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Maybe try this sense you are having so many issues, connect the MAP input to the clamp to +5V like this:
Turn the key to the on position without turning the car on(dont turn car on lol!). At this point you are just passing straight 5V through the clamp and are basically jumpered around the MAP sensor. Connect to ECU via torque or what ever and check pressure reading with car off but key in on position. Dial clamp voltage down until pressure displayed is where you want to clamp it (16.75psi?). Check voltage on the output of the clamp with a meter for every ones knowledge at this point. Shut car off, disconnect, reconnect clamp the right way.
Thanks drothgeb but I will have to wait.
Had to get engine and trans out to get the ball rolling. Just finished up the trans tonight and now the engine work next couple of weeks. By the time I finish it will be even colder so that will be a better test in lower temps with your way as well.
At it again....still !! Engine and trans done and weather around 35-40 with same issue ....some times. I have narrowed it down to this ..... I can normally make it happen if I am on the highway , in third gear at 60mph and hit the throttle real quick to the floor in very cold weather. Chances are it will go to limp. If I just roll into it, it will not happen. So I am thinking a quick instant boost spike that the ECU pick's up on and it triggers limp mode. Turned clamp down one turn more and so far so good but we will see Saturday. Temps will be a little warmer , 50* so that will help to lower boost a bit and is a more real world temp when I race, 50* -60* this time of year.
Still having an issue's.
Can't seem to get this sorted out. Loaded a new tune in and terminated the IAT timing pull and added some fuel but this has no relivance to my problem. First pull saw limp mode. Next 8 pull's no issue. Now I am wondering if it actually is a boost problem because it should do it all the time but it doe's not.
Still having an issue's.
Can't seem to get this sorted out. Loaded a new tune in and terminated the IAT timing pull and added some fuel but this has no relivance to my problem. First pull saw limp mode. Next 8 pull's no issue. Now I am wondering if it actually is a boost problem because it should do it all the time but it doe's not.
I got my issue sorted out last winter by lowering the clamp voltage, but I had to go a lot lower than expected. I think I ended up at 4.15V but I could be wrong. How low have you gone with it?
It's intermittent because it only happens if the boost spikes particularly high (higher than your normal boost level). This happens from time to time because boost fluctuates all over the place (try watching it with a fast responding (digital) boost gauge or standalone data logger). There may be some smoothing or averaging applied to the obd values because my obd logging never seems to show nearly as high as the spikes I see with my piggyback logger.
I just looked at the voltage setting because I keep going 1 more turn on the adjustment and now I am at 3.7 volts. This explains why overall the car is getting leaner and leaner as I keep going down with the adjustment as well.
So now......I do not believe this is an over boost condition if the clamp is set that low and it acts up just like it would without a clamp.Although it throws a implausible code.
Also it will act up long before there is a spike from what I can tell because I will tip into the throttle to see if she is good or it is lean already.
What's crazy is I can make run after run over and over with no issue....and then it pops into lean mode....cycle key, good to go !!!!
Hey buddy....thanks for helping me out.
Code is....
P02007-008 B28 pressure sensor
Just for the hell of it I turned the clamp up to 4.4v from the 3.7v to see what happens. Will test tomorrow.
Oh and one more thing....My Scan Gauge locks up every time this happens and will fix itself with a restart or unplug/replug the gauge, { will reset but of course not the ECU }. Very strange.
Hey buddy....thanks for helping me out.
Code is....
P02007-008 B28 pressure sensor
Just for the hell of it I turned the clamp up to 4.4v from the 3.7v to see what happens. Will test tomorrow.
That fault indicates an implausible signal. Typically with over-boost you will see fault "P2007-001 B28 (Pressure sensor) : Short circuit to positive". (When boost is too high, the sensor voltage is higher than the ME things is possible, hence short circuit to positive.)
I could see you getting the implausible code from turning down the clamp so far. Are you sure that's the same fault you have been getting the whole time (ie. since before installing the MAP clamp)?
I have not seen a -001 code but this time it does not say implausible ...just "pressure sensor". I will test soon , waiting for temps to be in the 50+ range so I can keep everything the same test wise. I will let you know soon.
I am completely screwed. I have less than two weeks to fix this for the next race and it is not looking good at all.
So...limp mode right out of the gate and almost every time with the clamp at 4.3 volts. Tried loading in my original fast tune just to see what would happen and no difference at all.
Looks like I am seeing around 17-18 lbs from what I can gather on quick pulls so could be more "spike" wise who knows.
I am guessing the only way around this is a bigger pulley....77mm like I used to have although every blue moon this issue would pop up with a 77.
I am completely screwed. I have less than two weeks to fix this for the next race and it is not looking good at all.
So...limp mode right out of the gate and almost every time with the clamp at 4.3 volts. Tried loading in my original fast tune just to see what would happen and no difference at all.
Looks like I am seeing around 17-18 lbs from what I can gather on quick pulls so could be more "spike" wise who knows.
I am guessing the only way around this is a bigger pulley....77mm like I used to have although every blue moon this issue would pop up with a 77.
It sounds like the MAP clamp isn't really doing its job. I have a suspicion that they don't work as well on spikes as they do on constant high voltage. You could try a piggyback, but no guarantee that would work, either. https://mbworld.org/forums/w211-amg/...p-running.html. If nothing else, the enhanced logging capabilities may at least be of some help.
Thanks SJC but I shouldn't need to bug you. Think it may be all set but also my tuner said he could raise the threshold to 20psi . only he is on vacation so since i am on a time crunch..............
