Overboost problem..

[GrndNatnl]

Hey folks, I e-mailed Scott about the problem, but I think he's been busy lately. I want to get more opinions on this, so I'll copy and paste the e-mail I sent Scott and another friend of mine describing the problem so I dont have to type everything again and leave any details out.....

Here is my problem. I put in the Thrasher a couple weeks ago, but hadnt had it out on the road yet. I ordered the chip for the stock FP regulator, since it can run with the stock reg, and still function better with the adjustable once I get it. I just washed the car last night, and took it out for a spin down the road behind my house. Idles great, and seems to run great, but I noticed as I pulled out of the neighborhood onto the road, the damn wheels broke loose with only about quarter throttle making the turn. So I let out, and get back in it a little, and I notice the boost gauge sweep up to about 12 psi with barely any effort. I'm thinking.. holy ****.. Then I just drive along and let the BLM learn for about 7 minutes. So then, even though I shouldnt have not knowing what was going on under the hood, I nailed it and it shot up and buried itself past the 20 psi mark (which is as high as my gauge goes), and it was kind of bouncy. I felt it kind of falling out a little, like giving out, and then some pinging. I instantly let out and just brought it back home. Why is it overboosting? It's for stock reg, so shouldnt it go easy on the boost for stock fuel pressure levels? What do I need to do here?

I dont understand why its spiking this high with the chip. When I bought my car from the friend of mine, he gave me the bleeder valve idea that I hooked up, but is unhooked at the moment. He said he ran it up to 19 psi before, and it ran like a rocket, and had no problems. I've only been running stock 15-16 psi or so. I disconnected the bleeder at the track one day, when I had problems leaning out and didnt want to risk the valve leaking. (Was only to make me feel safer). I dont think shortening that boost line to the WG solenoid a little bit would cause anything. I had to shorten it so it wouldnt stick up so high and get melted on anything hot. I cut about an inch and a half off it, and connected everything.

Now its just hooked up regularly, with the line having been shortened just an inch or so, going right to the solenoid.. no valve. But its showing way to much boost on the gauge. The LED gauge on the dash goes to red like lightning, and the analog will bury itself at WOT, maybe a little less then WOT. What in the heck is happening here? Any ideas? I'm running Sunoco 94 octane, as far as gas goes. And green stripe Tomco injectors, with an upgraded.. but old RA fuel pump. Any ideas are appreciated. Sorry for the page-long.

 

[GrndNatnl]

ttt

 

[TURBOV6]

Well first of all Thrasher works with the 237 regulator that from the Turbo Trans-am, it has a higher fuel pressure than the ones for our TR's. Stock turbo boost very quickly, so you got to becareful you don't over boost. Make shure you are tappng the right source for you boost guage. You could have a stuck valve on the downpipe that could be causing you over boost problems.

 

[GrndNatnl]

The one I ordered was for the stock regulator though.

 

[Eric Stage I]

Any air that leaks out of the wastegate control hoses will cause the boost to go higher. So be certain they are all in tip top shape. Also, if you have the original wastegate actuator, the diaphram could be leaking.
I would replace the hoses, make sure they are plumbed right, and buy a new adjustable wastegate actuator as a long term fix. For the short term, you can actually hook up the bleeder valve to the other port on the wastegate solenoid, so it becomes a restrictor valve, to lower boost.

Eric

 

[Gbody5]

I don't know the details about the boost changes in the Trasher, but from what I see on my POS factory gauge, the Thrasher pegs the gauge compared to only about 13 PSI, even in first gear, with my stock chip.

Of course the Thrasher does this in all gears too, so it obviously changes something significantly with activation of the solenoid in 3rd and 4th,since the stock chip backs down to 10 PSI in 3rd/4th.

I would not be surprised that the changes in your rod length has something to do with it, and it would need adjusting to work with the Thrasher chip.

 

[Danster]

The Thrasher is designed to give you a much quicker spool. If you have the boost set at 17 PSI, under WOT conditions you may experience 18-19 PSI (quicker spool) then settle back down to 17 PSI with a Thrasher chip.


Dannyo

 

[OKTurbo]

You might just have to turn down the boost to work with this chip....I know my Jim Testa chip spools like MAD! Take out a turn or two on your WG actuator....make the arm longer to reduce boost.

Some other ideas on overboosting...

Do you still have the stock restrictor Y fitting in the wastegate/solenoid hose assembly? You can't just use a standard tee or Y fitting....one side has an orifice in it.

An easy check on you wastegate spring setting is to use a MityVac and pump it up to see where the WG starts to open at. Stock "base" pressure is around 12 psi. Engine off of course.

Another test is to disconnect the hose to the WG solenoid and stick a golf tee in the hose. This will let you see what the "base" setting is on the WG actuator. Take it for a drive....If you go much over 12-13 psi with the golf tee in you probably have a hole in the hose/fittings or the diaphragm in your actuator is leaking.

Also make sure your WG puck arm moves freely. Take of the clip,remove the arm.... and the arm should move very easily.

