82mm tb lean hiccup
 

Just installed s550 82mm tb. Now have the infamous lean hiccup. I've had the hiccup since the very first tune but after the tb I now get the lean condition as well. Mid 13s at WOT, 16-17 afr when stopped. When hiccup happens afrs peg to 21 on my zt2. Key cycle remedies.

Has as anyone tried swapping the electronics from their stock 74 to their 82mm? This is my next step but would like to know ahead of time if someone's already tried this. tuner told me it's an issue with my tb which I do not believe. Over almost a decade I have not replaced a single 272/273 tb at the dealership. They just do not go bad on a regular basis. I fix mbs to oem spec, tuning and all that wizardry is out of my pay grade.

for me i recall we had to raise the idel RPM, in N , D etc, not sure if this will remedy ur issue

This is a tune issue on some ecus and unfortunately tuners can't figure it out. Raising the idle will not help. Denroll has had his issue along with some others for a long time

just to be clear the hiccup appeared with the tune and throttle body or just a tune ?

I have had a hiccup since the 2nd tune (I need to edit the first post). My first mod was headers, no hiccup. 2nd mod was 77mm pulley, hiccup. Third mod was 82mm, hiccup, stuck in lean loop, CEL on intermittently.

When I first got the pulley I just thought it was the more aggressive supercharger engagement due to the smaller pulley. Now that I have the wideband on I see that it was never the pulley it is a lean spike. THAT I can deal with since this happens when load is negligible, what I can't deal with is getting thrown into this permanent lean loop with the throttle body. One time it also cut throttle during the I want to say 3/4 shift which has never occurred before the throttle body and I have had her up there more times than I can count. This was a run to 150 and she cutout like she couldn't process the load inputs. That was the very first run and I knew I was gonna have issues right then.

I kind of want to fabricate a blocking plate of sorts to make the throttle body opening smaller (equivalent to 78/80mm but retaining the 82mm tb) and see what happens.

I've had the hiccup through two different 82mm throttle bodies and the 90mm. They showed up under the exact same circumstances on all three of them. I've had the three different variants of the MAP sensor and it still happens. The only thing that seems to have any affect is the tune. My most recent tune (from Tony) still gets the hiccup, but it happens much less frequently than it has in the past. I've had tunes from four different tuners and it has happened with all of them.

Talking to a co worker here and he found something in WIS that is insanely relevant to us IMO. The proverbial smoking gun?

Most people have come to the conclusion now that the ME variants will determine whether or not you have the hiccup. Take a look at this excerpt here

http://i63.tinypic.com/2jev812.jpg

There is the normal map sensor that is on the charge pipes b28. There is a SECOND pressure sensor INSIDE the ME to measure absolute pressure. It is my belief now that the pressure sensor in the ME does not match sensor b28 on the charge pipes and when a check is done at our part load application it freaks out and goes into a limp home. Makes sense as code p0106 states there is an implausible signal received from b28...

Somewhat similar to the 642 engines that get faulty readings from the pressure sensor and go into a limp home mode. Similar situation, usually no codes either.

Components change all the time based on mfg costs. Is it possible there are multiple variants of pressure sensors in the MEs? Ones that are more forgiving and others that are overly sensitive?

http://i68.tinypic.com/264i87m.jpg

This is the only sensor I see with holes in it. I can't confirm this is the sensor but nothing else looks like a pressure sensor.

Anyone without the hiccup wanna open up their ecu and show us your part number?

https://cimg9.ibsrv.net/gimg/www.mbw...b853fe40a6.jpg

For those as visually impaired as I. Thanks for this post mate! :)

No problem jmb614

I have looked at pressure sensor on digikey.com and can say with 100% certainty that is our pressure sensor. Some available ones look identically layer out but with a slightly different shape. Maybe if we can get some part numbers from multiple users both with and without the hiccup and resulting lean condition maybe we can piece together the puzzle. If we see a variation in sensors I'll send an email to digikey with pics and see if they can help us find the POTENTIAL mod friendly variant. No guarantees and I could be barking up the wrong tree but I think from all the threads I've read almost all other options have been exhausted so this might be the last hope.

Hmmm https://cimg4.ibsrv.net/gimg/www.mbw...3ee3a0c465.jpg

I wonder if it's like a Nintendo cartridge, blow on the contacts to get it to work...

Well that would be nice! There is definitely potential for sticking diaphragms on a 12 year old car

I'm kind of wondering if there is some scaling that needs to be done between both sensors when the new TB is installed on some cars. If ME expects X pressure at Y throttle and Z map sensor reading and they don't match based on a pre determined table this might cause it to wig out.

subscribed

Subscribing as well. My new to me 2004 e55 has a e550 82mm throttle body and I get surging as I creep in traffic (revs jumping up and down) and then sometimes after a drive into work the car wants to die as it sits in the parking spot before saving itself. Revving a little has seemed to fix that so I'm not sure if it's related. I have gotten on occasion a pending P0106 code that has never been actually thrown. Car currently has a RaceIQ dyno tune. Happy to do whatever research I can to help others resolve it as well.

imo take that tb off for now. Until this gets fixed it's dangerous IMO. I took mine off for now so I can enjoy my car tomorrow. I didn't see much but do the sl55 guys experience it when they go 82mm?

kustom2k1 has an sl55 and he had the hiccup as well. This is not narrowed down to models or ecus. It's very bizarre it's as if a certain small percentage of ecus do not like the the 82mm and bigger tb

Is it just an acute problem that others are facing, like only WOT pulls, etc? I've been looking at my LTFT and each bank is ~-5% over time. The car was tuned with the TB on if that makes a difference.

It seems that it can happen anytime. At least that's what I saw. I had it happen in stop and go traffic and 1 time at WOT. I don't want it happening at WOT again for obvious reasons so for now I'm back on the 74

on my old CL55 I had a 82MM TB and it drove me nuts, initially it was really bad and it turned out to be a crappy Tune I had the car re-tuned with someone else and it was soooo much better but I would still get the Check Engine light an occasional buck here and there it haunted me for over a year, then I sold the car to a friend of mine, who spent some time on it and finally resolved the issue by adjusting the flap on the TB (with the Star) after he did that he never had an issue again

From seeing this in person on kustoms car, it seems that it happens when cruising on the highway and slowly creep up on the gas and then let off you can trigger it, even a slight hill can trigger it while cruising. It can be dangerous because without knowing the car goes lean and if you do go wot while in this mode, the car can go in 19-20afr, cycling of the key fixed it. He had the car retuned by a retired tuner to give it a shot and he played around with the fuel trims and hasn't happened since.

So it sounds like if you pay the money for a custom dyno tune than the throttle body doesnt become much of an issue, but these generic box tunes seem to have all the issues. Is there anyone out there that has had a custom dyno tune and still has the hiccup and other issues?

Not true. Many that have this issue have done custom tunes as well. Denroll has logging equipment and still has the issue

Custom dyno tune and they weren't able to completely tune it out? These things sound like more headache than they are worth.. Im super curious if the OP has some solid direction that he is headed in to figure out a remedy for this issue that so many face. As soon as we start modding these things all bets are off. Chasing CEL's left and right. haha We have a lot of smart people on here, there has to be something that is being missed. Maybe this OP's idea is it. That would be cool. :zoom:

I don't see how when driving these 2 pressure sensors can have anything to do with each other. Maybe they can be checked and compared by the computer at key on just before startup. The absolute sensor is just reading atmospheric pressure and that's it.