E55amg0220

Ok guys so as some of you know that I have been dealing with a troublesome hiccup that only occurs at freeway speeds usually a hill or soft throttle tip in of the throttle at 70+ mph will trigger this weird hiccup. Recently I installed a new snout and founf that I had a small crack on the lil plug on the backside of the snout I dont know if it was leaking but instead of chancing it I removed the top innards and took the plug out filled with 5000 psi epoxy and let dry and then reinstalled with sealant and all new gaskets, Well I downloaded my tune and for like 200 miles car was great no hiccup and running nicely. Then out of no where the hiccup came back .... this was without touching ANYTHING. So part of the reason I wanted this new snout was being it was an adapter I could remove it and install my 74mm tb and see what happens.

So first things first I wanted to know what I would be giving up if I removed it and what I would be gaining .... so I took it to the dyno that my buddy owns in slc and first things first on the way there which is a good 45 mins away on the freeway I got the hiccup a few times. I would pull over cycle the key and head back on out and it would do again so QUITE annoying!!! But we got to the dyno, its a dynojet mind you and i let it cool down for 40 mins and put it on the dyno made 546 rwhp and 578 rwtq I was very happy to say the least. I then left it where it was strapped down and removed the 82mm tb and adapter and reinstalled my 74mm tb that has the throttle shaft smoothed and the stock ypipe and we redynoed .... it made 534 rwhp and 560 rwtq so all and all its a loss of 12 rwhp and 18 rwtq. So for me this isnt a huge loss at all but will it cure the problem .....

I drove it home and mind you i did not change the tune at all and the AFR was still perfect on the street and on the dyno 11.6 at redline but mostly 11.8 throughout the rev range not even a change of .1 in my afr was noticed. Tony at race iq said that i could use the same tune with or without the 82mm but what was noticed was better idle, smoother low end, and still pulled just as strong up top didnt fall off with the 74mm tb. Now what I did notice was there was a slight loss of low end seems the bigger tb has a slight edge down low but not a huge one this is where it lost most of what it had gained. But the biggest news not once did it hiccup on the way home .... nor has it done it since for almost 230 more miles on top of that. Highway driving feels much better and its smoother and more sharp as well .

Now before someone says it was your TB well I had 3 of them and I tried all 3 so that was not it changed gaskets numerous times changed snouts and anything else imaginable and ive come to the conclusion that some of these cars just do not like the 82mm tb and that its something in the computer that needs to be tweeked to fix the problem.

SICAMG

BC928

Question is 80mm okay?

E55amg0220

this is the main reason i wanted to do this was i have searched an searched an noone seems to have done a back to back with nothing else changed, usually they do a tune an pulley or 82mm an headers etc etc. Also mind u originally the tune thats in it was modified for an 82mm so if anything is a miss then a retune for the 74mm may gain me back some ... but running so good dont think ill touch it.

E55amg0220

that i dont know if i can get ahold of a tb an it will mate to my ported snout i may try it. But who knows

oneslow55

PieRat

I read a post by some German guy once. He reckons that the throttle body can create turbulence and cause the ECU to bug out. When the ECU bugs out it reverts to a backup map, he claimed that US tuners don't alter the backup maps and with mods the stock maps are obviously incorrect.

Maybe ask Tony if he adjusts these maps. It seems like something US tuners would know and do..

E55amg0220

ive asked tony an jerry an neither knows bout em or touches them.

but to me i have just proven its in the tune .... cus if were a vacuum leak why would it suddenly just come back without touching anything .... why would changing the tb back to the 74mm fix it .... and i tried 3 different tbs so i know thats not it either.

JoeJErnst

This is good information. I may go back to the stock TB too. Keep us posted as time goes by, even if there's no change!

E55amg0220

Of course i will always do

Also may be looking into getting a weistec supercharger system havent decided yet

actech

well i have a 74mm and always have and ive got the hiccup. i just removed the shout plug and used right stuff rtv to fill hole. hoping that is the fix. i do not plan on going up to an 82 but i may shave down the shaft on my 74. cant thank you enough for constantly posting your updates as it helps the rest of us.

E55amg0220

well i do know how annoying this is to me an so it would be nice to get it all sorted out so that we can all enjoy our cars without this prob that shouldnt be there to begin with.

oneslow55

E55amg0220

agreed i can go to the weistec an make it up if need be lol

oneslow55

E55amg0220

ive already done the whole ls1, ls7, lq9 turbo, thing ... i lobe trying new stuff and something thats different.

Davednconfused

I have been saying this for a while now, but with no proof besides empirical data. The 82mm TB really just isn't worth it! Too many headaches! My car is on a 185mm crank pulley and stock TB and pulls like a freight train.

E55amg0220

Hey guys just wanted to do an update .... i have been driving the car with the 74mm tb on it an only thing i have done is had Tony do a retune with it slightly richer and a lil more timing as well. He did the changes i requested an wow what a difference. Also had the tb ported out to its max potential which is just short of 79mm and it works flawlessly!! Car has been redynoed an its making 558 rwhp and 589 rwtq so its making more now than with the 82mm with the retune an being ported tb.

I have another project in the works as well i am working on making a true 3.5 in cold air intake and hopefully it works as planned if not ok but cant hurt ... its gunna be similar to weistecs.

PieRat

So what was the gain with the ported stock TB vs just normal stock TB?

jumph4x

For those of us trying to wrap our heads on this issue, what is the size reference on throttle body sizes?

- 74 mm stock size
- 80mm upgrade
- 82mm ported/polished upgrade

Did I get that right?

E55amg0220

i dont know exactly cause i got a retune as well with more timing an slightly richer afr from 11.8 too 11.4 and before at reline it would dip too 11.6 an now its 11.2 and with the extra timing and more fuel it really woke the car up. But before it made 534 rwhp and with the ported stock tb which is 78.5mm its making 558 so thats a gain of 24 rwhp and tq is up as well.

and as to the tb sizes

stock tb with thinned shaft
82mm stock mb tb
and ported 74mm tb measured at 78.5mm

tw2

Do they laser cut a new throttle body "circle" with a larger diameter to match the new bore size? Just steel?

E55amg0220

yep thats exaclty what they did even same thickness as the stock one an no codes thus far

drothgeb

Both the 80mm and 82mm are standard Mercedes TBs (for other models obviously). No porting/polishing required to get to that 82mm size.

cation

You have maxbore do the work on the stock unit?

Any codes show up? I'm in the p0106 boat with an 82mm tb. Having maxbore do my tb with a thinned shaft. Wanted to see what your long term experience has been.