(VIDEO) 327i hunting and running rich at idle

[hotballs]

What size injectors are you running? 173 Stock chip DME?

Stuck open injector, bad AFM, clogged up ICV. That throttle 'hunting' is typical dirty ICV.

[Dj Buttchug]

check your oil pressure. the lights turning on at idle... completely non related but might want to check that out too

[rcfanatic]

What size injectors are you running? 173 Stock chip DME?

Stuck open injector, bad AFM, clogged up ICV. That throttle 'hunting' is typical dirty ICV.

Stock 17lb inj. Stock chip with 173 dme. Injectors were professionally cleaned about a year ago but I guess could be stuck open. Tested the AFM per bently about a year ago and was fine. Tested ICV per Bentley about a year ago and it was fine. Cleaned both thoroughly as well.

check your oil pressure. the lights turning on at idle... completely non related but might want to check that out too

I think the low oil pressure is due to low idle ~ 600 rpm not pumping the oil up to pressure. Dipstick shows there is plenty of oil and at 700+ rpm the light goes off.

[rcfanatic]

What's the best way to check the injectors if one were to be stuck open?

[328ijunkie]

ECU temp sensor. Your ECU is prob stuck in cold start mode.

[rcfanatic]

Just to reiterate

New:
Rebuilt i head decked .020"
Fuel pressure regulator
Coolant temp sensor
Spark plugs
Wideband/Narrowband o2

1 yr ago:
Motronic 1.3 conv, 173 dme
Stock 325i injectors professionally cleaned and flow tested
Air flow meter
Idle control valve
Throttle position sensor

The car is running very rich, when idling/hunting it fluctuates between 11.3 and 12.0 AFR.
Fuel pressure is 5 PSI too low at idle and load

[nando]

Try stock injectors, or a chip meant for larger ones.

also, if you overtightened your valves they can get "stuck" open when the engine is cold (valve clearance increases as the engine warms up). Might be worth checking into.

[rcfanatic]

The injectors are stock.

When you say overtighten the valves do you mean the eccentrics? Still haven't had a chance to get back in there and check the valves for adjustment.

Only thing I can figure as far as the valves is that they aren't opening all the way, allowing enough air in. In seems like it would have to be pretty bad though to make it run that rich

[nando]

no, when you put pressure down on the eccentric as you are tightening it, you can actually press down enough to compress the valve spring a little. So when the engine is cold, the valve is stuck slightly open. as the engine warms the valve clearance gets bigger and the valve can close slightly.

it doesn't really *sound* like your issue, but it's not a big deal to check. see if you can fit a .010" shim in there with the engine cold.

you also said you have 17# injectors, which are not stock. stock is 14.5#.

[rcfanatic]

I see. Yeah when I did the valves I checked them all multiple times for .010 clearance after they were tightened. My guess is maybe one or more loosened up causing a larger than .010 lash and not letting the valves fully open.

My error on the injectors. I have stock, 325i injectors. For some reason thought the stocks were 17

[nando]

could be.

I replaced all of the eccentric nuts and bolts on my head. The nuts were of uknown age, and a lot of the nuts/bolts had gotten soft and wouldn't hold a torque any longer. a few of them even stripped out (lucky I had extras).

[rcfanatic]

What might be causing the low fuel pressure?

[nando]

bad FPR?

a bad pump could cause low FP but it wouldn't run rich.

the only other thing is the vac line from the manifold to the FPR could be clogged for some reason.

a bad FPR can leak fuel into the intake manifold through that vac line though.

[hotballs]

11.3 and 12.0...I mean honestly it's not like EXTREME rich. It's an old m20 that you've changed a bunch of stuff around using 80s technology management.

Get a tuner involved if you want perfect AFRs. If everyone had a way to read their AFRs I'm sure we'd all be off.

Also how you measure them and the brand of o2 sensor etc is going to effect the reading. I say take it to a tuner at this point if you're really worried about it. Not trying to say you can't figure it out, but as far as the parts you've listed, there isn't really anything else to check if all those are good and working correctly. I guess question is if they're good.

[rcfanatic]

I'm planning on tuning it with a WAR chip but I want to fix this problem first. It's running way too rich and the idle should not hunt like that.

This may provide a hint. There is a normal AFR for about 10 seconds when the car initially starts up (whether the engine is hot or cold), and then it reverts to very rich again. If it's not related to engine management then maybe it has something to do with the O2's heating circuit kicking in?