Need Help With Timing 1.8 L-jet Options

[Porsche Rescue]

Trying to get aa's "fossil" to run well. Confused about timing a 1.8. We have found a red mark on the impeller. Is that TDC or the 7.5 BTDC mark? Haynes says it should be timed at about 900 rpm with vac. retard line disconnected and plugged. I seem to recall that there is also a black mark. Haynes or some such source says there is only "one" mark. Right now we have it timed at the red mark and it won't idle.
HELP!

[Rockaria]

The best way to know where degrees of timing on a 914 impeller are to use the blades in the impeller as well as the marks. But since most impellers sometimes do not have all the marks, or the correct ones I made this image to help.

(IMG:http://lib.nmsu.edu/~clandt/914parts/914impeller.jpg)

7.5 degrees is 3.5 fan blades from the wide part on the impeller. The image is laid out as you are looking down the hole in a 914 with the engine in the car.

enjoy,

[Mueller]

You can double check what mark is on the fan by using the mark on the flywheel for referance....if you have an adjustable timing light (highly recommended)...paint a new 0° line on the fan...this new mark can be used for timing at idle and at higher rpms when you get your new Mallory distributor for your car (IMG:http://www.914world.com/bbs2/html/emoticons/smile.gif)

with the adjustable timing light, you set the light at 7.5° and use the 0° mark

[Dave_Darling]

BTW, not all of the castings for the fan are identical... (IMG:http://www.914world.com/bbs2/html/emoticons/sad.gif) They can vary slightly--so far I have seen about a half a fan blade's worth of variation. Check "timing a 914" tech article on the Bird site, and you'll see two fans that are a little "off" WRT each other.

Double-check the fan TDC marking against the flywheel TDC notch. You'll need a mirror to see the flywheel notch through the top notch in the transmission bellhousing...

--DD

[Porsche Rescue]

Dave, is there a TDC mark on the impeller? So far all we have found is a red mark which we take to be 7.5 as per Rockaria's very helpful image above.

[double-a]

thanks for the info guys, i think i understand that chart. here's what's happening:

engine now starts fine, and runs fine, as long as the go pedal is pressed. when i let off, the revolutions drop to next to nothing and the engine sputters and dies.

so, i've got one opinion from a local vw guy who says the reason for this behavior is that our dwell of 42 is way low and should be set around 44 to 50. any other opinions? for reference, fuel pressure is good, fuel and vacuum lines are all new, aux air valve is working, etc etc.

~a

[SLITS]

If your points are to closed (not enough dwell), your car will not run.........

If it starts fine but won't idle, have you checked the postion of the airbleed screw on the Vane Airflow Meter that it is not closed?

[Rockaria]

My impeller only has one mark at 7.5 (and it's not red, just factory cut notch.)

How I got my 75 1.8 FI to idle.

Let me first start with the fact it took me six months and all new parts to get it all figuered out. But once I did it all made perfect sense and now idles perfect.

First I replaced all of the hoses and AAR meter and made sure I did not have any vacuum leaks. I also made sure I was getting good engine vac at idle from the plenum.

I still had a vac leak somewhere. [Vac leaks are hard to notice, find and fix. You think its fine BUT IT'S NOT. Everyone swears they do not have a leak when they do. Not in a hose maybe, but there are other places. CHECK THEM ALL.. Dizzy canister, idle screw, Decel can, etc...] I traced it to the vac advance canister on the dizzy. Advance held a vacuum, retard side did not.

I then set the points to 48 degrees dwell. Timed to 7.5 at 850 and then checked at 3500 to find it in spec.

Still rough idle.

Tried a zillion things to get the idle up. Silly, stupid, dumb things I will not repeate. Decided I needed it to be stock threw away all of my shame and went back at it.

I noticed that I was affraid to open the idle adjust screw too far. I would only do about 2 to 4 turns because I was afraid the screw would fall out. I found out the damn thing will do more than 16 full turns.

This helped a little, but still rough idle and the idle would change. Basically it would be good for one drive then slowly get rough.

Then I decided to try a new AFM. Boy did that help. I think my old AFM must have been realy bad. Idles better, but still gets slowly worse once I set it. [I think someone messed with the idle air mixture "CO" screw on the AFM on my old unit. What do I mean someone.. IT WAS ME!] It's the tinny recesed screw in the AFM casting where the large hose to the throttle begins.

Picture:
(IMG:http://lib.nmsu.edu/~clandt/914parts/914ljetAFM2.jpg)

Then one day it hit me and I marked the Idle adjust screw on the trottle. After a drive I noticed it was changing. The screw was a little loose and it would change.

So I put some plumbers pipe tape on the screw, put the screw back in and it has been solid and perfect ever since.

Now my 1.8 FI starts, runs and idles perfectly.

