only making 5 psi

Topic: only making 5 psi (Read 1852 times) previous topic - next topic

only making 5 psi

July 13, 2008, 07:59:05 PM

my t-5 swap is complete and the car is running great, however, it's only making 5PSI at full throttle. it's pulling 20 psi at idle so i don't think i have a leak. i have the original auto computer in but i read that shouldnt make a difference. the only thing i did different putting it all back together was that i capped off the 2 vacuum lines of the turbo inlet because i didnt put the boost controller back on. i've put all new vacuum lines on so i'm not sure why it's stopping at 5 psi. i think that's the limit of the original auto so i am thinking computer? any ideas? thanks
L24

only making 5 psi

Reply #1 – July 13, 2008, 08:18:53 PM

if you didnt put the boost controller back in, the PCM has no control over the wastegate.

what line do you have on the wastegate now?

only making 5 psi

Reply #2 – July 13, 2008, 10:30:41 PM

the wastegate vacuum line goes to the tee on the neck of the housing just below where the stock intercooler attaches. the other end of that tee goes to the block on the intercooler itsself which rund to the vacuum block. i need to post a pic...i'll do it tomorrow.

only making 5 psi

Reply #3 – July 14, 2008, 11:50:16 AM

anybody?

only making 5 psi

Reply #4 – July 14, 2008, 04:02:33 PM

Are you hitting 5psi quickly and then staying there, or is it taking forever to make boost and barely reaching 5psi? Also, is this the original IHI, or a different turbo?

My XR4Ti has the engine (and IHI) from an '87 TC, and somewhere along the line, the C-clip for the wastegate popped off. With the wastegate hanging open, it basically only makes boost when out-flowing the wastegate (which happens to be relatively easy to do on the tiny internal on an IHI). That causes a very, very slow climb up to about 5psi. If that's the problem, it shouldn't be hard to fix; however, I've heard that it can be slightly difficult finding the right C-clip. Fortunately, I've also heard that you can wind a paper clip around it and it'll work just fine too! I haven't actually fixed the problem on my Merkur yet (until I fix the suspension, the last thing that critter needs is any real power), so I can't give you more solid advice.

On the other hand, if you're actually making 5psi when you should, but it just never goes higher, it's probably just how the wastegate is set. All manual-trans 2.3Ts had 10psi wastegates, but I seem to remember that some automatics were lower. (Definitely if you've swapped in a turbo from another car, that could be the case too.) If that's the problem, the easiest thing to do is put on a boost controller and adjust to your liking.

The simplest way to figure out if the wastegate is working like it's supposed to is to unhook the line going to it. If it's not working, you still won't make boost; if it IS working, your boost will climb until you either get off the throttle (recommended) or blow up your motor or turbo (not recommended). That might help you narrow the problem down.

only making 5 psi

Reply #5 – July 14, 2008, 05:47:55 PM

it pops from 20in vacuum to 4-5 PSi of boost almost instantly. since i capped the 2 lines to the boost controller, would it do anything if you connected a hose between the 2? I'll test the other method tonight and see what happens. it's a stock 88TC so it's got the original IHI. when you say set a 10PSi, do you mean the EEC sets the limit? i'm still learning turbo-speak. Also will the premium fuel switch knock down boost? i think i have it in premium setting....though i when i took the dash and wiring out i for got to mark which was which(antennae is obvious). pretty dumb but oh well. is the premium switch the one with the light on it? please forgive my rookiness

only making 5 psi

Reply #6 – July 15, 2008, 11:54:11 AM

Well, I can't help you with the premium switch, since I don't have one. However, with the boost control solenoid unhooked, the switch (actually, the computer) can't make any difference to the amount of boost you make. It still adjusts your timing map, but that's not particularly important to you at the moment.

Basically, different cars control boost in different ways, but the most common way is with a wastegate (although there are a couple of other ways to do it also). A wastegate is basically just a door that opens to allow some of the exhaust to go around the turbine rather than through it. Now, the wastegate can be controlled in different ways also. Some cars (VWs and Audis come to mind) use an electronically-controlled wastegate. The computer says, "stay closed, open a bit now, more now, close up a bit," etc. Some cars (like my '84 TC) use a purely mechanical wastegate. Basically, there's a diaphragm and spring mechanism (the actuator) hooked up to the wastegate. A hose runs from the compressor output to the actuator. When the pressure from the hose exceeds the pressure of the spring, the wastegate opens. In the case of my TC, it takes 10psi to completely open the wastegate.

