SOLVED: Need help with bogging and misfires, persistent P0171 & P0174 lean DTCs

[Effduration]

Can you please describe your DIY smoke tester and method?

I have a decent compressor-fed "Stinger" smoke tester bought on amazon and on 2 recent occasions, my indie has found vacuum leaks I was unable to find.

[80stech]

If the gauge is slow to respond going up it can be slower going down, or not go down at all under load so that needs to be dealt with to get an accurate picture of the fuel system. Does the gauge drop 5 or 10 PSI instantly as soon as the pump shuts down? More than once were the OP has not done a fuel pressure test before and doesn't know what things should look like get fooled by the gauge/connection. +1 one one the smoke tester, not the most reliable way to prove no vacuum leaks me thinks
++ fuel pressure test includes driving under load with the gauge taped to the windshield, again common thing for a DIY'er to be fooled by not doing properly.

[Bdc101]

OP is your pressure gauge fluid-filled?



It looks like the slow speed is just due to gauge damping that Andrew's gauge may not have had.



If you use it to check the pressure on other things does it respond just as slowly?

[X5chemist]

What's the fuel reading in grams/sec?
Are any intake runners showing signs of oil residue? Mine had a vac leak along the intake seam.

[victell]

Originally Posted by Factory6speed

…the circular plug for the ignition wire harness wasn't totally plugged in. It was half way in…check electrical connectors.

Ok I checked the connector and wiggled the harness with the engine running, no change.

Originally Posted by Effduration

Can you please describe your DIY smoke tester and method?
… my indie has found vacuum leaks I was unable to find.

I used a version of the smoke machine below. Manually blew smoke into the intake boot just after the MAF. The DIY tester was leaking smoke from the cap and the test area was windy. What method did your indy use to find the vacuum leaks?

Originally Posted by 80stech

If the gauge is slow to respond going up it can be slower going down, or not go down at all under load so that needs to be dealt with to get an accurate picture of the fuel system. Does the gauge drop 5 or 10 PSI instantly as soon as the pump shuts down?… +1 one one the smoke tester, not the most reliable way to prove no vacuum leaks me thinks
++ fuel pressure test includes driving under load with the gauge taped to the windshield, again common thing for a DIY'er to be fooled by not doing properly.

Originally Posted by Bdc101

OP is your pressure gauge fluid-filled?

Originally Posted by andrewwynn

What I'm noticing is the pressure didn't go to 50 until started. Or should hit 50 at key on. If you key off then key on does it go to 50? In any event I'm getting some deja Vu. It'll take half an hour but no$ to pull the FPR and look at the o-rings. At the age of the car I'll need surprised it's not flattened like mine was

I’ve now removed the schrader valve from the fuel rail and adapter, and opened the tester’s purge valve until fuel filled the hose up to the gauge displacing the air making it fluid filled. Previous fuel pressure video was a taped-to-windshield drive but did not do that this time as I couldn’t get a leak-free tester setup and didn’t want to risk it. Response is much faster now, but overall the same. Video below.

Originally Posted by X5chemist

What's the fuel reading in grams/sec?
Are any intake runners showing signs of oil residue? Mine had a vac leak along the intake seam.

I do have oil residue inside my intake (pics below). How would an intake vac leak cause this? For fuel reading do you mean volume test or Foxwell fuel consumption live data?

[Effduration]

Originally Posted by victell

I used a version of the smoke machine below. Manually blew smoke into the intake boot just after the MAF. The DIY tester was leaking smoke from the cap and the test area was windy. What method did your indy use to find the vacuum leaks?

Manually ? You mean like blowing on a hose or something???

To do a decent smoke test, you need 10 minutes + of steady smoke at a steady pressure. and you need to introduce smoke in several locations...like the brake booster...as well as the intake.

My Indy used a professional-grade smoke tester that costs $1,000's...

You need to get a proper smoke test done...I suggest you pay a tech to do one.

[workingonit]

Originally Posted by Effduration

Manually ? You mean like blowing on a hose or something???

To do a decent smoke test, you need 10 minutes + of steady smoke at a steady pressure. and you need to introduce smoke in several locations...like the brake booster...as well as the intake.

