Overboost at 2psi?

[Viprklr]

87 GN.
I'm getting an overboost code at only 2 psi. The aftermarket gauge and dash indicators both agree.
I've been searching and have only found overboost issues with high boost numbers.
What do you guys suggest that I look at?

 

[TurboDave]

Overboost code???

Since our cars ECM doesn't monitor boost, how are you getting a code? What kind of car are we talking about here?

 

[BMF_Racing]

87 GN.
I'm getting an overboost code at only 2 psi. The aftermarket gauge and dash indicators both agree.
I've been searching and have only found overboost issues with high boost numbers.
What do you guys suggest that I look at?

Also no code known for this, but I might have experienced what you might be talking about. Is the engine act like the Injectors turn off at 2 psi? Then if you let off and it idles fine? Sadly it only happened twice to me and I reset ECU and prom. Then it never did it again, so I don't know what caused it.

Worth a try.

 

[TurboDave]

BMF,

That was probably "limp home" mode. Hard to say what caused it without a code readlilly at hand. Did you have Direct Scan at the time.

 

[BMF_Racing]

BMF,

That was probably "limp home" mode. Hard to say what caused it without a code readlilly at hand. Did you have Direct Scan at the time.

Scanmaster was saying either 41 or 51 under NAL. I can't remember which one it was now, but do remember it was a Prom code.

 

[TurboDave]

Scanmaster was saying either 41 or 51 under NAL. I can't remember which one it was now, but do remember it was a Prom code.

that explains it. 51 code will put the car in limp home.

 

[BMF_Racing]

that explains it. 51 code will put the car in limp home.

So can I assume that the prom was just not seated correctly or the ECU just was due for a rest with the MAFT Pro ?? Just wondering if its something I need to address as preventive Maint?

 

[Viprklr]

87 Grand National
Code 31 - Wastegate failure/turbo overboost

 

[TurboDave]

So can I assume that the prom was just not seated correctly or the ECU just was due for a rest with the MAFT Pro ?? Just wondering if its something I need to address as preventive Maint?

Usually a chip seating issue, but could be some minor corrosion issues in the chip socket. Usually corrected by just removing and re-inserting the chip.

 

[Viprklr]

Also no code known for this, but I might have experienced what you might be talking about. Is the engine act like the Injectors turn off at 2 psi? Then if you let off and it idles fine? Sadly it only happened twice to me and I reset ECU and prom. Then it never did it again, so I don't know what caused it.

Worth a try.

Nope. It's not going into limp mode. The car runs fine. It still accelerates fine.

 

[pacecarta]

sounds like you have a stock chip in there, most modern chips ignore the wastgate solenoid if its disconnected

31 doesnt mean overboost , just once you get to where the boost solenoid is supposed to be activated to raise boost its throwing a code

either the wastegate (boost) solenoid on the passenger valve cover is defective or electrically unpluged (red two wire connector) or has been removed for another type of boost control

 

[Viprklr]

I'll look into that tomorrow. The car is my dad's at his house.
Does anybody know the resistance value range of the solenoid?

 

[pacecarta]

its just a coil , service manual says any reading less than 20ohms calls for replacement

 

[Viprklr]

Wonderful! Thank you very much.
I've done some searches through parts stores and haven't had any luck looking for a wastegate solenoid (in case it needs replacement).
Does it go by any other name?

 

[pacecarta]

yeah discontinued
if you want one (i dont run them ) post up in the parts wanted forum ...maybe someone has a used one

 

[Viprklr]

Another intelligent move by GM.
Thanks for the heads-up.

 

[Viprklr]

Turns out somebody removed the solenoid. Apparently it's also not turned off in the ultrachip.
It's always fun buying a car that somebody else has already started to modify.

 

[TurboMonte 2]

I moved-on with a manual boost controller (Q-boost) in my case, but RJC makes one also...

Your most recent post was first indication of non-stock chip info (or any info on car for that matter...). Why don't you create a "signature", with some car/ build details...

As previously suggested, you can post in "Parts Wanted..." section--if you wish to pick-up a used one--hopefully in good working condition!

Good Luck,,,

 

[salvageV6]

You can simulate the solenoid in circuit (accross the two wires) with a 100 ohm resistor, I'd use a 1/2, 1, or 2 watt version should be available at Radio Shack.

That should kill the code, probably can get a 2 cavity connector from Caspers to wire it into if you want, Pep Boys also carries some weatherpak stuff on the shelves.

Better double check what's running your boost and how it's being controlled check how the hoses are routed and if there's a bleeder valve somewhere that could cause over boosting.

 

[TurboMonte 2]

When I went to manual boost controller w/ bleed, I did not get any codes when removing the WG solenoid & running with the wire/connector just laying loose--disconnected. I was, however, then running TTwk chip, 16'ish # boost on 93 pump gas...

I went to the manual boost controller to eliminate a 1.5-2.0 # boost spike--which, thankfully, it did...