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Best things to monitor with gauges?

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First post here, literally on any forum.

I recently upgraded from an 03 N/A Legacy to an 09 Legacy GT Limited 5MT.

I've been a diesel guy all my life, so I have an addiction to gauges. Anything that can be monitored, should.


I plan to have a Perrin 60mm dedicated boost gauge.

All other items to monitor will go to a Edge CTS2. Simple to install sensors and set up on the CTS2. Also, very "clean" install.




My question is this:

What items "should" I monitor with my 09?

Why or why not?


Here is what I'm thinking so far.

1) Boost

2) Coolant temp

3) Oil temp

4) Oil pressure

5) Exhaust temp

6) Trans temp

7) Fuel PSI.


Yes, I have read post about pods and which gauge manufacturer is better or worse than the other. But have yet to find concrete answers on what to watch and what to ignore.

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  • I Donated Too

Of course you can get whatever you want but depending on the model of this Edge thing you are well on your way to the cost of an AccessPort which besides having the ability to swap tunes and work for you as a tuning tool, it can monitor OBDII values in the same way. Albeit it will have a smaller screen however I think it would far improve on the usefulness of the Edge CTS2 as it can read codes, reset ECU and log and...


But more to the point of your question. Why are you monitoring, just for fun or trying to be serious about keeping track of the performance and safety of your engine? If all this is just to show off a flash display then monitor whatever values move a lot because it doesn't matter then if you're not taking this seriously.


Note the stock sensors are monitored in a very binary way so aren't accurate for precise values if you really want to know what's going on as soon as possible. Exhaust temps can only tell you what's already melted and won't help you prevent an issue so if you are looking to stay ahead of expensive engine issues you need a wideband O2 reading and that's not in the ECU now. The stock ECU only has a narrowband. You can go ahead and read the value on your fancy display or an AccessPort but it won't be as good as putting in a dedicated Wideband gauge with a good quality wideband O2 sensor. This is what can be used to stay ahead of bigger issues in your engine, especially if you plan on tuning or modifying.


Boost/Vacuum is useful but mostly more of fun thing although it will help you spot problems with leaks!


Oil Temperature is useful and I would argue you don't need to also monitor coolant temps as one will follow the other.


Oil Pressure is useful and will tell you when you have no oil/clogged pickup or a broken oil pickup tube and can inform you quickly that you need to shut the car off. The stock ECU light (and signal to your device) will come on after it's too late. Stock ECU sensor is also based on the 'hey it's too late' principle and you would need to add accurate auxillery sensors to really be ahead of a problem.


Wideband O2 values are very useful and tell you when you are too lean and too rich well ahead of rising EG temps.


KNOCK values are good things to monitor too as well as the DAM/IAM value as that will tell you if the ECU is pulling timing because other issues are occuring which you may not have seen happen on the other signals.


That's my 2c anyway. I wouldn't put in the CTS2, it's not that clean - you don't have a big diesel truck just a 4th Gen legacy dashboard. You need something a bit smaller or it's just going to get in the way of something else.

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Firstly, thank you for your info. As of right now, I'm looking to monitor to save my newly purchased car. I might upgrade/tune in the future, though right now I'm looking to have warning signs before the "hey it's too late" point.


Maybe clarifying a bit would help?

Having the CTS2 with a 5" display, I can have up to 12 "values" that are very easily read. Having one location where I can see the different items, and only take up the same space as a GPS seems the cleanest to me. The AccessPort is an option I hadn't considered and will look into. If I end up purchasing both, cost isn't really a factor.


As for monitoring the coolant and oil temp, in my diesel, if the spread is over 15 degrees it's time to pull over or you will cook/kill your motor. I was thinking along those lines... C


From your recommendation, would you install the Wideband O2 into a downpipe for best accuracy?

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Im currently running a CTS because I got a stupid good deal on it. I run it as a basic heads up display. MPH, RPM, Coolant temp, and intake air temp. Mine is just there for a heads up/wanted some live data type display. I would never tune off my numbers from there.
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I feel this has been a little distracted from my main question.


Other than the items sigmafour mentioned (Boost, Oil/Coolant temp, Oil PSI, knock, DAM/IAM, and Wideband O2 with dedicated gauge) what are you guys watching or montoring?


