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Tech Forum : Fuel Distributoor - extra line!?

- BMW E21 Community
   - Tech Forum
      - Fuel Distributoor - extra line!?
melloh   Posted Wednesday, Feb 7th 5:28am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 468
   
California, USA (San Jose)
1980 320is, 1991 318is

Car is 1980 320is

Ok, so I took a bunch of things apart when trying to put the AFM rubber boot on. Unhooked most lines to the distributor. I was smart enough to note the order of the lines running to the injectors, but thats about it.

I figured everything out except the one w/ the arrow



I have TWO (2) banjo lines that can go in there, but only ONE openning (that I can find) left. Both banjo lines are identical (thin black plastic line comming from somewhere under the starter).

a) Which one of these goes to the arrowed hole in the distributor, and

b) where does the other banjo line go?

TIA.

Henry

Madhatter   Posted Wednesday, Feb 7th 5:46am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 105

Australia - QLD
E21, E24, E30
You should have

Fuel in
Fuel return
Warmup regulator (2)
Injectors (4)

Thin black lines are usually the plastic fuel lines going to and from the regulator.

imaradiostar   Posted Wednesday, Feb 7th 9:08am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 1006
   
Nashville, TN
81 323i, 82 525i, 85 524td, 90 535i
maybe a cold start valve?

jt

TJ   Posted Wednesday, Feb 7th 10:01am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 22

NY, USA
82 528e2i 84 320i/4 80 320i
hmmm... the frequency valve is another thing to consider. Maybe one of the warm-up regulator lines connects to that and the other to the fuel dist? I'm having a hard time remembering.

Madhatter   Posted Wednesday, Feb 7th 10:06am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 107

Australia - QLD
E21, E24, E30
I cant remember if they connect to the top of the distributor, i think they do. Its the only port not marked in his diagram.

Greg323i   Posted Wednesday, Feb 7th 3:36pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 288
   
Melbourne, Australia
1982 Hennaröt 323i
Well, the arrow is definitely pointing to the fuel return and the one to the right of it is the fuel inlet. To the WUR is usually on the top and the return is probably the one to the left of the arrow.

melloh   Posted Thursday, Feb 8th 2:06am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 469
   
California, USA (San Jose)
1980 320is, 1991 318is
Eureka, I'm a fumbling fool.

Thank you all. I think Madhatter had me in the right direction. There was an attachement in the middle of the 4 lines (A) that I had missed completely!



Unfortunately, I obviously neglected to mark which line went where (yes, lesson learned).

Right now, it is set up one way b/c one line happened to reach A better than the other.

The question remains, if I am wrong, can A and B be interchangeable? I ran the car for about 2 minutes. Fuel-wise it was running and holding idle and revved up to 3k (but spewing out coolant under the plenum somewhere... ). I just want to be sure something isn't going to explode after prolonged running or anything like that.

Greg323i   Posted Thursday, Feb 8th 5:07am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 289
   
Melbourne, Australia
1982 Hennaröt 323i
A and B are not interchangeable. A is a return from the WUR, controlling the distributor pressure (and idle speed) and B is sending excess fuel back to your fuel tank. If you reversed them, I don't know if it would run, but if it did I imagine it wouldn't run very well.

melloh   Posted Thursday, Feb 8th 8:19am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 471
   
California, USA (San Jose)
1980 320is, 1991 318is
Oy. That sounds scary. Should I try reversing and see what happens? Or leave as is?

Greg323i   Posted Thursday, Feb 8th 3:59pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 290
   
Melbourne, Australia
1982 Hennaröt 323i
I'd just make sure that A is going to the WUR and you should be okay.

Greg323i   Posted Monday, Feb 19th 4:15pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 293
   
Melbourne, Australia
1982 Hennaröt 323i
Well, I screwed up big time!!

I was working on my car today and I found that A and B both go to the WUR. I'm not sure if it matters which one goes where on the WUR.

