| [ Total Views: 2843 | Total Replies: 25 | Thread Id: 84512 ] |
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 kazmattsas
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| posted on June 27th, 2010 at 02:11 PM |
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Idle Problems on 76 EFI kombi
HI all
I have a pretty broad question. Firstly I have a 76 EFI kombi. Recently the idle has been very erratic - after the cold start finishes the bus has a
problem keeping idle and stalls.
When driving at normal speeds the bus is great and feels strong
After driving for a while the revs at idle are very high on occasion and can then switch to a low idle and stall.
So naturally I have tried to source any potential air leaks and replace as many hoses as I can.
I have clamped and tied down any offending potential air leaks I can find and even used "Start You Ba#%tard" spray to see if the revs increase
around any of the manifold etc and there is noting I can hear (does not increase idle after spraying)
So my question is - should I still be looking at air leaks or is there any other advise from anyone that has had the joy of working with EFI
thanks
Matt
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 Bizarre
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| posted on June 27th, 2010 at 02:19 PM |
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Definitely sounds like an air leak
Main culprits are the brake booster vacuum hose on the manifold
Futue te ipsum!!!
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matberry
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| posted on June 27th, 2010 at 03:15 PM |
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| Quote: | Originally
posted by Bizarre
Definitely sounds like an air leak
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I had one with similar issues come in last week. It has head gaskets leaking and so as far as the efi is concerned, is like a manilold leak. To check,
there should be no compression leaking noises during cranking, before it fires up (or take a coil lead off). You'll need to have someone else operate
the key while you stick your head at the engine  .
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
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kazmattsas
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| posted on June 27th, 2010 at 07:41 PM |
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OK - thanks guys
Firstly - to Bizarre - thanks mate _ will look into that area (um where is the break booster vacuum hose on the manifold )
Matberry - your response I guess is the one I don't want to believe.
So does this mean pulling the engine and doing a "top end" rebuild or is it more simple than that.
thanks
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Bizarre
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| posted on June 27th, 2010 at 08:03 PM |
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Does it die when you put your foot on brakes at idle??
Futue te ipsum!!!
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matberry
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| posted on June 27th, 2010 at 09:48 PM |
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I'm meaning it's possible to be state of engine and not efi or intake system problem, need to get things checked out if your not sure. Start with
the simple cranking check or even a compression test.
Where are you to recommend somewhere to go ask?
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
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kazmattsas
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| posted on June 28th, 2010 at 01:35 PM |
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Hey Bizarre - yep it does (but not always)
After I have traveled for a while - say 20 mins the revs can stay pretty high.
However up until then it does die - I have to put my left foot on the clutch to hold it in, then the brake with my right toes and the accelerator with
the right right heal - getting pretty good at this.
Matberry - hey mate - I'm on the sunshine Coast - and I saw a great guy the other day around my way, but he was talking a full engine build, so I was
just looking into solving this darn idle problem while I figure out how the hell I am going to get the $$$ together to do a bigger job
thanks Guys
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Bizarre
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| posted on June 28th, 2010 at 01:37 PM |
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Have you got yourself a manual???
Futue te ipsum!!!
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kazmattsas
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| posted on June 28th, 2010 at 02:06 PM |
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Well I got Muirs VW book and I did just download a l-jetronic manual from ratwells site - so I can start to educate myself on the EFI issues - but I
tell you it is a lot different from your standard carbie model
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Bizarre
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| posted on June 28th, 2010 at 02:49 PM |
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If you could eliminate the cracked hoses it would be a start
that fact it changes with brake pressure it is at least worth a look
Would be a lot easier if you had a manula so you could find the hoses
Futue te ipsum!!!
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kazmattsas
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| posted on June 28th, 2010 at 03:15 PM |
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ok thanks Bizarre
got this link to go off for now - http://www.ratwell.com/technical/VacuumHoses.html
getting off this computer so I can start the fault finding again - also should I be able to hear the leaks or is testing with Start ya b#@tard the way
to go?
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1303Steve
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| posted on June 28th, 2010 at 08:07 PM |
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Hi
Every now and then VW failed in some areas, the vacuum booster hook to the motor up is one of them.
Have you given the throttle body a clean? Also make sure that the throttle stop is stopping the butterfly from jamming.
Steve
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kazmattsas
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| posted on June 30th, 2010 at 09:39 PM |
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Thanks Steve
I haven't given the throttle body a clean - not sure where to start there
For the throttle stop - is this easily accessible?
I have this image here to go by
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matberry
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| posted on July 1st, 2010 at 07:21 PM |
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There's lots to look at for your symptoms.
Throttle body worn or sticking
idle speed controller not working or has intermittant electrical connection
air leaks.
Need to start with basics too, when were the valves last adjusted, plugs changed and timing set?
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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1303Steve
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| posted on July 1st, 2010 at 11:25 PM |
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Hi
I'm not sure where the stop is located, but it will be there.
If you have leaky tappet covers or a torn dipstick boot these will cause an erratic idle.
Steve
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matberry
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| posted on July 2nd, 2010 at 09:27 AM |
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Throttle stop is just the beginning of the throttle body problems. The problem is the return spring loads the butterfly laterally and wears the bore
and the throttle plate badly, thus allowing more air therefore increasing the idle speed. You need to remove the throttle body for inspection/repair,
but this won't necessarily cause idle to be erratic.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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kazmattsas
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| posted on July 3rd, 2010 at 02:57 PM |
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| Quote: | Originally
posted by matberry
There's lots to look at for your symptoms.
