1974 1.8L engine fast idle then stalls, Fuel injection issues Options

[tshih914]

I have every vacuum hose hooked up the same as the diagram that wonkipop posted. My photo show the 2 plugged ports to the side of decel valve and the t leading to the boot (I will be ordering a new one from AutoAtlanta as the one currently in the car is an old used one from eBay that I got when the AFM explosion triggered the search for cause of stalling after starting). I have also removed the hose connecting the two ports
as instructed for this test. The idle adjustment screw at the base of the throttle valve was adjusted 2 turns from fully closed. I did mention that while the engine was idling at 2500-3000rpm I did try to cover the air filter box's snorkel with my hand and the engine did not stall indicating that there must be a vacuum leak. When I get the new boot installed I will hunt for the source of air leak with the Smoke in a can used to test fire alarm smoke detectors.
I just reattached the hose and started the engine after many cranks to get it idling at 2800 rpm before repeating test3 and 5 (wonkipop's earlier posts). When hose to side port of decel valve was pinched closed RPM dropped by 400-500 rpm. When AAV hose was pinched rpm dropped by 800-1000rpm. The smoke in a can wasn't useful in finding the source of air leaking pass the AFM pathway.

[Geezer914]

I had a hell of a time finding a vacuum leak. It wasn't until I did a smoke test, pumping smoke into the engine that I found it was leaking around the intake manifold gaskets. The hoses could be fine, it could be the injector seals. Do the proper smoke test, it will save you a lot of aggravation. On my engine, I ditched the decel vavle and the charcoal filter.

[Van B]

Ok so, I checked my AFM to see what I settled on for screw turns after all my tuning before starting this rebuild. I have three turns out on the AFM airscrew and 1-1/4 turns out at the throttle body.
Every car will be a little different, but you should be in that ballpark as a baseline.

[wonkipop]

I have every vacuum hose hooked up the same as the diagram that wonkipop posted. My photo show the 2 plugged ports to the side of decel valve and the t leading to the boot (I will be ordering a new one from AutoAtlanta as the one currently in the car is an old used one from eBay that I got when the AFM explosion triggered the search for cause of stalling after starting). I have also removed the hose connecting the two ports
as instructed for this test. The idle adjustment screw at the base of the throttle valve was adjusted 2 turns from fully closed. I did mention that while the engine was idling at 2500-3000rpm I did try to cover the air filter box's snorkel with my hand and the engine did not stall indicating that there must be a vacuum leak. When I get the new boot installed I will hunt for the source of air leak with the Smoke in a can used to test fire alarm smoke detectors.
I just reattached the hose and started the engine after many cranks to get it idling at 2800 rpm before repeating test3 and 5 (wonkipop's earlier posts). When hose to side port of decel valve was pinched closed RPM dropped by 400-500 rpm. When AAV hose was pinched rpm dropped by 800-1000rpm. The smoke in a can wasn't useful in finding the source of air leaking pass the AFM pathway.

ok thats interesting @tshih914 about the snorkel.
it wasn't clear to me whether you just had your hand near the snorkel feeling for air flow or had you actually blocked it off.

yes the engine should die if you fully block the snorkel.

positives so far.
you definitely have a farked up decel.
it might come back to life with an adjustment.
if it doesn't you might still be able to source one but they are hard to get hold of.
or you can do a decel delete.

for clarification when you first did the tests i suggested, you reported the opposite results. decel dropped it by about a 1000 rpm from 3000 to 2000. AAV drop was less.
you did not give a specific number but described it as less than the 1000 drop due to the decel.
EDIT correction. went back and read the first test results. decel was 3000 to 1000. drop was 2000 revs.
AAV drop was less.

this repeat of the test seems to be the other way around/different?

guessing difference in part is due to you having the t/b idle screw out on this second test?

----

i think both of these components need to come off and be tested.

onward looking for more.

do the second smoke test.

i would also suggest a proper f p test.
i think i can see you still have your fp gauge plumbed in.
and its in the circuit before the regulator? which is good.
so you can do this test now fairly easily.
when its running you either pull and plug the vac hose into the back of the regulator or just pinch it tightly shut. the fuel pressure should be 35+/-. with the hose back in or the clamp taken off it should fall to 28. i know you have tested it and got 28. but that would have been the vac hose on value. be good info to know if its building the full pressure thats needed to acceleration/load phase.

