Adjusting Turbo Pressure Step by step

[EricN]

Since someone asked, here it is.
It isnt going to hurt anything by not having enough boost, it is just alot more fun with more boost. The injection pump uses the pressure from the turbo to adjust the amount of fuel to let in (as far as I can tell).
Just unplug the hose (red arrow) where it meets the top of the injection pump (red circle), put a small "T" in place with a pressure gauge of any kind (doesnt need to be a boost one, any pressure gauge will work, just be sure the range is up to 20 or 30 psi max, otherwise it might not be as accurate).

. . . . . .Gauge
. . . . . .. I
. . . . . .. I
Hose____I____Injection pump

"T" fitting connection (too lazy to take a pic but if this doesnt make sense, perhaps you should consider paying someone to do the job for you)

[EricN]

Drive full throttle for about 10 seconds under load to make sure any lag in the gauge is gone and note the pressure.
Ok in this photo, I am lying on my back with my left arm touching the RF tire and I am looking up towards the motor. The 3 arrows are the adjusting setup for the waste gate rod. The waste gate is the bottom of the linkage and the actuater with the spring is the top. In case you are wondering, your turbo is just in front of all this, hard to see but unimportant to know for this adjustment.
You will need 2 10mm open end wrenches. Hold the adjuster (it is the very long nut) and turn the upper and lower locknuts in the same direction that my red pointer arrows are pointing. Make sure the force is transfered through your second wrench so you dont put any twisting force on the actual waste gate rod.
Spin the locknuts out of the way. Now turn the wastegate adjuster nut (the long one in the middle) the same way as my red arrows are pointing to increase pressure (this makes the rod shorter) and the opposite way to decrease pressure (duh). It took me 4 full turns to gain 2 psi but do yours at whatever rate you want.
Drive full throttle for about 10 seconds under load again to make sure any lag in the gauge is gone and note the pressure. If you are happy with it, crawl under and lock down both locknuts (holding the adjuster of course). If not, keep adjusting it.
Now as far as I can tell, 10-12 psi is the spec for it. I have read on the internet that 15 psi is safe and nothing on the internet is ever wrong (sarcasm in case you didnt get it). The higher you go, more power you get but the greater risk of damage. To be really safe, stop at 12psi.
Hope this helps someone.

[DelicaMark]

Thanks Eric. I have bought a turbo gauge and will be installing it soon. I am kind of hoping to find that the boost is a little low so I can increase to get a bit more power.

I'm also wondering if the boost is low would that cause too much fuel to be supplied to the injectors and possibly some excess black smoke. Or would the fact that a boost signal is going to the injector pump adjust the fuel to be in proportion to the amount of boost being supplied?

-Mark

[Adrock]

I will also be looking into doing this, but it really really needs to be stressed, this is at your own risk, and yes, there is a risk guys. If you don't think you know what you're doing, or you can't laugh at y ourself if you crack the head, then don't do it.

[DelicaMark]

Adrock makes a good point. My plan is to verify what my pressure is and maybe increase it if is really low. Trying to maximize what you can do with the boost pressure is best left to an expert and the right setup.

[BCDelica]

Eric quick question, if your plan to adjust your boost to a 'safe' level AND need to replace your exhaust - does a wider pipe and a less restrictive muffler change intake boost much?

Most likely I'll wait until after I get a new 2.5, side exit pipe before checking the boost; but would the before and after pressure be any indicator of how restrictive the stock exhaust system is?

Thanks,
Kev

[EricN]

Eric quick question, if your plan to adjust your boost to a 'safe' level AND need to replace your exhaust - does a wider pipe and a less restrictive muffler change intake boost much?

Most likely I'll wait until after I get a new 2.5, side exit pipe before checking the boost; but would the before and after pressure be any indicator of how restrictive the stock exhaust system is?

Thanks,
Kev

In theory it is possible that the exhaust can be restrictive enough to limit the boost but you would know it (plugged). The stock exhaust should allow for the turbo to spool up to full pressure where the waste gate spring is overcome, so no matter how free flowing your new exhaust is, it will not change the output pressure since the spring pressure is the same. Free flowing exhaust WILL allow the turbo to spool up quicker though.