My Indy used a professional-grade smoke tester that costs $1,000's...

You need to get a proper smoke test done...I suggest you pay a tech to do one.

from another thread, just now

Originally Posted by workingonit

I spent half the afternoon trying to smoke test my X5, with little luck because I was using the vinyl/rubber glove trick to seal off the intake, and they'd either develop a hole, or the clamp would slip off...the Autoline Pro "shop Series" tester worked fine, and one time It ran for 10+ minutes before a hole appeared in the glove. During that time, I detected no leaks anywhere, though this was just a test of the machine, and I didn't take off any covers. I'm buying a bladder to fill the intake, etc. before the actual test.

I agree with Effduration, it would be better to have a professional shop do your smoke testing, rather than piece together a homemade tester (in my case, a sauerkraut jar + soldering iron + $7-10 manual siphon pump), or make one that you have to blow thru a hose to furnish the air. I wasted money making my failed tester (twice), time doing that, and more time ordering and sending back two Chinesium cheapo testers; finally, I bought a decent one on Amazon (third time's is a charm), in November, but only got around to testing it today (preliminary to the actual smoke test, just to see if it works..it did).

I'll have to get a sealing bladder to keep the smoke in (unlike Lucas Electric equipment, famed for letting the smoke out, haha). That'll add another $25+ to the $101+ I bought the tester for (Black Friday deal, plus I got Amazon to throw in $25 credit, due to the fiasco caused by my previous two tester orders...it was a differnt brand). So, in all, I will have spent $101 for the good tester + $25 for the sealing bladder I'm ordering, minus the $25 I was credited...equalling $101 for the complete test outfit I'll use.

Of course, the same tester is up to $120 now, + $25 for the bladder ($145 total), but that doesn't include a compressor at home (which I would assume most of us DIY'ers have, mines a Husky 20-gallon), but I'm not adding that into the cost to test. If one doesn't have a compressor already, Autoline offers the same tester, but it has a small air supply attached, for another $10 @$130 (bringing the cost to test up to $155).

So, why didn't I get my BMW tested at a pro shop?

• 1) there are no BMW Indy shops within 40-50 miles (except for one that is a glorified tire shop/ricer shop),
• 2) the two local shops I went to last year (general mechanics) quoted me $150 and $160 for a smoke test, and
• 3) I have five old vehicles that need maintenance off & on, including emissions and engine bay smoke tests (I've had to redo several Evap systems at home, had to test & replace leaking gas caps, too, and now the intake smoke test on the X5); whereas I used to have a friend, back in the day, that had the gear at home, now I will, so I the gear I've bought should pay for itself several times over.

I could be wrong, and might never find any leaks, nor have to repair Evaps again, but at least I'll have the gear, which I can pass on, later, to friends or relatives.

[andrewwynn]

What I'm noticing is the pressure didn't go to 50 until started. Or should hit 50 at key on. If you key off then key on does it go to 50? In any event I'm getting some deja Vu.

It'll take half an hour but no$ to pull the FPR and look at the o-rings. At the age of the car I'll need surprised it's not flattened like mine was

https://youtube.com/shorts/AEjiWbrrP...VEy8TkHUtTdSzm

[andrewwynn]

That jiggle at isle exactly matched mine with the FPR leak!

After the fix it rests exactly 50.00 and doesn’t waver at all.

That’s the sign I was looking for! 90% certain FPR is your problem. When FPR is working properly the needle should be rock stable at idle.

https://youtube.com/shorts/AEjiWbrrP...VEy8TkHUtTdSzm

[aureliusmax]

Originally Posted by andrewwynn

That jiggle at isle exactly matched mine with the FPR leak!

After the fix it rests exactly 50.00 and doesn’t waver at all.

That’s the sign I was looking for! 90% certain FPR is your problem. When FPR is working properly the needle should be rock stable at idle.

https://youtube.com/shorts/AEjiWbrrP...VEy8TkHUtTdSzm

I recall a video in 2021 I made with my E66 N62 having an unstable fuel pressure like shown above. The FPR is integrated into the fuel filter, but I've since changed the filter assembly. Currently repaired multiple issues on the engine but I will have to check and see if this one is still remaining, and look into the regulator.