(IMG:style_emoticons/default/beerchug.gif)

[Van B]

I have every vacuum hose hooked up the same as the diagram that wonkipop posted. My photo show the 2 plugged ports to the side of decel valve and the t leading to the boot (I will be ordering a new one from AutoAtlanta as the one currently in the car is an old used one from eBay that I got when the AFM explosion triggered the search for cause of stalling after starting). I have also removed the hose connecting the two ports
as instructed for this test. The idle adjustment screw at the base of the throttle valve was adjusted 2 turns from fully closed. I did mention that while the engine was idling at 2500-3000rpm I did try to cover the air filter box's snorkel with my hand and the engine did not stall indicating that there must be a vacuum leak. When I get the new boot installed I will hunt for the source of air leak with the Smoke in a can used to test fire alarm smoke detectors.
I just reattached the hose and started the engine after many cranks to get it idling at 2800 rpm before repeating test3 and 5 (wonkipop's earlier posts). When hose to side port of decel valve was pinched closed RPM dropped by 400-500 rpm. When AAV hose was pinched rpm dropped by 800-1000rpm. The smoke in a can wasn't useful in finding the source of air leaking pass the AFM pathway.

The AAV is designed to increase idle by that amount until the engine reaches operating temperature. So, nothing revealing there just yet. I think the aspect that should be focused on right now is the non-response to throttle input.

I’ll tell you that in getting my L-Jet sorted, I replaced every old hose on that entire topside. My car was very original but what had been replaced wasn’t exactly the right size most times. Belmetric has almost all the correct hoses at a good price and wonki has provided you with his artisan diagram that I just love!

We also need to consider your fuel injectors are full of garbage and not spraying correctly or at all. Have you looked at plugs?

[wonkipop]

ps
in addition to blocking off snorkel the only other way it could pull air into the air cleaner is via the hose from the charcoal can to the air cleaner. i can see that hose is either very badly frayed in center or somehow joined. not clear. if that hose has leaks in it it could pull air via that into the a/c despite you having your hand over the snorkel.

maybe it can even pull air through the charcoal can?
anyway if i close off my cars snorkel with my hand it will die. but its not running at 3000 rpm either when i do it.

if you wanted to take that hose out of the picture for now you could pull it out of the aircleaner and plug the port on the airbox.

[Van B]

ps
in addition to blocking off snorkel the only other way it could pull air into the air cleaner is via the hose from the charcoal can to the air cleaner. i can see that hose is either very badly frayed in center or somehow joined. not clear. if that hose has leaks in it it could pull air via that into the a/c despite you having your hand over the snorkel.

maybe it can even pull air through the charcoal can?
anyway if i close off my cars snorkel with my hand it will die. but its not running at 3000 rpm either when i do it.

if you wanted to take that hose out of the picture for now you could pull it out of the aircleaner and plug the port on the airbox.

Yes. All these hot garbage hoses need to be fixed or else we’re shooting in the dark and wasting time.

[wonkipop]

I have every vacuum hose hooked up the same as the diagram that wonkipop posted. My photo show the 2 plugged ports to the side of decel valve and the t leading to the boot (I will be ordering a new one from AutoAtlanta as the one currently in the car is an old used one from eBay that I got when the AFM explosion triggered the search for cause of stalling after starting). I have also removed the hose connecting the two ports
as instructed for this test. The idle adjustment screw at the base of the throttle valve was adjusted 2 turns from fully closed. I did mention that while the engine was idling at 2500-3000rpm I did try to cover the air filter box's snorkel with my hand and the engine did not stall indicating that there must be a vacuum leak. When I get the new boot installed I will hunt for the source of air leak with the Smoke in a can used to test fire alarm smoke detectors.
I just reattached the hose and started the engine after many cranks to get it idling at 2800 rpm before repeating test3 and 5 (wonkipop's earlier posts). When hose to side port of decel valve was pinched closed RPM dropped by 400-500 rpm. When AAV hose was pinched rpm dropped by 800-1000rpm. The smoke in a can wasn't useful in finding the source of air leaking pass the AFM pathway.

The AAV is designed to increase idle by that amount until the engine reaches operating temperature. So, nothing revealing there just yet. I think the aspect that should be focused on right now is the non-response to throttle input.

I’ll tell you that in getting my L-Jet sorted, I replaced every old hose on that entire topside. My car was very original but what had been replaced wasn’t exactly the right size most times. Belmetric has almost all the correct hoses at a good price and wonki has provided you with his artisan diagram that I just love!

We also need to consider your fuel injectors are full of garbage and not spraying correctly or at all. Have you looked at plugs?

bit by bit we are heading towards the Van B/wonki situation.

you ended up doing everything and checking everything on the EFI system as you went.
i did all of mine before we even attempted a start. the whole lot. after a 16 year sleep.
but i had mike looking over my shoulder. do this. etc. now do that. and on.
injectors, injector seals, hoses, distributor operation, ......on and on.

anyway, it should be solvable. trial and error. tick off the bits one by one.