I hope my ramblings help a little,

[double-a]

QUOTE (SLITS @ Jan 5 2005, 09:34 AM)

If your points are to closed (not enough dwell), your car will not run......... If it starts fine but won't idle, have you checked the postion of the airbleed screw on the Vane Airflow Meter that it is not closed?

not sure what that is. the only adjustment screw we have been using is the idle screw. adjusting the idle screw seems to have no effect on the engine's lack of maintaining idle. i see a small screw on top of the afm, but have not bothered it.

~a

[SLITS]

(IMG:http://www.rccauto.com/ebay/idle.jpg)

[double-a]

yup, that's what i thought. haven't touched that one.

~a

[Porsche Rescue]

Aaron, mark/note position of the screw so you can put it back. Then turn it counter-clockwise a half (?) turn and see what happens, better or worse? If worse go back to "0" and turn a half turn clockwise. Nothing to lose. Emissions are not the issue at this point.
I am convinced that two degrees of dwell are not the problem. It starts too easily and runs too well at higher rpm.

[double-a]

i'll do that and post an update later.

~a

[double-a]

update: the adjustment screw on the afm seems to work. i don't know what it is or what it does, but turning it all the way clockwise until it stops allows the engine to maintain idle without drifting to lower rpm and dying, which is a first. occasionally, rpm drifts lower, but the engine seems to recover.

~a

[Rockaria]

QUOTE (double-a @ Jan 5 2005, 02:12 PM)

update: the adjustment screw on the afm seems to work. i don't know what it is or what it does, but turning it all the way clockwise until it stops allows the engine to maintain idle without drifting to lower rpm and dying, which is a first. occasionally, rpm drifts lower, but the engine seems to recover. ~a

Sounds like you have "Lean Idle" Screwing the thing clockwise all the way closes the "Controlled Vacuume leak" And making it run richer.

Diagnosis: Vacuume leak in the system somewhere or Warped AFM Flapper.

I am no expert, but I did stay at a Holiday Inn Last Night, while Watching HOUSE on Fox and if that guy "Dr. House" can piss in the air and guess on a diagnosis, So can I! At least No One Dies... (IMG:http://www.914world.com/bbs2/html/emoticons/pray.gif)

[double-a]

sounds like a disease (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif)

actually, that's very good info. i tested the afm flapper and it didn't look warped, but what do i know. next step i guess is to use the propane wand method on the hose connections.

what are all the possible sources for vacuum leaks? i'll need to test them all. the oil filler cap is out of the running as the culprit, got all new seals for that. but everything else is fair game i think.

~a

[Rockaria]

QUOTE (double-a @ Jan 5 2005, 04:56 PM)

sounds like a disease (IMG:http://www.914world.com/bbs2/html/emoticons/biggrin.gif) actually, that's very good info. i tested the afm flapper and it didn't look warped, but what do i know. next step i guess is to use the propane wand method on the hose connections. what are all the possible sources for vacuum leaks? i'll need to test them all. the oil filler cap is out of the running as the culprit, got all new seals for that. but everything else is fair game i think. ~a

Do a leakdown test "Pull a vacuum" on both Dizzy Advance and retard pots. They should both hold a vacuum for a long time.

Do a leakdown test on the Decel Valve, and the Fuel pressure regulator.

Check that darn huge elbow thing from the AFM to the Throttle. Cracks and breaks can hide really easy in there. As well make sure there is a tight fit to all hoses going into it.

I renewed and put hose clams on the 4 intake runners from the plenum to the intake ports on the head.

Check the small seals on all of the Fuel injectors.

Have a beer.

Check the Cold Start Valve (Though when it goes it makes things rich I think) Well check that is is tight and not leaking.

Have another beer.

Replace the seal between the Throttle and the intake plenum.

That is all I can think of right now...

[Rockaria]

QUOTE (double-a @ Jan 5 2005, 04:56 PM)

...next step i guess is to use the propane wand method on the hose connections...

Also be carefull with the propane for false readings. I was doing that one day and it seemed to effect the engine a lot when I put it over a particular area. I worked for days on it then I noticed....

To myself: "Hey Dumn__s, the area right above the place that the propane effects is the air box inlet tube. No Duh it would effect it. It was sucking the propane directly into the airbox..." (IMG:http://www.914world.com/bbs2/html/emoticons/blink.gif)

[Dave_Darling]

The 1.8 pulls a vacuum on the oil filler as well. So the oil cap needs two seals in it, plus the cork gasket between the crankcase and the oil filler breather box. Plus maybe an O-ring where the oil filler neck mates with the breather box part?

--DD

[jim912928]

DD hit a spot that wreaks havoc and is often overlooked. A 1.8l with ljet will run really erratic if the seals/gasket for the oil filler cap and the oil box gaskets are shot or worn!