Fuel reassure Test
 

Hi all, 99 Boxster Base. P1123...P1125 CEL's

Did fuel pressure test and results are:

Engine Off 3.3Bar

Idle: 3.1 Bar

Question, with engine off (after running and shut down) the fuel pressure was 2.6 Bars if I let it sit... it crept up to 3.4 Bars...... which is the accurate reading?

Also....when replacing the fuel rail cap on the schrader valve I over torqued it with my cheapo torque wrench and popped the top of the cap and scored the top of the fuel rail with the bottom of the cap totally trashing the cap. Is this an issue I have to worry about. The valve seemed good and didn't leak...only a slight score or scratch at the base. Can I just replace the cap and move on. Thanks V

The higher reading.

Nominal values should be 3.8 bar +/- 0.2 engine off, 3.3+/-0.2 idling

You need to replace the brass cap.

Thanks for the reply JFP ...OK...so I'm low and out of range at 3.4 with engine off and low at 3.1 but with in range at idle. Is this okay or does the fuel pressure regulator need to be replaced to remedy the 1123....1125 codes??

I ordered the new cap already...as I said I scored/scratched the base of the schrader valve by over torquing, it seems the brass cap is designed to strip before doing any damage to the rail..it doesn't leak ....am I good with just replacing the cap.
Thanks V

Have you completed the vacuum test of the regulator, and did it pass?

OK....Thats new to me....read only to check fuel pressure. Will move on to vacuum testing regulator. BTW are my fuel # ok? No worries about the scored fuel rail?? I didn't see a vacuum test for the regulator in the shop man is it in the Bentley book??

No, but it is in the Porsche OBD II code diagnostics manual for the car.

One pressure is a bit low.

If the rail isn't leaking, it should be fine.

Well I don't have access to the OBD manual. Can anyone point me to instructions on doing a vacuum test on fuel pressure regulator. Couldn't find anything. V

Ummmmmmmmmmmmmm......Put a tee in the vacuum line at the regulator, hook up a vacuum gauge, start car and let idle, read gauge...............:rolleyes:

I figured you'd know. So I'm measuring vacuum being pulled from FPR correct? Thanks V

Yes, if the vacuum to the regulator is restricted, it will alter how the regulator works.

I did the test and got 18.5 in/hg of vacuum. Seems thats correct considering thats what it measured right from the vacuum hose as well. So it seems there are no restrictions. No gas coming from FPR at idle with hose disconnected. Any other thoughts for the 1123 1125 codes. It seems only to come up if I accidentally get close to stalling the car w the clutch or I rev high briefly getting into gear. Although the code is still pending shortly after reset. V


http://986forum.com/forums/uploads02/FPR_1568147776.jpg

Have you done an intake vacuum test????
If you get 18.5 in of vacuum that is within spec but on the low end.
I had a minor vacuum leak on my 2000S and still pulled 19.
If you have a vacuum leak it could contribute to your codes.

What is the spec for Vacuum?

0.4-0.6 Bar

So I'm at .63 Bar ....so I'm on the high side. Is that acceptable? V

if your asking for the vacuum spec. at the intake it is 18-22 in/gh of vacuum preferably with a steady needle.
At engine idle

Ok...well I have two specs going here !! 0.4-0.6 Bar and 18-22 in/hg I'm on the high side of 1 and low side of the other.

sorry not meaning to create confusion.
I would say your reading is fine

Thats fine thanks V

I don't know maybe its a quirky thing with the codes. I drove at length before they showed up. No pending codes now... I guess I'll see what happens. My oil filler cap checks out good and I sprayed some carb cleaner around the small hoses coming off the vac tank,plenum hoses etc...no change in engine note.Thoughts?? V

"For what it is worth"

I looked in my Bentley service manual (poor at best).

If I read it right P1123 and P1125 are for the O2senors. Below lower limit/lean mixture threshold.
One code is for the left bank the other is for the right bank. So going on that:
You have something causing to much air for the amount of fuel or not enough fuel for the amount of air. at all cylinders.

You already tested your fuel system and it checks good?

So that leaves to much air for the amount of fuel.

So your looking for something that has to do with air and affects both cylinder banks equally.
1.You could have a vacuum leak
2.You could have a faulty or dirty MAF sensor.
3.You could have faulty MAF sensor wiring, a short, a broken wire , a bad ground, a bad connection, or high resistance in the MAF wiring.
4. There could be a problem with the DME (hope not).

you could have faulty O2 sensors or O2sensor wiring issues.
But it is very unlikely that both O2sensors or their wiring would go bad at the same time.
So I would drive it and see if the codes come back.;)

I checked the codes in Bentley as well ....lean mix threshold I imagine is the engine is fully leaned out due to being too rich.(i Think) . As for the MAF it's new... DME just had it repaired for another issue,leaks I checked as well as I could w/o a smoke machine(not buying one!!)O2 sensors they say they're just sensing the fuel is too rich not necessarily faulty sensors. So....I guess I'm gona drive it see what happens. Thanks V

Leave it to me to interpret it backwards.

Well just hope that yellow demon stays away!!!!V

Well now that I know it is a too rich condition instead of a to lean condition.
I have read of a number of cases where a faulty purge valve is a contributor to your type of issue. Stuck open I think. that's from memory so prove it out, don't trust my word on it. I would wait to see if the yellow demon (as you justly call it) returns.
Hope at some point I have helped not confused.