Boost Gauge Bounce

[GT4 BOOSTER]

hi guys , i fitted this boost guage today , i have 1 question , after a minute or so on tickover the needle starts bouncing , about 3mm in each direction. you can see on the pic the fluctuations. is this normal ? if not whats the cause or cure. thanks.

ps- it reads upto about o.8 - o.9 bar on full boost , so its not a bad gauge for what i paid for it.

[LORD_ED]

not normal mate, could be a vac leak , does the car idle smooothly?

[GT4 BOOSTER]

yes it runs spot on.When its above tick over the needle dont flicker at all - i will take a look at the pipes again tomorrow. Would it make a difference if i t-pieced a bit too close to the throttle body .

[mikeb]

It's probably just picking up pulsations from the idle speed control valves, or some kind of induction harmonic from the low engine speed (inlet valves opening in sequence etc).

As long as it's not too annoying, I wouldn't worry about it.

[GT4 BOOSTER]

thanks mike.

[daktari]

As Mike says. But just to add. I had mine plumbed in around the same place as yours till i found out there`s a blanked off (Rubber cap) vacuum stub at the back of the inlet manifold. (Don`t know if the gen 6 is the same???) Took a bit of groping around to find it. But long story short.... I plumbed the boost gauge in there and its rock solid right through the range.

[GT4 BOOSTER]

where at martin . left ,right middle of inlet manifold ???

any pics. ??

[daktari]

Urrghhh Pictures... Probably but it`ll take a month to find them. If you follow the middle two inlet tracts down from the top you will find it at the bottom. The stubs about 6-8mm diameter and about 15-20mm long so you`ll need a reducer tube.

I`ll see if i can find a pic.

[adamgt]

that sound strange, never heard of a bouncing needle on a boost guage b4. I dont know about these vacuum pipes as my boost guage doesnt have one. good luck with it tho.

[GT4 BOOSTER]

that sound strange, never heard of a bouncing needle on a boost guage b4. I dont know about these vacuum pipes as my boost guage doesnt have one. good luck with it tho.

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mmmmmm ??? what makes the needle move then .

guys on gt4oc say its perfectly normal for the needle to pulse. specially on cheaper gauges , i'm gonna seal all the pipes i cut tomorrow , incase any are leaking a tiny bit , mainly the pipe that enters the gauge itself.

[adamgt]

that sound strange, never heard of a bouncing needle on a boost guage b4. I dont know about these vacuum pipes as my boost guage doesnt have one. good luck with it tho.

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mmmmmm ??? what makes the needle move then .

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Defi control unit is linked to the ecu. all defi guages just plug directly ito this control unit.

[Bibbs]

The bouncing could be the lack of "damping" in the guage. Cheapies are cheapies for a reason :)

On the MR2 there is a spare pressure thingy on the "Diagnosis" box that is hosed to the TB. But what you have done is fine :)

Don't worry about the length of the hose. I had a rubber hose that was about a meter long to the AVCR sensor (across the engine bay), and then a section of hard plastic hose about 4 meters long as it went from the back of the engine (MR2 remember) through the fire wall, down to the floor, along the door sill, up behind the dash and into the guage in the dash location. Made do differance.

[Sketchy]

that sound strange, never heard of a bouncing needle on a boost guage b4. I dont know about these vacuum pipes as my boost guage doesnt have one. good luck with it tho.

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mmmmmm ??? what makes the needle move then .

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Defi control unit is linked to the ecu. all defi guages just plug directly ito this control unit.

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Though each gauge came with it's own electrical sensor on the defi that connects to the control unit then conrtol unit powers gauge.

If it's the case that your control unit is wired into the toyota Map Sensor via wire at ecu then this could be why it's showing none stock boost, not sure if you can set the control unit to different sensors or not, they don't all have the same voltage/pressure range see.

The normal defi sensor is a 3bar one where as the stock toyota one is not a full 3 bar one it's between 2.5 and 3 bar. Fennies have found that it only varies up to about 1.8Bar positive pressure hence making it a 2.8bar sensor.

[GT4 BOOSTER]

i cured my jumpy needle by t-ing into the dump valve pipe , recommended to me by a fellow gt4 owner.

[daktari]

Glad you got it sorted Marc.

[GT4 BOOSTER]

yeah me too , car was chucking out black smoke also where i teed into -

just waiting now for k1ano to send me my controller zzzzzzzzzz 2 weeks now :fishyface: :D :D

[daktari]

I seem to recall it took a while to get mine as well. :D Worth the wait though.

Got the strut brace yesterday. Took about 2 hours to unwrap it. :censor: parcel tape.