Jb4 supra MT help please

[Deleted member 10795]

Anyone know how or where to run the obd wire through the firewall? I cant find a spot

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[wombo]

AT but I poked a hole through the firewall, there’s a hole that’s covered by a sheet, poke through it with a screwdriver or other pointy object

 

[Deleted member 10795]

Its all different because of the clutch pedal, but did you poke through the engine bay or bottom?

 

[Sal Rod]

Anyone know how or where to run the obd wire through the firewall? I cant find a spot

@kingdooksdb this guy had jb4 on a manual,maybe he can advise better

 

[Erty]

I had the same issue. The AT’s have a hole in the firewall but the MT’s don’t so I routed it up and around the hood and into the driver side door. The door closes on the wire but it shouldn’t be an issue. Second option is making a hole of course..

 

[6SPDA91]

I had the same issue. The AT’s have a hole in the firewall but the MT’s don’t so I routed it up and around the hood and into the driver side door. The door closes on the wire but it shouldn’t be an issue. Second option is making a hole of course..

So you're coming out of the engine bay, out of the car, then back in?? All while letting the door close on it??

Sounds like a recipe for a short in the wiring or potential failure from the elements.

 

[oreobbq]

So you're coming out of the engine bay, out of the car, then back in?? All while letting the door close on it??

Sounds like a recipe for a short in the wiring or potential failure from the elements.

Well it's not sticking outside the car lol. The device sits very close to where the hood and door panel meet so the only thing that closes on the wire is some weather stripping iirc. It's not exposed to the elements and many people choose this option for the ease of removal.

 

[Flann-man]

The MT’s have the same hole in the firewall as the AT, but now there is a hose running through it I am assuming for clutch operation and no plug. But, you can fit still fit the wire and connector through as the hose is rubber and doesn’t completely fill the hole. Try folding the wire in half running it from inside the cabin to the engine bay with a long flat tip pushing at the fold, once through grab the wire and only pull the end that has the little connector for the JB4 end while pushing on the hose to allow the plastic connector end to squeeze past. Slightly awkward when doing it alone, but it’s doable.
Good luck!

 

[superd6199]

I local DFW MT Supra owner was able to still feed the JB4 OBD cable through that hole along with the clutch cable. You’ll need to find something to hold the clutch cable aside as you feed the OBD cable through. GL, it could be done.

 

[Erty]

Well it's not sticking outside the car lol. The device sits very close to where the hood and door panel meet so the only thing that closes on the wire is some weather stripping iirc. It's not exposed to the elements and many people choose this option for the ease of removal.

Exactly.

 

[ColonelAdama]

Question for the JB4 users around here:

I've seen repeatedly on these forums that everyone has their Map 6 settings dialed in by Jesse for ~$500 or so. I found this rather unusual just coming from a MK7 GTI that I've been running Map 6 for 7+ years (never had an issue, even at 26+ psi stock turbo e30). I was able to dial it in myself after doing my research on the forums, and I can't really see the reason why the Supra would be any different. I guess GTI forum users are more willing to share their Map 6 settings/supporting mods. (No, its not tune-theft. The JB4 was designed to be user-tuned, I think it's wild that we try to gatekeep the performance of fellow enthusiasts)

Setting up Map 6 isn't rocket science, and it's no doubt a cake-walk compared to proper tuning.

My method on the GTI was:

1. Determine the boost curve from a base map (ie. Map 1 or Map 2). Usually 4-5psi across the board with some tapering on both ends.
2. Bump up from the whole Map1/2 curve in small increments (ie. 0.5 psi or so) at a time
3. Data log a 3rd/4th gear pull after every change (~2.5k rpm to redline). Watch for timing corrections in any of the cylinders. If any corrections observed, dial back down the boost at that RPM and log again. Do this in hot weather if possible to create a worst case scenario for IATs. If its winter, start data-logging again as weather starts to warm up and observe for IATs and timing corrections.
4. If you don't really care about a linear power band, you can usually bump up the boost more in the RPM ranges where the turbo is in peak efficiency (GTI was 3-5k rpm)
5. Watch fueling trims when bumping up the boost in higher RPMs (5k+) and go easier on the boost. On GTI, fuel trims need to remain under ~40. Not sure on Supra.
6. Boost curve below turbo efficiency range (<2.5k rpm) shouldn't be raised much at all over Map 1/2. You shouldn't be going WOT under 2.5k anyway. Lugging is bad for timing corrections and your clutch.
7. Adding ethanol required FOL adjustments but not sure how that works on Supra.
8. Re-evaluate your settings with the addition of any supporting mod.

Someone please direct me to a more applicable forum if there is one. I don't claim to be some tuning genius, but I feel that I understand the JB4 platform well enough to give some advice. By the way, when I get mine dialed in, those settings are getting shared publicly at $0.

FYI: forum users trying to scare others from doing their own map 6 are just trying to make money off you. Educate yourself on how the system works and make changes incrementally!!! Your engine or turbo will not blow immediately when you raise boost by 0.5 psi. DME failsafes are in place. Your car will go into limp mode if anything exceeds safety limits (AFR, timing pull, overboost, etc).

**Creating independent thread as to not derail this one: https://www.supramkv.com/threads/seeking-more-info-on-jb4-map-6-tuning.16759/

 

[MoTeC_R]

Anyone know how or where to run the obd wire through the firewall? I cant find a spot

I had the same issue. The AT’s have a hole in the firewall but the MT’s don’t so I routed it up and around the hood and into the driver side door. The door closes on the wire but it shouldn’t be an issue. Second option is making a hole of course..

Well it's not sticking outside the car lol. The device sits very close to where the hood and door panel meet so the only thing that closes on the wire is some weather stripping iirc. It's not exposed to the elements and many people choose this option for the ease of removal.

This is what I’ve seen most do:

 

[FuzzyRev]

I'm in the process of (finally) installing mine right now, and my God is the 'passage' around the hydraulic hose a tight fit for anything to pass through. At least I removed the wiper arms, cowl trim, and LH water drainage spout in order to see what I was trying to do. Good thing I own a wiper-arm-removal specialty tool, as that made it a lot less painful to pop them from the studs in order to remove the cowl trim.

 

[puzzled]

My high tech coat hanger tool gets excited when hearing about these firewall threads.

 

[FuzzyRev]

So, since nobody else cares to illustrate or elaborate in the name of the greater good, I'll do it.

After removing the cowl trim and left side drainage tube, the clutch master cylinder hydraulic feed line is staring you in the face. This is the same spot we all utilized in the AT version to puncture the liner with a screwdriver and run whatever wires, hoses, or urinary catheters we want into the engine bay.

I weaseled the screwdriver in from the outside just as a "feeler" for how much room I have, or more accurately, DON'T HAVE, as we're going to cram the wire through along the hose.

So, as the other guy suggested, the best way is to take and fold the wire over the end of a flatblade screwdriver, and firmly push it through from the underside of the dash. Here's a pro tip: Using some kind of lubricant will make it ten times easier, and lower the risk of damaging the wire or connector. I used this stuff, which has a name that sounds like a sex jelly.

..and here's the deed in action...

..and now we're prairie-dogging through the bunghole..

After giving it a further shove, enough came through in order for you to grab it with a small pliers and firmly pull the connector through. Pull in the slack, and viola! We can actually sleep at night knowing that we didn't run the wire externally past the door.

Lastly, I don't know why "short" (5' 10" or less) guys are so grouchy, because I'd never be able to do this if I was over six feet tall.

Now it's time to get that @Jesse DaBears tune and blast into space!

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