Newbie Question: What Else Do I Need to Check?

[Quinthirty]

I've got an 88 325i and had the car for a few weeks. I've been slowly fixing the car and trying to find the fault due to some rough idling issues and some fuel smelling around the engine bay when parked overnight. I've checked under the throttle body, the fuel lines from the fuel tank & they're new.

Changed the oil, oil filter, fuel filter, plugs and some of the vacuum hoses already but there is still a rough idle, and it is a bit sluggish going above 2k RPM, which I found quite unusual. Other things I noticed aside from rough idle.

1. A few times the idling went up to 1200 RPM, but when I flip the accelerator, it goes back to normal.

2. When I switch off the ignition, I can see a "surge of electricity" that flicks the gauges (speedo, tach, fuel, oil pressure). Is that normal?

3. Fuel consumption when I got her before the tune up was 10mpg, and not after a few full tanks, its improved to 15mpg. I know I have a long way to go because I haven't checked a good number of things.

Next on my list to check are:

1. charcoal canister: to fix the fuel smell
2. all other hoses
3. purge valve: to fix the fuel smell

I think that the bigger problem that I have is that the ECU does not throw an error code as the check light does not switch on. It does not even light up when the keys are on ignition.

What do I do next? Any suggestions? Thanks in advance.

[dnguyen1963]

The very first thing you need to do is a smoke test to find vacuum leak. No point of doing anything else until this is done.

[Quinthirty]

After doing some checks, I discovered that my ECU was for a 320i (152), no wonder she felt sluggish, hesitant, uneasy, idled roughly and drank like a college student on spring break @ 15mpg. Bought a 173 and replaced it, and voila! World of difference. Responsive, no hesitation, mixture (burn) smells less richer, shifting smoother. I hope she improves on gas consumption a lot too. One thing I noticed though is that after revving, idle dips low before recovering to 700-800 on the tach. O could also hear the valve ticking too. Fuel is 91 octane. What could it be? Is mixture too lean? Valve clearance adjustment needed?

[nates 87 325is]

You will always hear the valves its just an m20 thing, but an adjustment wouldn't hurt. And a stock m20 should do alright with 87 octane unless its chipped.

[Quinthirty]

You will always hear the valves its just an m20 thing, but an adjustment wouldn't hurt. And a stock m20 should do alright with 87 octane unless its chipped.

Thanks for the tip. I'd likely do a valve adjustment.

[Quinthirty]

I chose not to fill her up right away and let the gas fall to around 20 on the gauge (less than 1/4). When I parked it overnight, the same gas smell was still there, but what I noticed was a hard start. I did 3 clicks and nothing, as if there was no fuel going into the cylinders. Could it be that my FPR is shot? Rested her a few minutes, started her again, and vroom! Idle was dipping in the beginning though, as if starved.