over boost limter ?

[Kozmo930]

OK guys stupid question .....everything is new but I have found out at about .09 bar or just short of 1.0 bar boost we have a shut down issue , rev limiter , fuel pump shut off something is going on . Is it as simple as a over boost switch on intercooler that needs to be changed ? any help would be good

just a quick note / 1.0 bar spring in waste gate , but can't get there

Kozmo

[dos531]

Ground the overboost switch wire and see if it goes away. If it does its the switch. It shouldn't cut fuel until about 1.2 bar if I remember correctly.

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[aerochip]

Make sure you have accurate boost readings and know where you are reading them from. Stock boost gauge can be unreliable and/or inaccurate.

[infraredcalvin]

Yes see the above. Ive been sealing up exhaust leaks and removed HEs for a more efficient exhaust path. Now my wastegate can't keep up when hitting boost, I get a 1.1-1.2 boost spike that trips the cutoff. Very annoying on both accounts, as the switch gets tripped, it seems to wear out the threshold and trip at lower and lower pressures. You may have a combo of all of the above...

[fredmeister]

Originally Posted by dos531

Ground the overboost switch wire and see if it goes away. If it does its the switch. It shouldn't cut fuel until about 1.2 bar if I remember correctly.

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I just had the same issue surface on my 79 930. I grounded out the switch and everything was fine.

Replaced the over boost switch and "alles in ordnung".

Replacing the switch is difficult to get a socket over it since its like 22 or 24mm nut size.

Good luck,
Fred

[JFairman]

You can replace the extremely over priced overboost sensor that screws into the intercooler end tank with an adjustable hobbs switch with the same threads on it. Then adjust it to do it's thing at a higher pressure than the original one.

Or just ground the white wire and forget about it.

You don't need a socket to replace it, it's not in there tight. Use a combination wrench or a crescent wrench.

[kenikh]

What's the thread spec? Here's one that is pretty common:

Hobbs Switch, Boost Activated, Boost Level Adjustable : atpturbo.com

[JFairman]

The overboost sensor threads are 10x1mm. 1/8" NPT threads are really close but they are tapered a little.
Sometimes you can get them in far enough to use if you slowly screw them in and out repeatedly with some oil on the threads and you're careful. I've installed them in female 10x1 threads by running a 10x1mm Die over them or a 1/8" NPT tap into the intercoolers female threads.
It can be done or you can use an adapter.

[kenikh]

Can't tell what end is what, but this looks promising: Turbosmart FPR Fitting Kit 1 8NPT 10mm | eBay

[JFairman]

There's a sealing ring on the male threads so they would be the straight 10x1mm threads. There is no sealing ring on NPT threads because they are tapered getting thicker as you thread them in so they seal themselves with a little thread sealing compound or grease when you tighten them.

That said that's a really high price for that adapter you posted. I'm sure it can be found for less from a hydraulic supply place or fitting supply place.
BAT in Sarasota, Fl comes to mind.

British American Transfer

maybe on this page?
http://97.74.32.155/files/metric.pdf

Probably best to call them and tell them what you need. They have excellent phone service.
FWIW, I got my blue anodized aluminum Bosch 044 fuel pump inlet adapter and AN fitting from them for less than half what Len on the forum would have charged for a steel one.
Being on the other side of Florida from BAT I got it in a day or two regular mail.

I want to mention that Cole on our forum turned me on to British American Transfer or simply BAT

[kenikh]

OT but just noticed BAT is a Laminova vendor. S W E E T.

[Kozmo930]

Guys thanks for all the help

I will get busy and see if I can sort this out , like to be able to at least do 1.2bar without issues . Had CIS Flow Tech set up all new fuel system , so far it runs great with new motor just waiting to break in so I can find out on chassis dyno if we hit the goal of 400hp at the wheels .

Kozmo

[krasuskyp]

Kozmo!

Kozmo!!

KOZMO!!!

git'rdun...

...and then...

get yer goatass on up to PA fookin 7/23 eh???

Paulie's getting THRISTAAAAYYYYY!!!

Muuffuukkaahh!!!

[Kozmo930]

trying my best , sometimes life just gets in the way

This new motor really sounds good and with just short break in running procedures the hint of race fuel in the air and a dark grey soot in the zork tube.... hmmm must have got it close on the tune up. I'm really liking that hobbs switch looking into that easy to adjust



Kozmo