting full burn and the plugs had fouled.

So the plugs where replaced (with stock heat range) and i went on my merry way, everything was fine, but now its coming back.

So i grab the lap top and start with the programs....
First step No codes, no pending codes, 02 sensors read fine
2nd step datalog...

Well i found that it happens just below the 30mph mark, what i see in the log is a huge knock sum, the octane goes wierd (down from 100) and the injector pulse is off.

The logs are attached, please let me know what you think.


car mods:
Injen UICP/LICP/Intake
AMS Front mount
Walbro Pump
Forge MBC/Recirc
Stock Exhaust (for winter)
Tuned via email tune (anoymous for now)

for good measure i flashed back to the stock map and the problem still exsists

 

Malibu?

 

Ok, I'll take a stab at it. Pull the plugs. Are they fouled again? If so, get a wideband and fix your email tune or send the tuner logs of your overly rich car. Is your car tuned for the Walbro? The stock exhaust is making it richer as well.

 

What are your plugs gapped at? I had mine at .028 and the gap was too big. I just decreased the gap to .022 and I am getting the same thing at like 5000rpm. I am gonna try a .025 gap.

 

plugs where orange this time.....but im pretty sure that was from the fuel additive i dropped in (in case i got bad gas)


I dropped in a fresh set of BR7EIX gapped to .028....uninstalled & reinstalled my intercooler piping, pressure tested the system, and now im off to get a fresh tank of gas from a trusted station.

Im in the market for a wideband, but i have alot of reading to do on that topic....i had hoped email tune would have been sufficient for the pump....but i may have to uninstall that pump & tune until i get a wideband

 

it happend to me one time ,i drive my car about 40mph and after that i heard lil pop soud.. and my car start stumbles and my ECU going carzy i check every thing, but notting wrong with it , after 3 week i take some part off my car , it was my MAF senser get suck it ....... and that my prombles

 

^^ Yeah, Had a similar problem at the track when my MAF screen was dislodged.
Worth taking a look at.

 

We will need some AFR readings right after 5500 RPMS nto determine what is going on there. What is your octane?

I would lower the boost until you get this checked out!

BTW.... I just sent you a PM.

 

Well I threw the CEL and just pulled the code and it was the p0243 turbo over boost condition. The number might be wrong but it said over boost condition. I dont understand because I have been running 1.45bar for the longest time and have not had this problem before.

 

Man, you had an episode of some ugly knock in that first pull> Overheating?

 

Without a wideband the only guess is that since knock was at lower load (TPS < 80 also) maybe your fuel maps are leaning out there. Trace your map and see what value it is

 

well switching to new plugs & fresh gas yielded a drivable car. Time will tell....need to buy/install a wideband.

Im thinking it was just terrible gas....but we will see