Does 4 Bar Tmap require custom tune?

[Bob Loblaw]

Possibly a stupid question, but I installed a 4 Bar Tmap sensor, re-flashed with an MHD OTS tune with the 4 Bar Tmap sensor option checked, and afterward kept getting an error code related to the Tmap. I put the stock Tmap back in, removed the 4 Bar Tmap option in MHD and no more error codes.

I'm not sure if I had a faulty Tmap sensor or if the issue was with the tune. I assumed I could run an OTS map with the 4 Bar option checked, but just want to confirm if that is actually the case.

Thanks.

[R.G.]

Possibly a stupid question, but I installed a 4 Bar Tmap sensor, re-flashed with an MHD OTS tune with the 4 Bar Tmap sensor option checked, and afterward kept getting an error code related to the Tmap. I put the stock Tmap back in, removed the 4 Bar Tmap option in MHD and no more error codes.



Thanks.

I had a similar experience Blahblahblah. I think the issue at the time was something with IJEOS but it would not play nice. The 3 bar works fine tho

[R.G.]

nevermind it posted in quote. How many times did you hit enter before you type Thanks Bob, lol?

[Torgus]

Possibly a stupid question, but I installed a 4 Bar Tmap sensor, re-flashed with an MHD OTS tune with the 4 Bar Tmap sensor option checked, and afterward kept getting an error code related to the Tmap. I put the stock Tmap back in, removed the 4 Bar Tmap option in MHD and no more error codes.

I'm not sure if I had a faulty Tmap sensor or if the issue was with the tune. I assumed I could run an OTS map with the 4 Bar option checked, but just want to confirm if that is actually the case.

Thanks.

When I installed mine I went with a custom tune at the same time. There is no advantage of a 4bar or 3.5bar on OTS maps. Also, my tuner had to adjust some scaling on my custom map I believe even though I had 4 bar set in MHD. So it leads me to believe the OTS maps will not work with a 3.5/4bar. Again, no reason they should or need to as the OTS will never go above the stock TMAP.

Given how inexpensive custom lifetime tunes are you might as well get one and put the 4 bar to werk.

[Terry@BMS]

The 4bar requires special scaling/compensation that we have built in to the JB4, I'm not sure if the MHD only algorithm accommodates it properly so in those cases you probably need some custom tuning done.

Generally if you don't plan to run over 30psi the 3.5bar sensor is going to be the better choice flash only.

[hydra]

Experience has shown me that the 4-bar doesn't even play nice with a JB4 + MHD BEF. Issues on the afflicted car went away completely once we installed an OEM N20 TMAP.

[Torgus]

The 4bar requires special scaling/compensation that we have built in to the JB4, I'm not sure if the MHD only algorithm accommodates it properly so in those cases you probably need some custom tuning done.

Generally if you don't plan to run over 30psi the 3.5bar sensor is going to be the better choice flash only.

Too bad the 3.5 is more expensive...unless things have changed. This is why I went with the 4bar as well as: "The 4bar has a wider usable voltage range so the one potential drawback, lower resolution, isn't an issue at all."

[Terry@BMS]

Too bad the 3.5 is more expensive...unless things have changed. This is why I went with the 4bar as well as: "The 4bar has a wider usable voltage range so the one potential drawback, lower resolution, isn't an issue at all."

If there is a JB4 on the car happy to help you sort out any issue with it. Without the JB4, not much we can do on that front. The tuner has to know what needs to be adjusted for the 4bar.

[Terry@BMS]

Experience has shown me that the 4-bar doesn't even play nice with a JB4 + MHD BEF. Issues on the afflicted car went away completely once we installed an OEM N20 TMAP.

If you need help with that just let us know. The only known issue is a 2ABD fault that comes up if the BEF has a certain tmap sensor range set too narrowly.

[Milan]

Experience has shown me that the 4-bar doesn't even play nice with a JB4 + MHD BEF. Issues on the afflicted car went away completely once we installed an OEM N20 TMAP.

You mean to tell me a map sensor off of a vehicle that never sees vacuum is having an issue on our cars? No way!

[Terry@BMS]

The factory and 3.5bar TMAP sensors never see vacuum either, lol.

[V8Bait]

That 4bar is just a headache. Even when setup perfectly there's still issues, hesitation at part throttle, erratic IAT and boost readings, phantom codes that crop up occasionally no matter what you set it to. Gotta scale it right, disable codes, modify iat voltages, etc. Some cars do OK, but I don't recommend it for anyone ever really. Terry your continual support for them baffles me, I've been approached by people with jb4 looking for help after asking you and David and ultimately I talk them into a N20 and whatever problems go away. Do you have like a massive inventory you need to move or something? Real question... That sensor is crap man. I'm a GM guy, but my faith in that thing is zero. I've spent more time trying to run down issues with it than anything else, it's worse than stock O2 issues in ST cars.