Now, the later cars (like yours) get a bit more complex. It's still fundamentally a mechanical wastegate, but also has what's called a boost control solenoid. Basically, that sits between the compressor output and the wastegate actuator, and, when the computer tells it to, lets a little of the pressure out. So while you may be making 10 psi of boost with a 10psi wastegate, the BCS is letting 5psi out, so the wastegate only "sees" 5psi and is still closed*. The computer adjusts this based on several factors (RPM and what gear you're in for example). Incidentally, there's no way for the BCS to make the actuator see MORE boost than you're actually making.

What you've done is unhooked the BCS from the system. So, the wastegate is seeing whatever you're actually making for boost. The EEC has no control over it. It sounds to me like your wastegate is working like it should, but it's opening at 5psi. I seem to recall hearing that the wastegate on the automatic-transmission cars was set lower than the one on the manual-transmission cars. That may be what you're seeing.

What I'm advising you do to test is unhook the hose from the wastegate actuator entirely. Your turbo should then have nothing controlling it at all (except for your foot). The good news then is that if the actuator would normally open at 5psi, it doesn't matter. The bad news is that, with nothing controlling it, the turbo will just keep spinning faster and making more boost until you get off the throttle or else it either tears itself apart or you start detonating. Basically, get on the gas long enough to see the needle swing up past 10psi (or to decide it's not happening), then back off the throttle.

Now, if you find that you do make plenty of boost with the wastegate actuator unhooked, then you just need to find a way to fool it. You could go back to the stock boost control system, but it, frankly, sorta sucks. A better way is to put your own boost control system on there. There are plenty of options (ranging from a bleeder valve from the hardware store to a $600+ electronic unit made by HKS, GReddy, or some other company you've seen named on the stickers on some Honda

). I've heard great things about the Gillis valve, but don't (yet!) have any personal experience with them.

Let me know what you find, and we'll go from there. I'm guessing that you'll find that with the wastegate unhooked, the car takes off like a rocket, and then you'll know it's boost controller time.

*: When I said "closed" I oversimplified. In fact, a simple actuator doesn't just go directly from completely closed to completely open. It will slowly creep more and more open as your boost increases. One advantage of many aftermarket boost controllers (including the Gillis valve, but not including a bleeder or the stock BCS) is that it does go quickly from closed to open, meaning slightly faster spool. The quicker spool is not quite as big of a deal on the stock IHI as it is on a larger turbo (the IHI was the smallest turbo they put on TurboFords; good for quick spool, bad for maximum power).

only making 5 psi

Reply #7 – July 15, 2008, 08:29:02 PM

followed instructions and.....:burnout: wow. cant get the grin off my face! That would be a Gillis valve then right...:D
i only pushed it to 11PSI but , what a difference.

