Has anybody ever experience driving their car normally and u feel a slight stubble and notice ur car has lost boost/vacuum pressure? Normally when I drive my car around its sits around -10 ish vacuum/boost gauge. Well when I feel a stubble the pressure drops to -20 vacuum. When this happens it will only boost to 7/8psi instead of the 20. It only does it ever so often and no check engine code is coming up. I don't like wasting money so I was just gonna keep driving it until it does it all the time and take it in to have it checked out. I can't do it now because it has only happened like 4 times in the last two days of driving but it happen 3 times on a 15 minute drive home from work. It only last for a few seconds. The first time it occurred was during a heavy rain fall so I'm thinking something might have gotten wet and it been raining the last couple days. I have the following mods
Alta boost gauge, intercooler hot side tube, fmic, downpipe, exhaust, cold air intake with heat shield, jcw ngk plugs (gapped .028),new Alta version bov, and Accessport

Any ideas?

 

vanos solenoid?

 

Is this just recent or has it been going on for a while? Maybe bad gas? Have you done a carbon clean up yet? Take a look at this thread HERE and see if you feel your issue is similar. Last post indicates they replaced his HPFP.

 

Yeah I did the seafoam treatment before this happened. It just started. Again I hope something got wet. I removed the vent screen in the hood scoop trying to get more air in the engine compartment and I hope something just got wet. I parked it in my garage with the hood popped so hopefully everything is dried up for the weekend. Thanks for the suggestions but I would think if it had a bad solenoid or low fuel pressure ...wouldn't it through a check engine light like inadeqent fuel pressure or something?

 

The first time it happened it was low on gas. I put some shell 93 octane has in it. I guess I will throw some seafoam and some octane booster in her and see how she responses. I'll keep u posted

 

Well I watched those videos on hpfp and my car is not exempting any of those symptoms. I have no issues of starting my car and the way I see it if my hpfp was faulty enough to b affecting the driving the diving experience; it would deffently affect the starting first or at least. All videos I seen the symptoms of faulty hpfp was start etc. not driving

 

It sort of sounds like the DME is cutting boost intermittently to protect the engine. This could be related to ambient conditions or an intermittent false signal from a sensor. Without experiencing it while observing the fuel pressure data in the DME it's tough to say whether it's fuel or something else. You can check fuel pressure data, but you'll want to do it while the issue is present. Also, check fuel trim values and see if there is any trend towards a lean condition. I'd still also suggest inspecting your valves for build up and clean them if necessary. Maybe someone else will chime in with some more input for you. Good luck.

 

Thanks for all the great suggestions. Hopefully when I get back in it the problem is gone. It's no longer raining. So I'm going to take it out for a spin.

I believe it's something electrical because something mechanical wouldn't come and go. But I'm not going to buy anything until it does it all the time cause I don't want to waste money buying uneccassry stuff. My motor only has 60k miles

 

First question, using your accessport, what codes are you showing in the diagnostic screen? Secondly, I've got a similair set up and when this happens it's because my passenger side PCV tube blew off the valve cover under high boost. I reconnect the tube and clear the codes and it's fine. Check your all your boost connection hoses and PCV hoses. But first let your Accessport tell you what's up.

 

Because of the increase in vacuum, may the check valve in the PCV/valve cover is sticking.

It almost like the car is going into cold start mode.

 

How confident are you with pulling off the intake manifold & do you have access to a compressor. I had intermittent boost loss but also short stints of half power limp mode. Scrapped cleaned my intake valves problem solved.

At 60k your valves aren't going to be pretty mine at 60k were as bad as any thing I've seen on the net.

 

I thought the pvc valve was not accessible.

I'm not getting any codes

I data logged my fuel pressure using Accessport and fuel pressure did not change so no fuel pressure drop

 

Clean intake valves not PCV valve which is not serviceable. When I had loss of boost no codes either. Limp mode I believe was caused by knock at cruise because of the different AFR of each cylinder because of restricted air flow caused by dirty valves.

 

Ok well even though my check engine light was not on I use the Accessport and found two stored codes



Found online same symptoms as a faulty bypass valve. Is that the bov? If so I replaced mine with the new Alta bov.

 

Is it a vent to atmosphere BOV?

 

It's the brand new one Alta sells the one that uses vacuum

 

I talked to Alta and they just remind me why I deal with them. Great customer service as they stand behind their product. They told me my resistor my b bad or fallen out of the connector and to try and just install my old DV into the plug and see how it runs. If it runs great then the resistor is bad. And if that doesn't fix it just return it and they will replace it no questions asked.

 

Car is fixed. Thanks everybody. The problem was the resistor Alta gives u when u install their new bov. It wiggles in the connector which makes the car go into limp mod when no connection is being made. All I did was plug in the old electric bov and zip tide it up. The permanent solution is the make a harness that plugs into the oem harness.

Car drives great builds boost quickly and smooth ��

 

If anybody is looking for a gfb bov let me know I bought a slightly used one thinking my Alta bov was bad. I'll sell it for $100.00 shipped

 

Hmm. I've been experiencing intermittent boost loss as well. Thought it was the HPFP(which actually was bad) at first but had it replaced under extended warranty and I'm still having the issue. I've thrown CEL 3 times but my OBDII gauge displays "Error" but it cannot read the code for some reason so I just clear it with the gauge.

I have the Alta intake so during this intermittent boost loss I won't hear any boost recirculating through the BPV. Also my exhaust will start sounding very deep and loud(I have the stock exhaust on the car).

Any ideas guys? Wastegate? Sticky BPV?

*Edit* It's an 08 R56 with 79,XXX miles.