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First Drive in the books, questions on an issue


BlueCuda
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I got my first drive out of the way yesterday.  I haven't registered it yet so I kept it in the neighborhood.  Everything went really well, engine runs great cruising around and the rest of the car seems solid so that is a good relief.  

Only real issue I had was that it shows lots of boost on the stock gauge but the car doesn't seem to make any.  I didn't beat on it but I did roll in the throttle a little and it indicated 10+ lbs of boost but didn't really pick up.  It cut out a little as I assume it was commanding to much fuel.  I will try again with an actual boost gauge hooked up.  

Assuming I am right and it makes very little boost while the stock gauge shows 10+ lbs where should I look?  I have another air meter I can try and will likely do so.  It runs to well off boost to have much of a leak in the charge pipes but I will certainly double check.  

A little background that might help is I got this car not running and partially disassembled.  It had an ebay 16G rigged up, MAF T, and Apexi II on it.  When I swapped the engine I went back stock.  I went back stock turbo, stock air meter, and I removed the Apexi and repaired wiring where that was installed/hacked in.  So it is essentially bone stock other than an open downpipe right now.  It starts, idles, revs, and cruises as it should.  

I went back stock because if/when I modify it beyond what the stock stuff will handle I will either built a Megasquirt setup for it or buy one of Scott's.  My other car has an MS3X on it and I like the platform.  

 

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That is about all your going to get out of a stock set up. I would install a aftermarket boost gauge as the stock gauge is not that accurate. Autometer ATM-2601 Z-Series mechanical boost/vacuum gauge is a nice one and mounts where the stock gauge is with a little work. If your looking to up the boost safely, I would look into what mods your going to have to make:

Ecu upgrade.

Fuel mods.

Turbo upgrade.

Look on this site for information. We lost a lot of write ups when the site crashed, but there are members who can guide you in the right direction.

Good luck, 

Bill

Edited by Caliber308
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I am not looking for upgrades at this time, i am trying to figure out why the ECU thinks it is making 10+ psi when it is clearly not.  I will update this with more information once I get back out there and drive it with a real boost gauge hooked up. I didn't do any driving that would have allowed it to reach such boost but something is telling the factory gauge its making more than stock.  

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the ecu does not "think" it is making 10psi, it "expects" 10 psi. these cars do not measure the pressure. they only add enough fuel to cover the air. if you're having problems during boost I would start out looking at the secondary fuel injector. the factory boost gauge is known to not read correctly so there's no point in even looking at it. if you don't want to pay for upgrades to help diagnose your problems, you will not get far with these cars.

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Posted (edited)

I don't think my question is understood, I am simply trying to figure out why the ECU "thinks" or "expects" 10+PSI when I am lightly in the throttle and the car is clearly not making that much boost(nor should it be).  It seems to be fueling based off of that number and dumping way to much fuel.  Just cruising around it runs perfect, but it quickly rockets the gauge up to over 10PSI with just light throttle.  I am trying to get to the bottom of that, is it an air meter concern, obviously I need to look for leaks in the charge pipes and throw a real boost gauge on it.

In my mind there is zero reason to start throwing mods at it until it runs correctly bone stock.  When I figure this out I will post the results.

 

Caliber308 thank you for the Autometer part number, that is likely what I will go with.  I need to work on the cluster anyways because the oil pressure gauge doesn't return to 0.  

 

Edited by BlueCuda
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Here is information from the FSM. The boost meter is basically an ammeter. Based on the intake air volume signal from the air flow sensor and the engine speed signal from the engine speed sensor, the ECU computes the load and determines the duty ratio accordingly and drives the boost meter.

Just because i"m curious... When the p.o. had the 16G installed, did he have a boost controller installed?

Here is a bit of information on how accurate the stock boost gauge is. In 1989 when I bought my starion the boost meter would read 14psi at WOT. It was not until 2002 that I started to mod it and installed  the autometer boost gauge. The true reading......7psi on boost.

Here is a tip... When you install your Autometer boost gauge use the vacuum port below the row of three on the throttle body. Splice it into that hose. Why? You want the lowest source of vacuum for the most accurate reading on the boost gauge.

 

Bill

Edited by Caliber308
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Yes it did have a boost controller on it but it is currently not plumbed in.  

My previous 87 had a super 16G on it and it would peg the stock boost gauge then it would start to go backwards lol.  On a real gauge it ran about 13psi.  That particular 87 didn't seem to have a boost cut because it saw 20-30PSI while trying to dial in a home made boost controller, I was lucky to not put parts on the highway during that process.  

 

 

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9 hours ago, Edde said:

I've seen this exact thing with the boost guage swinging with a bad MAS.

I have a spare one and I plan on trying it this weekend after some other checks.  Thanks

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Can a MAS be damaged if the plug is reversed?  I know that happened to the one in the car now because all of the tabs are broken off the plug on the car side.  It wouldn't start when plugged in, reversed the plug and it fires right up.  

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I got home tonight and changed the air meter out to the one off of my parts car.  FIXED, it runs great.  I made a couple of wide open pulls in first and second and it felt pretty good.  Just a couple of more items and this thing will be ready to get some miles on it.  

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