Sorry if I screwed you up.

melloh   Posted Tuesday, Feb 20th 4:26am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 483
   
California, USA (San Jose)
1980 320is, 1991 318is
Heh.. I'm glad you posted b4 me. I felt the fool when I checked today (trying to do the fuel pressure testing per Bosch Injection manual) and saw both connected to it. I've tried searching the book and the net to see which one goes where. If I recall, this is my current setup:

A <-> 1
B <-> 2

[EDIT: deleted image]


I did find this, but have been unable to correlate whther B = 1 or 2 or C = 1 or 2

http://www.auto-solve.com/mech_inj.htm#MFI10

jrcook320   Posted Thursday, Feb 22nd 7:46am [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
The port on the top of the fuel distributor (A) runs to the inlet of the WUR (2 in your diagram, the larger of the 2 ports.

(1) is the return line from the WUR and should go to port (B ) on the fuel distributor. You will notice a small triangle pointing toward the fuel distributor to indicate fuel flow direction.

Fuel flows from the top of the plunger rod, through the WUR, then to the fuel return circuit on the side of the fuel distributor.

While the car may run with them crossed, fuel flow through the WUR will be reversed so the control pressure will not be the same.

The WUR controls fuel pressure over top of the plunger rod only and is nothing more than a metering valve. This serves only to control the air/fuel ratio by limiting the motion of the plunger rod and thus the sensor plate for a given amount of air flow. Higher control pressure yields less movement, which yields less fuel which yields a leaner mixture. Changes in the mixture will have an effect on idle speed, but the WUR does not control the idle speed directly, it can only control fuel mixture.

System pressure in the fuel distributor itself is controlled by the pressure regulator in the fuel distributor.

melloh   Posted Thursday, Feb 22nd 11:48am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 488
   
California, USA (San Jose)
1980 320is, 1991 318is
Sweet! Thanks, that helps. I'm trying to do the fuel pressure test and it requires me to hook up to that line. So, i have it hooked up correctly, but now I don't know whats wrong.

I am following the instructions for k-jet w/ lambda for my car (later generation w. O2 sensor) in the bosch manual by Ben Watson.

I hooked up the pressure guage w/ the valve on the WUR side and disconnected the electrical leads to the WUR and Aux Air valve.

How do you jumper the fuel pump relay? All my attempts in jumping 87 - 15 (w/ the relay in and out) haven't gotten the pump going. It only came on when I turned the ignition to the ON position (motor NOT running and cold).

With ignition ON and valve ON (assuming on=open on my valve), the guage read 10 psi and 33psi with valve in off (closed?) position. Strangely, when I turned the ignition off, the guage when up to ~35psi with valve in both on and off positions.

I'm so lost... what am I doing wrong?

jrcook320   Posted Thursday, Feb 22nd 7:17pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
You have to have the ignition "on" to send power to the fuel pump, even with the relay jumpered, so you did that correctly. The relay only allows the fuel pump to run when their is an ignition pulse, and that only happens when the motor is cranking over or running.

The first step is to measure cold control pressure, so you want the valve open. If it's cold out, it should be very low. To know exactly how low you also have to measure the ambient air temp. By interpolating the chart in Ben's book, at

30 deg F - 9.8 psi,
40 deg F - 13.4 psi,
50 deg F - 17 psi and so on.

when you close the valve, you're now measuring system pressure. This should be between 65-75 psi. If it's really around 33 psi then you either have a clog in your return line, a clogged fuel filter, or your fuel pump is bad.

Now open the valve again, reconnect the plug on the WUR and start the motor. Let it come up to operating temp, your warm control pressure should be between 39-45 psi.

When you shut the pump off with the valve open, you're now measuring rest pressure. A rise in pressure after shutting the fuel pump off is normal (don't know why). This pressure should stay above 22 psi for 20 minutes. If it doesn't it indicates that you have a leak somewhere in the system, such as the check valve (most common), accumulator, cold start injector, WUR, or system pressure regulator. Low rest pressure usually causes hard warm starts.




melloh   Posted Saturday, Feb 24th 1:52am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 493
   
California, USA (San Jose)
1980 320is, 1991 318is
Okay, so here are the results:

My e30 temp was reading 53 deg F in the shade, so ~55 for the e21. In parentheses is the specs per Bosch manual.

Cold Control: Just under 10psi (17+)
System Press: ~70 psi (65-75)
Warm Control: ~50.5 (39-45)
Rest Press.: ~24 (22)

So this means:

Cold control - LOW
Sys Press - Normal
Warm Control - a little high?
Rest Press - Normal

According to the symptoms listed in the book, this is not in there. I'm assuming I should then take the 2 that are out of norm individually? (so, something wrong w/ WUR and the System pressure regulator?) Or, does it indicate I messed up in the testing procedure?

