Starting Problems, Starting with Throttle but Won't Idle Options

[nmkimosabe]

My 1974 1.8 with fuel injection will only start by manually opening the throttle but I can't get it idle and thus run properly. I recently had the AFM rebuilt and replaced the points, plugs, condenser and replaced the CHT sensor but the problem continues as it did before. I've looked for vacuum leaks to no avail with starter fluid. I now seek the expertise of the members of this forum for additional suggestions.

[rfinegan]

get a smoker from amazon, cheep and multi purpose.
L-Jets are notorious for vacuum leaks.. Great place to start
Check the timing again...Dwell effects timing

[nmkimosabe]

get a smoker from amazon, cheep and multi purpose.
L-Jets are notorious for vacuum leaks.. Great place to start
Check the timing again...Dwell effects timing

Thanks for the suggestion as that may be the next step in the diagnostic.

[fiacra]

I'm going to add a few more things I know about this car and the journey that this owner has been. Some of these are from previous threads about this car, and some from personal communication. I suggested he start a new thread to keep things a bit cleaner as circumstances have changed. However I think a recap of things would be helpful so I'll take that on as best I can. Briefly, the car came out of 2 months of winter storage, ran fine for a day, and then while being driven lost power, "chugged," and then died. At that point the car would only start on occasion and then briefly run and then die no matter what. The owner did a bunch of diagnostic work on it, a lot of it suggested by other board members, but no success so it went off to a shop. That shop couldn't solve the problem so it went to a second shop. That shop diagnosed poor compression and leak down numbers (reportedly "less than half of what it should be") but that didn't fit the circumstances and didn't sound right to him so it is now in the hands of a third shop. The current shop found good compression and leak down numbers (!) and basically went right back to the basics with a full tune up (new points, condenser, valve adjustment, etc.) and that has gotten it to the point where it is now - running when given gas but dying at idle. They have diagnosed a bad CHT (even though the current one is new) and have recommended a smoke test for vacuum leaks.

To me, their approach sounds really reasonable. L-Jet won't idle with a vacuum leak (unlike D-Jet) but will keep running with your foot on the gas so a smoke test (vs. using starting fluid) seems appropriate. It is running now with new ignition parts and based on a past similar experience I suspect it had a bad condenser, although I recognize I could easily be wrong.

There has been significant progress in that at least it is running now, but let's help this guy get his car fully sorted out and back on the road. He's had a rough (and expensive) journey to get to this point. I've been as helpful as I can, but you all are a bunch smarter than me and he wants to have meaningful suggestions to give to the shop. So many hands (with dubious skill levels) have been on this car that my money is on a vacuum leak, likely from something getting knocked loose or broken. I think originally the problem lay in the ignition system, and that problem has now been solved with the work done by the current shop. That's my take, but again I know I could easily be wrong.

Here are the previous threads:

http://www.914world.com/bbs2/index.php?sho...=377499&hl=

http://www.914world.com/bbs2/index.php?sho...=377590&hl=

[fiacra]

(IMG:style_emoticons/default/popcorn[1].gif)

[rfinegan]

It is running now with new ignition parts and based on a past similar experience I suspect it had a bad condenser, although I recognize I could easily be wrong.

did you reset the timing after the add-on of the new parts? The answer must be Yes or next thing to do...

Point dwell effects timing
Timing does not effect Dwell

[nmkimosabe]

It is running now with new ignition parts and based on a past similar experience I suspect it had a bad condenser, although I recognize I could easily be wrong.

did you reset the timing after the add-on of the new parts? The answer must be Yes or next thing to do...

Point dwell effects timing
Timing does not effect Dwell

Update---the condenser, points, and cylinder head temp sensor were all replaced as well as the timing was checked. A smoke test revealed leaks at the oil filler cap and both valve covers. Both of these will be corrected. The car will start and run but the idle is still not right but the car is now starting and running. Further fine tuning will be done as soon as the oil filler cap seals and valve cover gaskets are replaced this week. This is a major improvement, and the final tweaks should also help.