Throttle body worn or sticking
idle speed controller not working or has intermittant electrical connection
air leaks.
Need to start with basics too, when were the valves last adjusted, plugs changed and timing set?
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HI Matt
Adjusted the valves just 2 weeks ago after I got it back from the auto electricians (they had to put a new armature in the starter motor)
To be honest - the car was going well before going in to the auto Electricians and then 3 weeks later after coming out it hardly ran - the number 1
valve was really loose - so I adjusted them then
Not saying they did anything - but just that 3 weeks of sitting didn't seem to help
I am going to try and track do the throttle body to see if that is worn
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greedy53
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| posted on July 4th, 2010 at 08:06 AM |
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just pop under the back and kake sure the leads to the starter are tight i once had a similar problem with a carbyed van
dont ask me how but the heavy lead to the battery was loose tightened and no more shit
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kazmattsas
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| posted on July 9th, 2010 at 02:55 PM |
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Thanks All
It never rains .. it pours. Looks like I need new heads, so I'm going to source those and then look at doing the job myself. I'll update this with
what I find and hopefully be able to solve a few issues when the motor is out
cheers
Matt
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Bizarre
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| posted on July 9th, 2010 at 03:58 PM |
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Matt.............what happened??
How did you get to that stage??
Futue te ipsum!!!
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matberry
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| posted on July 9th, 2010 at 06:41 PM |
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| Quote: | Originally
posted by matberry
| Quote: | Originally
posted by Bizarre
Definitely sounds like an air leak
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I had one with similar issues come in last week. It has head gaskets leaking and so as far as the efi is concerned, is like a manilold leak. To check,
there should be no compression leaking noises during cranking, before it fires up (or take a coil lead off). You'll need to have someone else operate
the key while you stick your head at the engine .
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Probably like I said 1st post ????
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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kazmattsas
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| posted on July 15th, 2010 at 09:06 AM |
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Yep like MattBerry said earlier - there is no doubt there is a leaking noise when cranking - I ahve been flat out with work so haven't been able to
do the formal compression test. In saying that - the recommendation are all good from Matt regarding throttle body sticking. I know the heads are on
their way as well due to the number 3 inlet valve closing after about 2000km
So I figure - lets just get the engine out and explore all of the option put here
I'm planning for about a week from now to start so will let you know.
Also for reference Mics Motors have confirmed the AMC complete heads are fine and it was a bad run back a few years ago that got them a bad rap -
apparently they have amended and all cut with the 30 -45 -30 ratio
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kazmattsas
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| posted on July 18th, 2010 at 07:58 AM |
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| Quote: | Originally
posted by Bizarre
Matt.............what happened??
How did you get to that stage??
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Just ran the compression test and No.1 is at best (after oil squirt) - 50
the others are strong at high 90 - 100's. Being as though the intake on number3 is always tightening it seems like all that is left is heads.
Cant afford the $4k that I have been quoted so need to do myself. Should be interesting!!
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Dyno
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| posted on August 15th, 2010 at 10:04 PM |
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| Quote: | Originally
posted by kazmattsas
| Quote: | Originally
posted by Bizarre
Matt.............what happened??
How did you get to that stage??
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Just ran the compression test and No.1 is at best (after oil squirt) - 50
the others are strong at high 90 - 100's. Being as though the intake on number3 is always tightening it seems like all that is left is heads.
Cant afford the $4k that I have been quoted so need to do myself. Should be interesting!!
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90-100 is also low, #3@50 is a dead pot. Comps should be around 130psi at least for a 2L
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kazmattsas
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| posted on August 27th, 2010 at 04:38 PM |
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OK still going.
So did the whole new heads routine in the backyard job. Never do that again. Taking the engine out with a jack and blocks of wood was bad - getting it
back in the same way was a nightmare - but good news is new heads on, check all rings and and pistons, cleaned and replaced all fuel lines and any
houses that were suss. Basically updated anything I could at the time.
The bus now runs so well - loads of compression and just fly's along BUT ...
still have a fast idle.
I took note of what Matt mentioned in the early part of this post about the throttle body and thought it looked ok but then again I don't really know
what the hell is ok or even what I am looking at half the time.
There didn't seem to be any sticking of the butterfly type mechanism in the throttle body but is possible as stated I don't know jack. I could push
it freely and it retuns ok.
So now the idle screw is all the way in and it is still high.
I remember that my old 1800 carb buss had a similar issue with irratic idle and it turned out to be a distributor issue with the vacuum. Is this a
possibility?
I guess all that is left are the AFM if all of these are exhusted
any advice as always greatly appreciated
cheers
Matt
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matberry
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| posted on August 28th, 2010 at 12:14 PM |
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Well done on the repairs.
As for fast idle, it'll be the buterfly/throttle plate in the throttle body.
Remove the tb, while looking inside at the brass throttle plate, crack ofen the throttle and then move the shaft up and down. You'll see the brass
plate has a lot of the side worn away from the return spring loading the shaft upwards and wearing the plate on the side of the tb. This needs to be
replaced! I usually modify one from a 40mm Weber to suit the efi tb.
Problem is due to too much air bypassing the plate when fully closed.
Matt Berry Motorsports...air cooled advice, repairs and mods Ph 0408 704 662
OFF-ROAD,CIRCUIT,DRAG,STREET,ENDURANCE
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