Zappo Posted August 12, 2018 Report Posted August 12, 2018 Not sure that is what it is, but under boost I can't run above 4500 RPM without the ignition breaking up. I can get past 5000 without boost. New plugs, gapped to .22, new cap, new rotor, new coil, new plug wires. Log shows AFR at 11.9 when it happens, and that was only 6 psi. I can't figure it out. Any ideas?
gdog Posted August 12, 2018 Report Posted August 12, 2018 That's very odd; you shouldn't get "spark blowout" with only 6 psi of boost. Did something else change recently? Ck compression?
Zappo Posted August 12, 2018 Author Report Posted August 12, 2018 None of my problems are easy to diagnose. Turns out it was the ECU. I swapped it because I was running out of things to check. Compression was on the list to check, but that would have given me other problems if one or more cylinders were low. Stock ECU with a custom Marco tune on it. I have been running it for years. Swapped in my TT ECU and was able to hit 6k without a problem. The Marco tune was better for daily driving, so I haven't messed with the TT for a while.
gdog Posted August 12, 2018 Report Posted August 12, 2018 Glad you found it! Man, you need to get into the M4.4 world!
Zappo Posted August 12, 2018 Author Report Posted August 12, 2018 12 hours ago, gdog said: Glad you found it! Man, you need to get into the M4.4 world! I probably should. I haven't even looked at the 4.4 stuff.
BlackT5 Posted August 16, 2018 Report Posted August 16, 2018 If you don't wanna tune it yourself then just talk to Aaron. surprised the marco tune suddenly shit the bed. have you tried putting it back in to see if it still acts up?
Zappo Posted August 17, 2018 Author Report Posted August 17, 2018 I doubt the tune has a problem. Maybe the ECU died, but I might have a fuel pressure issue as well. I need to find my gauge to test the regulator.
Zappo Posted August 30, 2018 Author Report Posted August 30, 2018 Still searching. I doubt it was the ECU as the TT ECU started to have issues a few days later. I ended up switching them back. I should rename the post to What the F*** is wrong with my car?! Right now, the entire ignition system is new, even the coil. New FPR, new fuel pump and filter. I am not sure what to look for now.
Zappo Posted August 31, 2018 Author Report Posted August 31, 2018 Not the fuel pump relay either. Next I am going to trace the evap system. Sometimes I can smell raw fuel. I thought it was a leaky seal for the fuel pump access, but I did find the vacuum hose to the tank was disconnected under the car after I had some work done on the car. I figured that might be part of my lean issue under boost because from what I remember the system will take vapors from the fuel tank under load. As it turned out, it didn't make a difference when I reconnected, but there could still be another break in the system, so this weekend I will trace it all the way to be sure. I have to do an emissions test on the car for new tabs next month, and given my bad fuel economy right now I am not sure it will pass.
gdog Posted September 1, 2018 Report Posted September 1, 2018 So what's your setup now (size turbo, mods, etc)? What MY, N or RN engine, etc.? Stock FPR or other? Things I would check: Compression; cold and hot engine Fuel pressure while driving; you need to see what it does under boost. Make sure your connection at the rail is tight (don't want to have to call the fire dept!) and tuck the gauge under the wiper blade so you can see it through the windshield. May have to tape it down. When you replace the ign coil, it included the pwr stage too? Ck the pwr and ground connections at the pwr stage too; ohm out the wire that fires it between the pwr stage and ecu. Not very likely but problems with the ign primary wiring could give you these symptoms. Considering the size of injectors you're running, I'm assuming you're using a good sized turbo and pulling considerable pwr out of the engine? Assuming so, I'm surprised you haven't run into spark blowout before with the stock ign system.
goobernoodles Posted September 7, 2018 Report Posted September 7, 2018 Have you checked your spark plug wires? I had a failed coil pack and bad spark plug wire that was causing blowout only under boost, but those issues were in reality caused by the oil leaking into cylinder 5 and constantly fouling plugs.
Zappo Posted September 8, 2018 Author Report Posted September 8, 2018 New wires, new plugs, cap, rotor and even coil.
Boxman Posted September 9, 2018 Report Posted September 9, 2018 I think @gdog's post is an accurate one. With the stock setup - even in pristine condition - you'll run into trouble past 300 BHP.
Zappo Posted September 9, 2018 Author Report Posted September 9, 2018 I am not stock and haven't been for many years. This issue only cropped up in the last year.
Boxman Posted September 9, 2018 Report Posted September 9, 2018 You should tell us what setup you're running (block, turbo, tune, injectors etc). You say you're running a single-coil setup still, with stock rotor+wires I assume? I'm not sure what kind of power figures you're running, but significantly above stock power the single-coil ignition system is just too weak, too many points of resistance where you're losing sparking power. Maybe the O2 sensor aged and 11.9 now isn't what 11.9 was a year ago. With a richer mixture, it'll become harder to ignite and you might run into the limits of the stock ignition system where you didn't before.
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