Hia,

Ok this is strange and any help will be appreciated. I recently got an AVCR installed and its setup to run at approx 20PSI. On the dyno the car is fine but on the road once the car is warmed up in 2nd,3rd (i suppose 4/5/6 same but cannot try cuz of speed limit 100kph) at over 5.5k rpm there is a strange psssst sound and the boost completely falls off. it only happens over 5.5k rpm and only on the road, we had it on the dyno for 10+ runs but not once and as soon as it was on the road it did it.

the car is a JDM 8MR, with front pipe, high flow cat, muffler delete piple and a walbro fuel pump + avcr. i dont think its a fuel cut.

any help or ideas appreciated as its got me and my mechanic stumped.

 

hmm might have to think a little on this one.

 

Stock airbox? Check the clips that hold the snorkel down. On the dyno, the hood is open so it won't suck up and stick to it. On the road, its attaching itself to the hood.

 

awesome idea. i will check in the morning :-)

 

when you say boost completely falls off, how much psi are you dropping too?

 

good question, yesterday i saw it drop to about 0.8 on avcr (i think its gate pressure) but not 100% sure as i was sure it was dropping to almost zero before. its hard doing all this alone. i did re fix my intake snorkle and while going to work give it a sqeeze a few times and seemed ok. i need some more decent testing to check to make sure its still not doing it, and will keep an eye on the AVCR to see how much it drops to.

the noise seems to be comming from the passenger side of the engine bay (snorkle side, and its a RHD car).

 

hmm fingers crossed looks like problem fixed. thankx mixmaster. i went for a dive today and after numerous tests its not doing it, the real test is on the weekend.

so it wasnt boost leak but a block. :-)

 

Believe me, it's fixed. Unfortunately, mixmastermatt didn't point you to Bat-talon.

My crew of saved Gotham City Residents:

someone help please
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Boost drop/leak
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Help on boost loss issue

PS. Search is your friend.

 

hmm i did try boost leak but that came up with too many results. and i thought i was special.... also it only came up after the avcr install. but now i know

 

Well I tried removing the snorkel thing *completely* and it stopped doing it for a few pulls last night, now this morning up'd the boost turned on my meth and it's doing it again...5500-6krpm...Any other ideas?

 

It can't be doing it again if you removed the snorkel, because the snorkel is what causes it. If whatever you're experiencing was happening before and is happening now, then it's a different issue.

Can you describe your symptoms in detail?

 

I step on the gas with my right foot ... no seriously. I step on it from 2nd Gear 2500rpm to start my log(WOT)...pulls hard then right on queue at 5500rpm-6krpm it's like I hit a WALL hard...whole car SLams hard...bogs down, i lift right off the throttle when this happens...I looked at my logs... it goes from Load 240 @ 25psi to 207 or 197...

...definitely freaks the isht out of me...i'm scared to WOT seeing how hard this thing stops/SLAMS into that "wall"

 

That's fuel cut. The intake snorkel syndrome has a loud whistle that occurs right at 5500-6000, and the boost pulls back to 10psi and keeps going lower until you let off the gas, but there is no brick wall effect. The brick wall effect is caused by fool cut. Aren't you tuned? You shouldn't have fuel cut.

 

yes the car is tuned. I recently modfied maps to a patched rom with the "Flash CEL on Knock" I also added a data for the 2byte load...other than that my flash is the same. Any ideas? I'll look over my flash later...

..oh, i threw a overboost code yesterday too...first time...

 

If you threw an overboost code, then that proves it once again...fuel cut. You have a fancy ROM, I guess, but fuel cut hasn't been removed. That's exactly what's happening. When you hit fuel cut multiple times in a row, it throws the overboost code.