Yesterday I finished up my gauge installation. I selected Glowshift Blue Digital and consisted of Coolant Temp, Trans Temp, EGT and Boost, they are installed on the pillar. I selected the Glowshift on price and wanted to see how they performed against the Autometer Red Digital I installed in my other F250 last month.

1. The glowshift gauges are economical only because (imo) they don't provide all the reducer bushings needed or gauge wiring length needed to complete the job. I needed to buy a reducer bushing to mount the sender for the coolant. I then needed to buy 5 rolls of different colored 18 ga wire (connecting 18ga to 22ga) and a large box of butt connectors to get all the gauges hooked up. By comparison, Autometer supplied enough wire to get the job done and included the reducer bushings for both the trans temp
(if needed) and the coolant temp (needed). The wiring with the Glowshift gauges came in at 22 ga whereas the Autometer gauges (I think) was 18ga. It would have been nice to have enough wire to complete the job without splicing (adding) into it.
2. Installing the pillar set of gauges from Glowshift was more time consuming than installing the Autometer gauges. About 3 hrs longer. The Autometer gauges were installed with a dash mount pod instead of a pillar pod.
3. I didn't buy the Boost Gauge for the Autometer setup and here is my question:
This is the first time I have used a boost gauge so I really didn't know what to expect when the engine is running or driving the truck. The boost gauge is plumbed into the map sensor vacuum line. At idle the digital gauge read -2 or -3. When I start to accelerate the gauges moves to 0 and then moves to 1, 2, 3 and when I accelerate hard to move into traffic from a stop it maxed out at 15lbs let off the accelerator and the boost goes back down to 0. I assume this is correct operation? Why do I get -2 or -3 at idle? I would have thought 0 would have been the end of the line. Is 15psi the max boost for these trucks that are stock?

Bottom line...I won't buy the Glowshift gauges in the future. I'll stick with Autometer.

Jeff

 

Those readings are completely within the normal range. I get the "negative" readings, at idle, with my Aeroforce Interceptor scangauge. I asked Jody @DP Tuner about this at RRE a couple of years ago. He and Clay both stated they've seen these readings before. Even with my new billet wheel moving more air, I still see the the slight vacuum at idle at times. BTW, I have Autometers.

 

Thanks for that info Jeff. I was deciding between glowshift and autometer for my X and if I have to buy extra suff to finish the install then I will get autometers instead.

 

The negative number will be effected by the type of intake fileter and how clean it is.

 

I have the glowshift gauges. I have a whole supply of wire and connectors on hand and actually expect to need connectors and wire when doing any gauges (even have to with auto meter gauges). I have the boost and trans temp gauges and needed nothing for plumbing.

 

I think you should get everything needed to install a guage when you buy them. When I bought my Banks gauges I had enough wire to do two vehicles and connectors out the wazoo.

 

Yes I agree, however if it drives up the cost to near half the gauges actual worth just to have 20 different fittings and a roll of wire in the box I would rather source my own and save the money.

Also many times the connectors and stuff they supply are the cheapest possible thing they can find. I like to use solder and heat shrink whenever I can. Even at connectors.

 

It's a 6673 filter installed 3 months ago.
Jeff

 

I agree. When buying gauges specifically for the 7.3/truck the gauges should come with all the pieces needed to do the job and the wiring should be the correct length. One should not need to drive around looking for additional parts. With the Autometer setup I didn't need to go find parts..spent my time installing them.

Jeff

 

I agree, quality soldered connections can save a lot of headaches later.

 

The negative value at idle is normal for a lot vehicles using the manifold absolute pressure sensor for a gauge sending unit.

Why? There are a couple possible reasons.

1. Look at Tugly's myriad of posts concerning skewed exhaust backpressure sensor readings. Do you think the manifold pressure sensor is immune to this anomaly?

2. On a 99-up 7.3L, the PCM receives a voltage input from the sensor. This voltage IS NOT ZERO at "0 PSI". The base voltage for 0 PSI is going to depend on ambient atmospheric pressure and this voltage input to the PCM is compared against the barometric pressure sensor voltage on to validate on initial key-up. 1.1 Volts is supposed to be 14.7 PSIA. If you're in a region (elevation) of less than 14.7 PSIA, the voltage output will be less than 1.1V. Lower voltage will result in a MAP reading from scan data being less than 0 PSIG.

 

Wouldn't there also be the "Turbo no blow" factor at idle? I'm thinking the turbo was made to make good pressure at higher performance, and idle is one for those scenarios where the turbo is out of its zone. The engine is going to take what it wants, whether the turbo is providing pressure or being "suck-driven".

 

I got into this "vacuum" discussion a while back. Tugly's statement about a plugged filter or restriction in the intake side of the turbo could cause "a vacuum reading". However I discussed this with a friend that has been a cummins trained diesel/automotive mechanic for 30 some years. In order to have MANIFOLD vacuum you need a throttle plate to create a pressure differential between ambitent atmospheric pressure and the manifold side of the throttle plate. Diesels do not have a throttle plate, they are open to atmosphere. If one indeed has a vacuum in the manifold you have a problem.

 

Just found this.
A MAP sensor will never display a negative reading because it is measuring absolute pressure, where zero is the total absence of pressure (it is possible to have conditions where negative absolute pressure can be observed, but none of those conditions occur in the air intake of an internal combustion engine[citation needed]). Boost sensors can display negative readings, indicating vacuum or suction (a condition of lower pressure than the surrounding atmosphere). In forced induction engines (supercharged or turbocharged), a negative boost reading indicates that the engine is drawing air faster than it is being supplied, creating suction. This is often called vacuum pressure when referring to internal combustion engines.
In short: most boost sensors will read 100 kPa less than a MAP sensor reads. One can convert boost to MAP by adding 100 kPa. One can convert from MAP to boost by subtracting 100 kPa.

 

That fits with what I was thinking. An external boost gauge is free from the bondage of the rules of the Ford MAP sensor. The turbo blows air at idle, but I don't know if it's as much as the engine sucks. A restricted air filter could further reduce the turbo's ability to supply air so low on the turbo's operation envelope.