This sounds damn near exactly of the cruising issues I have with the 82mm TB. What are you proposing that you are going to change? Did you have STAR hooked up and logging? My car has been at Eurocharged ATX since April '21 trying to get this damn hiccup resolved once and for all.

 

Thanks for the offer, very nice of you....but I have already replaced the sensor with the latest and greatest part number from MB. The sensor is good. I've been reading through the other threads on the hiccup. I found this thread because of the same fault code. We had the same fault code "Signal Implausible" aka "doesn't compute" but for different reasons. Your boost was too high for the ECU reference values, my boost was either too high or too low for the ECU reference values in relation to (just guessing here) throttle flap position; engine RPM; load. I may move this conversation to one of the hiccup threads as this is my issue, not the one posted above.

 

I'm not logging with DAS, per se, but the freeze frame data captured by the ECU serves the same purpose. This problem (fault code) comes from deep within the ECU coding for the fault code strategy. The ECU does not like the parameters it sees. I don't know if tuners can access this part of the ECU, maybe you can ask Eurocharged or Jerry himself? This chart, posted in another thread, explains what triggers the fault. Key words being....

Upper limit value:
- At a throttle flap angle greater tan about 60° the vacuum must be greater than 300 mbar. - Vacuum of 500 to 1200 mbar; depending on performance map for motor speed and throttle flap angle.

NOTE: The word "vacuum" may be used in translation error instead of "pressure or boost", or, this table is for the N/A 113 engine. Still trying to decipher this. Regardless, here it tells us the fault is checked in relation to the throttle flap angle, engine RPM, and pressure sensor reading!

So what's my plan? I'm still thinking it through, but if we can fool the ECU with one of these parameters at the very point the fault is set, we can avoid the "hiccup"
Changing the RPM? Not practical.
Changing Throttle flap position? Possible but not easy
Changing the pressure reading? Bingo! But how to do it, and how much without causing other problems? Could we drop the entire boost range reading, say 1 psi by changing the sensor voltage output? Yes we could. But this may also move the parameters so the fault will then be set higher or lower on the scale anyways. Without being able to see the table coded in the software, it'd be a guessing game. That table is referred to in this sentence: "Vacuum of 500 to 1200 mbar; depending on performance map for motor speed and throttle flap angle."

 

Brad I think you should take a step back and start from the beginning. If the car ran fine before and now this problem popped up it could just be a totally different problem.
4.5 psi is so low that to have a map clamp will have no effect. But.... the clamp is also adjustable for vacuum as well just to let you know.
True the ECU is seeing something it does not like and when mine did it an AFR of 17.5 was the norm until a key cycle.

 

This problem has been happening to me for several years, since my 82mm TB install. It's just that I drive 95% in-town, and this will only happen to me twice a year on long highway trips, so I've just been living with it. A map clamp won't help here, but some other way to lower or increase the voltage of the sensor may keep the parameters happy....at least that's my theory. If the ecu sees one pound more or less of boost than it's actually making, that might work, and I can't think of any detrimental effects.

 

It would be awesome to fix this issue for people wanting to run the 82mm. I had this same exact code and issue and it only resolved after switching to an 80mm.

I also wonder if relocating the MAP would make a difference, I remember there being discussion around air velocity making it unhappy. I wonder if you could install one on one of the y pipe rubber couplers or IAT hole, just to see if it makes a difference.

 

OK that makes sense. Didn't know this has been going on for a while.
You could try the clamp then and set it really low. In other words see what the voltage is at 4lb of boost and than set the clamp to 3.5 and see how it reacts.

 

I've got a better idea. I'll use a voltage regulator to bring the 5v reference down to 4.5v-4.9v which should drop the signal the same amount. I'll leave a spare sensor plugged into the M.E. on the power and ground side to keep any open circuit codes from setting. I can also go up to 5.5v if that's what direction I need to go, but then will require an amp clamp. The frustrating part is not knowing what is a safe value to keep the code from setting. It will be trial and error, which also creates another problem, as I can't get the fault to occur on command. I just have to get on the highway for a while...and really don't have time for that.

 

Keep an eye on the AFR. Just an FYI my clamp needed to be set around 3.8 volts to keep the ECU happy.

 

Not to hijack too much @SICAMG when you went back to the 80mm TB, were you able to just bolt it onto the 82mm adapter plate? @E55Greasemonkey I can ask Eurocharged your question but after not having the car in my possession for going on 10 months now I'm probably going to give up on the 82mm throttle body and either go 80mm or go back to stock and sell the car. I'm so frustrated by the amount of time and money thrown at this at this point. The platform is old and I don't get the sense that Jerry really wants to spend his time trying to fix this from a tuning perspective.

