VDO boost gauge installation with piccies (in dash, through front guard)

[Stan]

nice neat job, looks good

[JCM308]

However i remember talking to a few people and reading it online a few places.

They strongly recommend against connecting the boost gauge on the FPR vac lines.

Why's that? From what I've seen (and done) that's where everyone is running them from.

[Roodosutaa]

Had the 15kkm service at Chatty Classic Cars about a month ago, bloke said "nice boost gauge", no problems whatsoever.

[glidn]

i'm trying to track it down, I'll take some pics of mounting on the missus GTI over the weekend and post that too as a reference.

It's to do with a leak, it could cause the engine to run lean or something along those lines.

Once i find the relevant info i'll post it up.

[JCM308]

i'm trying to track it down, I'll take some pics of mounting on the missus GTI over the weekend and post that too as a reference.

It's to do with a leak, it could cause the engine to run lean or something along those lines.

Once i find the relevant info i'll post it up.

Yes please do. Would be nice to know any potential issues that could be caused.

[bfeboi]

I've fitted the vdo boost gauge to my pog but recently i've noticed that it has started to make a buzzing sound. I've googled around and found that this problem is caused by the pulses caused through the vac line. Has anyone had this problem with their gauge?
People say the fix is a restrictor in the vac line but my t piece im using has already a restrictor in it. Any suggestions?

[DeanB]

Are you sure they don't mean an electrical resistor ?

[Roodosutaa]

No, they definitely meant a flow restrictor. A VDO gauge is mechanical.

I didn't use a T-piece with a built-in restrictor (dio you have the NewSouth gauge?), because I bought the T-piece after market. But the VDO line kit does come with a small cylindrical-shaped restrictor so I forced the whole thing deep into the nylon tube before connecting it to the T-piece. Never had any buzzing whatsoever.

[bfeboi]

i have a vdo gauge. i didnt get a "small cylindrical shaped restrictor" but only got a restricting t piece. i went to MRT to see if i could get a "restrictor pill" but they had various sizes and i didn't know what size to get. Know what size should be recommended?

[Roodosutaa]

I don't think the size matters that greatly. Does your line kit come with a thin (but strong) black nylon hose? My restrictor "pill" is slightly bigger at the brim than the internal diameter of the hose (maybe by about 1mm?) so all I did was heat up the hose with a heat gun so it softens a little (not too much obviously so you'd melt the thing), and then put a bit of detergent around the rim of the pill and pushed it in far enough so when I connect the hose to the T-piece the end of the T-piece would sit against the pill.

I'm sure that's not the usual way to do it, if I followed the instructions correctly the restrictor's brim should be fitted to the end of the hose (hence it has a wider brim than the internal diameter of the hose) and this in turn is connected to the brass fittings that hooks the hose up to the gauge. But either a part is missing or I got it all wrong I couldn't connect the hose to the gauge with the restrictor sitting at the end of the hose. But I think as long as there's a restrictor anywhere in the pipeline whether it be closer to the manifold or closer to the gauge it'd stop the buzzing as the pressure will still remain consistent.

[bfeboi]

what would happen if i put the smallest restrictor pill in the line would it affect the reading of the boost gauge?

if i end up putting a larger one then wouldn't that have no effect at all?

[Roodosutaa]

what would happen if i put the smallest restrictor pill in the line would it affect the reading of the boost gauge?

if i end up putting a larger one then wouldn't that have no effect at all?

Others may be able to explain better than I can but I think the purpose of the restrictor is to limit the flow of turbulent air between on-boost and going off-boost when the system is getting pressurised and released, which causes the buzzing in your gauge.

By having a smaller hole the air pressure and volume of air in the entire system still remains the same hence you're still getting the same reading.

As long as the hole in your restrictor isn't as small as a pinhole and the outer diameter is big enough for the pill to sit snugly in the hose without sliding down the tube I guess it would still work.