LML Low Boost...maybe?

shooter5635

New member
Jun 18, 2017
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Hey all,

Not sure I even have an issue but want to check as my warranty expires in August. 2013 LML. 42,xxx miles. It had a very, very easy life before I got it. I get roughly 16.5 mpg hand calculated daily driving (a good amount on the expressway.) no codes. No hiccups. Truck "feels" fine. If you smash the go pedal, she goes. It's completely stock.


I kicked her in the behind on the on ramp this morning and watched my ultraguage boost and it maxed out at 11.5 psi...

As I said, the truck has no codes, runs fine, gets decent fuel mileage from what id consider for a completely stock truck.

I've had issues with this ultragauge before, so I'm leaning towards that being the issue but I'm not sure.

Thoughts on the low boost? Also, how long at WOT does it take you guys to build max boost?


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kiwilml

Member
Nov 4, 2015
454
0
16
Not long, if it downshifts and rpms go to 2500 or more it'll hit full boost in a second or two.. 12 pounds is not right, so either a leak or a bad gauge..
 

shooter5635

New member
Jun 18, 2017
7
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0
I should mention for those that don't know, the Ultraguage is a OBD2 plug-in style gauge. Its a cheaper version of the Scangauge.


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shooter5635

New member
Jun 18, 2017
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I've been doing a ton of reading on diagnosing boost leaks, MAF sensors, baro sensors, and MAP sensors.

The ultraguage is reading baro at 100 key on engine off, which is correct. It's reading the MAP at 9.4 key on engine off, which is wrong. It should read 14.x at key on engine off from what I've read. Turning the engine on lowers the MAP value by 0.10-0.20 at idle. When it spools it acts accordingly and increases pressure.

If the MAP sensor was that wrong all the time, wouldn't it throw a code?


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496 BB

Head Thread De-Railer
Feb 20, 2009
697
5
18
43
At your girlfriends house
If you want accurate readings Id throw that in the trash and get a CTS2 or add mechanical gauges. Especially if youve had issues before. Being stock though the ecm will tell you when theres a problem most times.
 

shooter5635

New member
Jun 18, 2017
7
0
0
If you want accurate readings Id throw that in the trash and get a CTS2 or add mechanical gauges. Especially if youve had issues before. Being stock though the ecm will tell you when theres a problem most times.



Thanks for the response. I can't wait to pitch this thing and get a CTS2. It's next on the list


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shooter5635

New member
Jun 18, 2017
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Just an update for if this ever ends up in a google search.

Picked up a CTS2 Insight. All is well with the truck. MAP is reading correctly. Boost is where it should be.

The ultraguage ended being the issue.


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