[Terry@BMS]

I can't speak for your support experience but in house we haven't had many customer problems reported. When they are it's normally one of David's customers with a locked BEF map that we can't directly help them with, so I tell them to contact David directly to rescale it. If you are trying to fix the sensor by disabling fault codes then you're going to have a bad time and that would explain a lot. Trying to disable fault codes will guarantee odd hesitations and performance from it.

For the flash only guys each sensor has to be individually scaled which the JB4 does automatically at startup so I can see where the flash only guys are having problems with that end.

In terms of why we sell them in the first place it's because for every 10 sensors we ship out we hear from maybe 1 customer who needs assistance. That said we probably won't bother reordering them since there seems to be a lot of negative feedback on it coming from yourself, Tony, and David. Tony said there was another higher quality 4bar sensor out that GM guys use? You familiar with it? We'll see if we can track those down going forward.

[Milan]

Terry, didn't you have to set up a function on the JB4 to calibrate the 4 bar on start up to the manifold sensor? The fact that you had to do that in the first place should be evidence alone that the 4bar is not good fit for us. You shouldn't feel bad, it's not your product. But it's not a coincidence that people have a problem with them all the time. It's less of an issue on the JB4 because the JB4 is manipulating the signal the DME is seeing because it's scaling the MAP itself.

[Torgus]

Terry, didn't you have to set up a function on the JB4 to calibrate the 4 bar on start up to the manifold sensor? The fact that you had to do that in the first place should be evidence alone that the 4bar is not good fit for us. You shouldn't feel bad, it's not your product. But it's not a coincidence that people have a problem with them all the time. It's less of an issue on the JB4 because the JB4 is manipulating the signal the DME is seeing because it's scaling the MAP itself.

To play devil's advocate, if it works with JB4 what does he care about it working flash only or with anyone else's tuning platform? That is not his problem or his market. His market is people using JB4, if the 4bar works with his JB4 what does he care or why should he?


That being said if there are issues flash only a note might want to be made online.


Looking up the price the 3.5 is only slightly more expensive so different strokes for different folks.

[jyamona]

There will be a better 4 bar sensor available eventually. If you want more now, you can run the AD-E 5 bar kit. One of those is on Jake H's car.

[Terry@BMS]

Terry, didn't you have to set up a function on the JB4 to calibrate the 4 bar on start up to the manifold sensor? The fact that you had to do that in the first place should be evidence alone that the 4bar is not good fit for us. You shouldn't feel bad, it's not your product. But it's not a coincidence that people have a problem with them all the time. It's less of an issue on the JB4 because the JB4 is manipulating the signal the DME is seeing because it's scaling the MAP itself.

Yes, we setup an algorithm within the JB4 to calibrate them. We do this for the OEM and 3.5bar TMAP sensors also internally but their variance is generally much less sensor to sensor. It's easy to add in extra logic to do that with the JB4. With a flash only setup, you'd have to measure the voltages and do a similar calculation to get the zero point perfect. If the sensor is not calibrated you'll get a 2ABD. If you try to disable 2ABD rather than fixing the root problem the car will run like total crap.

In any event we'll work on sourcing another 4bar sensor solution that does not require that initial calibration. And if someone out there has a 4bar setup from us that is not working for them by all means email us so we can make it right with you.

[Bob Loblaw]

My plan all along was to get a custom tune, but my clutch started slipping so I put off the tune until I replaced the clutch. That was done last week. The car was running well and logs looked good at 18 psi so I figured I would get a custom tune and maybe add a few psi, bringing it close to the limit of the stock TMAP. It was only after I bought the 4 bar that I started reading of people having problems. This was the first and only time I cheaped out on a part for this car to save a few bucks, but I think I will just get the 3.5 bar instead.

[V8Bait]

The only way I've been able to calibrate the 4bar is with Tony, who sat there with a manual gauge and pump and fed me voltages and pressures. I calibrated to his altitude and it worked OK, and he still switched back. The problem is, I can use the values from his calibration on another car, and they get hesitation and erratic performance, sometimes even with a JB4. Some people don't notice it, and sometimes just guessing with a calibration can get it "good enough", but the codes will come if it's not perfect, especially flash only. I'd say about 1/2 the flash only cars with the 4bar are successful for me, I consider that pretty poor numbers. JB4 is much better but not without issues, especially with the IAT at idle and cruise. I don't want to have to make people physically test that for each sensor just to get it right either.

I'm not sure of the best 4 bar to use these days, it's probably only due to the sensitive nature of our car that these things suck so much for us, but I'll ask next time I'm at LMR.

[Terry@BMS]

You have to calibrate each sensor. The JB4s process is to compare the voltages at startup where both sensors represent the same atmospheric pressure, then apply an offset to the 4bar to rescale it to 0. While the JB4 does it automatically I understand it would be more of a PITA on the flash only situation especially if the sensor calibrator floats around a bit. No changes should be needed with the JB4 except to adjust the lower end of the map conversion from 2.90 to 2.50 in some cases.

Anyway I'll keep hunting around for some alternatives.

[jlcf22]

Why are you guys still selling the 4bar? I had nothing but issues with it 2abd code was so annoying