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Hey guys, I hope this is the right place to start this thread. I acquired this gorgeous 07 SS Supercharged back at the start of winter which I have grown a love/hate relationship with. The previous owner seemed almost like he wanted to just get rid of the car so I got it for a good deal. First thing I noticed was insanely horrible fuel mileage. Second is that everytime i come to a stop I throw the car in neutral and hit the brakes (5spd trans) the rpms drop normally, but will drop below idle say 550-750rpm and the car will go into extreme vaccume it says on the boost gauge like - 80kpa then the car will almost rebound it the vaccume goes to normal - 60ish and it Revs back up either over idle or to normal. I recently got it to throw a P0171 and checked the freeze frame it said it was throwing the code while at 720rpm. Now to attack this problem I have done.. -throttle body clean -new air filter (CAI) old one was wet and rusty -cleaned spark plugs ( they were discussing)
-added seafoam to gas (haven't used much yet) -gave the maf a quick clean when I changed the air filter
checked purge valve
checked all vaccume and pcv line/brake booster line sprayed throttle body cleaned down some, replaced a few vaccume lines that were brittle.
-checked boost bypass solenoid and valve ~ car is building proper boost under load 80-90kpa all day long -sprayed throttle body cleaner around the valve cover and on all hoses and didn't get any idle changes which leads me to think it's not a vaccume or boost related issue Today while gandering in the engine bay I noticed a loose Allen key plug on the timing cover, oil had been leaking out of it. I assume this is for checking to see if your timing is on? Could that have been creating a vaccume leak? Where do I go from here? Have I possibly fixed the problem and I need to do some kind of idle relearn? Any help would be greatly appreciated thanks guys.
Known things done to the car -Upgraded supercharger pully ~ I measured it, just over 3" -#60 oversize injectors -"Stage 2 tuned" (what this means I have no idea some guidance would be greatly appreciated -Zzp Cold air intake
The big Allen plug? About an inch around? If so it’s an access plug for one of the timing chain guide bolts.
P0171 is for a lean condition. May or may not be caused by a vacuum leak.
Slightly over 3” on the pulley would be like the GM stage 2.
GM stage 2 used 42 lb/hour injectors, not 60’s.
GM stage 2 comes with a GM tune. I suppose some shops call their tunes stage 2 as well.
At any rate, 60lb injectors would require a custom tune.
Crappy fuel economy. Hmmm. Maybe someone threw 60lb injectors in with no tune?
Fouled plugs btw will cause the O2 sensor to show lean due to misfires. I’d replace them. Cleaning rarely works.
Any Tuners around there? Reading and evaluating the tune would reveal a lot.
[QUOTE=RonSS;7743880]I see the problem, it’s buried in snow!
The big Allen plug? About an inch around? If so it’s an access plug for one of the timing chain guide bolts.
P0171 is for a lean condition. May or may not be caused by a vacuum leak.
Slightly over 3” on the pulley would be like the GM stage 2.
GM stage 2 used 42 lb/hour injectors, not 60’s.
GM stage 2 comes with a GM tune. I suppose some shops call their tunes stage 2 as well.
At any rate, 60lb injectors would require a custom tune.
Crappy fuel economy. Hmmm. Maybe someone threw 60lb injectors in with no tune?
Fouled plugs btw will cause the O2 sensor to show lean due to misfires. I’d replace them. Cleaning rarely works.
Any Tuners around there? Reading and evaluating the tune would reveal a lot.
Hahah hey man! Thanks for the reply! I have been posting in someone else's thread that was similar for a while and have made a little bit of progress on the car. So I found out my car actually has the ZZP stage 2 kit which does come with #60'S, and a 3.1'' pully. Me and my tuner were looking over the car... And found weird cuts before and after the cat lol. Previous owner hollowed it right out and cut the mufflers out hahah! So regardless we are putting a new standard duty cat and new stainless exhaust with a muff and resonator. We have also replaced a **** load of stuff, had the wrong plugs in it, wet air filter, throttle body was dirty AF. I'll keep you updated after we do the exhaust he thinks it will probs fix it for the most part. Will deff help with the fuel economy and hopefully will fix it from running lean too!!
03-03-2021, 07:33 AM