Is there any reason to watch the transmission temp? (I'm never going to tow anything)

I have read the ECU chooses Fuel PSI, is there any reason not to trust this?


I will look into the AccessPort more and the BtssM as mentioned. Thank you again.

Knowing diesels, this legacy is a whole new ball game.

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as long as the tune in the car is good, there isnt much you should worry about watching. the main ones should be oil temp (so you know when its warmed up and can start racing the engine), air/fuel (wideband), and boost. beyond that the rest are not really necessary for a stock / mildly modified car.


beyond that an accessport is just about the best investment you can make (and a protune), and if you want to see what the top monitors are there, its "A/F Learning 1, Boost, DAM, Fine Knock Learning, and Feedback Knock Correction; "check out this article for more info: https://cobbtuning.zendesk.com/hc/en-us/articles/200025134-How-to-Datalog

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Transmission temps... no. Unless you're racing the car at a track... and then get a proper gauge and an oil cooler anyway. No. No point to monitoring a lot of these things - some are important and some the car just gets on with quite well without you trying to look over it's shoulder trying to second guess it.


I think the roundabout thing we are saying to you is you don't need to monitor very much and certainly not 12 things on a stock car. A modified car sure... you monitor more things and you take it to the next level with better sensors but even then you don't need to monitor 12 things, might be better to concentrate on objects in front of the car.


Another thing you need to realise is the stock ECU is not a cray supercomputer. It may just about pass as a 32bit machine but it still struggles to output all of that data on request while trying to get on with everything else. IF there is an event and the ECU is dealing with it the requested values won't be updated to the external device especially if you're monitoring too many of them. It will lag behind and may skip over events. You are therefore better to monitor a few important values and not just add as many as you can.


I will keep saying... unless you're getting this Edge CTS thing really cheap, putting that kind of money towards a dedicated AccessPort will be better, even if you're not tuning. The smaller display will work out better and you won't be tempted to monitor too many events that aren't important.

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  • I Donated Too

For today 3/11 only... AccessPORT V3 ** 586-797-9083 - CALL TO GET PRICE **


Flash sale Friday is here... this time with the insanely popular AccessPORT V3. Price is so raw we're censoring it... this is a PHONE IN ONLY flash sale... call us for guaranteed LOWEST price you'll ever see on the V3. Sale ends at 5pm Eastern time TODAY... move quick.


It's $585 shipped apparently. I got this in my email at lunchtime from autocityimports.com. A vendor here on LGT.

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yep. I have seen it even lower too but I wasn't too impressed with the price when I called in. Just thought I would throw it up there. Cobb are very strict with resellers banging it out too low...


Checked KNS - nice site. But their advertised price is $650 like everyone else...

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  • 2 months later...

Well, ended up buying the AP for my car anyway. I'm working with a tuner on the future of my planned mods. I will be going with a wide-band O2 as well.


I tried the AP and decided on my "old" CTS1 (given back from a friend since he upgraded to a CTS2). Here's my reasoning: easier to read, looks cleaner IMO, and if my car is broken into it's half the cost to replace. Also, my tunes on the AP would not be lost either.


I'm pretty happy with how it looks.

Now I'm just going to add certain sensors as time goes.


Thanks for all the input guys.




(sorry about the reflection)



Sent from my One M8 using Tapatalk

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Wouldn't the side curtain airbag turn those gauges into ballistic face smashing missiles?


yes, yes they will, that's why its popular to do the vent gauge pod set up, still will get thrown but perhaps less violently.


having responded to a lot of accident scenes and personally seen GPS and cell phone mounts, etc... end up everywhere it gets crazy.


fact: responded to a MVA off a local road in my departments area. gentleman was already out of the vehicle complaining his head hurt...

his rear view mirror was lodged in his head! plastic housing and glass sticking out of his head with the half sticking out still usable mirror wise.


moral of the story crashes can throw anything anywhere they want. but a little precaution in proper set ups and not ghetto rigging interior components might pay off. ( in no way am I saying OP is bad set up) just people do forget about curtain airbags

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The airbag on our cars is on the top 1/3rd of the pillar, of which it's supposed to "peel" away if deployed.


I investigated this when deciding my mounts, and partly why I went with a dual pod and not triple.


The mounts are the least of my worries if I were to be T-boned at any moderate to high speed.


Sent from my One M8 using Tapatalk

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