Modifications makes turbo boost too fast

[RRees]

Do you know what gears the axles have? 3. 73 or 4. 10 or something else?



From what I've heard or read rather, the 4. 10 gears cost about a 2mpg penalty when used as a daily driver (unloaded). I have 3. 73 gears with an auto and am getting about 16mpg (only about 4k on the odometer now). I don't know what my boost numbers are because I haven't installed my guages yet.

 

[J_Da_Fox]

And if I tell you that putting a dirty stock filter in place of the new clean wix filter, my mileage goes up, what does that say, if anything?

 

[J_Da_Fox]

no surging or anything with the fuel. Although It seems like there is a delay in the fueling process. Acts as if the air coming in happens a lot sooner than the fuel

 

[robertyoke]

no surging or anything with the fuel. Although It seems like there is a delay in the fueling process. Acts as if the air coming in happens a lot sooner than the fuel

it takes fuel to spool!! no fuel no spool!

-robert

 

[J_Da_Fox]

Air coming in doesn't mean boost. take the turbo off and the engine still sucks air

 

[DPKetchum]

Once you pop 1950 rpm mileage falls off. Its the truth and the facts. But at 2100/2200 rpm it sure pulls a load great!

 

[CHolman]

"Help" me understand this better... What is your boost at going down the road at lets say like 60MPH? "cruise set" It's been along time since I had a stock turbo, but your boost should be around 6 or 7 psi, it shouldn't be anywhere near 20 psi... If it's holding at 20 psi cruising down the road something is really wrong... I have tons of fuel and move lots of air and at 65 mph my boost cruising is around 6 to 8 psi...

 

[cerberusiam]

Air coming in doesn't mean boost. take the turbo off and the engine still sucks air

You indicated the turbo was spooling too soon by looking at the boost numbers. That statement just doesn't make any sense.



WHAT are your boost numbers? Max boost? Cruising? If the waste gate is sticking it may be making more than normal boost which could lead to more fueling. What exactly is your mileage? You may just be seeing the effect of the new fuel.

 

[Bodie]

If I put the throttle down from fully closed down one inch, by boost will build to twenty or so. At WOT, I peg 35 psi, then my wastegate will open, drop to 25, then hit 30, then drop to 25, the hit 30 again and so on and so forth. Does this happen to anyone else? And I haven't crawled under the truck to see which transmission I have... I know its a 6 speed with revese to the right and up

This is normal for a stock truck, mine did it too. That is just the wastegate keeping it from building too much boost (so DC says ). Your mileage is normal also. Get you some electronics with boost fooling and you wont have to worry about that pesky wastegate ever again.

 

[CHolman]

You indicated the turbo was spooling too soon by looking at the boost numbers. That statement just doesn't make any sense.

That's what I was thinking...

 

[J_Da_Fox]

You indicated the turbo was spooling too soon by looking at the boost numbers. That statement just doesn't make any sense.



WHAT are your boost numbers? Max boost? Cruising? If the waste gate is sticking it may be making more than normal boost which could lead to more fueling. What exactly is your mileage? You may just be seeing the effect of the new fuel.

At 55 mph, I'm running about 3 psi. At 60-65 mph, I'm running 5 psi, under extremely light throttle conditions. Should I lay into the throttle any at all, or run cruise, my boost will spike up to 20. At 70 mph, under light throttle conditions, I'm running 15 psi. Any more throttle, or cruise control, it will spike 35 psi. Max boost is 35 psi. Cruise control was always decreased my mileage. I know that with two trips to the same place, 400 miles round trip.



And when I said That air coming into a motor, any motor for that matter, doesn't mean that its boost makes perfect sense when you read some of the posts above it when we were taking about air, not turbo boost, going through the air intake, through the turbo, through the head, and out the exhaust. Every motor breaths air, whether its forced induction or not. At that point in time we weren't taking about the turbo, the turbo spooling up, or the boost the turbo produced. We were taking about the quantity or air moving through the motor. Hopefully that will clear everything up and we'll all be on the right page, or at least you guys will be on the right page. I'm always off :-laf



Also, small note **according to what the gas stations say, we're not running the new fuel yet, but that doesn't mean they're wrong... ran new fuel through truck twice. first time got really bad mileage, the second it was normal**

 

[JHardwick]

Too much boost isn't your problem.



The fact that you are cruising over 2000-2100 RPM is your issue.



The fuel mileage difference between a 1800 cruise and 2100 cruise is astounding.



~Wes~

You guys who say this are never towing.

 

[2broke2smoke]

absolutely ... but the original post didn't mention towing either

 

[McLaughlin]

At 55 mph, I'm running about 3 psi. At 60-65 mph, I'm running 5 psi, under extremely light throttle conditions. Should I lay into the throttle any at all, or run cruise, my boost will spike up to 20. At 70 mph, under light throttle conditions, I'm running 15 psi. Any more throttle, or cruise control, it will spike 35 psi. Max boost is 35 psi. Cruise control was always decreased my mileage. I know that with two trips to the same place, 400 miles round trip.

Could it be the gauge vice a real problem? I'm running older Diprcols and a see boost gauge response similar (but a bit lower) to what you do. My daughter's 96 has the Diprcol Optix guages and the boost gauge responds much slower even though the truck is set up about the same as mine (except it has a stock exhaust and exhaust manifold).

