Fuel Pressure Test Results OK?

[88Sedan]

I've been chasing a rough idle, and hesitation on throttle. New cap/rotor. Checked valves 3x (despite them being good each time), every gasket and hose is new besides the head gasket. New bmw CPS, new bmw coolant sensor. Did extensive wiring checks to/from dme and connectors etc. All passed, everything perfectly in spec. Basic resistance test on afm seemed good and door moves(unsure how else to test afm). So I moved onto fuel testing. Here's what I got:

-cold start pressure 38-39psi idle
-Warm idle pressure 38-39 psi
-3k rpm 38psi
-WOT 42psi
-Pressure with vac line to regulator disconnected and plugged 42psi@idle AND at WOT
-Pressure with engine off, pump running and return line clamped 80 psi
- Pressure in system held stable for over 10 minutes with everything off
I also got good results from the fuel flow test, ~900ml in exactly 30 seconds

Interestingly, the hesitation/stumbling on throttle did improve with the vacuum line disconnected and plugged (not perfect but better).

Look normal, or should I order a new regulator?

I'm running out of ideas, so many parts were replaced since this car had leaks everywhere. The reason I did electric diagnosis is that removing the harness connector to the blue coolant sensor (thus putting dme in its base tune or whatever its called) seems to improve the running state. Literally checked all wiring, hot/cold tests, connector wiggle tests with friend helping and all. Ive sprayed every airway connection with no change in idle. Idle stable and doesnt hunt, but seems rough. Significant hesitation/roughness on throttle when everything is connected.

[MrBurgundy]

post a vid

[88Sedan]

I don't have access to a good video camera (old cellphone with bad audio). I can try to show in video, but my previous attempts didnt display the significant roughness felt throughout the car. Even just trying to get the microphone to pick up the rough idle wasnt really happening. I will try again, but forecast has bad weather coming my way so this will be delayed.

I am going to swap the injectors with a known good set since it kinda sounds like the issue in in 1 cylinder.

edit: forgot to mention intermittent check engine light, stomp test not working and e30 specific code reader not picking anything up. CEL goes away when battery unplugged, sometimes comes back sometimes doesn't. I think its picking up an AFR issue.

[litu]

Sub to this threat, when i have similar issue. But for now it sound ok, i mean i was adjust TPS and idle srew better, now it runs better at idle. Also i have adjustable FPR, so i was lower little bit fuel pressure, when i have M50 injectors. When it feels there is something still, i can hear/feel little shaking at the engine

[digger]

seems normal to me.

[Old525i]

I did these measurements a while back on my 1990 525i. I think the pressures were a little higher by some 8-10 pounds. Also, I remember that the pressure changes when you go WOT. Hope that helps. Good luck.

[digger]

3b is 43.5psi, that's what you should get +/- with the engine off pump suitably primed or at WOT. You will get 3-5psi less at idle and light load because of vacuum and the regulator working relative to the vacuum in the manifold, but the gauge you measure with is not referenced to vacuum it's referenced to atmosphere hence it does not always read 3b and this is normal.

[88Sedan]

The injector/(s) were the problem, back to running good now. The bad ones were supposed to be rebuilt and hadn't been used until recently, but i bought them many moons ago so I doubt the seller will work with me. Can anything prevent an injector from working well if they are sent out for a rebuild?

[digger]

rebuilt injectors are a scam

[TobyB]

cleaned injectors, however, work better than ones that are gummed up.
The places that do it for money say that if you let them sit for many months
with the cleaner in them, they may stick.

I tend to soak them in something chemically nasty, and then flow test them and
use the 6 that match, and if they don't, go find some more and clean them and
flow test them and so on and so on...

Smart would be to use a later (E36?) injector that flows similar, as they
don't tend to clog nearly as often or as badly.

t

[88Sedan]

cleaned injectors, however, work better than ones that are gummed up.
The places that do it for money say that if you let them sit for many months
with the cleaner in them, they may stick.

I tend to soak them in something chemically nasty, and then flow test them and
use the 6 that match, and if they don't, go find some more and clean them and
flow test them and so on and so on...

Smart would be to use a later (E36?) injector that flows similar, as they
don't tend to clog nearly as often or as badly.

t

They were e36 injectors (greentops). 2 out of 6 were definitely not spraying right despite opening (excess fuel on spark plugs and horrible roughness).

I made sure they all opened before install. Maybe one day I'll try and squirt something volatile through them, but I have to prioritize other things first. If anyone has a good 'how-to' check or test them I will bookmark it.

[digger]

rebuilt injectors are the equivalent of running some seafoam through an engine and changing the air, fuel and oil filters and calling the engine rebuilt

[88Sedan]

rebuilt injectors are the equivalent of running some seafoam through an engine and changing the air, fuel and oil filters and calling the engine rebuilt

What do all the fuel injector companies actually do then? Is there zero value beyond a person doing it themselves? These q's are genuine, not trying to be smart. There are so many companies doing rebuilding, flow matching or both.

[digger]

What do all the fuel injector companies actually do then? Is there zero value beyond a person doing it themselves? These q's are genuine, not trying to be smart. There are so many companies doing rebuilding, flow matching or both.

cleaned, flow tested (but there is flow testing and there is flow testing), new o-rings, new basket filter and pintle cap

[88Sedan]

So flow testing is the only real value added beyond what we can do ourselves? No offense intended but your short answers aren't helping guide someone like me who thought they were doing the right thing by buying injectors supposedly ready to go (which clearly weren't).