only making 5 psi

Reply #8 – July 16, 2008, 12:53:02 AM

Gills Valve also known as a Manual Boost Controller/ MBC I have one but I didn't buy one I made my own. They are very simple and took me about 40min to make the whole unit. That includes the time it took me to find all the parts and assemble them as needed. It only cost me about $15. Works great. It is a real simple piece. It is just a air pressure relief valve. I used brass pieces to make mine 1st I found 1/4" brass T and then found 2 1/4"NPT-1/4 hose barbs. Then I got me a 1/4NPT pipe plug. Next I needed a metal Ball that fit inside the brass T "make sure it can roll free inside the T" Then I needed a spring that would also fit inside the T and have good pressure. Need pusher Springs. Like inside a pen only larger and stronger" Then I needed a Bolt to make the adjuster." Find a bolt that is just large enough to fill the Hole in the inside of the pipe plug." Then I also needed a Tap."same size as the bolt thread with matching drill bit. Drill out the plug and tap the hole. Now we just need to put it all together. So we take the brass T hold it so it would be a T on its side. Now screw one hose barb on the bottom opening in the T and then screw the 2nd hose bard into the opening on the side. Next drop the Metal ball inside the T so it goes over the inside hole of the hose barb on the bottom. Then take your spring and put it top of the ball. Then screw the Cap piece on the top opening in the T. Then take your bolt and screw it down into the tapped hole in the cap. TA DA now you have a MBC/Gills valve. Now all there is left is to hook it up. The pressure line from the turbo to the actuator goes to the bottom port on the MBC and then run another line form the side outlet to the Actuator on the turbo. You are set and ready to roll. Just some dialing in of where you want the boost set to. To get more boost tighten the bolt to get less loosen it. You might also have to play with different springs to get it to the setting you want. And also once you get it set your want to hold it there so most do this by using a Nut on the out part of the bolt to Jam the bolt in place. Also a MBC will make a slight decrease in turbo lag as it delays the signal to the Actuator until the set boost level is reached. Hope that helps you guys out. Also I found my info on the google. But I did rob my spring and ball from a marine outboard fuel line connector. Build it buy it whatever just crank the boost and Let it Rip!

only making 5 psi

Reply #9 – July 16, 2008, 01:20:51 AM

Awesome! Those motors can be a blast, but if you're not making decent boost, they have no business being in something the size of a 'Bird. Stock (on the 5-speeds at least) they ran up to 15psi. I believe the overboost buzzer kicks in at around 18psi. If you're running a stock turbo and intercooler, you probably don't want to go higher than that anyway. The motors can take some insane amounts of boost (and need to to overcome the dreadful head design) but you need to keep the intake air temperature down to avoid detonation. The IHI gets pretty inefficient pretty quickly, and the stock intercooler isn't a huge help (although it's better than nothing). Anyway, get that valve, pop it in, and have fun!

By the way, if you haven't been there already, you might want to check out TurboFord.net. There's a lot of experience floating around there; even if you never post anything, it's worth just looking through the techboard archives if you have questions.

only making 5 psi

Reply #10 – July 16, 2008, 08:30:51 AM

i'll take a shot at making one this weekend...hopefully ACE has the ball and spring. thank goodness for the internet eh.:D

only making 5 psi

Reply #11 – July 16, 2008, 09:11:03 AM

Sounds like you're making it more difficult than it should be.

I ran the IHI on my Ranger conversion and what I did was this. There should be a 2-port fitting on the compressor side of the turbo. Take the side that has the big hole to the WGA. Take the other one with the smaller hole (the bleed orifice) and run it to one of the connections on the turbo inlet you capped.
You can kind of see it here in this pic..

.

That should net you at least 15psi boost without any other issues., all the time, no fuss, no muss. It's not quite the same as having a ball/spring valve connected in there, but it costs you nothing.

If you don't get 15psi boost this way, there is something else wrong.

only making 5 psi

Reply #12 – July 16, 2008, 12:14:13 PM

Oh, that's interesting, I don't recall having seen that trick before... Basically, you're just using the fitting that's already there as a bleeder, and dumping the waste air back into the intake rather than losing (a bit of) metered air. That's pretty clever.

I'm a bit surprised that you have an IHI in there in the first place, though. Why did you choose it? Also, what intercooler is that?

only making 5 psi

Reply #13 – July 16, 2008, 12:35:26 PM

That's all that fitting is in the first place, a bleed. All the BCS is doing is allowing that port to be open when the ECU tells it to.

I'm guessing you're asking me about why the IHI? The truck was not built as a top end vehicle and the IHI was low miles. That IC is a Dodge one. Been too long and the truck has been gone for 2-3 years to remember what one it was.

only making 5 psi

Reply #14 – July 16, 2008, 07:01:32 PM

hmmm...i tried that method and it didnt work. that fitting your talking about broke on mine(rust) so i replaced it with a brass tee. one end of the tee goes to the actuator and the other end of the tee i connected to one of the outlets i had capped.....dont understand why it aint working. i'll do up a vacuum diagram...maybe i screwed something up when i put it all back together. Also the idle "hunts" from 900-1200 and occasionally it'll did to 500 like it's gonna stall so i mighta messed up the vacuum lines.