Exotic-metal55

This is the lean spike that I suffered with for 3 weeks, until the blow by started. I suggested MAP sensor right away, as I always held 80 psi of fuel pressure at the spike RPM. When MAP exceeds limits, it seems to lock and not allow tuning or any changes to be made. It is a dangerous situation, as timing also seems to go up. Pretty wild AFR, huh? Rich down low and lean up top. Looks like two totally different maps.

What do you think? Anyone else?

skratch77

I would try a new map sensor and see if that helps,my friend had a problem with his supra and he was mazing out his map and could not tune it without getting the next higher reading map sensor.

I have the oposite problem,im lean down low and ok up top

Exotic-metal55

New Map sensor would be the same voltage from MB ? I suggested the tuner change voltage a few weeks back, if they did not do it already. I would assume that would work by expanding the parameters?

I know I could build a map clamp but was hoping for a clean tune adjustment to make everything work with the tuners work?

chiromikey

i've gone through several map sensors and i don't think another oem one will solve the problem. regardless, i've got a couple in the garage if you need one.

Exotic-metal55

Thanks! I have a few too but I also agree it is not my sensor, it is the calibration, size or adjustment of it that was needed for the mods I ran. With ported heads, my boost was not that high (about 15 ish) with the 200mm. Even though I saw 15 psi ish, still could have spiked higher but either way, it was not tuned out. I suggested more blow off on the by pass and or voltage change to MAP to help . After 4-5 road test and flashes, I was told that I was good and solid in the 11 afr range. Drive down to dyno and the MAP /lean issue was still there but with blow-by also present, You could say a buzz kill hit.

The 200mm ran great on everyday driving. Response time to the the throttle was extremely fast! Even on the dyno down low, the tip of the pedal allowed RPM`s to scream up the dial! It hit more like those 25 psi big turbo motors. lol Just a great combo with the heads! They logged my road runs for a couple weeks but I never saw the info, so just going by my own data and logs .

adianaty

Looking at it, it seems odd that there was no major HP or torque change given that significant of AFR change. Makes me wonder if your Afr is even accurate like perhaps the O2 sensor got wet. Datalogs would tell the story and call me an optimist but maybe the blowby and AFR are unrelated. It doesn't look like it but was this with E85 unless this is a lambda sensor that is calibrated for gas.

GT-ER

I was actually about to post this. I've had large A/F ratio changes during a pull in the past and power would dip pretty drastically...yet yours doesn't. Seems kinda odd.

adianaty

Forgot to ask if you have done a leak down test. Last time I went to dyno my car, the guy before leaked a quart of oil everywhere because his dip stick came loose and crankcase pressure forced it out during the run. He freaked of course and started blaming the tuner for it immediately. They tightened it up and ran it again and it was fine. Probably unlikely but worth a double check if the leak down checks out ok.

chawkins2001

Brooke, you thinking the lean speak should have been tuned out?

98aggie

there are other graphs posted and taken than show the big swing in torque and HP.

adianaty

Ok. I'll take a look but any idea how this one was possible? Maybe it added timing back in making up for it.

sneakyneon

This is exactly what I was taking about. A map clamp will fix this and is clean. You just need to clamp it at the right threshold. I believe mine is set to 3.60 tI should also make tuning easier since the map voltage will stay liner.

sneakyneon

Look familiar

sneakyneon

FYI
Your all the casual lookers
If your not running a BIG pulley this is not an issue. You need to be seeing 17+ psi to even consider this. One small mistake with a Map Clamp and its new engine time.

stevebez

The AFR looks pretty messy all along to me.... and torque curve not really reflecting the jumps in AFR displayed.

Are u getting AFR from OBD2 or sniffer? I dunno but it does not look reliable to me.

Exotic-metal55

Just like with MAF meters, MAP meters also have to be calibrated for the mods you add to the car. They all have calibration limits and they all can do nasty things when they exceed those. Sneakyneon was a big help with this early on. I just wanted it tuned, VS building a MAP clampo that could effect what the tuner installed. A Map Clamp is kind of like a micro tuning device and that could mess with the tune parameters.

All my dynos are on race gas over the last 4 weeks. I road tested E85 but it only enhanced the lean condition from 4500 and up, I was driving and Jerry was reading the gauges and he said 13AFR to 16 AFR on those road tunes with E85. AFR would not tune then either.

I can post my last dyno but on my engine when oil comes out the dip stick and I drop 140 foot lbs of Torque,,, then it is time to stop. That is blow by! I promise you, if you have oil come out your dip stick (even with it removed) then you have a problem on these AMG engines.

