Engine/Transmission (1998.5 - 2002) boost gauge "twitches"

[Devan Manis]

When i start to make approx 20 psi of boost and anything over, the needle on my autometer boost gauge will shake rapidly fluctuating maybe 3psi. I have it Tapped into the aluminum intake and teflon taped. It did it with stock turbo and now does it with an hx40, I've tried two boost gauges and new nylon line with same result. Also egt's seem to run pretty high for my taste as far as cruising goes. used to run 750-800 at 55-60mph, now with the hx40 it will run anywhere from 800-900 cruising the same speeds mentioned. Any idea's what would cause the boost gauge to fluctuate that much on a stock engine with just some 80hp injectors? no boost fooler or anything, but don't think thats the problem with the fluctuating gauge. do i have a boost leak? any opinions appreciated.



2000 auto 80hp injectors hx40.

 

[Cummins724]

I think you should check for boost leaks, also it sounds like you are having a surge issue. The hx40 has more air flow than the stocker, but it needs more drive than what you have is what it sounds like. I would check for boost leaks first then start downshifting to control the surging if you don't find any leaks. If you add a box to your buggy it will make a difference too, but the automatic may slip and those upgrades aren't cheap. my truck surges on a hill in 5th gear pulling a load so I've got a smaller compressor in the mail. Sounds like the hx40 is a little too large without a "chip" to get it spooling. That's just my $. 02. but I'd call HT Turbo & ask what they thought. Good Luck

 

[Devan Manis]

i don't think that its surging, it sounds and runs normal, even spools decent. with just the injectors. i have a comp in the mail should be here tomorrow, i'll put that on and see if maybe some boost fooling helps, and check for leaks as well. it does slip like a mad man, but im all over the auto up grades as well.

 

[TGibbs]

Same "twitching"

My gauge is also doing that too ever since I put on the hx-35, before that I was running the stock hy and the needle was rock solid. Now it is "twitching". Could it possibly just be the bigger turbo??



Thanks

Tristan

 

[lsenus]

My guage started twitching so bad that the needle looks solid over a 3 psi range. Stock Turbo.

 

[Nate]

Mine does that as well. 2 guages. . still does the same. Must be normal.

 

[Devan Manis]

it can't be normal, why would it only start at 18-20 psi?

 

[CumminsAholic]

Mine never did it stock (with the stock turbo I should say) , but did it REALLY bad between 20 and 40 lbs of boost after I put on the sps 64. I had a k&n air filter, similar to an re880. I just put on a AFE Proguard 7 Stage 2 intake. My fluctuation is 99% gone. Mine was definately turbo surge, I knew the 64's surged when I bought it. Well, with the intake they don't surge. Try a bigger air filter, you may be surprised.

Corey

 

[Devan Manis]

i have an afe stage one.

 

[TGibbs]

I have the BHAF on right now but maybe I will throw the stock one on for kicks to see if that changes it at all.

 

[lsenus]

Mine will do it starting around 5 psi up to my max of 17. Not always though. K&N filter in the truck.

 

[TAbbott]

When i start to make approx 20 psi of boost and anything over, the needle on my autometer boost gauge will shake rapidly fluctuating maybe 3psi. I have it Tapped into the aluminum intake and teflon taped. It did it with stock turbo and now does it with an hx40, I've tried two boost gauges and new nylon line with same result. Also egt's seem to run pretty high for my taste as far as cruising goes. used to run 750-800 at 55-60mph, now with the hx40 it will run anywhere from 800-900 cruising the same speeds mentioned. Any idea's what would cause the boost gauge to fluctuate that much on a stock engine with just some 80hp injectors? no boost fooler or anything, but don't think thats the problem with the fluctuating gauge. do i have a boost leak? any opinions appreciated.



2000 auto 80hp injectors hx40.

Contact ISSPRO and get one of their dampened guages. It'll be rock steady. Had same problem in my big truck (18 wheeler running 700 hp + or so after mods) when boost went up over 30 psi. Really bad when boost exceeded 40 psi. Problem really was that sensor was too close to individual intake port and guage just reflected what it was seeing, but it "bugged" me so put on the dampened guage and reading is now rock steady.

 

[TGibbs]

Where does everyone have their boost gauge reading from? I have a bolt from Geno's, I have to make a run to Utah but when I get back maybe I will try a few of the other bolt holes and maybe tap the intake horn to see if any of them help.

 

[Nate]

I pulled one of the plugs off the side of the block for mine.

 

[lsenus]

Block plug behind the MAP sensor for mine.

 

[CumminsAholic]

Side of the block for me too.

Corey