Again, thanks for your patience w/ me!

jrcook320   Posted Saturday, Feb 24th 7:54pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
It is strange to have low cold pressure and high warm pressure at the same time.

What drivability symptoms is the car presenting?

melloh   Posted Monday, Feb 26th 5:12am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 494
   
California, USA (San Jose)
1980 320is, 1991 318is
it seems to have poor power overall. It was most noticeable going through the somewhat infamous "grapevine" in southern CA. At first I gave way to the possibility that the car felt slow b/c I had been driving the e30 for so long. But, it was clear when I was trying to drive up hill and barely able to hold speed (jumping between 2nd and 3rd gear @ 35-45 mph i think), whereas in the past I was able to cruis up in 4th @ 70mph. Most of the power loss FEELS like its above 3k (but, I could be wrong).

jrcook320   Posted Monday, Feb 26th 6:52pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
What do your plugs look like? With your control pressures, you should be running fairly rich when cold and running too lean when warm.

melloh   Posted Wednesday, Feb 28th 12:19am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 495
   
California, USA (San Jose)
1980 320is, 1991 318is
Ok, so I ran the car for about 20 minutes (to school & back) and looked at the plugs:

Background:

Bosch silvers (w9ds or something like that)
~1000 miles or less
about 1 year old
New wires (<1 year)
Tune-up and smogged about 1 year ago (incl new o2 sensor)

Plug observations:
1&2 relatively clean on the threads - a little bit of oil grime, but easily wiped off and not "cooked in". The spark arc/arm slightly ashed.

3&4 both a noticably more oil and grime on thread and on rim of the node/tip. Some cooked in. Slightly more ashed on the spark arc/arm.

1,2,3,4 - did not notice any fuel smell.

Are there things I should be looking for? Ideally I'd post a pic, but I have no digi camera besides my cell phone (I know, I'm still in the dark ages).

melloh   Posted Friday, Mar 2nd 1:02am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 498
   
California, USA (San Jose)
1980 320is, 1991 318is
http://ww1.autopartauctions.com/a.asp?A=538446&ap=13276&C=18&G=

What do you think... for 80 total. Beck/Arnley. Worth a shot for me to try it out?

melloh   Posted Tuesday, Mar 6th 10:11pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 502
   
California, USA (San Jose)
1980 320is, 1991 318is
Ok, so I'm still at an impasse here. I know my description of the sparks was somewhat useless (sorry), so I managed to get some pictures. The number in the upper left correlates to the cylinder #.











jrcook320   Posted Wednesday, Mar 7th 8:19pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
Your plugs look clean, but why are they wet? Is it fuel?

At this point, provided you have done your tests right, you need to correct your control pressures. I suggest you take your WUR apart, clean it and reinstall it and do your tests again. If not then you will either need to adjust it or replace it. If you want, I can either make yours adjustable for you (I charge $50) or help you with how to do it yourself.

Your fuel distributor is not the problem, you have good system pressure and good rest pressure which indicates everything else should be good including fuel pump, fuel filter, system pressure regulator, and cold start injector.

melloh   Posted Thursday, Mar 8th 12:24am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 504
   
California, USA (San Jose)
1980 320is, 1991 318is
Thanks so much for getting back to me on this jrcook.

I tried to smell for fuel, but couldn't smell any. It smells, looks, and feels like oil. There is considerably more on #3 & 4.

The WUR currently in is one i purchased (used) that was supposedly working. I actually have my old one I can tinker with. I know I've seens some FAQ somewhere online on how to recondition them. I will try those first (unless you have additional steps/suggestions) and retest.

I cannot tell you how relieved I am to hear that I dondt have to mess w/ pumps and distributors!

jrcook320   Posted Thursday, Mar 8th 12:35am [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
No problem. Here's a .pdf on how to clean your WUR. If you decide to make it adjustable I can provide all the info you need.
http://bmw320i.com/library/howto/WUR%20Servicing.pdf

melloh   Posted Thursday, Mar 8th 6:20am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 505
   
California, USA (San Jose)
1980 320is, 1991 318is
I curious what the benefits of being adjustable are? I realize if i plan on doing modifcations it would be handy... but I am way too far away from that stage.

jrcook320   Posted Thursday, Mar 8th 7:24pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
if your control pressure is incorrect, you have 2 options:


1) replace the WUR with a new or used one that may or may not be adjusted properly for your system, costing maybe $50 for a used one and $300 for new or reman.

