N62 4.8is thermostat swap from 105 to 90c problem

[bmwktm]

Hi, two years ago i swapped OEM to 90c thermostat because i was getting "thermostat stuck" error and was not able to reach temps over 70c. I have decided to give it a go with custom 90c so i can keep the pressure down. It is 17 y/o car so just trying to prevent coolant leak problems. Now my temps are just fine, around 85-90c, but I am still getting same error message because the car expects temps well over 100c.

Everything is working properly and i have no problem with that. BUT i think it is consuming more fuel since DME thinks the engine is still cold and it is throwing more fuel in it, hence lower MPGs.

Also I do not know if there are any other problems i could have in several years because i want to drive this car as long as i can since i like it really much.

MY MAIN QUESTION:
I have been trying to find out for several months now, is there a way to code 90c instead of 105c using INPA, ISTA or NSCexpert/dummy?

Anyone switched to 90c? What was your experience with these problems and how did you solve them?

Thanks!

[bmwktm]

WOW, no one? At least a comment from people using t-stat with lower temp. Are they seeing any side effects?

[EODguy]

Did you change out your cap too? That's where you'll get relief on your system by dropping the pressure.

Do you run some real time software while driving, like Torque Pro on your head unit? Are you getting good temps in all conditions?

Any codes coming back after resetting with a good scanner and not just seeingold codesdue to scanner not being up to it?

*(My setup while driving)

Sent from my SM-A730F using Tapatalk

[bmwktm]

Well thank you for your effort but I can just repeat what I already wrote.
- I am getting good temps… 85-90c
- I am running INPA and ISTA (Rheingold) for live data (and many more). Google it, those are BMW OEM software and way better than any scanner or phone app, you could give it a go, but Windows laptop and OBD2 eBay or Amazon cable are needed to run those. You can do with this software literally everything people in BMW can do, if you know how to use it. And that is my problem at the moment, I don’t know how to program a new operating temperature.
- Yes I am getting an error “thermostat stuck”
And lastly, I did not change the cap. Normally it is acting only as an emergency pressure release if things go wrong, it is not a part of regular engine temperature regulating system. It is not opening and closing when you normally drive a car. It activates only in extreme situations (when the pump brakes and coolant recirculation stops, or blown head gasket, or radiator gets all smudgy inside so it limits coolant flow and so on…) and I am far from it. And OEM one is going to do its job if it comes to it. To drop the operating pressure, I used the 90-degree Tstat.
So basically, it is all good, I just need to “tell” the car that normal operating temp is not 105 but 90 degrees and the error message wont reappear and I will get my MPG back.
Thanks for your help and I hope I helped you too!

[crystalworks]

I bought a Logic7 lower temp thermostat. They claim to "recalibrate" OE thermostats so as to not cause a CEL. I don't know how they do this, could be as simple as a resistor. But I've never heard of someone coding the car to run a lower thermostat, just modifying the thermostat.

Not saying it can't be done. Just that I've not heard of it.

[EODguy]

Yes I know ista and inpa, the Torque Pro runs on the head unit full time so you don't have to run a cable and it is just an informational app that about 90% of us use in our BMW'S and I use a Foxwell unit when I want to do deep scans and or maintenance (it's so much better than ista-d.

As for the cap BMW used to use a lower bar/psi cap and for some reason (temperatures they wanted) they went with a higher bar/psi or else the coolant would boil, but as it stands with your new lower temp thermostat you don't need the extra pressure so going with a lower pressure cap will slow down the wear and tear on the whole system especially the expansion tank. Hope I've explained it well enough to help you on that reason.

Now your lower temp thermostat should still be getting warm enough to not cause any codes and if it is, then you could have a failed open thermostat just installed or not sometimes things fail even when new.

Did you clear all codes stored/pending? No intake implausible readings?(can cause your symptoms I believe because numbers don't jive in the PCM powertrain control module/DCM)

Sent from my SM-A730F using Tapatalk

[bmwktm]

- yes, sure, Foxwell is better than OEM software
- my brain hurts while reading this
- that is not how thermostat works, it has 0% dependence on the cap release pressure as long as it is up to OEM spec.

- for the 3rd time yes, deleted all. No other messages.

At this point I do not know if you are a troll or serious but please stop what ever it is.
Thanks anyways

[EODguy]

Ok you misunderstand what I'm saying about pressure.

The reason that the cooling system gets so worn out is because BMW went with a higher temperature thermostat and to ALLOW that temperature increase they had to increase pressure. You seem to think it's the temperature causing wear and tear (it's not, hence expansion tanks popping) and running a lower thermostat cures it all. With a lower temperature you do NOT need to run that higher pressure so reducing pressure will also reduce stress on hoses, tanks and header plate/tube welds. I used to build/rebuild radiators for a industrial applications about 35 years ago.

I do know how a thermostat works but since the original BMW thermostat is partially controlled electrically to help manage fuel economy and so forth it's not just straightforward like a thermostat that is just a bi-metal valve AKA bellville spring.

Does your new lower temp thermostat still have an electrical connection? If it doesn't then there is how you can fix it by providing the circuit with whatever data it's expecting.

Also you might want to understand that just because you asked a question no one here has to answer you and your (Wow really!?!) post set the tone, plus we each have our own way to troubleshoot or flowchart things, after posting it's advisable to wait since we are from all over the world and timezone issues can delay responses. Especially when being asked by someone with only 15 posts, a free account who is such an expert in BMW OEM software.

Foxwell does all the same things as ista-d and can even code some modules like ista-p though for doing coding it's definitely not as good.


Sent from my SM-A730F using Tapatalk

[bmwktm]

You seem as some frustrated fella. You did not help at all with all this writing with my question which is "how to code in a new temp?". I had more useful info in my 15 free posts than you in your 1000. Feel free not to write any more on this thread.

[Overboost]

Man I love this forum. A newbie with 16 posts scolding a couple members trying to help with a combined posting count of over 5,000 posts.