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Discussion Starter #1 (Edited)
Hi Everyone,

I'm running a stock setup on my 1994 K1500 6.5TD (except have the K-47).

Boost is maxing out at 7psi (from what I've read seems normal I think). But it hits 7psi then immediately drops to 5psi without any change in RPM or throttle input. Tried attaching a video but isn't appearing...will keep trying.

Is this the computer/solenoid immediately backing off the boost? Is there any way to keep it from the sudden drop? Is there a way to safely increase the boost with the stock setup?

Thanks!
 

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Hi Everyone,

I'm running a stock setup on my 1994 K1500 6.5TD (except have the K-47).

Boost is maxing out at 7psi (from what I've read seems normal I think). But it hits 7psi then immediately drops to 5psi without any change in RPM or throttle input. Tried attaching a video but isn't appearing...will keep trying.

Is this the computer/solenoid immediately backing off the boost? Is there any way to keep it from the sudden drop? Is there a way to safely increase the boost with the stock setup?

Thanks!
The best way to post a video is to upload it to Youtube first then copy the video link from the address bar and post it here in the forum.
As far as boost goes it is commanded by the ECM based on load and will not be constant.

The drop is normal.
 

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Discussion Starter #3
Happy Thanksgiving OkDually!

Thanks...yeah, I figured it was normal. Not that it probably makes a huge difference, but would be nice if it stayed a constant 7psi rather than the sudden drop to 5psi.

Is there a safe and easy way to raise the boost with the stock setup? It's really just a want rather than need. The K-47 I put in recently made a difference, so i'm pretty happy with it all the way it is now. Just don't want to leave any performance on the table if there's something simple.

Thanks!
 

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What you are describing sounds pretty normal to me.
If you want more boost. The best way is with a tuned PROM chip for your truck.
You can make more boost manually with a turbo master. But you don't get the fuel to match with the stock tune. But you usually can set it to maintain around 7 PSI, without issues.
If boost is set too high. The PCM will see too much boost, de fuel the engine, and set trouble codes= Loss of power.
A good 4" exhaust system will help a lot if you are changing boost pressures or run a better performance tune.
 
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Happy Thanksgiving OkDually!

Thanks...yeah, I figured it was normal. Not that it probably makes a huge difference, but would be nice if it stayed a constant 7psi rather than the sudden drop to 5psi.

Is there a safe and easy way to raise the boost with the stock setup? It's really just a want rather than need. The K-47 I put in recently made a difference, so i'm pretty happy with it all the way it is now. Just don't want to leave any performance on the table if there's something simple.

Thanks!
As member Tommygunner mentions you can get a tune to enhance boost performance.
Install a manual wastegate controller for some boost performance.
Or you can install a Boost Fooler (aka 10kpot) in your stock setup like I did to enhance the boost.
 

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With your lift and tire combo I would opt for a GM-8 Turbo upgrade, 4" turbo back exhaust and a Tune ( if you can still find one available).
If no tune is available then I would go for a Boost Fooler or manual wastegate controller
 

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Discussion Starter #7
Thanks guys. Really appreciate the input. Like I said, more of a want than need. Mine takes a chip and I did see one available from SS diesel. I kind of like the idea of the ECM controlling the turbo, and given I just had the heads replaced i'm not looking to get crazy with the boost LOL. Maybe i'll start with the 4" exhaust being as that's probably just good do to all around for a number of reasons.
 

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You have removed the soot trap right?

Do the boost fooler and the optic bump to enhance the amount of fuel. Make sure you have fuel pressure at wide open also. The sock in the tank is notorious for cutting back fuel flow under high demand.

I prefer the stock type boost control . You can fabricate an assist spring to help it hold boost. Fooling the computer with boost fooler lets the computer think the boost is low for any given speed and gives the signal for more fuel which equals more boost

If you read this stuff anywhere on the net you probably read it here first.
 

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Discussion Starter #9
All things I need to do...I have not removed my soot trap...i'll check that.

It seems to be running really well, so it's not like I think anything is clogged up...just wouldn't mind getting the reasonable max boost.