2) or adjust your WUR so the pressures are in spec.


If you, like me, decide to go with route 2 rather than spend a bunch of money, it can be time consuming to tune things in. You basically adjust it with a hammer and a drift, which is fairly crude. If you go too far, you have to take the WUR off and and apart to pound things back out and you're back to ground zero. If it's externally adjustable you don't even have to take it off, just turn a wrench and it backs things out.


jrcook320   Posted Thursday, Mar 8th 7:29pm [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
Here's a diagram I drew on how this works. I can't take credit for the method, I read an article on how to adjust warm pressure and one on how to make the cold pressure externally adjustable. I just expanded on what I've read to make both externally adjustable.

I've done a few WUR's like this so far and it works very well.


melloh   Posted Thursday, Mar 8th 10:44pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 506
   
California, USA (San Jose)
1980 320is, 1991 318is
Looks like this would require tools and adequate skill and proficiency in using them - of which I most likely have neither.

But, my #'s don't seem so terribly off the mark that I might be able to get away w/ old-school tinkering. This diagram REALLY helps me visualize what I will need to do to correct my pressures, though!

I'm so glad that I kept my old one so I can practice or have a backup for when I undoubtedly will mess up... Thanks much for your help. If I run into any hiccups, I'll post back here.

melloh   Posted Tuesday, Jun 26th 8:29pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 565
   
California, USA (San Jose)
1980 320is, 1991 318is
I know it's been a while, but I finally had a chance to crack the WUR open. According to the diagram JRCOOK provided and my control pressure readings, both sides/portions need to go up. But, i cannot figure out how to acheive this. There was nothing inherantly obvious to me when I unbolted/unscrewed/unclipped all that I could. Apparently I could change one of the internal o-rings to change one of the control pressures, so does this mean I need to find a narrower o-ring?

Greg323i   Posted Wednesday, Jun 27th 5:39am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 368
   
Melbourne, Australia
1982 Hennaröt 323i
I haven't done this and I'm sure that JR will pipe in, but if you're not modifying your WUR like he did, you can probably just lightly tap both fixtures from the inside to move them out. At least that's the way that I understand it.

jrcook320   Posted Thursday, Jun 28th 9:33am [Edit] [Quote] [IMS] [View car]
Junior Member
Post nr. 1
   
Van Wert, OH
'81 320i
Yes, you just use a drift and hammer to tap the post and valve body out a mm or so. Then assemble the WUR, hook your gage up and tap back in from the outside till your pressure is where you want it.

If you go too far, you have to take it off, apart, tap things back out and start over again. Thus the benifit of the externally adjustable WUR, no removal or disassembly required.

Here's a decent writeup which is where I got the basic idea, I just took it to the next level by making both cold and warm adjustable.

http://www.landsharkoz.com/tt/ttwur.htm

melloh   Posted Sunday, Jul 1st 3:02am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 567
   
California, USA (San Jose)
1980 320is, 1991 318is
Okay, here are the results.

Temp: ~75

Cold Control ~22

Warm Control ~43

So, the cold control is ~4 psi below what Watson's manual indicates. It took me about 4 hours to acheive this number (basically, my hamfistedness jumped me from 45-9-55-10psi... ). I was afraid to tinker more for fear of messing it up. Should I try to tap it into place to get that 4 psi?

Oh, and JRCOOK, I now see why you made it adjustable. You don't know how close I was to scrounge up the 50$ to paypal you.......

PPS: After re-reading this thread millions of times, I realized I implied something negative to the person who sold me the WUR - my apologies! Not intended at all.

melloh   Posted Monday, Jul 16th 12:33am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 578
   
California, USA (San Jose)
1980 320is, 1991 318is
Ok, so was able to get it pretty darn close today (26-28 @ 80 degrees). Afterwards, the car wasn't idling quite right, so I adjusted fuel mixture by ear until idle was stable (CCW until stalled, CW until stalled, then set to midpoint between those positions).

