Dan Sarandrea (Phila)
Waitin' On Parts...
Coulda had all four plugs out, pix taken and posted by now......just sayin'.
I'm sorry to frustrate you DSpieg. Maybe "as an engineer" you should know how to troubleshoot your own car. How was I to know your car is missing it's catalytic converter? It might serve you better to remember that people are spending their time trying to help you. Were in my case. Best of luck!Pardon my frustration with some of the replies, but let me restate the situation: The car was running great, but sprung a leak from a split fuel rail hose. I removed the intake manifold, replaced all the little hoses, and (unrelated to the fuel leak) replaced the 02 sensor because it 'looked old'. Afterwards: The car still starts and idles and runs perfectly, just as before my repairs, except now the gas mileage sucks. BTW there is no catalytic converter on the car (ahem....)
As an engineer, when something changes suddenly, I look first for gross errors (such as unconnected or mis-connected vacuum hoses as Carl suggests), or a defective replacement part which in this case might be the 02 sensor. It does NOT make sense to start poking at gradual degradation-type problems such as dirty injectors, fouled spark plugs, dirty air filters, etc. because any of these would have manifested themselves before my fuel line problem occured, right?
And if the suggested problems were the cause, wouldn't the car run crappy, or idle roughly, or be hard to start? And wouldn't I feel or hear a difference? Like I wrote: It's the disease with no symptoms.
A funny aside: Right after I replaced the fuel lines, the electric windows stopped working. You can imagine how my brain hurt trying to correlate fuel hose replacements with power window operation. Of course there was no relationship, the power windows relay simply failed at that moment all by itself.
Troubleshooting question: Would it be worthwhile for me to hook up a multimeter to the 02 signal wire and rev the engine while watching the voltage output from the sensor? If so, should I leave it connected to the wiring harness or disconnect it first?
aside from burning oil, the other way to get soot is a very rich mixture which would also cause high consumption.soot
Thanks - will read.there is a thread about it here on the BB. Eventually found the culprit to be a failed FI coolant temp sensor.
couda shouda - lots of things we all couda shoudaSteve, the fuel pressure no longer bleeds down. I'll speculate that was the start of the split in the one short hose which then started blowing visible fuel a month ago and led to the repairs we've been talking about here. Perhaps I should have inspected the hoses back then, eh?
Now that would make me a Santa believer! Note to Santa - even unrestored is fine but no replicas pleasemay Santa put a restored Lancia Stratos under your tree*
Understood but I don't think so in this case - looking at other OP threads gives some history on this car/engine. Past fuel consumption was on a par with other FI cars and consistent. In other words, the FI system was operating correctly for an extended period so I don't think a long standing air leak accidentally getting fixed is likely. Comment on the AFM is interesting tho. Ignoring the idea of deliberate adjustment for a second - how do they fail? Progressively? In any known pattern? If there is a spring involved, then that will weaken over time for example. As y'all may have guessed, I have no hands on time with X FI. If failure is progressive, then that is probably not the problem in this case as OP reports sudden change in consumption.Often, a mechanic will adjust the AFM a.k.a. intake air sensor, either by moving the toothed baseline adjustment, or changing the spring tension, to richen the mixture and compensate for the lean condition caused by the air leak.
So, my money is on your fixing an air leak without knowing it, and now you're running rich.
You tightened up a clamp or seated a hose or o-ring better than it was...
I have, unfortunately, far too much experience with L-Jet - more than i ever wanted!Understood but I don't think so in this case - looking at other OP threads gives some history on this car/engine. Past fuel consumption was on a par with other FI cars and consistent. In other words, the FI system was operating correctly for an extended period so I don't think a long standing air leak accidentally getting fixed is likely. Comment on the AFM is interesting tho. Ignoring the idea of deliberate adjustment for a second - how do they fail? Progressively? In any known pattern? If there is a spring involved, then that will weaken over time for example. As y'all may have guessed, I have no hands on time with X FI.
Thankfully, all mine are fed by Mr Weber...L-Jet
Just pretend that you are running dual DCNFs and 21 mpg won't seem so bad.With the new Bosch lambda sensor installed, another tank of gas has been run through, but resulted in another 21 mpg fillup So the problem doesn't seem to be the oxygen sensor I had replaced a month ago.
A full 50% more fuel is being used somehow, but the car still starts and runs perfectly. I'm about at the end of my rope with this thing.
Should I disassemble and reassemble everything I had done in replacing the old short fuel hoses?
Should I find a local shop with an exhaust gas analyzer and have them measure the A/F ratio at a variety of throttle settings?
Should I sell the goddamned car and forget about it?