So what I did was match my Mity Vac pressure tool to a very accurate Apexi boost gauge . It was dead nuts. So calibrated the boost pressure of 19psi to the Map Clamp and saw 3.8 volts. This is what I came up with very early in the beginning but thought something was way off....but apparently not !! Turned the clamp down to 3.5 volts and tried it. No limp mode but to lean and boost showing 14 lbs due to lower map reading input to ECU. " Going to test with mechanical gauge Tuesday morning and see what the real boost reading is...finally."
Anyway loaded in a 10 percent richer tune and she's right on the money.
So the 4.5 volt staple with these cars is a no go with my ECU and 3.8 volts is 19psi ...way off from what everyone has reported.
4.5v came out to 23lbs and thats why limp mode constantly popped every time.
Fingers crossed and hope she stays LOL
Thanks SJC but I shouldn't need to bug you. Think it may be all set but also my tuner said he could raise the threshold to 20psi . only he is on vacation so since i am on a time crunch..............
So what I did was match my Mity Vac pressure tool to a very accurate Apexi boost gauge . It was dead nuts. So calibrated the boost pressure of 19psi to the Map Clamp and saw 3.8 volts. This is what I came up with very early in the beginning but thought something was way off....but apparently not !! Turned the clamp down to 3.5 volts and tried it. No limp mode but to lean and boost showing 14 lbs due to lower map reading input to ECU. " Going to test with mechanical gauge Tuesday morning and see what the real boost reading is...finally."
Anyway loaded in a 10 percent richer tune and she's right on the money.
So the 4.5 volt staple with these cars is a no go with my ECU and 3.8 volts is 19psi ...way off from what everyone has reported.
4.5v came out to 23lbs and thats why limp mode constantly popped every time.
Fingers crossed and hope she stays LOL
It's good to hear that you have it working. Please let us know if it keeps working and what you see with the boost gauge.
I actually bought a second MAP sensor to test with to find the actual voltage curve, but never got around to it. Sounds like the general consensus on the range of these sensors is dead wrong, though. That explains why I had to turn mine down so much further than expected.
Who is your tuner? I haven't heard of anyone even attempting to change those kind of parameters with the ME2.8, but if someone really can, that would be good to know. Removing this limitation will require changing the fault detection parameters, not simply modifying a fuel or timing table: this capability isn't built into any tuning software (as far as I know) so it would need to be done manually.
Thanks SJC but I shouldn't need to bug you. Think it may be all set but also my tuner said he could raise the threshold to 20psi . only he is on vacation so since i am on a time crunch..............
So what I did was match my Mity Vac pressure tool to a very accurate Apexi boost gauge . It was dead nuts. So calibrated the boost pressure of 19psi to the Map Clamp and saw 3.8 volts. This is what I came up with very early in the beginning but thought something was way off....but apparently not !! Turned the clamp down to 3.5 volts and tried it. No limp mode but to lean and boost showing 14 lbs due to lower map reading input to ECU. " Going to test with mechanical gauge Tuesday morning and see what the real boost reading is...finally."
Anyway loaded in a 10 percent richer tune and she's right on the money.
So the 4.5 volt staple with these cars is a no go with my ECU and 3.8 volts is 19psi ...way off from what everyone has reported.
4.5v came out to 23lbs and thats why limp mode constantly popped every time.
Fingers crossed and hope she stays LOL
So did some testing tonight and I am making about 18lbs of boost with a mechanical gauge so that explains alot LOL So far so good and no limp mode !!
SJC my tuner is Tony Lawshee Race IQ
So did some testing tonight and I am making about 18lbs of boost with a mechanical gauge so that explains alot LOL So far so good and no limp mode !!
SJC my tuner is Tony Lawshee Race IQ
Interesting, I have a boost line tapped into my intake manifold for the w/m controller, think I must tap into that line to check actually boost in there via a mechanical gauge too.
Boy I tell ya I just can't get ahead of the 8 ball !!!! So far after many pulls.....no limp mode....perfect !!!! But decided to check my injector duty cycle just to see where it is and I am at 125% with 52lb injectors. Only have a week to go before the race and need to get bigger injectors and a tune dialed in some how or will have to chance it.
Good times !!!!
SICAMG is this problem still fixed? I'm having the same issue, with the same fault code. I think this is the legendary "hiccup." I've attached the actual code and freezeframe data from my car. Strangely the code sets at only 4.5 psi while cruising around 30% load. I may try the map clamp...or a resistor to change the entire voltage sweep of the sensor by .1v or so, as an experiment if the clamp doesn't work. My mods are: 175mm crank pulley; 82mm TB, Long tube headers w/race cats. Finally got my new wideband installed and saw 12.5 AFR on a 3rd gear pull, when usually I'm at 11.5 or less. I was on a long highway drive and didn't have a chance to cycle the key to see if the AFR went back to normal.
Last edited by E55Greasemonkey; Jan 13, 2022 at 09:44 PM.
There is limited information from MB on voltage data for this sensor, I am still researching. So far:
Ignition: On 1.5-2.3v (one can assume this would be atmospheric pressure)
engine at idle < 1.2v
connect vacuum tester > 300 mbar (???)
The sensor is a 2.5bar one per WIS:
Last edited by E55Greasemonkey; Jan 20, 2022 at 08:12 PM.
Still fixed but you should not see this until sensor see's a high boost number that goes off the scale. Mine only did this just about every winter and boost would spike to 17psi and trip up the ECU. Stop , cycle key and back to normal until 17 psi again. You are seeing it at 4.5psi so can't be the same issue.
I would think the sensor is faulty ???. I have one I can send you to try if needed and my cut down little wrench to get it out.
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