Warmed it up and test drove it, but it still has severe power loss. 0-60 was 18.3 sec one direction, 17.8 the other, so about 18 seconds. That's about 2x normal, isn't it?

Power loss still seems to come mostly from higher revs (above 3k). It feels like its truggling just to rev that high. So, what should I check next? A couple years ago I had replaced vacuum hoses with all the ones I could buy online (from either Bavauto or BMP).

Also, there's a popping noise still, but I don't know what it is - ping? Backfire? It happens only when revs are above ~3k and only after I let off the gas.

TJ   Posted Monday, Jul 16th 8:40am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 30

NY, USA
82 528e2i 84 320i/4 80 320i
Try disconnecting your O2 sensor and connecting it to a voltmeter and see how your A/F mixture is doing under various conditions. After it warms up it should read roughly between .3 and .9 volts under load (higher is richer)

I have sometimes suspected fuel system problems, and when I would actually check it with a meter I would find the opposite of what I expected.


melloh   Posted Friday, Jul 20th 12:45am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 583
   
California, USA (San Jose)
1980 320is, 1991 318is
I don't know how to do what you described, so I looked up the Bosch manual.

Here is what I did:

Set multimeter to dwell - 4 cyl
Black/com/ground to ground (tried 2 spots - bolt on cylinder head and strut tower)
Red/test lead to where o2 wire meets green wire (to ecu?)

Started engine cold and let it warm up with dwell meter on. The entire time it stayed @ 90 degrees. Manual says it should read 45 deg. warm. I'm quite sure I'm doing something wrong!

I am new and very very bad at electrical systems and probably lack what you guys know as 'common sense/knowledge', so you may need to give instructions like you're talking to a 13-yr old... I've looked up the haynes, clymer, internet, and bosch manual but I somehow still managed to not get it right. If you've got the details, I've got the empty space in my head ready to be filled up!


PS: History on the car.. it passed smog 2 years ago and supposedly had the o2 sensor changed. I've driven it less than 2k miles since then.

melloh   Posted Friday, Jul 20th 5:45am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 584
   
California, USA (San Jose)
1980 320is, 1991 318is
Oh wait... just read yours and compared it to a FAQ on pelican parts and it makes more sense. Will try that tomorrow.

melloh   Posted Monday, Aug 6th 1:17am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 585
   
California, USA (San Jose)
1980 320is, 1991 318is
Here are the test results (with the abreviated instructions I followed)

From Bosch book by Ben Watson, Ch. 5:

Connect Lambda [= o2 sensor, right?] wire to ground... rpm and Lambda voltage should both rise.

I must have done something wrong because rpm went down, and voltage dropped to 0. There was another test in this chapter, but it apparently involved me touching my hand to the positive battery cable and I'm just not ballsy enough to try this.

From Pelican Parts website http://www.pelicanparts.com/bmw/techarticles/JF-Tech/about_oxygen_sensor.htm:

Voltage readings (all at operating temp)

Power on, engine off.... .042 and dropping slow and steady

Idle (1000-1100 rpm).... 0.58 - 0.71
1900 - 2100 rpm......... 0.28 - 0.68
2900 - 3100 rpm......... 0.32 - 0.64
Idle with Vacuum leak (removed oil fill cap)
Initially drops to .03 and slowly goes up
Replacing oil cap and reads ~.94

If I understand this correctly, the Lambda/o2 sensor is working?

TJ   Posted Monday, Aug 6th 5:03am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 35

NY, USA
82 528e2i 84 320i/4 80 320i
Yes it looks like the fuel injection is in good shape then. The problem with the first part is that you were supposed to disconnect the wire from the O2 sensor and connect the wire to ground, not the sensor. But I would say check out your ignition timing now. If you don't have a timing light then you can just try advancing it a bit (turn the distributor clockwise) and see if it runs better. Make a mark on it first so you know where you started.

melloh   Posted Wednesday, Nov 21st 3:19am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 611
   
California, USA (San Jose)
1980 320is, 1991 318is
Only a decade later, I finally manned up and did as you suggested. I loosened the 10mm bolt, turned the distributer a few degrees clockwise (about 1/4 inch), fired it back up (it was already warmed up to operating temp), and right away noticed the idle is now @ ~1900 (was at ~1100). Revved it up a few times and lo-and-behold, the gurgle/popping noise is inaudible and response seemed better. Drove around the block and found that power was more consistent (too much traffic to test 0-60). So, it looks like it's about time for me to buy a timing light to really get the timing down right. Also, all the little things I've done (WUR adjustment, new intake bellow, new fuel filter) have probably also messed w/ the A/F mixture, too. So which comes first - timing or A/F adjustment? I am assuming Timing as it is mechanical and would affect A/F?

