leak acceleration
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- Posts: 101
- Joined: Tue Feb 05, 2008 8:08 am
leak acceleration
Me again. I have a '77 2liter stock engine(I think). My problem? I had it running the best ever in 5 years. Then I started noticing that it was getting harder to take off from a stop. It just didn't seem to pull as well. Then I noticed that it was about the same engine speed in second or third. It slowly pulls up to about 12 mph and then "vroom", pull much stronger. Same in second and so on. I have fuel injection. The first thing I always think of is valves, points/dwell/timing. All are good.
So why would I have weak acceration at low rpm and sudden increase at higher rpm?
Thoughts anyone?
Thanks
I did try the search fuction first but didn't see anything that sounded like my problem
So why would I have weak acceration at low rpm and sudden increase at higher rpm?
Thoughts anyone?
Thanks
I did try the search fuction first but didn't see anything that sounded like my problem
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- Posts: 101
- Joined: Tue Feb 05, 2008 8:08 am
Re: leak acceleration
I should add that it starts great and idles perfectly smoothly. It just doesn't have much get up and go/sluggish until it hits higher rpm. Then it feels great.
- ajdenette
- Posts: 717
- Joined: Wed Jan 20, 2010 1:18 pm
Re: leak acceleration
The 2 things that come to mind is the AFM and the Throttle Position Switches. (cant remember if AFC has them or not) but with age the area the wiper in the AFM drags across getw warn and doesnt gove acurate readings so the computer does not register the change in the amount of air going through the system until you get to the top where it spends less time. your 2 options are find a different afm and try that or open the top and adjust the arm so it works with a new section of the track.
Alex
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I I======[]IIIIIII[]
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/ /__/____[_____\
I I======[]IIIIIII[]
()_)-----()_)----)_)
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- Joined: Tue Feb 05, 2008 8:08 am
Re: leak acceleration
Thanks ajdenette. I tried just replacing the afm and made no difference.
I'm not that familiar with fuel injection and have no idea what would cause this
Wait.
With a svda distributor, if the vacuum hose was leaking would that cause the advance to not work until higher rpm when the machanical advance comes in?
I'm gonna try that and see if it makes any difference if I pull the vacuum hose off.
I'm not that familiar with fuel injection and have no idea what would cause this
Wait.
With a svda distributor, if the vacuum hose was leaking would that cause the advance to not work until higher rpm when the machanical advance comes in?
I'm gonna try that and see if it makes any difference if I pull the vacuum hose off.
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Re: leak acceleration
Well that made it worse but it was just the kind of worse that I had just more of it.
With the higher rpm the bus is fun to drive but this just takes the fun away.
With the higher rpm the bus is fun to drive but this just takes the fun away.
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- Joined: Thu Jun 03, 2004 12:42 am
Re: leak acceleration
Is your mechanical advance coming in smoothly? If it is sticking it might come in all at once but at a higher rpm than it should. Put your timing light on it and watch the advance as you slowly rev the engine, and as you then slowly let it drop again. The timing shouldn't jump, just smoothly advance as the revs pick up and then retard again as the rpms drop.
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weak acceleration
If the mechanical advance is sticking that might give a sudden boost in power but wouldn't explain the sluggishness before it kicked in.
I wondered if the vacuum hose was leaking so I just replaced it to no avail.
I can't think of what to look into now
I wondered if the vacuum hose was leaking so I just replaced it to no avail.
I can't think of what to look into now
- fusername
- Posts: 6806
- Joined: Sun Jan 28, 2007 11:26 am
Re: leak acceleration
mine started doing the same thing, never did figure it out. I swapped out the engine (914 2.0 ) and haven't run FI since. I am putting FI back in in a few weeks, if you find a solution tell me, I probably have the same issue.
give a man a watch and he'll allways know what time it is. give him two and he can never be sure again.
Things are rarely just crazy enough to work, but they're frequently just crazy enough to fail hilariously.
Things are rarely just crazy enough to work, but they're frequently just crazy enough to fail hilariously.
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- Posts: 101
- Joined: Tue Feb 05, 2008 8:08 am
Re: leak acceleration
I decided to try another distributor from another engine. Fired it up and said "this is what it is supposed to feel like. Yay!. Went about three blocks and turned around and it died. Power to the coil and to the distributor but no fire from the points. No way. I struggle to get it to work for awhile and then said, "Screw this". Put the old distributor back in and starts and idles fine. Just won't rev from a standstill at all, then the rpm gets high enough and the power kicks in.
Drove it down I5 for 100 miles and back. Ran pretty good at speed, just doesn't want to accelerate.
What part of a distributor would prevent power to getting to the points? I replaced the condenser. Points look fine.
Drove it down I5 for 100 miles and back. Ran pretty good at speed, just doesn't want to accelerate.
What part of a distributor would prevent power to getting to the points? I replaced the condenser. Points look fine.
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Re: leak acceleration
Have you actually put a meter on it to see what is happening? Maybe the ground on the breaker plate is bad.
- Piledriver
- Moderator
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Re: leak acceleration
Clean the points, or at least rub them together when they are closed (power off)
A non-conductive oxide layer forms with age, I've fixed a few "$50 dead cars" doing only that, sometimes after the owner spent serious $$ having it "professionally" repaired...
There are other possibilities, but given a set that have sat in a toolbox for an indeterminate amount of time, I'd start there.
...Right after checking the distributor clamp and that the dist is fully down.
The obvious stuff hurts the worst.
A non-conductive oxide layer forms with age, I've fixed a few "$50 dead cars" doing only that, sometimes after the owner spent serious $$ having it "professionally" repaired...
There are other possibilities, but given a set that have sat in a toolbox for an indeterminate amount of time, I'd start there.
...Right after checking the distributor clamp and that the dist is fully down.
The obvious stuff hurts the worst.
Addendum to Newtons first law:
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
zero vehicles on jackstands, square gets a fresh 090 and 1911, cabby gets a blower.
EZ3.6 Vanagon after that.(mounted, needs everything finished) then Creamsicle.
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- Joined: Tue Feb 05, 2008 8:08 am
Re: leak acceleration
Finally got fed up with the bus not running right and took it to the local wise man Bill Trafton.
He has been servicing vws for something like forty years. He took just a moment to adjust the arm in the afm and told me to try it and I have to say that for the first time in years it was a pleasure to drive. Power, smooth, no stumbling. It was fun again.
He has been servicing vws for something like forty years. He took just a moment to adjust the arm in the afm and told me to try it and I have to say that for the first time in years it was a pleasure to drive. Power, smooth, no stumbling. It was fun again.