[TRP]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

[nmkimosabe]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

[TRP]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

Ahh! Yeah, that makes sense. I didn't think it all the way through. You are getting close to solving this one. (IMG:style_emoticons/default/driving.gif)

[wonkipop]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

good stuff.

the curious thing about the 1.8 L jets is the oil cap itself is also the pcv valve.
its all built into the cap (the bit that screws off), quite unlike the D jets.

there is a vacuum operated membrane built into the very top of the cap.

the membrane and therefore the entire cap can fail, (at this point in time after half a century) - not just the seal which is a giant o-ring on top of the thread.
the EC engines in the VW 412 just had the top portion of the oil filler cap as the pcv valve - those engines had a separate oil filler cap and tube that came out in the body work on the inners after you lifted the engine lid.

so if new cap o-ring does not do the trick, investigate the cap itself further.
if the membrane (diaphram) has failed smoke will blow through the tiny hole in the centre of the top of the cap. if the o-ring has failed smoke will trail out around the edges of the cap.

[wonkipop]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

yeah.

but i don't call open AAVs or open decel valves vac leaks.
i call em throttle assist valves. (IMG:style_emoticons/default/biggrin.gif) thats basically what they are when they misbehave. throttle openings on the sly that activate the AFM flap. because they are piped such that they are between the AFM and the throttle plate.

anything else thats pulling in air after the throttle body is a true vac leak in an L jet.
and usually they won't idle at all and if they do very badly. and probably won't really like to run at all eiher. they can't tolerate any significant air leaks after the throttle plate.

the throttle bodies can leak too around the pivot axle points.
but a smoke test would pick that up.

[nmkimosabe]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

good stuff.

the curious thing about the 1.8 L jets is the oil cap itself is also the pcv valve.
its all built into the cap (the bit that screws off), quite unlike the D jets.

there is a vacuum operated membrane built into the very top of the cap.

the membrane and therefore the entire cap can fail, (at this point in time after half a century) - not just the seal which is a giant o-ring on top of the thread.
the EC engines in the VW 412 just had the top portion of the oil filler cap as the pcv valve - those engines had a separate oil filler cap and tube that came out in the body work on the inners after you lifted the engine lid.

so if new cap o-ring does not do the trick, investigate the cap itself further.
if the membrane (diaphram) has failed smoke will blow through the tiny hole in the centre of the top of the cap. if the o-ring has failed smoke will trail out around the edges of the cap.

Thanks for the info. I also have a new oil cap coming just as backup in case the new O-ring & gasket don't help.
Gary

[wonkipop]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

good stuff.

the curious thing about the 1.8 L jets is the oil cap itself is also the pcv valve.
its all built into the cap (the bit that screws off), quite unlike the D jets.

there is a vacuum operated membrane built into the very top of the cap.

the membrane and therefore the entire cap can fail, (at this point in time after half a century) - not just the seal which is a giant o-ring on top of the thread.
the EC engines in the VW 412 just had the top portion of the oil filler cap as the pcv valve - those engines had a separate oil filler cap and tube that came out in the body work on the inners after you lifted the engine lid.

so if new cap o-ring does not do the trick, investigate the cap itself further.
if the membrane (diaphram) has failed smoke will blow through the tiny hole in the centre of the top of the cap. if the o-ring has failed smoke will trail out around the edges of the cap.

Thanks for the info. I also have a new oil cap coming just as backup in case the new O-ring & gasket don't help.
Gary

another gasket that can go is the throttle body to intake plenum gasket.
mine went hard and no longer seated properly - caused me similar issues to what you have experienced.
about 5-6 years ago after i had recommissioned it from 16 years of storage. (IMG:style_emoticons/default/sad.gif)
got a replacement repro gasket. problem solved.
but i think your smoke test would have picked up that one if it was a problem.

[nmkimosabe]

Congratulations on getting it to start and idle. The struggle with 1.8 and vacuum leaks can be a pain. a 60.00 smoke machine is completely worth the investment.

I'm trying to figure out how you found leaks down at the valve covers!!?

One area that plagued me for a bit was that my Auxiliary Air Valve wasn't sealing all the way once the car was warmed up, causing the idle to hang a bit. My deceleration valve was also not fully closing causing extra air to get pulled back into the system... and again... high idle. Those two items are the opposite of what you are getting.

Keep after it! it sounds like you are close.

Ted

Here is my understanding of leaks at the valve covers: Because the engine's crankcase is connected to the intake manifold via the crankcase breather hose, smoke fills the entire vacuum and crankcase system simultaneously. Since the pushrod tubes create an open tunnel between the engine crankcase and the valve rocker boxes, any gap in the valve cover gaskets becomes an instant exit point for the smoke. I'm hoping the new oil filler cap seals and valve cover gaskets will help smooth out the idle. Stay tuned and thanks for your response.
Gary

good stuff.

the curious thing about the 1.8 L jets is the oil cap itself is also the pcv valve.
its all built into the cap (the bit that screws off), quite unlike the D jets.

there is a vacuum operated membrane built into the very top of the cap.

the membrane and therefore the entire cap can fail, (at this point in time after half a century) - not just the seal which is a giant o-ring on top of the thread.
the EC engines in the VW 412 just had the top portion of the oil filler cap as the pcv valve - those engines had a separate oil filler cap and tube that came out in the body work on the inners after you lifted the engine lid.

so if new cap o-ring does not do the trick, investigate the cap itself further.
if the membrane (diaphram) has failed smoke will blow through the tiny hole in the centre of the top of the cap. if the o-ring has failed smoke will trail out around the edges of the cap.