I'll do the search function to look for the boost fooler...not sure what that is.

Thanks!
 

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Laughs and giggles > I had one truck that was low on power. Took hose off turbo to inspect fins. I revved the engine up and killed the engine. The turbo stopped turning and quickly started turning backwards with exhaust coming out. The back pressure was unbelievable. Soot trap plugged slap up!

You got a truck that's 24 years old > soot trap is shot.
 

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Larger exhaust will really help your truck. It the first performance upgrade I did, and always do in any of my vehicles when I want better performance. It gives one of the best Bang for the buck you can do. Plus paves the way for more upgrades later if you choose to do so.
I have a 1/2 ton like you. When I pulled my Cat/soot trap at only around 60K miles it was clogged up with carbon. The stock muffler is also restrictive. Replacing with larger free flowing exhaust made a very noticeable difference in all around performance, lower EGT too. A tune and other performance mods soon followed. 1/2 ton trucks are light. They respond very well to performance upgrades.
 
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Guess someone here needs to show a DIY boost fooler for the pre 96 models with the added added barometric pressure sensor and one for the later models that don't have it.

The way I would fool the manifold pressure sensor would be mechanical and I can't find anything on that. Basically it just involves removing the sensor and fitting a "T" of sorts in the line. An orifice on the inlet, an air bleed orifice on one outlet sized for boost desired and the other end of the "T" connected to the sensor. As the boost builds some is bled off before it reaches the sensor so the sensor sees a reduced amount of pressure.

Out of the box thinking again.
 

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Discussion Starter #13
Sounds like the first thing I need to do is find and remove the soot trap. Do most guys just put a piece of pipe to replace the length missing after removal?
 

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Yes. It can be simply replaced pipe. But if you have emission tests where you live. It will fail without the convertor.
 

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But if you have emission tests where you live. It will fail without the convertor.
Check your local regulations, they vary by location. For example, in California, all diesel vehicles that are model year 1997 or older are exempt from the bi-annual inspections.

The funny thing is that when my 1999 truck was brought into the state from Nevada by a previous owner, the DMV screwed up and labelled it a 1995. Before I knew about the inspections, I tried to get the title corrected, but when I brought it up to the DMV clerk, she looked in the computer and said “your truck is 1995, it says so right here”. Rather than cause any trouble with the transfer into my name, I shut up. Later, I found that as far as the California DMV is concerned, my truck is exempt. So I’ve got the best of both worlds, newer truck with airbags, without inspections. So I didn’t hesitate for an instant when switching to the DE turbo-back exhaust with the cat delete.

PS. all the numbers and features on the truck and driveline are 1999. There’s not even the excuse of a swap or any other reason for the error...:thumb:
 

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Her's my :2cents: worth

I've had pretty good success with just having a local shop cut out the soot trap & stock muffler replacing with them with straight pipe...no drown sound in the cab and exhaust note is a lot like the big block V8 sound I enjoyed years ago (many) when there was no replacement for displacement.

Yes if you are towing heavy with this light duty motor ya need the 4" exhaust, but how heavy should we be towing with a 1/2 ton anyways :confuzeld
 

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Discussion Starter #17
I'll take out the soot trap, then eventually get the 4" exhaust, but with a muffler...hopefully that doesn't defeat the purpose. I know it's not the norm, but I really do like quiet vehicles. I realize it's a diesel and only going to be so quiet, but I don't want it to be like the rigs I hear accelerating from a stop light and be heard the next county over...just not my style.
 

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You'd need to hear it than, 4" exhaust with quiet muffler defeats the size advantage and the 2.75 OEM exhaust with straight pipe IME will give you very similar performance and less noise in the cab at a fraction of the cost $$$.

The turbo does more noise reduction than one might think :nail:
 

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Discussion Starter #19
hmm...figured that might be the case.

Well, soot trap first because with the truck being almost 26 years old, it's probably clogged. It's certainly not helping anything.

Then I'll see about the exhaust.

Thanks!
 

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I straight piped my truck... very little difference than with a muffler. 3" pipe from the downpipe to just behind the cab.
 
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