Oil leak and high fuel consumption

[Supr4]

Hello.

I have an issue with my 4.4i 2001 automatic.

Garage changed the rocker cover gasket 2 times and I still have lot of oil in the spark plugs wells.

I also have a very poor fuel mileage. Only symptom is strange feeling on first gear or low throttle like it struggle to move or is too jerky and it little bit harsh when it goes from 1st to 2nd gear.
Can it be a faulty secondary air pump even if I got no codes?

Does someone has an idea ?

[Themoog]

What gas mileage are you talking about as they are not frugal anyway..

[Supr4]

22-23L/100km

[Themoog]

Don’t know what that is but mine does 19mpg average.

[Supr4]

I'm at 10mpg

[Henn28]

That’s terrible, even for the 4.6. Mine is a huge pig, but stilll gets 13ish in the city and can touch 17 mpg hwy lifted and on bigger MS tires. Can you read out your codes, or get someone to do it for you with a good diagnostic tool? Assuming you aren’t smelling a fuel leak, it could be related to any number of things from a bad injector(s) to MAF or O2 sensors, etc. Given that they were working on the top end of the motor though, I’d do a thorough general integrity check of all hoses, injectors (properly seated, etc) vacuum lines, intake boot, etc.

As far as the oil leak, hopefully it’s just residual oil from the work you had done. Clean it up and keep an eye on it. If it fills up again then likely your valve cover is still leaking.

The codes should tell a story if it’s running rich, or some has failed.

[Supr4]

I scanned it with inpa, dis ect no codes related to injection.
Spark plugs, O2, all sensors are new. A lot of hoses have been replaced so I don't see what's causing the issue

[Henn28]

That is strange. 10 mpg and nothing on inpa. Weird. I know very little about the O2 sensors but some guys here are super smart on them, and I think inpa can tell you a lot about O2 sensor performance, which can help with troubleshooting.

[Supr4]

Today I noticed when I was in a traffic jam that braking at very low speed the fuel consumption gauge goes to the maximum without pressing the gas pedal is that normal?

I noticed that when it specially run badly I hear the secondary air pump marching the engine rpms

[Henn28]

I seems to recall that the fuel consumption gauge is vacuum driven? Not smart enough to know what that might mean when it comes to your problem and it being pegged at idle. Doesn’t seem right though.

Try unplugging the SAP and driving it for a while to see if fuel consumption is affected. It will pop a code, and likely the SES light too. When working properly, the pump shouldn’t run for more than a few minutes on cold start, and only at colder ambient temps. You may also need to unplug the vacuum control switch that sits on top of the motor that opens the SAP valve to allow the air into the heads. That valve should stay shut too for a proper test.

Also, I think my foxwell has SAP text functions and live data. You could both test it, and see if it is in fact running when it shouldn’t be.