[wonkipop]

two suggestions by other members re injector seals.
sensible suggestion.
i did mine after the sleep along with new injectors.

put them on your list to get some if you haven't done them.

another thing to get hold of is a throttle body to plenum gasket.
914 rubber has them.
worthwhile replacing that regardless. they do go hard with age.
pretty cheap little part so its not a heavy investment.

and another suggestion the plenum itself can corrode and have pinholes in it is very true.
they will likely be underneath and very had to see without getting it off.
bit of a job. notice there is a bit of surface corrosion on the intake runners.
so its a possibility.
smoke test should find them however if they are there.

[tshih914]

two suggestions by other members re injector seals.
sensible suggestion.
i did mine after the sleep along with new injectors.

put them on your list to get some if you haven't done them.

another thing to get hold of is a throttle body to plenum gasket.
914 rubber has them.
worthwhile replacing that regardless. they do go hard with age.
pretty cheap little part so its not a heavy investment.

and another suggestion the plenum itself can corrode and have pinholes in it is very true.
they will likely be underneath and very had to see without getting it off.
bit of a job. notice there is a bit of surface corrosion on the intake runners.
so its a possibility.
smoke test should find them however if they are there.

Considering all recent suggestions my plan going forward is
1) replace all hoses with new (Someone posted that Belmetric sells all hoses but when I looked at their website the search under vacuum hoses gave no results) I also need to know if someone sells a complete kit that allows complete replacement of all vacuum hoses for the 1.8L L-jet (at least list the correct id and length of each hose needed.)
2) replace FI boot (already ordered from AutoAtlanta)
3)replace throttle body to plenum gasket from 914 rubber
4)fuel injectors appear to be fine as the engine was running fine and idled at 3000 rpm so may replace the injector seals which are old.
5) measure the Fuel pressure and adjust the running pressure on FP regulator 35psi and 28 psi
6) systematically go and check/test each component as per factory manual

[wonkipop]

two suggestions by other members re injector seals.
sensible suggestion.
i did mine after the sleep along with new injectors.

put them on your list to get some if you haven't done them.

another thing to get hold of is a throttle body to plenum gasket.
914 rubber has them.
worthwhile replacing that regardless. they do go hard with age.
pretty cheap little part so its not a heavy investment.

and another suggestion the plenum itself can corrode and have pinholes in it is very true.
they will likely be underneath and very had to see without getting it off.
bit of a job. notice there is a bit of surface corrosion on the intake runners.
so its a possibility.
smoke test should find them however if they are there.

Considering all recent suggestions my plan going forward is
1) replace all hoses with new (Someone posted that Belmetric sells all hoses but when I looked at their website the search under vacuum hoses gave no results) I also need to know if someone sells a complete kit that allows complete replacement of all vacuum hoses for the 1.8L L-jet (at least list the correct id and length of each hose needed.)
2) replace FI boot (already ordered from AutoAtlanta)
3)replace throttle body to plenum gasket from 914 rubber
4)fuel injectors appear to be fine as the engine was running fine and idled at 3000 rpm so may replace the injector seals which are old.
5) measure the Fuel pressure and adjust the running pressure on FP regulator 35psi and 28 psi
6) systematically go and check/test each component as per factory manual

check auto atlanta if you want a convenient vac hose kit.
i believe you specify your model when ticking the box and get all the right hoses right length. (IMG:style_emoticons/default/beerchug.gif)

the fuel pressure regulator on the 1.8 is non adjustable unlike the earlier D jet ones.
if its not working right its a new regulator. but don't necessarily blame the regulator just yet. check the values. it might also be that the fuel pump is not delivering sufficient pressure. i rebuilt my original fuel pump completely from top to bottom (its not supposed to be serviceable apparently but the germans forgot australians love to take things apart and make them work when its not supposed to be possible). at the end of that i tested the fuel pump independantly of the car to make sure it was making pressure and also tested flow. i was making 38 ibs out of the rebuilt pump and got the spec flow rate (delivery volume over a timed period). so insufficient fuel pressure can be down to a weak worn out old pump. basically the regulator bleeds off some of that pressure the pump makes to take it down to 28 lbs at idle. but there is no adjustment nut on the correct 1.8 fp regulator. (IMG:style_emoticons/default/beerchug.gif)

[wonkipop]

direct link to AA vac hose kit.

http://www.autoatlanta.com/Porsche-Vacuum-...BAAVACKIT2.html

(it was under accessories section, not hard parts, and was listed in engine misc.) (IMG:style_emoticons/default/beerchug.gif)

[tshih914]

direct link to AA vac hose kit.

http://www.autoatlanta.com/Porsche-Vacuum-...BAAVACKIT2.html

(it was under accessories section, not hard parts, and was listed in engine misc.) (IMG:style_emoticons/default/beerchug.gif)

I just ordered that kit but it says the kit doesn't include the 19mm hose. So Where do I get the 19mm hose (where does this hose connect? the charcoal cannister?)

