Help me kick my off idle miss/hesitation

[Jordan]

You can be my assistant for a day :)

I'm actually not ordering new plug wires, I'm just going to use this as an excuse to upgrade to coil on plug ignition.

[DaN]

ding ding ding, Do I win a prize?

[Jordan]

Problem has been identified!

I went to to Teaguer's place to swap some parts off his 318i trying to find my problem and the first thing I swapped fixed it. My spark plug wires are aparently bad although looking at them doesn't show anything conclusive as to them being bad.

New wires need to be ordered!

[Jordan]

Well I got my injectors back from service today. I carefully put everything back together.. and sadly no joy. Everything looks really nice, but nothing has changed.

I installed 4 basically new injectors (with new orings)
I installed a new FPR
I cleaned the gunk deposits off the intake surfaces until sparkling clean
I reinstalled the manifolds with all new gaskets
I once again looked over every single vacuum line. Nothing to leak!

[Jordan]

Yeah yeah... I got all my parts from Patrick @ BMA today, but my injectors won't come back until Thurs/Friday.

[xLibelle]

keep us posted

[DaN]

It sounds like there is an ignition miss at high load/cyl pressures. At low rpms and WOT the load is super high, once the mis starts it keeps going.

I would double check the plugs around the porcelain for any black marks, perhaps swap plugs and wires if they are available.
The plugs look slightly oily, is there a valve cover leak into the plug holes?

my .02

[Jordan]

Well I started to fiddle with the FPR today, and no sooner then I touched it did it start leaking fuel around the o-ring...shit.

One thing led to another and before I knew it I had the upper and lower manifolds removed along with the fuel rail. A simple attempt at diagnosis has turned into a slew of while I am there maintenance.

I am going to:

Replace upper and lower manifold gaskets.

New FPR and associated o-rings

Send out my injectors for a complete service, ultrasonic cleaning and flow matching.

Replace all rubber fuel line in the engine bay with new metric fuel line and OEM clamps.

Clean and paint upper and lower manifolds.

[fretburnr]

I'd still recommend a vacuum pump for conclusive results as to whether it leaks. Besides, you can purchase it and then return for full cost after using it. Most of their "loaners" are just off-the-shelf items that routinely get used. (my friend works at autozone, sees this all the time)

[Jordan]

Hmm.. well I know I can pull the vacuum hose off the FPR with it pinched (so the engine doesn't see a vacuum leak) and it makes no change what so ever in the engines idle or behavior. I just tend to not feel thats entirely conclusive to warrant replacement of the FPR.

[fretburnr]

of course. My guess is that the FPR isn't running too rich for the computer to compensate for, but maybe the compensation is cutting out injectors at times. That, or the FPR isn't totally leaky, but may be intermittent and the valve may be fluttering. Either way, you should notice idle changes from unplugging a good fpr.

[Jordan]

But if you are right the engine would be running very rich at idle would it not? best I can tell its not as the plugs always come out clean and dry, and the exhaust does not smell like unburned fuel.

Rich running conditions make for wet, sooty plugs.

[fretburnr]

Those plugs look fine to me.

Pulling the vacuum hose off the FPR with the engine at idle doesn't seem to do anything for the FPR. With my thumb over the end of the hose the idle is the same and off idle free revving doesn't seem any different with the FPR seeing atmospheric.

I think you may have found it. The FPR should open/drop fuel pressure under vacuum (idle, light load) and close/increase pressure under close to atmospheric. ...apparently this one sees atmo all the time or doesn't hold vacuum.

[browntown]

I'm just guessing at this point because it looks like you have a good motor. Have you swapped oxygen sensors with a known good one? I know they're blamed for everything, but just a guess.

[Jordan]

This morning I popped the plugs out again to check their condition once more. They look pretty much the same as they did last time I checked, which is good.. because to me they look good.

While I was there I did a compression check. Results are as follows:

Cylinder 1: 201psi
Cylinder 2: 195psi
Cylinder 3: 209psi
Cylinder 4: 195psi

All in all pretty good looking numbers, within a reasonable range. I was actually surprised at how well it did.

I also removed the Main and Fuel Pump relays to do the test and while out cleaned the contacts on the relays.

Pulling the vacuum hose off the FPR with the engine at idle doesn't seem to do anything for the FPR. With my thumb over the end of the hose the idle is the same and off idle free revving doesn't seem any different with the FPR seeing atmospheric.