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I don't know if I posted this in the right place but if not I apologize. 2006 cobalt SS lsj stage 3 kit zzp tune 60lb injectors with 2.9 pulley. Headers with one 3 inch cat with 3 inch exhaust. Cat was installed a month ago. Need some help here please!! Car bogs down kinda jerking an surging while driving an cuts out like you see in video wants to stall but hasn't yet. It only does at idle usually when ac is on but when driving it doesn't matter ac or not. Just started this. I cleaned maf no use so I swapped it with another I had. Replaced the bypass solenoid also a spare I had. New fuel filter. Clean tb checked an replaced hoses. New o2 front bank. No codes. I have a live stream of my data while running. If that will help. Idk what the problem is I did all I could before reaching out. Any info is appreciated..
Have you replaced the spark plugs recently? Only use NGK BKR7E's.
Also... who installed the cat? Was it a premade downpipe or did someone weld one in for you? Drive around at night and get everything hot, then look under the car. If the cat is glowing, you likely have a clogged cat. It being a new cat, that seems unlikely, but that's the kind of symptoms that one gives.
I was thinking about the car also cause it was working for about two weeks after I had it done just fine. Than I heard something while driving one day looked back an seen nothing. Sounded like I kinda ran over something but nothing was there at all not came off I went back an looked. But I did notice I had a small crack in the heat exchanger so that was repaired but problem has only steadily consisted an gotten worse. I had the old set of plugs from when I changed them a month or two ago. An I threw them back on just to see an yes there the ngks same from zzp. An no change. I was thinking clogged injector or bad fuel pump but.. idk if your good at data logs or feeds but here's a live stream photo of it at idle. My short term fuel storage 3 idk what storage 3 is but it's way off. An I replaced my bank one sensor due to a p0171 code an light an it went away ever since. But bank 2 is running really diferent reading than bank one. Could that be the cat as you said Fuel ratios O2 sensor readings
I don't see any glaring issues with that live data. The problem with those cheap/generic live data systems is that you see a bunch of stuff that you don't need to see, and often, the context and output that is shows you gives you little useful info.
The STFT and LTFT associated with "storage 1" seem reasonable.
Did this problem start immediately after the cat install?
No a few weeks later probably about two weeks. I def heard something under the car can't say where but nothing was ran over nothing flew out my son was with me an we both got out an looked. But since that moment I have had the big issue. An it's steadily gotten worse over time. I've done the bypass mod even swapped solenoids. The bypass mod seems to help slightly it cuts the big in half like if I bog usually four times before I hit 3rd than I'll only bog twice. Just for example. I've replaced maf. An clean throttle body I'll attach a link to show what it's doing I posted the video on YouTube so I could upload it here. The boost use to read -21 at idle now -17 to -18 an it idles fine untill I put the ac on than it will have an eratic RV sometimes not all the time but without ac. It's fine doesn't bounce rpms. In the video when you see the rpms to a dive after I slightly tap the gas that's with ac on. But wether I have ac on or not when I go in first it'll bog down like severely hesitate. I have no codes at all last code was p0171.
Also I have a typhoon intake it came with the car. But the tune according to zzp was only for the 60lb injectors the sticker even says factory air box. But I was getting 16 psi when I first got it an before this all happened I can only max out at 12 psi. I have a 2.9 pulley stage 3 zzp kit. Think maybe it's time for a retune? The car was catless prior to me installing the cat. Think maybe the computer took awhile to register the change it happened about two weeks after cat was installed. Another funny thing is the tune name on the ecm isn't by the past owners it's another name not associated with him. So was curious if he maybe bought a second hand ecm from someone that was tuned I'm not sure. But when I bought it it did run fine it was only after the cat install an the coolant issue was found. But car never overheated. I replaced the coolant after fixing the issue. I'm lost I can't even assume what to do with no codes or factual data logging. It's basically guess the issue now. Could be weak fuel pump bad cat or injectors or bad TB? But most of these I think I'd throw codes for. Even if I had low engine compression I'd show throw a misfire code. Or something. I'm so lost. Never in my years of working on cars have I had this lol
Btw I also have the stock idler pulley an tensioner. Just noticed the tensioner arm is slightly loose I can wiggle it with my hand a decent bit. Also the stock idler pulley mount is loose too. I have a brand new belt but it's not a stage belt from zzp. Could it be belt slippage. As I said never happens at idle unless ac is on. Maybe more stressed on the bad pulley?
I would definitely work on swapping out the loose pulleys. Tensioners and bearings go bad over time; just a fact you have to deal with.
I don't think the issue you're experiencing is tune related. You have an issue somewhere else. It'd be nice if you could swap out the catted downpipe for a non-catted one, just to help rule it out. As I said before, drive around at night and get everything hot, then look under the car. If the cat is glowing, you have a clogged cat.
It just hit me. I'm betting that ZZP tune is setup for a catless car, so all the Catalytic Protections built into the OE tune are probably turned off. You quite probably blitzed that cat.
I'd reach out to ZZP and see if they can pull the tune based on the information on the back of the PCM.
Yeah checked the cat last night an no red but I know that doesn't guarantee anything. An you know that makes since dude ordered all this stuff from zzp at once so probably is tuned for catless. I'm about to by this weekend a HPtuners so I'm sure that's over an beyond if that's the issue they can find an fix it.
Think I found the issue bro. Took the sc out an there was alot of carbon build up in the intake manifold. Time for seafoam. Also I noticed a huge amount of belt residue on my sc snout. Probably from slippage from my loose tensioner. It's a brand new belt an it's fresh soot on the snout so I cleaned it all up ordered oversize pulley an stage belt should tighten that up. Also painted the sc black with blue splats while it's out lol. Changed the coupler an the oil.
Drive around at night and get everything hot, then look under the car. If the cat is glowing, you likely have a clogged cat. It being a new cat, that seems unlikely, but that's the kind of symptoms that one gives.
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