[DelicaMark]

Well I put in a boost gauge and mounted it on the dash (i'll take a picture tomorrow). It reads a max boost of about 9.8psi. That seems a little low too me and is confirmed in the manual that Noel has posted. According to http://www.enviroimports.com/pdf/L300_inletexhaust.pdf page 2 the waste gate actuator activation pressure should be approx 83kPa, which is about 12 psi (right in line with what Eric was saying).

A side note on the installation of the gauge and line....it was a bit of a pain!!! I am about 6' tall and don't fit into most places in the van. At one point I had my head, shoulders and arms jammed down by the pedals and my feet were planted about 5' up the wall outside the door. Maybe a there is a better way to route the line.

If you are just curious what your pressure is just do a temporary gauge install and forget about the gauge on the dash. It is cool looking on the dash, but did take probably 4+ hours to figure out the best way to route the line and to actually feed the coiled-up nylon tube.

-Mark

[DelicaMark]

On closer review of the pressure it was more like 9psi. I can confirm that one full turn approximately equals 0.5 psi. I did 4 full turns and the gauge is now reading about 11psi. Test drive revealed a marked improvement on the power....not night and day but definitely improved.

Here is the gauge on the dash:

Boost1.jpg (50.6 KiB) Viewed 13665 times

Close-up.

Boost2.jpg (39.17 KiB) Viewed 13665 times

[EricN]

I have mine set at 13psi, checked with a proper ($4000 scanner) gauge. My boost started reading 16psi and i got a little scared so wanted to double check with the scanner. Stupid POS Princess auto gauge gave up a little soon. I agree, you arent launching off the line but it sure goes better. Wait untill you change the exhaust, it should make a huge difference for you.

[EricN]

Ok, little note of interest here. On the weekend I started routing the temp sensor for my pyrometer. I pulled the drivers seat and unbolted the engine cover so I could take a proper look at the turbo and get an idea as to how I was going to remove it and where I was going to drill to mount the probe. Since the egr valve was sitting right there I yanked it off and gave it a quick cleaning too. During this whole process I noticed a blowoff valve sitting on the manifold. Now I had to know how high it was set. Turns out, about 15.5 psi. I only have it set to blow when I am at max revs (makes a nice rev limiter) but that creates a small problem. If you want to run higher boost, you need to be able to adjust that valve.
I was looking at adding an intercooler too. It is a tight fit still, but if there is no egr valve, the job is reasonable doable.

[BCDelica]

Hi Eric, quick question, is the item that the red arrow points to the blow off valve and there adjustable? Have always wondered why our 90' has one just like that and my 91' has one the size of a tuna can.

Did you check out that Taiwan (I think) user group and there various installs, they mount a few intercoolers too. There Delicas are LHD and the engines look slightly different, found info about Taiwan pollution regs aren't as strict as Japan. Nothing to the install, just find space to run those two 2.5 inch (plus) hoses and mounting the cooler in front of the rad.

[EricN]

Yep the red arrow is it. I didnt take it apart to see if it is adjustable or not,,, yet. As for the taiwan site, I looked around but I never saw any installs at all. I usually end up at the page selling stuff or just completely lost. Do you have a link with an install pic??

[BCDelica]

http://tw.msnusers.com/yamanotw/page42.msnw?albumlist=2
http://tw.msnusers.com/yamanotw/newtdo0 ... lbumlist=2
http://tw.msnusers.com/yamanotw/dly.msnw?albumlist=2
http://tw.msnusers.com/yamanotw/general ... 7228079556
http://tw.msnusers.com/yamanotw/general ... 7228079556

Sure there is others, and I can't find the photo's of there mods to the air box area - looked interesting. Some of those have more then one page of pictures.

[docsavage]

Before the road trip to Alberta this Christmas I was able to get the boost guage installed and the boost adjusted. Prior to adjustment the boost was maxxing out around 9 psi. The adjustment was not quite as simple as most as the adjusting rod must have been on the last thread on the top piece and did not thread into the long adjusting nut. As a result I ended up with only 7 psi boost. Back underneath to see what was happening and the two parts had seperated. After getting it threaded on right and cranking a few turns on the adjuster the boost was back to 9 psi. One last trip under and the boost is now maxxing at 12 psi.

It has made a huge reduction in smoking as the air flow now matches the fuel metering. Also, a big difference on the highway. It keeps speed on hills better and against the wind. Made the trip a lot nicer without having to worry about smoking out he people behind me.

James