View Full Version : M8 W/Slp pipe set and Bdx intake loading up!

03-25-2008, 09:40 PM
I have an 07 M8 with pipe and intake that keeps loading up when I coast down from big climbs. I'm not running a fuel controller, just an adjustable BMP fuel reg. and guage. Fuel pressure was 48psi stock, and I'm now at 46.5psi with the same prob, no fouled plugs though. Should I drop down a couple psi? Any ideas would be great. Thanks.

03-25-2008, 11:15 PM
My 07 M8 is 42 PSI stock pressure, SLP pipe, RKT head, BD box.

03-26-2008, 07:21 AM
anyone else?

03-26-2008, 10:30 AM
mine does the same thing..........I just "BLIP" the throttle on the way down. I think it is something you just have to deal with.

03-26-2008, 09:12 PM
mine does the same thing solved this problem with control box had to take away fuel and have had no more problems

03-26-2008, 11:09 PM
I pulled 2 psi of fuel pressure, hopefully this gets rid of it.

03-27-2008, 12:42 AM
08 M8 with Black Box. Mine was at 45 1/2 psi, dropped it to 44 and it still loads up coming down hill. I'am going to drop it to 42. Keep us posted your results. Thanks Snostrm

02-13-2011, 02:06 PM
mine does the same thing solved this problem with control box had to take away fuel and have had no more problems

I have read a lot of posts here and on other chat forums, and there seems to be an issue with bogging and loading up, and no one really seems to have a consistent answer as to what is going on...
I have an all stock 2009 M8 Sno Pro, with side panel vents. It has always run perfectly, with no bogs, hessitation, or loading up. I absolutely loved it. Last week I put an SLP Exhaust (y-pipe, pipe, and can) on my sled. I also put the SLP 40/36 helix in the secondary, as per SLP setup instructions. THOSE ARE THE ONLY CHANGES I MADE, and now it has big problems!
At an idle, and especially after moving at very low speed (turning slowly to get lined up for a turn or climb), the sled loads up extremely bad, and blubbers for the first 50-100 feet with next to no power. It very much sounds and feels like it is getting way too much fuel. I am sure that it is not the helix, as it has not even had time to ramp up or down at idle to low speed where this problem occurs. Thus it is a simple matter of the process of elimination, the only thing that has changed is the exhaust, therefore this problem is a direct result of this SLP exhaust.
I am very frustrated, as I spent $700+ on this setup and it performs worse than the stock exhaust. Just from looking at posts on discussion boards and forums, it is obvious that I am not alone with this problem. Does anyone have an answer as to what is going on and how to fix it without spending more money on a fuel control box which is supposed to be not necessary with this setup?
Also be aware that SLP designed this exhaust so that it does not clear your hood by the speedo, and it will melt a hole in your hood if you do not make some mods to the hood to raise it up, or wrap the pipe with header wrap just to the right of the EGT sensor. Very dissapointing! SLP really seems to have missed the mark on this exhaust.
I am at a loss as what to do from here. I can not live with the loading up problem. The sled needs to be reliable, and perfom correctly when the throttle is pushed, otherwise you will end up in a real bad spot real quick. I spent way too much money on this exhaust to scrap it, so what to do now????

02-13-2011, 05:33 PM
mine does the same thing..........I just "BLIP" the throttle on the way down. I think it is something you just have to deal with.
I have 2 2010 M8's and they both do it too. One has always been worse than the other. Some days they don't do it hardly at all, but other days they do it regularly. I've tried sever different things and haven't found the solution (including the o-ring on the oil pump arm). I think it's just something you have to learn to deal with. I just blip the throttle regularly on the way down...

02-14-2011, 03:36 PM
Thanks for the suggestion, but blipping the throttle does not work.
If you have the throttle held just above clutch engagement, where the sled is moving 1-5mph for a short distance (getting lined up for a wheelie off an object, or a jump, or climb), and then punch the throttle, it falls flat on it's face blubbering. It will only go away if you let off the throttle (very bad idea right before a jump!), and ease your way back into the throttle, then it will clear up in a second or two. I have talked to SLP about this, and all they were able to come up with is having the dealer check the TPS, oil pump, and fuel pressure, along with changing the sparkplugs. They said that their pipe is more efficient than stock, so overfueling would become much more apparent with their pipe, but were not sure what was going on.

As I stated before, this problem only appeared after putting the SLP exhaust & helix on. Thus, intuition suggests that it most likely has nothing to do with the TPS, or my oil pump. Further, just from the sound of the engine (blubering), it most likely has nothing to due with clutching. I plan on putting new plugs in, and checking the oil pump, and rechecking my belt defelction, but am confident that will not fix it. I do not have the tools necessary to check the TPS (requires cat diagnostic computer). As far as the fuel pressure goes, does anyone have any suggestions on a brand of fuel pressure gauge to buy, where to mount it, and how to adjust the fuel pressure on an 09 M8?

I have seen many other post here with people talking about the same or nearly the same issue as what I am having. And people are still talking about it left and right. Has anyone at all out there, who has experiencd this problem, been able to fix it, and how did you do it? I am sure we would all really appreciate your input.

02-15-2011, 11:38 AM
I am running the full slp exhaust/clutch set up and never had a problem. The only thing I can think is non of you guys are mentioning your PCV. If your not running a PCV with an adjusted fuel map for the new pipe your sled is gonna run like crap. You also set you min throttle voltage in the PCV to match the map. This way the correct amount of fuel is dumped when you pin it because it knows exactly where the "0" throttle position is. Maybe that would clear up the hesitation off idle your getting.