 

[DJennings]

At 55 mph, I'm running about 3 psi. At 60-65 mph, I'm running 5 psi, under extremely light throttle conditions. Should I lay into the throttle any at all, or run cruise, my boost will spike up to 20. At 70 mph, under light throttle conditions, I'm running 15 psi. Any more throttle, or cruise control, it will spike 35 psi. Max boost is 35 psi. Cruise control was always decreased my mileage. I know that with two trips to the same place, 400 miles round trip.

Everything you are stating seems normal to me, except your boost at 70 mph. You say if you hit the cruise at 70mph, it spikes to 35psi? What is the difference between cruise and light throttle if you are maintaining a certain speed?



In order for people to help you here, we need some facts:



Boost WITH CRUISE SET at 55mph, 60mph, 65mph, 70mph on a flat stretch of road. We need to know what the wind is doing.



Here's an example from my experiences:



No wind/warm summer day

55mph boost 3-4psi

60mph boost 5-6psi

65mph boost 7-8psi

70mph boost 9-10psi



That's typically what I see under the above conditions.



When you say the boost spikes, that is relative to how heavy you are on the go pedal.



Are you getting any black smoke under acceleration/cruise? Like RobertYoke said "It takes fuel to spool". I'm not familiar with the Van Aaken box, but what is it doing to improve performance and mileage? i. e. hp gain? is it adjusting timing? duration? rail pressure?



No offense intended, but so far I don't think you have provided any information that will help you determine if there is a problem. Again, no offense intended, but, it is a fact that you get better mileage with cruise set.

 

[SKneeland]

At 55 mph, I'm running about 3 psi. At 60-65 mph, I'm running 5 psi, under extremely light throttle conditions. Should I lay into the throttle any at all, or run cruise, my boost will spike up to 20. At 70 mph, under light throttle conditions, I'm running 15 psi. Any more throttle, or cruise control, it will spike 35 psi. Max boost is 35 psi. Cruise control was always decreased my mileage. I know that with two trips to the same place, 400 miles round trip. **

thats about normal, 15psi at 70mph is a little higher than what mines at but possibly factor in a little more drag/load/headwind etc...



if you were running 20psi at 55mph, unloaded, no wind & on flat terrain i would say something is up. even then it doesnt mean your turbo is spooling too fast. you have to burn fuel to make boost, it doesnt come from nowhere. more boost is more fuel being burnt = more load on the engine.

 

[bmoeller]

And as far as the stock turbo, I happen to think it does a fine job for a stock truck. Right now I think its working too well.

A turbo really can't work to well. Part of the problem is, the turbine housings are pretty small, and are a real choke point. I was making 12-15# with my stock turbo and fueling. I have 4. 10s also.



Since you removed a lot of restriction (cat and muff), the turbo is able to breath better, but the housing is the next restriction, even before the stock size air filter. I'm guessing you need a boost fooler. If the VA doesn't have it built in to it, that is. I suspect the computer is thinking you have to much boost, and cutting the fuel back, hence the jumpy boost gauge. When the boost drops, the fuel comes back on. So, back and forth it goes. That could hurt your mileage as well.



BTW, I get better mileage by driving with my right foot, vs using cruise. Always have.

 

[J_Da_Fox]

I suspect the computer is thinking you have to much boost, and cutting the fuel back, hence the jumpy boost gauge. When the boost drops, the fuel comes back on. So, back and forth it goes. That could hurt your mileage as well.



BTW, I get better mileage by driving with my right foot, vs using cruise. Always have.

The VA c3. 2 does has a boost fooler, but it doesn't work if the chip isn't on. By all means, my truck has power to spare without the box. I'll try turning it and seeing if it makes a difference. The harder I acclerate from any given speed, my truck produces more boost. It seems you are the only person that is getting that. Also, you're theory would explain why my truck runs more normal with a dirty stock filter than it does with a clean wix filter. I wasn't having any problems until I lost the cat, muffler, baffles, and the silencer ring. Am I going to get in trouble if I reiderate what was said by saying that my intake of air is working too well for my current turbo setup?

 

[bmoeller]

The VA c3. 2 does has a boost fooler, but it doesn't work if the chip isn't on. By all means, my truck has power to spare without the box. I'll try turning it and seeing if it makes a difference. The harder I acclerate from any given speed, my truck produces more boost.

Ya, go ahead and turn the box on, and report back any changes.

It seems you are the only person that is getting that. Also, you're theory would explain why my truck runs more normal with a dirty stock filter than it does with a clean wix filter. I wasn't having any problems until I lost the cat, muffler, baffles, and the silencer ring.

Just a matter of deduction. With no other changes to the truck, other than the exhaust when the problem reared its head, that is what it came down to, for me.

Am I going to get in trouble if I reiderate what was said by saying that my intake of air is working too well for my current turbo setup?

It is only "working to well" as far as the computer is concerned. Other than that, I see no problem with it. With the VA on, and if it goes away, I'd say you're all set to run.

 

[J_Da_Fox]

I will get out and run the truck today and see if the va box helps... Since there is between 1 and 3 feet on the ground, this should prove interesting... I'll be sure to keep the log chain in the back!!! Thanks to all who have participated in this mess. I apologize for my lack of tolerence for new ideas. All have contributed to finding a solution to this "problem. " Thanks again and I will get back with a report about using the boost fooler.