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  #1  
Old 09-27-2009, 08:45 PM
1984 Federal 300D Turbo
 
Join Date: Sep 2009
Location: Portland, OR
Posts: 59
Poor acceleration at low speed

I have a 1984 300D that I got done changing the motor on (previous owner threw a rod). I rerouted all the vacuum lines correctly, with much help from this site. The car starts and idles perfectly, but acceleration at low speeds (below 20mph) is HORRIBLY slow. I know these things aren't acceleration machines, but there is something definitely abnormal going on. Here's all relevant info I can think of:

- Car is very sluggish until about 20mph. After that the acceleration REALLY picks up.

- Hard lines running to and from the ALDA system are all clean and properly connected.

- The car DOES has a vacuum leak somewhere, as the motor still runs when the key is out.

- Turbo functions properly. I can hear/feel it once the acceleration picks up.


I did have to time the injection pump (using the drip method) since I swapped it over to the new block. I'm thinking adjusting this might be the first step. I'll want to turn the IP away from the block to create more fuel flow correct? Any other ideas of what the problem could be?

Thanks,
Brendan

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  #2  
Old 09-27-2009, 09:50 PM
t walgamuth's Avatar
dieselarchitect
 
Join Date: Apr 2005
Location: Lafayette Indiana
Posts: 38,604
Is this by any chance the first turbo 300d you have driven?

They are quite sluggish for the first 50' or so. Also there are two turbos offered, one in supposedly more sluggish on take off.

Also, are you sure you are not taking off in second? They are extra sluggish if that happens.
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  #3  
Old 09-27-2009, 10:20 PM
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Location: Philadelphia
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Adjust the screw on top of the ALDA and your problem will probably disappear. Sounds like its not getting enough fuel until the turbo kicks in.
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  #4  
Old 09-27-2009, 10:22 PM
1984 Federal 300D Turbo
 
Join Date: Sep 2009
Location: Portland, OR
Posts: 59
It is the first turbo 300d I have driven, but not the first turbo diesel. I know they are very slow at start, but when I put the pedal all the way down it literally does nothing for about 10 seconds. I wouldn't feel safe pulling out into any kind of heavily trafficked street at the moment.
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  #5  
Old 09-27-2009, 10:54 PM
1984 Federal 300D Turbo
 
Join Date: Sep 2009
Location: Portland, OR
Posts: 59
Quote:
Originally Posted by tbomachines View Post
Adjust the screw on top of the ALDA and your problem will probably disappear. Sounds like its not getting enough fuel until the turbo kicks in.
Thanks, I'll try that out. Do I basically unscrew it a little to adjust it?
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  #6  
Old 09-27-2009, 11:23 PM
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Location: Long Beach,CA
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When my car was slow like that I found I had an incredibly sloppy throttle linkage. Taking out as much slack as possible greatly improve my acceleration.
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  #7  
Old 09-28-2009, 08:46 AM
toomany MBZ's Avatar
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Quote:
Originally Posted by Silver_300D View Post
Thanks, I'll try that out. Do I basically unscrew it a little to adjust it?
It has a black cap that you need to remove, you'll also find a metal cup, you may need to remove that also. It has a lock nut surrounding a slotted screw, turn counterclock wise to increase fuel.
As Diesell911 mentions, check the linkage and that bushing on the firewall.
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  #8  
Old 09-28-2009, 09:08 AM
Banned
 
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Location: Blue Point, NY
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Quote:
Originally Posted by Silver_300D View Post
Thanks, I'll try that out. Do I basically unscrew it a little to adjust it?
Be a bit careful with this adjustment. You wish to turn the screw counterclockwise by about one turn. However, after 20 years, the screw might need a bit of Kroil and some TLC. If you snap the screw, the device is rendered inoperable and you cannot procure a new one. You'll need to find a salvage unit as a replacement.

Extreme care is the operative word here.
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  #9  
Old 09-28-2009, 02:57 PM
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Originally Posted by maxjlone View Post
The symptoms do seem to be what I would expect to see with an air leak especially from the manifold, I only suggested to look at the carbon canister as it is close to one of the rad pipes. I guess that you have swapped the restrictor pill over for the turbo control pipe between the 't' piece and the outlet on the turbo compressor?

Have a good look for air leaks mate, if you dont find anything we can look at a few other options.


What Carbon canister? Restrictor Pill?

Charlie
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  #10  
Old 09-28-2009, 03:52 PM
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Quote:
Originally Posted by charmalu View Post


What Carbon canister? Restrictor Pill?

Charlie
The carbon canister is right next to the blinker fluid reservoir and the restrictor pill is the little plastic thing on top of the flux capacitor...only operates at speeds above 88MPH.



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  #11  
Old 09-28-2009, 04:16 PM
winmutt's Avatar
85 300D 4spd+tow+h4
 
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Location: Atl Gawga
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Before you go off screwing with the ALDA is your throttle linkage hitting full stop?
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  #12  
Old 09-29-2009, 09:13 PM
1984 Federal 300D Turbo
 
Join Date: Sep 2009
Location: Portland, OR
Posts: 59
Yes, the throttle linkage is properly set. Does my car have a kickdown switch? Now that I think about it, it does feel as though the car is starting off in second gear. I guess one way to tell would be testing the acceleration in reverse. If it's still slugish then I'll look into messing with the ALDA.
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  #13  
Old 09-29-2009, 10:10 PM
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Quote:
Originally Posted by Silver_300D View Post
Now that I think about it, it does feel as though the car is starting off in second gear.
It should start in second gear when in "Drive" or the intermediate gear selection. But it should almost immediately downshift to first under anything more than the slightest load. In the lowest gear selection, it should start in first gear regardless of load.
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  #14  
Old 09-29-2009, 10:52 PM
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Quote:
Originally Posted by Silver_300D View Post
Yes, the throttle linkage is properly set. Does my car have a kickdown switch? Now that I think about it, it does feel as though the car is starting off in second gear. I guess one way to tell would be testing the acceleration in reverse. If it's still slugish then I'll look into messing with the ALDA.
It should have a kickdown switch, feel underneath/behind the accelerator pedal on the floorpan for a black cylindrical plastic piece that can be depressed like a button.

Mine does not downshift at the "slightest" load as indicated by the post above, I need to mash it kind of hard when coming from a rolling start. I will admit my transmission is pretty tired at this point though.
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  #15  
Old 09-30-2009, 08:02 AM
toomany MBZ's Avatar
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Quote:
Originally Posted by tangofox007 View Post
It should start in second gear when in "Drive" or the intermediate gear selection. But it should almost immediately downshift to first under anything more than the slightest load. In the lowest gear selection, it should start in first gear regardless of load.
I've owned three 123 turbos, none started in second. My SD did before I adjusted the ALDA, now it starts in first, as it was designed, AFAIK.

Silver... count how many gear changes in forward, that'll let you know what gear you're starting off in.

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