fuel pressure regulator vacuum diagram..
 

hey Guys ,
so I have been chasing high negative numbers on LTFT both banks around - 18 % I think I m dealing with a Rich conditon - decided to test the fuel pressure

getting fuel pressure numbers with car off 48 psi , car running 58 psi also I m trying to test the fuel pressure regulator and vacuum hose problem is CAN NOT DETERMINE exactly where the vacuum hose goes for sure at the moment it is connected to what I think it may some kind of switch

wondering if anybody can help me with a diagram and are the fuel pressures correct and pressure regulator testing procedure ??

this relates to a 2001 boxster 2.7 manual transmission believe vacuum lines might be different than automatic !!

On a 2001 model the vacuum hose for the fuel pressure regulator should go directly from the rubber boot on the intake cross-tube to the regulator on the fuel rail.

http://986forum.com/forums/uploads02...1692881885.jpg

http://986forum.com/forums/uploads02...1692881911.jpg

It sounds like you may have the vacuum lines on incorrectly. The diagram above is for a 2001 2.7L manual. There is more discussion of it here: https://986forum.com/forums/boxster-general-discussions/64576-vacuum-line-clarification.html#post518618

I have seen this before .
are you sure this applies to 2.7 manual transmission?

cause my FPR seems to be coming from top of "J" change over electric valve and other end of electric valve goes to a the Flapper valve !

:confused:

thanks for all your help.

I'm sure that diagram is for a 2.7L with Manual. The connection for the fuel pressure regulator should be direct from that rubber boot. Change over valve (J) should only be connected to vacuum source on one end and resonance flapper valve (K) on the other end.

that makes sense NOT sure why previous owner had it like that ! where else would the FPR get any vacuum otherwise !!

I disconnected the hose going to the FPR there was no change at all almost no PSI at all thought that was weird then now it makes sense

i m gonna correct that as soon as possible . wanted to replaced some of these small OD vacuum hose any idea where I could buy those ?

thanks for verifying the diagram believe I m ON to the real cause of my high negative LTFT issues now..

thanks again

do you know if these 2 items :
SAI: Vacuum source -> electric change-over valve (E) -> change-over valve (D).
are located next to the vacuum reservoir ? I'm debating whether I should pull the
intake to get to it ( hate to mess with these intakes) although maybe I should change the gaskets on both sides too

I can't get to these items if they are underneath the intake which most likely they are !! unless the vacuum intake is removed

Yes, they are in a difficult to reach spot, forward from the vacuum reservoir. I have reached it by removing the alternator instead of the intake, but having the intake off gives better access. I have a couple engines in the garage and can get some pics tonight if that helps.

if you have some pictures that will be great
at least I know now where to look at removing alternator one last question
where did you get your vacuum hoses ? or do you remember the sizes the rigid smaller black hose and the larger rubber material hose ?

thanks again:cheers:

Hope this helps visualize...
From the right rear of the engine looking forward under the intake:
http://986forum.com/forums/uploads02...1693059087.jpg

Looking down to the right side of the engine with the front cross-tube removed:
http://986forum.com/forums/uploads02...1693059108.jpg

From the front of the engine looking back under the intake:
http://986forum.com/forums/uploads02...1693059125.jpg

I buy this with a 3.5 or 3 mm ID and use it on a wide variety of cars with fittings from a local auto parts store to connect them or cut scraps from old tubing to connect.

http://986forum.com/forums/uploads02...1693059456.jpg

great .
I actually ended up removing the intake wanted to get a better view on things !!

found all the small vacuum hoses broken from reservoir, change over valve, injection check valve a mess all over pretty much .. lol

also, found some hoses at Oreilly's small plastic hose and large one I m thinking of using it fits great into the " Y" connections.

list of parts to getting :

long AOS vacuum hose to PVC found broken connection or NOT sure if I broke it ! anyways Im buying a new long hose found it at AutohauzAZ.com for 32.00
. Intake gaskets (3) 23.00
.check valve 15.00

parts from europarts.com change over valve 28.00
fuel injector lower O rings $ 3.0 or SHOULD I GET THE KITS ??

SHOULD I GET THESE PARTS ??: vacuum reservoir 21.00 , air injection check valve 135.00 these parts are right there underneath next to each other...

your thoughts ??

My thought is that while you are in there it's a good idea to replace those 20+ year old plastic parts now rather than deal with it again 6 months from now.

