Boost Gauge and Digital Multi-gauge

Boost Gauge and Digital Multi-gauge

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Discussion

cornflakes2

Original Poster:

230 posts

76 months

Saturday 10th March 2018
quotequote all
I have an EOS P3 OBD2 multi-gauge and a Boost gauge by Defi (see picture)


Earlier today went into shop and the guy took out my throttle body to check it (all clean no problems) and put it back in.
On the drive home, I noticed my boost gauge wasn't working. The needle was at -0.2 or -0.1 and never moved even if I floored it or put foot off the pedal.
So I thought it might just be a plug he didn't connect back. So then I checked my Digital multi gauge and when I went to Boost option, it should me
it was moving but only a little between -0.2 to -0.4 whether I floored it or not. Normally it should go up when flooring it (boost) and go down (vacuum) when foot off the gas. I noticed my throttle also only maxed out at 35 in the reading when I floored it but should go higher than that.

So lastly, I checked plugging my obd2 bluetooth device into the obd2 port and connected it with my phone and used torque pro app. There it should the boost/vacuum properly. It would go up into boost when flooring it and - into vacuum when letting off. Throttle worked also as the readings showed it went well over 35 when i floored it and went down when i let off.

Did the mechanic plug all my wires the wrong way? Or did he mess something up to get such odd readings like this and why the boost gauge doesn't move (needle)? I don't really know if it's that he forgot to reconnect something or he crossed them up probably...putting a wrong hose into a wrong part? Is that possible?


cornflakes2

Original Poster:

230 posts

76 months

Saturday 17th March 2018
quotequote all
I was just watching a video about the boost gauge and found out there is a small part called the boost tap that has to be plugged into the hole on the manifold. If you forgot to put a boost tap back in there and just plugged a hose on, would that be the reason why my boost gauge is not reading correctly?
Boost levels show up normal when checking with OBD2 reader live while driving, but my mechanical boost gauge needle doesn't move much at all...maybe only half an inch, and the P3 digital gauge also doesn't read my boost properly either. Only the OBD2 reader shows my boost/vacuum at proper levels while driving.


jkh112

21,889 posts

157 months

Saturday 17th March 2018
quotequote all
The boost tap is the part that is tapped into the manifold to permit the hose to be connected, without the tapped fitting the hose will not fit and if it left off you will have a leak.

stevieturbo

17,229 posts

246 months

Saturday 17th March 2018
quotequote all
So are you saying both are incorrect, or one OBD system/reader is still reading correctly ?

Generic OBD do not always give correct information, so one of them may need reset or settings adjusted.

And does your separate boost gauge get its info via OBD, or via an external sensor or plumbing to the intake ? And has this been refitted correctly after whatever work was done ?

GreenV8S

30,150 posts

283 months

Saturday 17th March 2018
quotequote all
I suspect that if you look around in the general area of the throttle body and intake manifold you'll find a spigot designed to have a vacuum line on it, and an unattached vacuum line dangling around.

cornflakes2

Original Poster:

230 posts

76 months

Tuesday 20th March 2018
quotequote all
The OBD2 app that I use shows all the levels correctly while driving.
The mechanical boost gauge shows incorrect readings (it barely moves),
and the P3 digital gauge for some reason also show incorrect readings for only the boost/vacuum and throttle readings.

Since the last check up, the guy took out my throttle body to look at it and put it back in. I suspect he forgot to plug
something back in or he switch something up (like a boost line into the throttle line and the throttle line into the boost line if that makes any sense or if that's even possible?).

I did take a look inside near the intake manifold but I couldn't find anything dangling or loose. I don't really know which line leads to what either. I was just looking to see if there was any loose or unplugged connections/hoses etc.

I will just mention this to my next checkup and they can probably figure it out.

cornflakes2

Original Poster:

230 posts

76 months

Tuesday 20th March 2018
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As I've been self-studying, I've come across a lot of confusing terms and the reason is because I found out many parts/tools go two or more names! It's really confusing for a newbie when studying/researching. It would help if any of the more experienced mechanics here could point out some more tools/parts that often go by two or more different names.

Here are a couple that confused the hell out of me until I realized they are actually the same thing, just different names!

-allen keys are the same hex keys
-cam follower is the same also known as the fuel pump tappet (WTH?)
-coils/coil overs are all the same things as ignition coils or coil packs ---> they all mean the same thing!!
(previously some people were telling me to change coil packs and then another was saying change ignition coils and I was like....wth? only to find out later they are actually the same thing).

any others you can let me know of? thanks

Mr2Mike

20,143 posts

254 months

Tuesday 20th March 2018
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cornflakes2 said:
-coils/coil overs are all the same things as ignition coils or coil packs ---> they all mean the same thing!!
(previously some people were telling me to change coil packs and then another was saying change ignition coils and I was like....wth? only to find out later they are actually the same thing).
These are very different things, there's no relation at all. "Coilovers" are coil-over-damper suspension struts with adjustable spring platforms, which typically use standard sized springs (e.g. 2.5 inch diameter) , and may have adjustable dampers. They give a simple way of adjusting ride height and there is a wide selection of spring lengths and rates available in these standard sizes.

An ignition coil is a single unit, that may deliver a spark to one or sometimes two spark plugs (double ended coil). A coil pack is an assembly that integrates more than one ignition coil.

stevieturbo

17,229 posts

246 months

Tuesday 20th March 2018
quotequote all
You are maybe confusing things, but there should be no confusion.


It does sound as simple as whoever was working at it has not refitted everything correctly...most notably a pipe for the mechanical gauge.

cornflakes2

Original Poster:

230 posts

76 months

Tuesday 20th March 2018
quotequote all
stevieturbo said:
You are maybe confusing things, but there should be no confusion.


It does sound as simple as whoever was working at it has not refitted everything correctly...most notably a pipe for the mechanical gauge.
Agreed. I tend to believe that more than anything, but just trying to cover a wider net of possibilities...part of my learning experience. It's a common reaction when one doesn't know very well the topic at hand. It's like in medicine, if one doesn't know what the exact symptoms of a particular disease is, then one will think that ANY and ALL symptoms could be related to that disease.

cornflakes2

Original Poster:

230 posts

76 months

Tuesday 20th March 2018
quotequote all
Mr2Mike said:
These are very different things, there's no relation at all. "Coilovers" are coil-over-damper suspension struts with adjustable spring platforms, which typically use standard sized springs (e.g. 2.5 inch diameter) , and may have adjustable dampers. They give a simple way of adjusting ride height and there is a wide selection of spring lengths and rates available in these standard sizes.

An ignition coil is a single unit, that may deliver a spark to one or sometimes two spark plugs (double ended coil). A coil pack is an assembly that integrates more than one ignition coil.
thanks mike!