Mileage just dropped...

[Bogaat]

I recently noticed a pretty severe gas smell after starting my 87 325is. It was kicking out some smoke as well. After a few minutes, it all went away and the car seemed to run fine. However, now my mileage has dropped significantly when accelerating. The gauges both drop down to single digits if i even hint at hitting the pedal. It seems fine when cruising at highway speeds. No engine lights or anything. That same day/trip I popped my alternator belt, but that "seems" to be unrelated. I put a new belt on, but the mileage is still a problem. Mileage has probably dropped 20% overall due to poor acceleration mileage. Any thoughts? I bought some seafoam, but I do not expect that to fix the problem. Thanks in advance :D

[StereoInstaller1]

My '87 325is has shit mileage too, plus the "smelly start" you are talking about. It has been that way for quite some time though. I do not believe in just random swapping of parts, I believe proper diagnosis will tell you what is actually wrong, then you can fix that.

The only issue is that I just don't give a shit about my 280,000 mile noisy-as-fuck-abused-for-years-by-a-fag-in-Portland-worn-out-pile-of-shit-motor, so I have not bothered to truly diagnose it, other than popping the hood and sniffing around.

I believe it is sticky injectors.

I am gonna swap a set of 17.5 M50 "4 pintle" injectors in and see what happens. I am also gonna replace every o-ring in the injector rail, and on the fuel pressure regulator.

My motor is only due to be in the car until I can find a good enough deal to double the valves, but the wifeys '89 325i is having a similar issue now and then...


Luke

[e30serg]

My mpg went down then my o2 sensor dies. I used to get aroun 24mpg, and it dropped to 21. I replaced it, and the mileage went up immediately.
My gauges didn't do what yours do though. I would start with cleaning out the injectors and replacing all the o-rings, like Luke mentioned.

[rafiki]

my gas milage is still good, and my car smells like gas sometimes too. it sucks

[Reign]

Is the check engine light on? I want to suggest something that it most likely is (depending on the check engine light), but like Stereo said, make sure you get a proper diagnosis. Replacing parts you "think" it is is a very retarded move that people do when they have money.

[free]

Is the check engine light on? I want to suggest something that it most likely is (depending on the check engine light), but like Stereo said, make sure you get a proper diagnosis. Replacing parts you "think" it is is a very retarded move that people do when they have money.

So... what is the suggestion? I have a similar situation, car has started running a little rich, everything seems fine. O2 sensor tests fine using the Bentley method(voltmeter, crack the dipstick or oil fill to create vacuum, see the changing volt reading). TPS, coil, wires, coolant temp sensor are new. Injectors are Bosch replacements about 15k old by PO. FPR is new. Compression is good, valves are adjusted. Can't find any vacuum leaks (maybe I just need to create one to lean it out!) ICV tests good.

Mileage has dropped, plugs are showing carbon buildup, power has dropped. Nothing drastic, but noticeable. Driving me crazy. Stomp test all clear.

[Reign]

Your exhaust and emissions system sounds good. You didn't say the check engine light was on. If your power has dropped, I would recommend making sure you have good, clean filters. Specifically your fuel filter. Do you hear a noise whenever the car is started? Specifically when it's cold and at idle? It should be a high pitched and not normal noise. If so, it can be narrowed down to the fuel pump. Again, it can't be diagnosed over the Internet like this, but those are a couple of suggestions going by what you told me.