Exotic-metal55

As you know, I am very scientific in my test. I do not take one thing or another for granted. One reason I did a base dyno on my car before even starting this build on July 29th. I knew my car had two part throttle flashes over the summer, because I was fouling 02`s and running rich. Was not sure why either. I have a wide band hooked into my fron 02 bung ,, plus we used two new 02 sensors on 98Aggies dyno over the 4 weeks of dynos. Then used a data logger to back up timing and IAT`s.. Timing ws hitting 27 deg, after the spike came in and would carry to the top. Only seeing 10-16 before 4500 on that pull. Again, I have at least 9-12 pulls that look like this over a 4 week period, plus road tuning.

My baseline showed a 34 HP drop and 40 TQ drop (from best dyno ever) on that day, turned out my tune had somehow had 7% fuel added across the map and was just killing power and fouling out the motor. I had changed 02`s twice in only 3K miles! Here is how much carbon was on my pitons, when I chaned the heads. Only 24K on those forged pistons .

The purpose of this thread is to discuss MAP or other issues that may cause this event! Just sharing my information to help the community grow and keep everyone healthy! Like I said I would do by thge time the mile started. It is related to the larger pulley`s. Say 195mm and up. Again, I have not logged boost much over 15 psi. Maybe one run at 16.2 on a data logger. Not sure how accurate that is.

adianaty

Thanks Brooke! Didn't realize that the run you had shown wasn't the one with blow by. Map clamp sounds like the solution...

sneakyneon

I agree 100% that a map clamp can mess with the tune. If you get greedy with it. Most of the platforms that use these clamp do stupid things like clamp the voltage way way down and the timming goes through the roof.
I guess another option would be a GM 3 bar map that reads the same boost at lower voltage, but this going to effect the Vacuum side as well and allot more tuning is going be needed

skratch77

Would a 185 pulley have map issues?

skratch77

My car is lean down low,like 14.5 at peak torque.if I run a map clamp can I trick it to add fuel?

Jakpro1

I wonder where Ali is on this issue. He says there are (please forgive me if I don't know the PC name to call them) Arab guys running all over with 200mm pulleys in the Middle East.

One of them would have to know how to solve this. Maybe they don't care and just run til poof but I can't imagine that.

Ali????

Heres just one post. Brooke may not wanna read this. He said the 200mm pulley just DIED up top racing....uh oh

Exotic-metal55

185 has never had this problem! Mine started with the 200mm but Nick`s started with his 195mm. My ported heads kep boost lower, so I may be just on the ragged edge. Again it is a great size, just needs the proper tuning. I know a few other cars have been putting them on since I posted the original info about mine. I guess that post generated sales for some people..hehe

I think most any tuner can solve or fix the problem, if they know where to look. I suggested changing the voltage in the file of the tune but who knows what all has to be done. Many tuners like COBB and others tune this all the time. Just like the tuners that tune the MAF`s when they are also exceed limits or put stroker motors in. I supplied all my info to Eurcharged a couple weeks back but I am out of the game right now! It SUCKS too! Weather is awesome down here finally.

May pull motor out Sunday, if my other wrenching wounds over the last 3 months have healed. lol Last motor, I just sent the car, motor, parts to my local MB dealer to build but they were slow back in 09. Two weeks later, it rolled out with forged Wisecos and a one year dealer warranty! Sure is tempting again this time.

Exotic-metal55

Sorry, I did not get that dyno pull yet. I felt like I just got kicked in the Nuts and really needed a break from looking any further. The dyno posted was from the first set of runs with the 200mm pulley back on Sept 25th. Things were still adjusting to the new mods and a week later, torque and HP climbed up to the highest of 612hp/ 719TQ. Still had the spike and I was being remote tuned then and it never tuned out. I asked that the car be de -tuned then (pull timing and add more fuel), to make sure it stayed safe until road tuning with more monitors was in place. I asked to only run 1 deg of timing more over normal and 1.5 over normal above 5K (after peak torque). So timing was not increased much for VP109 oxygenated race gas! I do not know what the normal timing is in my tune these days but It usedto be 1 deg lower than what others used. If that makes sense? Well, I was on my second motor , so even though I like to push it, staying safe is job 1.

adianaty

Totally makes sense and understand the kick in the nuts feeling since after wrenching as long sa you have to get there it always hurts to get stuck on something both complicated and unforeseen. Wish I was in Texas since i would have helped on Sunday...