I’ve definitely enjoyed reading this thread. My car does not have a modified TB, but it does have a 83MM pulley and tune from EC.

Occasionally after getting off the highway at speeds into stop light traffic my car will surge and lurch a bit as if it wanted to keep going. I’ve always attributed this to just a boost side effect from the tune. It will shake for a few seconds and I will hit the brake and that’s it back to normal spirited driving.

Seldom, I will get a check engine light P2007-2008 which corresponds to B28 Pressure Sensor under normal driving. I will keep driving it normally and it goes away after a few sessions without me clearing the code. As I understand it’s something intermittent. I notice no difference in power.

Now if I’m reading this correctly does this mean my box tune is flawed and when these situations happen it creates a dangerous lean condition swapping back to a stock map?

I’m inclined to data log the car now. I’ve had this tune since 2018 and I’ve read posts about this with no known solution insight unless a vacuum leak was present.

It’s just odd I can do 5 hours of spirited backroad driving and nothing and then I can be doing 60mph on the highway and a check engine light will appear.

Please share your findings or need I switch my tune? I guess this is the AMG hiccup?

In your case, with a stock TB, I might suggest replacing the MAP sensor (and maybe front O2s depending on age/mileage). Has this been happening since the tune in 2018 or has it started recently? If the latter I would lean towards these sensors or a vacuum leak that has developed rather than a tune issue. There isn't much tuners can do with the backup maps, just internally up to the ECU to decide when to make a switch when it sees something it doesn't like. In your case it could be running some kind of 'self-check' on A/F ratios, the MAP etc when you're at a steady highway speed which would explain why it doesn't do it under other driving conditions.

Either way data logging is always a great idea, and it might be nice to get a baseline before changing things too to see if they've made a difference. Even just using an OBDII reader to watch fuel trims can be very helpful at times.

Best of luck!

I’d say since the tune but it wasn’t frequent, I just learned to live with it and always assumed it was a byproduct of the tune.

What variables and ranges should I be on the lookout for?

Thanks!

I like to see under 5% for long term fuel trims (and that will remain pretty steady) and you'll typically know that you have the 'hiccup' if the car is acting up and short term fuel trims peg at 25%. Usually you don't want to see anything over 10-15% on those, if they are pegging it's reached the limit of adjustment and you could be running lean as a result.

I tried replying to your PM, it won't let me, says your inbox is full.

Hello!

I also had this problem, that the mixture was lean for more sudden acceleration.My car has a larger crankshaft pulley and written engine control, the flow valve is factory. I measured a fuel pressure on the injector bridge and it was only 2.2bar (32psi). According to factory data, there should be a minimum of 4.95 bar (72 psi), even more when the engine is running.I replaced the fuel pump and filter, but that didn't make a difference.I saw that there is a transmitter after the filter, I pulled the plug from it and my fuel pressure immediately increased to 4.95bar (72psi) with the ignition on, and 6.62bar (96psi) with the engine running. I drove the car like this for a while and the lean mixture and the hiccups completely disappeared. I ordered a factory fuel pressure sensor, which I just received, and I will install it soon and write about the results.I am attaching a photo of the sensor.If this also helps the group with troubleshooting, measure the fuel pressure as well! (I apologize for the spelling and intelligibility, I am writing with a translation program.)

What model car is this on?

2003. CL55 AMG V8 kompressor