L-jet running rich Options

[Ctrout]

I know that everyone here has D-jet but does anyone know of any L-jet gurus anywhere? My car has smelled like it runs rich since I got it. While doing some exhaust work this morning, it was confirmed by the black soot everywhere. I thought I read somewhere that these cars ran rich from the showroom floor. I have backed the idle adjust all the way out with no apparent change in the richness of the mixture. It did change the RPM to a point though. I read in one thread something about coming in from working on the car and smelling like I had been standing next to a diesel campfire. That's me!

[jwalters]

(IMG:http://www.914world.com/bbs2/html/emoticons/laugh.gif) This thread makes me giggle!!! (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif) (IMG:http://www.914world.com/bbs2/html/emoticons/lol2.gif)

Point from another point--BRANDO IS RIGHT!

The spring on the flapper has lost tension and is letting too much fuel in vs. air at ide--and prolly all over the rev range--

As a import tuner in a mostly german shop for over four years there is no worry about taking the large plastic cover off to see the guts move--

Inside there is even script telling you wich way is lean along the circumference of the adj. wheel-

There is also a spot specifically designed to put a flat blade screw driver and reposition the adjuster wheel one tooth at a time--
Hint: the tighter the spring, the leaner the mixture

You can easily do this yourself, just keep yourself and the area clean.

Tighten the spring until your ide drops allot--say less than 500 rpm

Adj. your airbypass screw for the highest possible rpm not to exceed 750--if you cannot reach this do not worry--

Now lessen the spring tension until you get to closely within stock idle parameters--better to err on the low side of stock idle setting.

Now put a small amount of silicon on the lip of the plastic cover a replace

You are now done

I and about 100 other mechanics worth their mettle that I know personally do this on a daily basis. Mostly on beemers--they have real problems with it when they exceed 200k miles.

they do not tell you this (porsche) because they would rather sell you a new 400 dollar airflow meter---

It is ok--it is safe--do not be swayed--you can do it---

But also, while you are in there--fix whatever vacuum leaks you may have before this adjustment--- (IMG:http://www.914world.com/bbs2/html/emoticons/beer.gif)

[Cap'n Krusty]

QUOTE (rhodyguy @ Mar 27 2005, 09:54 AM)

the CIS-E from a jetta, golf, etc? i think ed morrow ran it on the turbo car.

Naaaahhhh. Digital EFI from an 86+ 2.1L Vanagon. It should drop right in. Put the ECU in the interior, maybe behind the seat, and everything else goes right on the engine. Use the old fuel pump and a Jetta CHT sensor screws into the block somewhere. Injectors fit in place of the L-jet (or D-jet) ones, AFM in place of the stock one, distrobutor drops in. Oh, and that was Ed Villela. The Cap'n

[Reiche]

I agree with jwalters, but...
I would mess with the AFM only after methodically eliminating all the other possibilities (cold start, FPR, etc.) No need to jump to the most expensive/difficult possibility first. All the others can be tested in situ. I would remove the AFM to work on it to avoid contamination.

And make sure you write down or photograph exactly where you started on the AFM so you can go back to square one if necessary.

[jwalters]

Dude--do you know how time consuming it would be to pull the afm, adjust it, then stick it back in and test it--over and over???

Do it with the engine running--adjust it while it is running--period.

But as I said before and in agreement with reiche--check everything else out first--if any, fix them thar vacuum leaks first---

[ConeDodger]

Wow... L Jet sure wakes people up and gets them vocal.

L Jet as I recall has a series of sensors that report conditions back to a brain and given the condition reported the mixture is either richened or leaned.
If I recall from my EFI L Jet Datsun Z days you should have an AFM which is a big flapper box reporting its flap position via resitance change to the brain, it has an idle screw that only works at idle. If the box wears out you can mess around as others have suggested tightening the spring as a loose spring will just allow the flap to swing wide open with any air flow and send a resistance signal indicating a need for richer conditions.
You have a cylinder head temp sensor that sends a resistance signal to the brain telling the brain when the engine is hot. Hotter engines need more fuel.
You have a throttle position sensor which sends a resistance signal that richens the mixture at both wide open throttle and at closed throttle.
You have a cold start injector which gives a momentary fuel burst in the intake plenum during cold starts.
You have injectors which open for a fraction of time. Think of wide open throttle as a bigger fraction of time, possibly even 1/1 or steady squirt. Think of any position on the gas pedal as a steadily increasing fraction heading toward 1/1.
You have a thermotime sensor that senses if the engine is cold and closes as it warms. This could be FUBAR.
Most problems people associate with the EFI are not EFI at all.
First of all, lean conditions are often actually vacuum leaks. L Jet depends on a known amount of air getting to the engine past a flap which reports its position to the brain. Introduce a leak and more air gets to the engine causing a greater AIR/fuel ratio. This will cause a fast idle and lean condition. Probably not your problem but lets not rule it out since you could have a rich running condition superimposed on vacuum leaks.
Second, your injectors could be all gummed up from what? centuries of use? A gummed up injector dumps fuel instead of spraying it. This bad pattern disributes fuel poorly in the chamber and it just doesn't burn as well. Clean or replace your injectors.
Low fuel pressure can result from clogged fuel filters or a weak pump. This will cause the same bad fuel spray pattern discribed above.
Electrical problems are big gremlins for EFI. Low voltage will not even allow the injectors to fire. Gummed up connectors will increase the resistance of electrical flow and after all, the brain is looking for a resistance signal.
Rule out fuel pressure and electrical problems first. Check and clean your connectors, check the resistance.
There is a fuel injection rebuild specialist in Orange County called Brett Industries. They could rebuild your AFM for about $135.00. They bench test it and preset the spring tension. I think they also rebuild Thermotime sensors.
There are a couple of injector rebuild places that clean and check spray patterns they advertise in Grassroots Motorsports.

Good luck. If your fuel pressure and electrical stuff is good, I would replace vacuum lines, have the injectors cleaned first then have the AFM rebuilt or replaced.

Rob

[Reiche]

QUOTE (jwalters @ Mar 27 2005, 03:55 PM)

Dude--do you know how time consuming it would be to pull the afm, adjust it, then stick it back in and test it--over and over???

Sure, for someone like you who does it all the time in the shop it isn't worth the time. However, for a first-timer or DIYer, it would build confidence to first acquaint yourself with what's in there and what it does before attempting such a significant adjustment.

[jwalters]

QUOTE (Reiche @ Mar 27 2005, 07:52 PM)

QUOTE (jwalters @ Mar 27 2005, 03:55 PM) Dude--do you know how time consuming it would be to pull the afm, adjust it, then stick it back in and test it--over and over??? Sure, for someone like you who does it all the time in the shop it isn't worth the time. However, for a first-timer or DIYer, it would build confidence to first acquaint yourself with what's in there and what it does before attempting such a significant adjustment.

Yea, you got a good point, but then again, that much work for someting like that can piss off even a seasoned veteran in a hurry, imagine what it would do to a newbie??