Good Luck,
John

 

[GrndNatnl]

Thanks for the replies guys. Here's answers to some of you questions...


No adjustable wastegate actuator rod, its all stock. The thing I was talking about shortening was the boost line that goes into the WG solenoid. When I hooked up the bleeder valve originally, I just cut an inch or so off so it wouldnt be sticking way up in the air, and would fit right onto the valve. I could do what Eric suggested, and use it to interrupt the pressure to the solenoid, so I could turn the boost down, for the time being.

I'm going to go out and check the boost hoses now to make sure. The Y fitting is stock type. I know it cant be just any fitting. It's hooked up the right way, and I've never touched it. I'm going to check the diaphragm and securely block off the hose to the solenoid to see if it dumps at abound 10-12 psi like it should. I'll post the results. Thanks again for the ideas. Now you see why I like the TR community so much. Very helpful people.

 

[GrndNatnl]

Well, here's whats up with this situation. Any more feedback on this?....

I checked the boost control lines, and everything is flawless. I decided to remove the hose from the wg-solenoid and connect it to the bleeder valve, secure it with a small hose clamp, and CLOSE the valve. I went for a blast, and sure enough, it would only build up to 13 psi and no more. So I pulled over a couple times and kept cracking the valve open a little at a time. I finally adjusted it to where it would hit right around 19 psi in first. It seems to stay at around 19 psi in 2nd and 3rd gear too. I'm guessing with a bleeder valve, its not computer controlled, therefor it hits that same boost level for all the gears. Is that safe?

I still just dont understand why it would overboost being hooked up to the solenoid. Could the solenoid be acting up? I figured the chip could be installed into a typically STOCK vehicle, with only necessary fuel system upgrades (although mine is for stock regulator), and increase boost safely without needing any adjusting. Before, with the stock chip, it would boost up to about 16 psi in first gear.

Is it ok to take the solenoid completely out of the picture and just cap it off? And just use the bleeder valve?

 

[OKTurbo]

Sounds like everything is working fine now. The WG solenoid may be messed up, but I really think it's working like it should. Every car is a little different....the computer has no feedback on boost. The chip just sends a pulse width modulated signal to the solenoid to bleed the boost...this is how you get boost levels above the 13 psi base setting.

You'll want to leave the connector hooked up to the WG Solenoid so you don't set a code and get the SES light.

The bleeder valve will work just fine. I've used one in the past. I've now gone to a BSTC electronic boost controller which allows some more tuning than a simple bleeder set-up....such as 3rd gear scaling etc. You might even try hooking up the bleeder valve to the outlet of the solenoid...that way you'll still have the boost scaling from the chip control.

You really should invest in an adjustable wastegate. Or you can make yours adjustable for real cheap.
http://www.gnttype.org/techarea/images/Adj_wastegate.JPG

BTW 19psi sounds pretty high for pump gas. Watch that knock retard!

John

 

[GrndNatnl]

LoL.. thats what everyones said so far about 19 psi on pump gas. I turned it back down a bit though. When I bought the car, he told me he had a bleeder hooked up before and ran it to about 19 psi with no problems. I'm still going to be more careful, and if I need to crank it up at the track, I'll can maybe add some octane booster, or a few gallons of 100 octane to.

I left the electrical connector connected to the solenoid, so it doesnt flash any codes. What would be the benefit of putting the valve on the solenoid outlet? Change the amount of boost per different gear? Right now it stays right around wherever I have it set at for all the way thru 3rd at WOT as far as I could tell. (Havent reached OD on the highway, dont really want to).

 

[GNANIMO]

Originally posted by GrndNatnl
The one I ordered was for the stock regulator though.

You don't order a Thrasher for a stock regulator.. you order it for stock or upgraded INJECTORS!

It needs the min of a 237 or having an adjustable set to 45 psi. Could this be your problem? You said you have green stripes.

(I didn't read all of the replys sorry if this has been duplicated)

 

[Eric Stage I]

Well, before Scott jumps in and cuts your head off , I'll just tell you now that there is a Thrasher version for the stock regulator.

 

[OKTurbo]

The outlet of the boost solenoid usually has a small foam filter on it. Most of these fall off though. You can run a hose from that to the bleeder valve. This way the solenoid will still ramp the boost down for 3rd gear. You'll definately have to play with the bleeder valve to get it set right.

You ramp the boost down in 3rd gear since the load is higher on the engine.....plus by the end of a 1/4 mile run the stock intercooler is starting to get heat soaked. This will keep the knock retard down at the "big end" when your going 100mph.

You can get away with more boost in 1st and 2nd gear. Typically on pump gas 18 psi in 1st/2nd and ramp down to 16-17 psi in 3rd. I can't run much more than 16 psi with the pump gas we have here. My SMC alcy kit lets me run 19-20 psi on the street but the tires don't have a chance. The key factors are to tune for as little KR as you are comfortable with.

John

 

[GrndNatnl]

Thanks again for the replies all.

John, you've been most helpful.