Double check the wires that go to the knock sensor too. If the car has ever sat where rodents can get to it, they chew that particular wire for some reason. Usually the car won't throw a code and will run fine with the wires chewed through. :cheers:

so many thanks to 78F350
have been able to redo the vacuum system all new hoses , new check valve , one new changeover valve , new vacuum reservoir
new passenger side intake gaskets ..
soon after it appears fuel trims numbers were GOOD not so fast ! after several driving cycles now its up to

- 14.0 bank1 LTFT B 2 - 15.0 LTFT short ones fluctuates up and down

so this afternoon tested again the FPR seems to react right when disconnecting the vacuum line pressure goes up to 60 psi

listened to the fuel injectors with a headset stethoscope seem to be working right ..

02 sensors on both banks seem to move up/dowm on voltage (maybe have to pay closer attention to those numbers )

interesting enough all my emission components now are completed ready (7 of them )

I m NOW getting the P1130 code oxygen sensing on BANK 2 ???

guess car wont pass inspection due to the code even though components are completed ???

what am I missing looking at NEXT ??

You have split this issue into 3 threads and it's hard to keep track of it.

What were your maf readings at idle with ac on and off?
Have you tried to disconnect the maf and see if the fuel trims change?

I know .,, its just being really frustrating still have not been able to figure this out .

gotten 2 new MAF sensors and the old BOSH one currently have a new BOSH and the Old one swapp those out from time to time DONT MAKE MUCH OF A DIFFERENCE ..

If I disconnect the MAF today I believe the might only indicate if its bad or NOT . correct ?

HAVE NOT DONE THAT ..

I will follow your advise ac on and off reading on the MAF and check the fuel trims numbers today ?

NOT sure if I mentioned this before have an after market air filter hose and filter ( actually was having issues even before this was put in DESTROYED THE OLD ONE GETTING IT REMOVED ) otherwise I would put it back on just to see if it makes a difference...

thanks

Reading about the air filter hose and swapping different MAFs in makes me wonder if the wire harness or connector for the MAF is damaged.
Any potential air leaks between the MAF and throttle body?

Also if you search for the P1130 you will find some threads where it was a problem with the evap purge valve: https://986forum.com/forums/boxster-general-discussions/67910-fault-code-p1130.html
Also check again for more vacuum leaks - Brake booster vacuum hose, oil cap and fuel cap, hoses connected to the AOS.

I have a strong suspicion the new intake might have something to do with the problem, perhaps the diameter of the MAF tube is somehow smaller than stock.

I also had a problem with my boxster running rich.
It was very frustating and among other things I bought durametric, two new MAF sensors, replaced O2 sensors and checked fuel pressures.
In the end I read a forum post suggesting to check the mesh just before the MAF which seems to collect trash thanks to the bad design of stock air box.
I had small pieces of leafs stuck around the edge of said mesh impacting airflow, but not on front of the MAF so the readings were normal.

Your problem shouldn't be the same I had but disconnecting the MAF might help pinpoint the problem, even if it's not the MAF sensor itself.

MAF's connectors wires bad ! I would think it would truly affect it and run rough ?

I have an audio stethoscopes planning to use it maybe I can hear any leaks and another smoke TEST on the plans .
will check those other items too .. fuel cap too

I had also read the tread on "evap purge valve " disconnect it and blow on it

the car has 7 emissions components ready completed - wouldn't this keep it from completing if there was an issue with the EVAP PURGE VALVE ???

should have a chance later today .. will report on it

A few things that could cause your issue........
Bad MAF or MAF wires...and or connections.
Leaking Fuel Injectors.
Bad seal on the Oil Fill Tube Cap
Bad Fuel pressure regulator
Bad Evap Purge Valve under the intake manifold
Exhaust leak ahead of the Pre Cat 02 sensor.

Blue... question...

Would having a Durametric at one's disposal eliminate a lot of "chasing"? I'm halfway familiar with the product, have never used it, but I believe you can see in the app the fuel pressure... bad connections... etc. No?

I ask because I've been considering the enthusiast version. I'm still working on a fuel smell... and that darned P0455 popped again. I've been unable to crawl under the car due to a bad back.

Thank you.

No electronic diagnostic tool, even the almighty PIWIS, can see fuel pressure and delivery, both require a mechanical test with a fuel pressure test gauge.

What JFP said..
Additionally diagnostic tools are great to have.
BUT you need understand the system,part, sensor, circuit that your testing and it's relationship to the other systems, sensors,parts, and circuits.
You also need a good diagnostic procedure... otherwise any diagnostic equipment will just give you another way to chase your tail.

right on Blue62!

