Diesel Place banner

1 - 19 of 19 Posts

·
Registered
Joined
·
23 Posts
Discussion Starter #1
I put together a mechanical wastegate that was designed after the Heath diesel system. I originally tried a 12# spring and found that the max boost I was able to generate was about 1.5 lbs. So I replaced it with a 24 lb spring and I was able to generate about 7 lbs under about ¾ throttle, but when I went to WOT the pressure dropped to about 2-3lbs . Any suggestions on how to correct this. Or is this how these systems work?
 

·
Registered
Joined
·
8,014 Posts
Reeps , don't go there, you need IC to run that high a boost, what is happening is defuel by PCM either on high IAT, or boost too high sensed by PCM clipping fuel. PCM corrects out of limit contition 1st by pulling boost which it can't when a mechanical boost bypasses the vac sytem, then if it can't pull boost it pulls fuel, any codes when this is happening??

What mods have you done 10 psi is max safe boost you should run with a mostly stock system, update your signature per welcome note info linked in my signature. Staying at 15 psi or attempting to get there the wrong way and you will be walking home before too long. In FAQ (more performance thread) is a safe way to set up your truck for sustained higher power operation.
 

·
Registered
Joined
·
684 Posts
I too am looking to fab my own wastegate controller, Tim I think you might have mis-read his post, the most he got was 7 the other #'s are his spring rating.

Reeps, have you found the right spring yet?
 

·
Registered
Joined
·
9 Posts
Doc, I too read this that at WOT reeps was only getting one and a half pound boost pressure.
 

·
Registered
Joined
·
2,006 Posts
I only saw his 7 lbs of boost, I'd like to know where to get the springs at myself
 

·
Registered
Joined
·
23 Posts
Discussion Starter #6
Doc,
I know that I have to stay under about 8 lbs of boost, but my problem is that at WOT the boost is lower than at 3/4 throtle.
 

·
Registered
Joined
·
23 Posts
Discussion Starter #7
After I get the system figured out, I will post the parts that I used and how I assembled it.
 

·
Registered
Joined
·
8,014 Posts
do you have a fooler on it, if not you most likely clip fuel with a TM only, update your sig with rest of the story are you OBD I or II it's important to know as PCMs work different depending on config

BTW my concern was with the 15psi I read in small font I missed the decimal point, What kind of EGT are you seeing
 

·
Registered
Joined
·
23 Posts
Discussion Starter #10
Doc, I updated my sig, let me know what you have for input.
 

·
Registered
Joined
·
6,945 Posts
The turbo operates on exhaust energy - with more energy at full throttle than at 3/4 throttle, under-sprung wastegate should bypass much easier.

You indicated your controller is a simulation of Bill's setup - how did you rate the spring tension?
 

·
Registered
Joined
·
684 Posts
TD, what do you need to fool the PCM reading on boost so it won't clip fuel when using mechanical wastegate?
 

·
Registered
Joined
·
2,883 Posts
i picked up my spring at home depot. my truck is set at max 11 lbs and driving down the highway it'll hold 4 lbs. i'm not a mechanic butt am impressed with the way i gotter done.
 

·
Registered
Joined
·
684 Posts
edzzed, what is your spring (size)rated for? how many lbs? Also are you fooling your boost to you PCM?
 

·
Registered
Joined
·
8,014 Posts
TD, what do you need to fool the PCM reading on boost so it won't clip fuel when using mechanical wastegate?
Search threads for boost fooler for pics on how to wire it, maybe in FAQ also; I don't remember if we put it there or not, 10K var resistor set for 8.5K ohm should be sufficient on boost sensor.

attached is the logic schematic for an OBD II, OBD-I works similar I think, high IAT will also defuel.
 

Attachments

·
Registered
Joined
·
684 Posts
TD, where can I get one of these resistors? local radio shack, which wire do you install it on?
 

·
Registered
Joined
·
8,014 Posts

·
Registered
Joined
·
684 Posts
Picked up some goodies today while I was out... Radio Shack had at 10k Pot that I think will do the trick, only one they had that was variable. Then went across the street to Lowes to look at stuff to fab a TM. think it'll do the trick, wait for my gauges to get here before I start foolin around but should be interesting.

Parts
12" 1/2" threaded rod
5" 1/2" bolt
compression spring
flat washers
1/2" copper tubing coupler
 

Attachments

·
Registered
Joined
·
8,014 Posts
Variable is one you want, it will allow for fine tuning to your specific truck needs, 8.5K ohm worked on mine before reflash at sea level, your altitude and truck unique characteristics may require more or less boost sensor signal bias
 
1 - 19 of 19 Posts
Top