Weird problem with Forge MBC
Originally Posted by anthonypazsd
What does "crushing the blow off" mean?
Plus, just wanted to say my UNOS is working great and totally consistant now. Its turned all the way down (stiff spring) and hits peak boost at 20, 21. It doesn't usually taper either. Holds it all the way to redline in any gear. I just made sure the spring is SECURELY snug on the nipple.
Plus, just wanted to say my UNOS is working great and totally consistant now. Its turned all the way down (stiff spring) and hits peak boost at 20, 21. It doesn't usually taper either. Holds it all the way to redline in any gear. I just made sure the spring is SECURELY snug on the nipple.
Originally Posted by joshd
Mike,
I figure adding to this thread is probably the easiest way to get your advice, other than just calling you guys (next step ...).
I had the Forge UNOS MBC installed on my IX yesterday. The first problem that I had was an immediate spike to 25+ psi with it set all the way to the -. I pulled it apart and of course the stiff spring was not seated on the nipple. That was a reasonably easy fix to get it seated and back together.
Then with the knob all the way to the - I hit around 14psi or so. Great. I started cranking it up attempting to hit a spike of around 21-22psi. Now the problem that I have is very erratic boost.
It usually goes like this:
Full throttle, boost builds to a spike of anywhere from 20-24psi ... boost then immediately drops 2-3psi, then starts creeping back UP to around 20-21ish or so, then it starts tapering down from there. All the while the boost occassionally bounces up and down a bit.
I have no clue if I have a boost leak, leaking BOV, weak WGA, bad install of MBC, bad MBC, bad boost guage/install? Not sure which of those could cause the erratic boost behavior that I'm seeing bouncing up and down?
By the way, Warrtalon rode in my car for a quick second gear (not as bad) and third gear (problem definitely noticeable) run, so he can verify the behavior as an independent observer. Unfortunately, I think he was mostly looking at my stock gauge, which is reading low (doesn't zero when car off) since the autometer guage was installed, but I think he observed the 'initial spike, then drop, then creep up, then drop again' behavior.
Thoughts?? Where should I begin the troubleshooting?
Thanks,
Josh
I figure adding to this thread is probably the easiest way to get your advice, other than just calling you guys (next step ...).
I had the Forge UNOS MBC installed on my IX yesterday. The first problem that I had was an immediate spike to 25+ psi with it set all the way to the -. I pulled it apart and of course the stiff spring was not seated on the nipple. That was a reasonably easy fix to get it seated and back together.
Then with the knob all the way to the - I hit around 14psi or so. Great. I started cranking it up attempting to hit a spike of around 21-22psi. Now the problem that I have is very erratic boost.
It usually goes like this:
Full throttle, boost builds to a spike of anywhere from 20-24psi ... boost then immediately drops 2-3psi, then starts creeping back UP to around 20-21ish or so, then it starts tapering down from there. All the while the boost occassionally bounces up and down a bit.
I have no clue if I have a boost leak, leaking BOV, weak WGA, bad install of MBC, bad MBC, bad boost guage/install? Not sure which of those could cause the erratic boost behavior that I'm seeing bouncing up and down?
By the way, Warrtalon rode in my car for a quick second gear (not as bad) and third gear (problem definitely noticeable) run, so he can verify the behavior as an independent observer. Unfortunately, I think he was mostly looking at my stock gauge, which is reading low (doesn't zero when car off) since the autometer guage was installed, but I think he observed the 'initial spike, then drop, then creep up, then drop again' behavior.
Thoughts?? Where should I begin the troubleshooting?
Thanks,
Josh
I can't really give any advise without some more information about your setup, so, if you can, please PM with a modifications list and I'll see what I can come up with.
It's possible that this is not related to the Unos, while conversely, it's quite possible that it is.
Let me know what you can.
Originally Posted by anthonypazsd
Al, Whats crush the blow off valve mean? Crush?
FYI, a few days ago I greased the ball quite well, and since then I haven't had a single spike. Also now I hold boost way better, let's say if I hit the gas boost jumps to 21.5 PSI and stays there all the way up to redline, no more settling 1 PSI below or so.
In my case the problem has been solved.
In my case the problem has been solved.
I'm still golden as well. Greased that little monkey up and everything is just peachy. Boost hits about 22.5 then drops to 21. All my gauges and logger info reads timing and A/F is PERFECT with 0 knock. I'm not sure how much the gallon of Toluene and 16oz of "Marvel mistery oil" account for this, but it sure feels like it's working?
Originally Posted by walkedu
I'm still golden as well. Greased that little monkey up and everything is just peachy. Boost hits about 22.5 then drops to 21. All my gauges and logger info reads timing and A/F is PERFECT with 0 knock. I'm not sure how much the gallon of Toluene and 16oz of "Marvel mistery oil" account for this, but it sure feels like it's working?
Originally Posted by JuancaROD
FYI, a few days ago I greased the ball quite well, and since then I haven't had a single spike. Also now I hold boost way better, let's say if I hit the gas boost jumps to 21.5 PSI and stays there all the way up to redline, no more settling 1 PSI below or so.
In my case the problem has been solved.
In my case the problem has been solved.
I am going to pre-assemble all the units I sell from now on with the heavy spring and with some lube
Originally Posted by Sgt Blamo
Toluene & Mistery oil, WITW?
I had to use this because all the local pumps switched to 91/10% ethanol and my flash is for 92 oct. Was hoping this little mix of home made race gas would allow me to keep my boost where it was at. My logger/gauges proved that it worked like a charm. I could have ran more boost had i wanted, but i'd rather be safe than sorry.
Originally Posted by Warrtalon
Just like it sounds, you crush it. It presses in the top of the metal BOV so that the spring inside gets compressed. You use a vise to make sure it crushes evenly.
Anyway - update here is that we crushed the BOV and still faced the same behavior ... boost spike, then drop, the creep up again, then taper.
We also 'greased the ball' with no change in behavior.
I switched back to the soft spring this morning and it pegs 18-19psi solid without the bouncing around behavior, so it seems to be related to using the stiff spring and/or trying to hit a target peak boost above 19 psi (I'm trying to dial in 21-22psi for 93 octane).
More troubleshooting to follow today I suppose ...