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Overboosting/LimpMode/Weird RPMs

AverageStinger

New Member
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I have had such a difficult month since I’ve installed my JB4. Have HKS plugs (did not gap), all connections good and good readings. Had a good E30 mix too. Ran MAP 3 for 2 days and loved it. Then it overboosted and went into limp mode. From then on it overboosted In MAP 3 whenever I hit the gas decently hard. So I switched to MAP 2, burned off the E30, filled completely with 93 and didn’t touch MAP 3. Now it’s overboosting in MAP 2, goes into limp mode, and when it goes out of limp mode, with or without being in a MAP, the car’s acceleration and RPMs feel all weird now. Like it’s hanging out in higher gears or lower RPMs even in idle. Kinda feels like it's lethargic until it hits 2k RPMs and then it takes off and overboosts.

This has been so frustrating. I’ve tried most of what I know to do including updating the firmware and checking all my connections. Has anyone else had a difficult time like this? I’ve heard wonderful things about the JB4 but figured you’d get to use the different maps when you buy it, I’m down to MAP 1 now and my car is driving all funny. Here is what I have been suggested to do

1. Overboosting and weird RPMs most likely due to not gapping the HKS plugs to .022 - .024
a. I also hear they do not need to be gapped and that overboost does not come from the plugs
2. Told to unplug battery, pump brakes and reset both ECU and then reset JB4 to factory and reload firmware
b. Not sure if this has anything to do with the overboosting, but might fix the weird throttle stuff
3. Drop FF/WASTEGATE ADAPTION to 50 or less fixes overboosting
c. No idea what this does and kinda don't wanna mess with the JB4 unless I know what I am doing
4. EWG cables fix overboosting
d. Have a buddy who has these installed and he overboosts on MAP 3 almost every time

If you have any ideas or anything at all to suggest please let me know. My current plan of action is:
A. Try to reset the ECU and JB4
B. Take it to the shop that did the plugs and get them gapped to .022 and see if I blew one of them
C. If that doesn't work maybe try to the FF/WASTEGATE ADAPTION thing?
D. Buy a LAP3 tuner, although I really would not want to do that.

Thank you for your time! I will send up a log soon.
 

Houstinger1

Member
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Houston, TX
I have had the exact same issue when running JB4 and higher e blends. I also have a catback exhaust. I did not have EWG wires (which means the FF/Wastgate settings wouldn't work) and was also getting limp mode and over speed often. The only fix being to add more 93 to lower the E content.

Before I started doing E, when I had just the JB4 and intakes, I had not 1 but 2 cracked plugs. The car never went into limp mode or turbo over speed just drove like crap, lot of jerking around.

The current working theory for my car given that I have a number of weird issues is that there is a fuel system issue of some kind as well as the catback exhaust is not providing enough back pressure to keep the turbos from spooling too fast. The HPFP and LPFP pumps have been upgraded and replaced along with the LPFP but I still get limp mode with the JB4 showing error code 3 low fuel pressure. Additionally, after getting the WMI setup and running, the performance has returned to expected levels, indicating the fuel system needs addressing.

I wonder if you are not in a similar situation where it isn't just 1 issue but multiple. What error code is on the JB4 when the car goes into limp mode? Like you, I have been beyond frustrated at my situation, seeing guys going crazy fast and having a lot of fun and I can't get stock numbers much less any return on my $12,000s worth of upgrades.
 

AverageStinger

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Good to know the FF/Wastegate thing wouldn't work unless you have the cables. What do you mean by overspeed? and was your throttle acting funny as well? Maybe I have a cracked plug? If its the fuel system then honestly that sounds like a lot of money to fix. I definitely didn't know that when I bought the JB4 I would have to buy so many extra things to make sure it actually worked. Are you saying the fuel pumps didn't help at all?

I really hope it isn't multiple issues. I don't know how someone can plug in their JB4 run MAP 3 on e30 and not have problems for months and months, and I do the exact same thing and overboost on MAP 2 on 93. It's the same car doing the same thing. I have a friend who had a similar issue with the JB4 and recently switched to Lap3 and said all of his issues went away. I will let you know how it goes but sounds like you have a lot more invested in this car! I just want to run MAP 3 speeds. Don't need to do WMI and can't afford it. Definitely can't afford to fix a bunch a stuff or fix fueling issues.
______________________________
 

Houstinger1

Member
96
47
18
Houston, TX
In theory, the pumps should improve fuel delivery, assuming A) the pumps aren't broken B) there aren't any other issues going on like pinched line and C) everything was installed correctly. The LPFP has failed once already and been improperly installed a couple times.

The other thing to remember is that cars are not perfect copies of each other and that there are slight manufacturing differences with each vehicle.

I am with you in that all I wanted was to run map3 and go fast. When I saw something was a weakness, I chose to upgrade it, like the fuel pumps. Financially a poor decision, but hopefully the end result is that I have all the pieces now to make it work well and that it is just a matter of putting it all together correctly and addressing the various smaller one offs.
 

AverageStinger

New Member
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I think if this continues to fail me I will switch to Lap3's Protuner. If that doesn't work then I will get a Stage 2 ECU/TCU tune by Lap3 and just go full send. Everyone seems to think I blew a plug but that still doesn't explain the overboost
 

Houstinger1

Member
96
47
18
Houston, TX
It’s not the plugs. Overboost and limp mode like that isn’t plugs. I also don’t think it is unique to the JB4. Those guys saying move to Lap3 have been JB4 haters for a while. I also don’t think it’s a tuning issue either. Having said that, it’s just a hypothesis. I’d be interested in seeing what you do and how you tackle this.
 

AverageStinger

New Member
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I don't think the overboosting and such is related to the plugs but I do think that the weird RPMs and lull is... I will let you know what I end up doing and how it goes
 

monusa

Active Member
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check all hoses/vacuum lines, etc. in the event that something came loose or was not connected correctly. Easy to do but hard to find.

Set the jb4 back to map 0 and run a tank or two of just gas (93 preferred). Also, get plugs gapped in range of 0.22 - 0.24. Verify everything is buttoned up correctly. Afterwards, move to map 1 and take logs. If still overboosting on map 1, something is definitely up that may require a pro......If logs look good on map 1 and no boost issues, try map 2. At some point, the issue should reveal itself or things will get back to normal.
 
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