[nihil44]

Here is the gasket on the AFM connector which wasn't allowing connector to seat home fully.

[nihil44]

I have been pursuing running issues and vac leaks for the past 8 months. I have used smoke machine, compressed air (as recommended by factory - Bowlsby website for this) and vacuum from a vacuum pump and a vacuum cleaner

Smoke machine:- I made one from PVC plumbing fixtures as in a few YouTube websites. Worked ok but the smoke went everywhere, it lingered in the engine compartment and it was not easy to see just where the smoke was coming from. Also, I had the machine going for too long, it overheated and melted some of the PVC - result one buggered smoke machine

Vacuum pump hand held: - intake chamber volume too large for pump and unable to pull a vacuum

Vacuum cleaner:- very simple construction. 6omm OD pvc plumbing pipe with end cap glued to pipe. Hole in end cap of a size to accommodate a grommet and the vacuum cleaner nozzle










I used kid's bubble mix liquid diluted with a little water into a squirt bottle, applied and waited for the bubbles to appear

Compressed air:- same construction as above except in place of the grommet on the end cap I used a schrader valve to connect to the compressed air via an adjustqable regulator





Some of the results:-

Small crack in the neck of the oil filler tower. George Hussey says in listing for this item used, that they always break. I had to get underneath with a mirror to find that one



Both inlet manifold gaskets had cracks in them. One obviously had a washer embedded in it which caused the crack





I bought a set of Victor Reinz gaskets which are phenolic resin with a thin gasket material applied to both sides. I fitted them and just to be sure I re tested them for vac leaks and sure enough, one side leaked. So I put a thin universal gasket on both sides of the gasket but the overall thickness was too much and I couldn't do up the nuts on to the studs. I ended up compromising by putting the thin gasket on just one side and this is working

Victor Reinz standard gasket. Note how thin the gasket facing material is

[wonkipop]

direct link to AA vac hose kit.

http://www.autoatlanta.com/Porsche-Vacuum-...BAAVACKIT2.html

(it was under accessories section, not hard parts, and was listed in engine misc.) (IMG:style_emoticons/default/beerchug.gif)

I just ordered that kit but it says the kit doesn't include the 19mm hose. So Where do I get the 19mm hose (where does this hose connect? the charcoal cannister?)

short answer is you cannot get the 19mm hose.
though PET and my measurements say its 20mm ID. splitting hairs i know.
its the hose from the oil filler tower PCV valve to the air intake boot.
originally a formed hose to make the S curve.
people have had to do all sorts of subs and use all sorts of different hose.
you will notice on your car it has already been rigged up as elbows to solve the problem of doing the curves and sealing the junctions.
that set up you have is probably ok. if you are worried about it keep the elbows and sub new hose. probably have to find rubber hose that is hydrocarbon resistant.
(IMG:style_emoticons/default/beerchug.gif)

[wonkipop]

love your work @nihil44

[tshih914]

love your work @nihil44

Thanks @wonkipop I do remember the old S hose was shot and I replaced it using the elbows. I went back to check the fuel pressure once I got it to start and idle at 2800 rpm. The gauge reads 28psi with vacuum hose connected and when pinched close reads 38psi so my fuel pump is working correctly.

Thanks @nihil44 for the compress air setup. I may try that.

@VanB how do you adjust the AFM (you mentioned 1-1/4 turns out in the throttle idle adjuster screw and AFM screw was 3 turns out.) Where is this screw on the AFM located?

[wonkipop]

love your work @nihil44

Thanks @wonkipop I do remember the old S hose was shot and I replaced it using the elbows. I went back to check the fuel pressure once I got it to start and idle at 2800 rpm. The gauge reads 28psi with vacuum hose connected and when pinched close reads 38psi so my fuel pump is working correctly.

Thanks @nihil44 for the compress air setup. I may try that.

@VanB how do you adjust the AFM (you mentioned 1-1/4 turns out in the throttle idle adjuster screw and AFM screw was 3 turns out.) Where is this screw on the AFM located?

@tshih914
beaudy. at least we can tick off the fp as A O K. (IMG:style_emoticons/default/biggrin.gif) (IMG:style_emoticons/default/beerchug.gif)
regulator and pump.

[Van B]

See the little hole near the front right off the AFM? That's your air bypass screw.