I have tested the FPR good - after removing the vacuum hose pressure went up t0 60 PSI

have not replaced seal on Oil fill tube cap - did not see any smoke coming out of there on my last SMOKE TEST ..

how to test Evap purge valve ?

had the car running for almost half hour now TOO hot for smoke test - SMOKE TEST TOMORROW with engine COLD should be smoke coming out of the exhaust if there is a leak !!

so this is what I observed today after car warm up "

MAF a/c off 3.25 a/c on 4.0 g/s

while car was running disconnected MAF sensor SOMEBODY HELP ME UNDERSTAND THIS
after disconnecting MAF car hesitated a bit almost not noticeable CAR KEPT RUNNING

numbers on old BOSH sensor are 0280 218 055 986.606.125.01
0280 218 055 986.606.125.02 on new BOSH sensor only difference last 2 numbers 02


:confused:

Your MAF readings are a bit on the lower side which should cause lean condition instead of rich.

There are three different revision of maf for e-gas cars, ending 00, 01 and 02.
If you change the version you need your DME flashed to match the new MAF sensor.
Or so I've heard.

With MAF unplugged your DME uses a default map which only uses O2 sensors and the throttle position to estimate amount of fuel needed.
It's not recommended to drive long distances with MAF unplugged but let's say half an hour shouldn't hurt anything.

In simple terms:
The Maf sensor is two sensors in one.
It senses Intake Air Temp. and Intake Air Mass.
From those two things the DME knows how long to pulse the Fuel Injectors thus creating the correct fuel air mixture. (all other things being correct).

When you disconnect the MAF sensor the system reverts to a preset default fueling strategy. That fueling strategy is derived from a fueling Map or table that is largely driven by the parameters of engine RPM and Engine load.
So if you disconnect the MAF with the engine running it takes a second for the system to change or adapt to the default fueling strategy.
That is my current understanding of how it works.

Your looking for a "Voltage Spec." at the MAF Sensor.
Key on engine off your looking for 0.9V - 1.1V
Engine running at idle approx. 1.4V

Testing Evap Purge Valve for vacuum leak:

Disconnect the hose from the intake to the valve. (at the valve).
Disconnect the Electrical connection.
Apply vacuum of 0.7 bar to the valve.
Vacuum should not fall below 0.5 bar after 10 minutes.
That will tell you if it holds vacuum correctly or not.

Great ! thanks for explaining that to me Blue62.

now I have to determine which wires on the MAF connectors are what ?? voltage , ground , signal and so on .. thought I was looking at bad MAF sensor dud...lol :o

got some homework to do on that is almost 6pm here in dfw tx I do still want to DO a SMOKE TEST tonight just for my own curiosity ..i will be looking at all possibilities.

intake ( under there have a borescope camera I can use to look underneath ) exhaust . oil tube .
oil cap , gas cap /..

thanks again to All.

update : got another smoke test done with cold engine - looked all over the car exhaust AOS which maybe leaking at the very botton connection NO SMOKE at all

however FOUND the oil dipstick tube leaking right under transition in between the trunk ( hard to get to ) .. NOT sure how I missed it a while back maybe cause I did it with a hot engine

I m going to try to fix it tomorrow wrapp special insulation tape around it and glue /adhesive all over area - it has worked on some other hoses i have done well SEE ..i will do a smoke test the next day ..

how could I missed it - it was there right under my eyes !!!

the oil filler tube connection under the firewall through the trunk - DID another smoke test after reinstalling the oil dipstick tube ( may or may not have been the culprit after all ) .

oil filler connection broken leaking real bad - just order one from ebay I m pretty sure that has been one of tghe biggest ISSUE all this time NOT the only one thought

vacuum system was all broken all good now ..

thank you very much specially to BLUE62

Sounds like your starting to get things sorted out.
Vacuum leaks can be pain to track down on these cars.
Everything is under vacuum including the crankcase which is usually under slight pressure on most engines.
When you get the oil fill tube replaced let us know if that fixes the problems.

Since you will be replacing the oil filler tube, I would suggest to replace the accordion hose that goes from the bottom of the AOS to the top of the engine (driver side) as these plastic hoses are 20+ years old and get very brittle with age and heat.
To replace this hose you don't have to remove the intake plenum, as you can get to it from the engine cover behind the driver seat.