PS: YOU ROCK!

melloh   Posted Wednesday, Nov 21st 7:52am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 612
   
California, USA (San Jose)
1980 320is, 1991 318is
Just did the 0-60 and there's already drastic improvement. 2 occupants (total weight ~315lb) and more than 3/4 tank - average around 13 seconds. That's already 5 sec off and probably an additional 50lbs (passenger heavier this time). So, if I can get it tuned right, we should be near the stock numbers (or possibly better w/ the addition of an Ansa exhaust?) of 10.5 seconds (meaning, to me, that it's almost back to tip-top shape)!!

TJ   Posted Wednesday, Nov 21st 8:40am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 46

NY, USA
82 528e2i 84 320i/4 80 320i
Yeah once you get the timing set to spec you can continue to tweak the fuel system if necessary. Here are the advance values I got from the Haynes manual

Bosch JGFU 4 (1.8L 320i), vacuum disconnected
1000RPM 10-16
1500RPM 14-22
2000RPM 20-28
2500RPM 26-34
3000RPM 32-39
4000RPM 32-38

vacuum advance should max out around 14 degrees

13sec is probably not too far off... I bet to get under 12 you have to dump the clutch at 5K RPM or so. I never dared try it in my 320i.

melloh   Posted Wednesday, Nov 21st 8:21pm [Edit] [Quote] [IMS] [View car]
Member
Post nr. 613
   
California, USA (San Jose)
1980 320is, 1991 318is
TJ wrote:
Yeah once you get the timing set to spec you can continue to tweak the fuel system if necessary. Here are the advance values I got from the Haynes manual

Bosch JGFU 4 (1.8L 320i), vacuum disconnected
1000RPM 10-16
1500RPM 14-22
2000RPM 20-28
2500RPM 26-34
3000RPM 32-39
4000RPM 32-38

vacuum advance should max out around 14 degrees


Thanks for the info. Unfortunately, I currently lack the education to utilize it. Winter break I should have some time to sort through some literature to smart up on the topic a bit and hopefully squeeze in tinkering time.

TJ wrote:

13sec is probably not too far off... I bet to get under 12 you have to dump the clutch at 5K RPM or so. I never dared try it in my 320i.


Yeah, as you can tell, I am really friggin' excited on the improvement. Surprised too that when I had the car in for a full tune-up (mind you it was free from a raffle at a BMWCCA driving school), they did not fix this as the car came back to me with the same gurgling, popping and power loss. But realistically, I am not looking to win any drag races. I just want this car back in stock/near-stock shape so I can take it to autcrosses/driving schools. I figured a rough 0-60 is the best gauge I have (no fancy tools or knowledge needed). You guys will hear back from me in a about a month (and a new thread) when I'll need to pick your brains to help me decifer the gearhead lingua from the literature.

TJ   Posted Friday, Nov 23rd 4:11am [Edit] [Quote] [IMS] [View car]
Member
Post nr. 47

NY, USA
82 528e2i 84 320i/4 80 320i
What the numbers mean is that, if you have the distributor vacuum line disconnected, then the spark plug should fire when the crankshaft is a certain number of degrees before Top Dead Center in its rotation (between 10 and 16 degrees when the engine is running 1000RPM, etc.)

The centrifugal advance mechanism inside the distributor basically increases the advance as RPMs rise, while the vacuum advance increases it further as vacuum rises (or as manifold pressure drops, ie when the throttle is closed).

There should be a mark on the crankshaft pulley that lines up with another mark on the timing cover when it's at TDC. Then you hook up the timing light and point it at the pulley. It will blink every time the spark plug fires so if there is 10 degrees of advance you will see the marks being 10 degrees apart.

With a more expensive timing light you can dial or key-in a value, which saves the trouble of having to figure out how far apart the marks are.

IIRC there is a mark on the flywheel for setting the timing at a certain RPM but doing it that way might not have the best result if the distributor is out of spec.


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