Very strange problem, hoping someone can point me right direction...

[AdmiralMubutu]

Hello all:

I'm in my second season of ownership of a 2006 Brammo Atom 2 with about 14k miles. GM Ecotec supercharged. I have chassis #50, which I believe was among the handful of cars that TMI acquired from Brammo and used for the Atom Experience until about 2008. On July 4, I decided to take the Atom to a Cars and Coffee that I like in PA on the first and third Saturdays of every month. It's about 30 back country miles from my house, no better way to spend a Saturday morning. I got there without any problem. Chatted with the boys for about an hour then jumped in to head home. I got about two miles in, just after to merging onto a 55 mph stretch of road, when I lost all power. The engine was still running, but only at idle RPM and it sounded very rough, there was an unusually loud rap-rap-rap-rap-rap like I had a cylinder missing or something. I coasted to the side of road and noticed that no matter how far I depressed the throttle, it had absolutely no effect on what the engine was doing. The engine just putted away. I shut the car off, trying to figure out how I was going to get home. After about 5 minutes, I decided to try starting it again, and behold, it was like nothing ever happened. I drove it home without any further problems, and I chalk it up to a one time glitch.

Fast forward to today. I haven't used the car since the 4th, but since its another C&C day this morning I decided to take it again. Get there no problem, hang out for about 1/2 hour and then get in to head home. IN THE EXACT SAME SPOT, ON THE EXACT SAME STRETCH OF ROAD, THE SAME THING HAPPENED. I pull over and figure that I know what to do, just turn off and turn on again. I try it, and it starts, but I'm getting the same rough idle and no throttle response. I turn off again, wait about three minutes this time, and try starting again. This time it's all back to normal, and I make it home without any more problems, exactly like two weeks ago.

The tank was about 3/4 full the first time and a little less than half today. Has anyone ever experienced or heard of anything like it?? I want to point my mechanic in the right direction (he told me he often uses this forum for info when he works on my car). I appreciate any advice someone may have. Thanks, Jim

[RyanD]

Maybe a long shot, but check the engine ground on the driver side of the engine. It's just below and to the right of the throttle body. Mine was loose and caused all sorts of intermittent issues. I added a lock nut to mine.

[MadMaxAtom]

Sounds like fuel starvation,probably caused from gasket deterioration,contaminating/clogging the fuel strainer/sock. I would check that first as it has been a problem with brammos as the fuel tank gasket material they used was lousy.

[Terry Kennedy]

I got about two miles in, just after to merging onto a 55 mph stretch of road, when I lost all power. The engine was still running, but only at idle RPM and it sounded very rough, there was an unusually loud rap-rap-rap-rap-rap like I had a cylinder missing or something. I coasted to the side of road and noticed that no matter how far I depressed the throttle, it had absolutely no effect on what the engine was doing. The engine just putted away. I shut the car off, trying to figure out how I was going to get home. After about 5 minutes, I decided to try starting it again, and behold, it was like nothing ever happened. I drove it home without any further problems, and I chalk it up to a one time glitch.

That is classic Brammo "limp mode". On the cars this engine was designed for (Cobalt SS / ION Red Line) it is "reduced power mode" but the throttle still gets a response. On the Brammo ECUs, GM configured it to completely ignore the throttle. The idea was that once there was more real-world info on the types of faults that happened, they would issue a new ECU calibration to enable limp mode. That never happened.

You will need an OBDII code reader (or go to an Autozone, etc. and borrow theirs - auto stores will usually let you use one for free on the theory that you'll buy whatever part you need to fix it). Read out all of the codes and post them here. Note that P0230 and P0650 are "red herring" codes - 230 is due to the anti-theft, and 650 is due to the lack of a check engine light. I have the service manual and can post the troubleshooting steps for the codes you find.

BTW, if you have the battery disconnect master switch, you can just flip it off, count to 3, and back on to get the car going. That will bypass the timeout. However, Murphy's law says that if you need to move in that much of a hurry, a) you can't reach it while your seatbelt is on and b) it will pop off and land on the ground and you'll have to get out of the car and hunt for it.

[AdmiralMubutu]

Thanks guys, I'll see if my mechanic has the code reader and post what I find.

[Chris McCarthy]

Thanks guys, I'll see if my mechanic has the code reader and post what I find.

Any news since then? I had the exact same thing happen to my early model ecotec aa2.

[BobK]

I hate when people come on the forum looking for help with a problem and then not come back to let us know what fixed it. It would help us all for future reference.

[AdmiralMubutu]

I hate when people come on the forum looking for help with a problem and then not come back to let us know what fixed it. It would help us all for future reference.

Sorry guys, I haven't been on the forum in quite some time. The issue was two separate bad sensors - MAF and supercharger pressure sensor - throwing crazy numbers to ECU that threw it into limp mode. Replaced both. Car was finally repaired in September. Been to the track once since at the end of September and had no issues. Will have it NJMP in early May, weather permitting.

[SAD]

BUMP!

My car is doing this exact same thing... Except it is a 2015 AA3 with normally aspirated K24. It doesn't always happen... but when it does, it's on the same point on track. At Hallett it's about midway through turn 9 running counter-clockwise. Turn entry is a short but quick down hill... and then transitions to off-camber, uphill sharp right-hand......

Oil starvation? I have no way to confirm this at the moment, because of the stupid 0/1 dash oil pressure display is about useless unless you're simply causing down the road (non-track conditions).... And I have not yet found the right driver/config on my AIM Solo2DL that would gather stats on oil pressure.

THOUGHTS?? This is driving me nuts... Car is otherwise perfect.

[McFred]

Historically, with Honda K20s and K24s, long, high G left hand turns will cavitate the oil pump even with sump baffling. If there's a significant drop in oil pressure it will disengage VTEC. There's usually a marked drop in torque/power above 3000rpm until oil pressure comes back up where it re-engages VTEC and again has the usual power/torque. In that case, it's not "limp-mode" and has nothing to do with the PCM/ECU or electronic engine management system. Get an oil pressure gauge and you'll see what's going on. In the meantime try adding a half a quart (or more) of oil extra and see if it affects the power cut-out location and duration through your Hallett Turn 9 complex.

BTW CCW turn 9 I believe is "the bitch." Theoretically, the oil pressure should have come back up before the left turn 8 then proceeding into 9. the fast, left/right might slosh the oil in just the right way that the pump sucks air. I don't know if TMI installed baffling in the AA3 sumps, it would've seemed prudent. I recommend installing some sort of gauge, and/or trying to add more oil as a pragmatic approach to diagnosing the issue.

FWIW, I ran Hallett in my K20 and K24 flavors of AA2 and don't recall power cutting out at that location.