Thanks for the info. I also have a new oil cap coming just as backup in case the new O-ring & gasket don't help.
Gary

another gasket that can go is the throttle body to intake plenum gasket.
mine went hard and no longer seated properly - caused me similar issues to what you have experienced.
about 5-6 years ago after i had recommissioned it from 16 years of storage. (IMG:style_emoticons/default/sad.gif)
got a replacement repro gasket. problem solved.
but i think your smoke test would have picked up that one if it was a problem.

UPDATE: Well, the car finally was running better in the shop but then died when the car was taken for a test drive. During this test drive the ECU was fried. The mechanic is in the process of replacing the ignition components including the points, rotor, cap, wires and possibly the coil as he thinks somewhere here is the issue that fried the ECU. He feels confident the wiring harness is in good shape. I wish I had better news and if any of you reading this has any further suggestions, they would be much appreciated. As an owner of many vintage Porsche's going back to 1966, I've never had such frustration especially with an engine that should be so simple.

[Artfrombama]

I too have a 74 1.8 with FI
I was having a similar problem but in addition to idle problems, was way down on power. Found the pipe from the air flow meter to the throttle body was cracked and was leaking a substantial amount of vacuum. Sourced a good replacement from the classified section and was amazed how much better the car runs.
Not saying this is your problem but is easy to check.

[nmkimosabe]

Thanks for the advice and I will double check that S boot again. When we did a smoke test it didn't show up there as an issue. Yes, vacuum leaks can be a major issue with these cars.

[Superhawk996]

Find a new mechanic that actually understands these cars. There is practically zero chance the ignition could fry an ECU.

There are possibilities I could imagine but they would all involve negligence on his part . . . Or pure coincidence.

[wonkipop]

Find a new mechanic that actually understands these cars. There is practically zero chance the ignition could fry an ECU.

There are possibilities I could imagine but they would all involve negligence on his part . . . Or pure coincidence.

i very much agree with this sentiment. (IMG:style_emoticons/default/beerchug.gif)

it is possible that some solder has gone dry somewhere on the ECU.
and it could be a cause of this persistent problem mr. nmkimosabi is having to experience no joy with.
its a pity he does not live down here near the north antarctic research station.
we would have his problem licked by now and i'm not making bold claims.
i've seen mike (our mechanic genius) pull the ECU out of one of my mates early range rovers. an L jet version. pulled out the circuit board and examined under his magnifier lens at his desk. spot the problem with the board and fixed it with a soldering iron. the boards in the L jet ECU are at big scale and are military grade construction.

needless to say the problem in the range rover disappeared instantly upon reinstallation.

i would not dismiss the ECU being the problem but if it is its not because it got "fried" - thats a pretty silly generalist sweep of the hands conclusion and does really indicate said mechanic has not got his head around the problem.

but it may be that there has been some degradation.
however i do not think the mechanic involved is capable of really getting to the bottom of this.

edit.
ps. the problem with the range rover was it started ok cold but as soon as it got hot it ran like (IMG:style_emoticons/default/stromberg.gif) usual sign of some electrical trouble somewhere that only becomes evident when component in question thermally expands in operation.

as an aside, has the EFI wiring loom been examined and tested for troubles.
you usually got to wiggle those around a lot while testing the pins.
any original wiring loom is getting pretty ancient by now and could also be a source of persistant but erratic troubles.

[wonkipop]

as i recall @nmkimosabe - you sent me a PM telling me your mechanic had diagnosed low compression. this was a couple of months ago.
i did ask you in reply what those compression numbers were and which cylinders.

i assume said mechanic meant all cylinders but you never got back to me to know exactly what he meant.

beginning to think said mechanic mistook inherently low compression of 1.8 L jet (as designed for low octane unleaded back in the day) for some compression loss using figures he had for earlier D jet 914s pre unleaded.

i mean this guy is throwing darts at the board and hitting the ceiling?
i dunno.