 

Lost.... I hogged out the bolt holes and bolted it directly to the inlet, no adapter. Also yea it's nice to have a 82 but are those 2 mm over an 80 worth the hassle ? I mean my friend Tim {99lightning} car rips and runs 11.25 et's with NO throttle body upgrade and not even a pulley. So .....
Would the throttle body up grade make a difference, yes but at this point look for another option over the 82 if it's that much hassle.

 

I will never wrap my head around since i have been tuning ford lightnings, mustangs since 03 i know its way different but to have one part cause so much trouble is beyond me lol. Some have added 90mm fired the car up no problems at all same with 80-82. It took years just to get my car to shift the way its should thanks to https://mkultra-electronics.company.site/ the car does its thing now. I have a 83mm pulley sitting in the box still think i have a tad more in stock form, but also bought vrp snout and 92mm cat tb. That is the other weird thing tony has done a bunch of 92tb's but i'am pretty sure he installed them and no problems. I would love the power from this combo but at the same time fear of this all not working the correct way.

 

That's the thing Tim....how much power are we talking, 20hp ?? I won't gamble on that when I can pick it up somewhere else. But for whatever reason the 90-92 has much much less complaints.
We need a guy like Troy to dig into this LOL. He will fix it !!!!

 

I'd wager a small sum of money that most if not all of these TBs larger than 80mm have this issue. From personal experience it took a while to find the right road, right conditions, and driver input to reliably reproduce this issue. How many folks with the bigger TBs are doing 80-85+ mph cruises under light throttle and load frequently enough to see their fuel trims go weird. Even if they were, it might be dismissed as a one off since the issue is reset when the car is restarted and you'd only know if you watch your fuel trims like a hawk. Furthermore, I just don't think folks report these issues much to forums (or facebook, I don't know I'm not on facebook). Vendors don't have much interest in actually trying to solve this anymore, how long has this been an issue on this forum? For example, VRP's response to the 82mm issue is to go 90 or 92, which if the ECU is detecting an issue at 82 how in the world would going bigger "fix" it?

Regarding is it worth the extra 20hp, at the time and looking at the dyno and how my car makes hp all the way to redline without dropping off, I'd say yes it was worth it at the time because I thought this issue had been figured out and I was having a known shop do the install/tune. In hindsight, I got greedy and thought this would be my last "easy" mod before the car was done. Two years later, 3 used TBs, 1 brand new OEM TB, 2 ME computers, multiple flashes, and the car in the shop for almost a solid year here I am still without a car and having missed out on many roadtrips I had planned to do with it. Do I regret it? 100%!

 

shame because that is a real nice set up.

 

Agreed! And to answer your last question....The fault is set by comparing the accepted values on the performance map dependent on "engine RPM and throttle flap angle." Change that throttle flap angle- with a larger or smaller TB for a given RPM, and you just passed the check for accepted values. I'll tell you what's more bizarre. I've been looking through WIS for a description of this particular fault code- for our engine 113.990 and I found every engine they make, with that fault code...EXCEPT the 113.990! The chart I posted earlier is for the N/A 113 engine, it seems.

 

Maybe this is why the larger throttle body's bypass so to speak the values at some point and / or they happen at such a low rpm from exceleration or cruise that the ECU never see's an issue for a long period of time. Think about it. If 1,300 rpm was the main tripping point for an issue who would ever be driving in that rpm. Where every one else with an issue is on the highway at a certain rpm, and we all have the same gear ratio so it's all the same.

 

This is exactly verbatim what I experience here in the winter as well.

 

Throw a clamp on it C32 !!

 

Look again at this freeze frame data....the fault is not being set under boost, but under vacuum! In cruise mode the supercharger is decoupled. The MAP sensor- manifold absolute pressure- is based on a zero value being a perfect vacuum. In other words the data showing 313 hPa aka 4.5 psi is NOT boost. That is 4.5 psi above a perfect vacuum, and 10 psi below atmospheric pressure at sea level (where I live) aka vacuum. The larger throttle body lets in more air....reducing vacuum at any given point compared to the smaller stock TB. Now this is getting interesting! I'm moving the conversion to here: https://mbworld.org/forums/w211-amg/...ssue-poll.html since this original thread was about over-boost, which isn't the problem I'm having:

 

BINGO! This is because the ECU checks the airflow when in vacuum! And now I think I know why there are no descriptions of the fault in WIS. The parameters would be impossible to predict when going from vacuum to boost, at different elevations and intake air temp changes. (Don't worry I'm not stalking all your old posts lol) What we do have though, are some of the checks it makes on the N/A 113 engine which we can use as a baseline. However, I keep reading it and can't quite make sense of what they are saying.

 

Exactly. I have bought one. Just fixing the crank pulley mess up at the moment then will fit the map clamp on 😁

 

Oh no !!! Not the Weistec pulley LOL!!
Always wanted one and crank is already keyed for it.

 

Map Clamp does not resolve the issue, The issue occurs on vehicles well under the boost maximum. and under very low throttle input. The odd thing is that the behavior is identical to the over boost error.