Re: How precise should my fuel pressure be? (RonG)

My limited experience with FI (fuel pressure) in this model Volvo...

- strong smell of raw gas at hot idle.

- wet end of exhaust tips.

- fouled plugs.

- oil on dipstick has gas smell.

- hot idle too low.

If the fuel pressure adjustment made the car run better you done good!

George Dill

 

Re: How precise should my fuel pressure be? (RonG)

I'd go with 30 psi and see if that isn't better yet. I believe Volvo upped the spec by two pounds at some point, but I can't document that.

 

Re: How precise should my fuel pressure be? (Phil Singher)

Thanks, Phil. Another question.....

I've had the car for several years, and have never checked the CO level or had it adjusted.

Important to do? Or better not to touch it?

 

Re: How precise should my fuel pressure be? (RonG)

The only CO adjustment is the knob on the top edge of the ECU. Set the fuel pressure first, and then adjust that knob for smoothest / fastest idle with the engine fully warm. If it doesn't do anything, it's likely your throttle position switch needs adjusting.

 

Re: How precise should my fuel pressure be? (Phil Singher)

That sounds too easy. No CO meter needed?

 

Re: How precise should my fuel pressure be? (RonG)

I wouldn't know what CO reading to set it to. If your goal is to get the smoothest idle rather than meet some other criteria, just adjust the knob for that - it will be on the "more CO / less CO2" side of the stoichiometric point. This only affects the idle.

Whenever the throttle is opened beyond idle, the only adjustment is fuel pressure. Everything else is hard-wired in. You can take a reading on the spark plugs to gauge the mixture: there should be no soot on the center insulators. if there is soot partway down, fuel pressure is higher than optimum.

 

Re: How precise should my fuel pressure be? (Phil Singher)

This is most helpful. Thanks.

Will pull plugs when I get home today and see how they look. I sandblasted them just before I adjusted fuel pressure the other day, so I get a good indication of what's new.

You're the best!

Ron

 

Re: How precise should my fuel pressure be? (RonG)

Quote, originally posted by RonG »

...sandblasted them...

Four new spark plugs are in order - what application is in the car now?

George Dill

 

Re: How precise should my fuel pressure be? (gdill2)

Plugs are almost new. Standard Bosch, can't remember the number.

Only sandblasted them to be able to see any difference.

After driving yesterday, they had a bit of soot on the edge of the body, but the insulator tips were clean and the electrodes were clean/light tan.

I think I'm OK for now. I might skip the CO adjustment exercise, since I think it's housed underneath the dash way behind the air conditioner unit....