Boost spike

randy merritt

randy merritt

Donating Member
I am not a stock truck expert, so I thought I would post this screen shot of my boost spike to see if anyone has some thoughts. The truck is low mileage (less than 41K), mostly bone stock, and it appears by looking at the exhaust on the lift, that the cat has never been removed and gutted (the bolts have surface rust, and all of the stock heat shields are in place).

I am running a Forge wastegate actuator that is supposed to have a 14-18 psi spring, but I suspect it was sent with a 10-14 psi spring based on what the boost stabilized out at. When I installed the actuator, the puck lever did not have any jams or sticky spots in the full movement of the puck arm. The boost spikes to 13 or so in 1st gear, then drops down to settle around 9-10 psi.

My goal would be to have it run a steady 13 or 14 psi. I am running a turbo tweak chip for a stock truck, but that should have nothing to do with the boost control as the Forge gate basically just runs on spring pressure.

Any thoughts?

 
randy merritt

randy merritt

Donating Member
Re: Boost spike

I have it set with zero preload. I understand where you are going, but even with zero preload, why would it allow the boost to spike above spring pressure?
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

gary sy said:
Ok thats right but is the electronic controlerstill plugeg in or tottaly out?
Click to expand...

Still plugged in. I saw an older post about disconnecting the stock controller because it was making the ECU run in "safe mode" and not build boost when you have a Forge gate, but I don't buy that theory. I still have plenty of timing, and the ECU has nothing to do with boost at this point.
 
G

gary sy

New member
Re: Boost spike

I just went threw this with Noelle s totally stock ty .Tom saidremove and unplug . And set boost with rod and all was good.
 
vinnieTy

vinnieTy

TY # 1889
Re: Boost spike

This is funny as I reached out to Tom today asking some questions of same issues that I had since I installed the forge wast gate and he said what Gary said to do. Didn't test yet but hopefully soon.
 
SEL777

SEL777

One of 101
Re: Boost spike

Old (low mile) / plugged cat? Mine would not do more than 10 when we installed my 20G & Forge WG (but stocker hit 15 always). Went with cat delete pipe, and hit 20. YOu can check the spring, as they are different colors. Don't know how you could check the cat tho, and why would it differ if all's you changed was the WG? So, not so helpful.
 
neildemo

neildemo

Administrator
Re: Boost spike

makes perfect sense if he installed the boost solenoid. Computer thinks a stock wastegate is attached at 8psi spring pressure. But the forge is a 17psi spring. So the computer opens up the solenoid and guess you should spike around 24psi. Disconnect boost solenoid and run of spring pressure should do the trick.
I just bought a sy motor with 45k miles on her with a blown head gasket. Only recent addition was the forge gate. Betting he also hooked up the solenoid and without racefuel more than likely detonated and pushed the gasktets. Just my 2 cents...
 
vinnieTy

vinnieTy

TY # 1889
Re: Boost spike

neildemo said:
makes perfect sense if he installed the boost solenoid. Computer thinks a stock wastegate is attached at 8psi spring pressure. But the forge is a 17psi spring. So the computer opens up the solenoid and guess you should spike around 24psi. Disconnect boost solenoid and run of spring pressure should do the trick.
I just bought a sy motor with 45k miles on her with a blown head gasket. Only recent addition was the forge gate. Betting he also hooked up the solenoid and without racefuel more than likely detonated and pushed the gasktets. Just my 2 cents...
Click to expand...

Thanks for the information. Definitely answers my questions.
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

neildemo said:
makes perfect sense if he installed the boost solenoid. Computer thinks a stock wastegate is attached at 8psi spring pressure. But the forge is a 17psi spring. So the computer opens up the solenoid and guess you should spike around 24psi. Disconnect boost solenoid and run of spring pressure should do the trick.
I just bought a sy motor with 45k miles on her with a blown head gasket. Only recent addition was the forge gate. Betting he also hooked up the solenoid and without racefuel more than likely detonated and pushed the gasktets. Just my 2 cents...
Click to expand...

I am not running my boost thru the solenoid. The line goes directly from the compressor to the actuator. I am trying to post a pic of a datamaster run from a week or so ago when I still had the factory setup. Showing the WG duty cycle may give someone some clues.
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

Here is a picture of what it was doing with the stock boost solenoid in place. The boost curve looks similar to the curve with the Forge. When I was trying to explain to Dave what the truck was doing, he was leaning toward a clogged cat. Maybe this picture will give a little clarity as to what the boost was doing vs. the wastegate duty cycle, as I don't think I did a very good job explaining it to Dave.

 
0966Sy

0966Sy

Code what?
How much preload did you put on the spring when installing the forge? The forge gates from what I've seen have a sweet spot for preload, and yes the are tuff to pull back even 1/8 of an inch over the pin.
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

0966Sy said:
How much preload did you put on the spring when installing the forge? The forge gates from what I've seen have a sweet spot for preload, and yes the are tuff to pull back even 1/8 of an inch over the pin.
Click to expand...

No preload at all. I followed the instructions that called for the initial installation to have zero preload, and then tighten it up as you want to increase boost.
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

After some Google research, I did a quick test. I hooked up datamaster and read the vac at idle to be 21.3 in. Hg. I revved the motor up to 2k and the vac rose slightly to 21.8 in. Hg. and held very steady.

It is my understanding that if the exhaust was clogged, the vac would drop at 2k rpm vs idle vac, and would continue to drop slowly.

It SEEMS as though I don't have a clogged exhaust, but I have been known to be wrong.
 
randy merritt

randy merritt

Donating Member
Re: Boost spike

I took the Forge actuator apart last night and verified that I DO have the blue spring (14-18 psi). This leads to the question of why is my boost holding steady at around 10 psi after the spike? I am missing something? Does the Forge need some preload to function correctly?
 
D

Damian

Member
Re: Boost spike

Tighten it up one turn and see how it goes. The only other explanation is there is something wrong with the turbo.
 
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