TIPSP: I understand that an ECU would probably be the easy way and you have shown me that it is in my budget.

There are a couple reasons I am being stubborn with the boost controller:
1. ECU is a plug-and-play. I want to feel some self-accomplishment
2. If I bought an ECU I wouldnt have money for gauges which I have always wanted
3. Since I don't know how long I will have this car, I have vowed to myself that I would only buy parts that could be moved to another car

I really do appreciate all your information on ECUs though because I like learning about that stuff.

Here is what I was thinking (please shoot me down if I'm wrong):
My ECU should be capable of supplying the fuel (T5-R in an 850T)
The monitoring gauge is just some reassurance (EGT, or whatever)
As long as the EGT tells me I'm running rich or lean, it doesn't really matter which one. If it runs rich/lean I can take it to the volvo dealership and have them diagnose if it is rich or lean...right?
But keep in mind, all this assumes my ECU malfunctions and doesnt supply enough fuel (probability probably low)
I was thinking I could run the car before installing the boost controller for about a week and take self-diagnostics on how the exhaust temp. behaves.
Then, once installed, I would have something to compare to.

Sound legit?

My setup on my 1991 740 turbo wagon (745T): MBC, and a boost gauge. I have been running my MBC @ 12psi for the past 6 months with out the A/F gauge or EGT, and have had no problems.
I Really think you will be okay with out an A/F gauge or an EGT gauge because you are still within the ECU capabilities. But if you want to get one of the two gauges, go for it.

So get the boost gauge in and record you stock numbers, then hook up the MBC @ 13-14psi, and enjoy.

Just remember that you will have to run 91 octane or greater.

Have fun with it.

I think I will get the EGT just in case...maybe
If I do, how would I monitor the gauge?
Say I drive 70mph constant with 8 psi and record the temp.
If I drive 70 mph with 14 psi will the temp be the same?
Basically, what my question is will the new boost level run hotter?

It might be hotter. I dont have an EGT hooked up yet so I really dont know.
I stick my hand after the tail pipe and see if the gases are hotter after the MBC...and I can't feel the defference between stock or more boost.
Another thing you can do is go by smell. Lean and rich mixtures have different scents, but I keep forgetting to try this out.

Hlm rica remap
 

I'm trying to relate the a/f gauge and the EGT because I have heard they accomplish the same task. I will google if necessary.

Sorry I myself do not know.
There is alot of stuff I am still learning.

Ditto on that one Tech, although you are probably 10 steps ahead of me on learning. I love these forums though, I learn so much from them. I haven't heard back from VJC yet but I sent him a message responding to his "just bought" thread. I believe he is currently running a boost controller with a stock 850T ECU. Whereas I have a T5-R.

Ok I did a Wikipedia search it says that people can get an "idea" of fuel ratio.

That still doesn't tell you your exact ratio like a WIDEBAND does.

So if you want to beat around the bush and just get an "idea" hen get an EGT gauge. If you want the real deal and the real readings get a WIDEBAND.

"An EGT gauge is an automotive meter used to monitor the exhaust gas temperature of a combustion engine in conjunction with a thermocouple type pyrometer. by monitoring EGT, the driver can get an idea of the cars air to fuel ratio. At a balanced air/fuel ratio, the exhaust gas temperature is lower than in a lean or rich air fuel ratio. high temps (typacaly above 1600 degrees F) can be an indicator of dangrous conditions that can lead to catastrohic engine failure.

This meter is most used in tuning turbo equipped cars. If the sensor is installed at the manifold collector before the turbo, the turbine inlet temperature can be monitored. If the sensor is installed after the turbo, the exhaust temperature can be monitored. Because EGT will typacally drop 200-300 degrees F across the turbine, installers in general will try to put the thermocouple as close to the heads as possible to give a true reading that will require less mental math to read properly, and a reading that will react faster to the engine's condition compared to a installation after the turbo.

using an EGT alone is considered an older technique for getting the most out of an engine as a gauge type wideband digital oxygen sensor can be purchashed for about the same price or for a little more. however some advanced racers will use EGT gauges in combination with a wideband o2 sensor to 'lean' the fuel ratio a bit to safely raise temps for more power."

I saw VJC's thread named "just bought". In it he described the boost controller he was installing on his 95 850 turbo wagon. Does anyone know if his ECU was stock because I figured the T5-R ECU would support more boost and that a stock turbo ECU wouldn't. Either I'm wrong or he is running lean.

The stock ECU will support the same as the T5-R. Both ECUs will have the same fuel cut, but the T5-R should run a little more boost from factory.

so as long as I don't run over 15.5 psi I am ok? Is that what it boils down to?

I mean, the ecu will know to dump more fuel if it senses more boost correct? And how does the ecu monitor boost and a/f ratio, etc.

Yes. Set your MBC to ~14psi and you will be fine.

Yes. the ECU gets all of its info from the corresponding sensors on the car. It use the MAF to see how much Air is is being sucked in by the turbo, and the O2 sensor to adjust the A/F ratio. Now I believe that volvo uses narrowband O2 sensors, so when ever you mash the pedal, the ECU will automatically run on the rich side.

Just remember that you will have to run 91+ octane from now one, if you don't already. The higher the octane level, the more boost you can run...well up to the fuel cut off.

my wifes ECU is stock and it is running 12 PSI.
After 30K the plugs came out normal not rich or lean burning. They came out looking perfect.

Hey thanks tech.

So now I guess I have two questions kind of off topic.

Since I won't be needing an a/f or EGT, what is another good gauge besides the boost. I was thinking oil pressure because my cars oil acts funny sometimes. Normally, it burns just as much oil as a 150,000 mile car should. However, one time it burned almost ALL my oil in two weeks. Because it had only been two weeks since I last checked my oil, I wasn't going to until my dad asked me to, almost like he had a hunch. I think I had to add like 2-3 full quarts it was so dangerously low.

My car as been smelling unnaturally funny lately. It goes through spurts of having good MPG then bad then good without any maintenance. You can tell it burns a little bit of oil by the smell but lately, and it could just be me imagining things, it has been smelling funny. Almost not like a car. It almost smells like the is an odd chemistry experiment going on in my tailpipe. lol. The only way I can describe it is a nose-hair-burning, toxic kind of smell. But like some other problems on my car it may just solve itself.

I basically have a stage zero tune already. Only a month ago I had issues with spark plugs not firing. Took it to Volvo and had them replace spark plugs, wires, and distributer cap. Air filter is pretty new but I believe my fuel filter is old. ONLY $30.00 ON IPD. That is amzing considering my volvo dealership wanted to sell it to me for $70.00 excluding labor.

Every once in a while I get weird-goings-on with that car. Today when pulling to a red light, I was braking with my foot off the gas and the car was still running between 2-3 rpm and so I threw it in neutral and it stopped after a second or two. WEIRD

The car is like a mystery how it's going to behave on certain days. Somewhat annoying but I love the performance.

First I would make sure the Vent system is working properly.

Is the check engine light on?

No check engine light.
Are you talking about th cabin venting system or like the exhaust

The engine vent system.

Can you elaborate? Im an amateur when it comes to that subject.