Ok, I still have some unresolved gas fumes from the fuel tank cover (part of the PE kit requires making modifications to the fuel tank cover including drilling a fuel return line hole) and I need to do some piping work but I was able to dyno the car today.

In short... the kit show GREAT potential but I still need to work out some issues. Everything looks great until I get to 4000 rpms and then I see a big dropoff in torque which causes the HP number to level off prematurely.

I'll scan the dyno sheets tonight, but basically here's what I'm seeing at various RPMs (Dynapack dyno @ full-load in 3rd gear) just to give you an idea. Target boost is 8.5psi and A/F measurements are at the tailpipe, which explains why they seem more lean than what I'm reading from my own gauges.

RPM Torq. HP A/F Boost
2500 320 160 11.6 6.5psi
3000 360 210 11.5 7.8psi
3500 375 260 11.5 8.5psi
4000 380 300 11.6 8.5psi
4500 350 320 11.5 8.1psi
5000 338 330 11.4 7.8psi
5500 320 350 11.3 7.2psi
6000 295 345 11.6 6.5psi
6500 265 335 11.5 6.0psi

You can see that torque and boost ramp up immediately and by 3500 they look great. However, just above 4000 rpms I begin to see a fairly sharp drop in torque as well as a drop in boost.

I'm having to run the Profec E-01 boost controller in manual mode because it will not "learn" in auto mode even with patient attempts on the dyno. You can also see that it is not keeping boost constant even though I'm trying to do RPM-based duty adjustment.

I know that boost dropoff is having some effect but would the drop in boost entirely explain the drastic drop in torque and the levelling off of my HP curve?

--Steve

 

One other thing is that the max boost reading on the dyno is consistently about 1psi lower than what the Profec reports and about 1.5 psi lower than what my Autometer boost gauge reports. This particular dyno has always seemed to measure low for boost, however, and I observed the same phenomenon when I had the Vortech supercharger.

In reviewing a couple of other dyno charts over the last few minutes, I'm seeing the torque drop off toward redline (obviously). On other cars it drops further than I had remembered it dropping so perhaps this is simply a matter of boost decay causing the low numbers.

--Steve

 

I understand that these are smaller turbo's than say on the GReddy kit....is it possible there is an efficiency problem at the higher rpm's???? I have seen this before with a stock twin turbo Z32 that had a JWT ecu change. It ramped up very quickly and then fell flat on it's face in the higher rpm's when the turbo's maxed out.

 

No way are the turbos maxed out at 8.5psi. They're good to something like 16psi. I'm pretty sure that this is related to loss of boost.

The Profec manual says that high exhaust pressure can cause the boost to decrease, so the jury may be out until I can replace my high flow cats with test pipes.

--Steve

 

Zimbo, the Profec is the most accurate boost measurement device of the three you are using. It uses a highly accurate 3 BAR MAP sensor...so it's electronic, and no chance of kinked lines or faulty calibration. I would trust it over the others.

Now, to answer your question...YES...the drop in boost is definately causing your power loss..no question about that. I know what you mean about the auto mode..but it should be learnable after 3 WOT pulls on the dyno. Sometimes, it may not look like it gets to your target...but once it learns, on your next run..like magic...it will be at your target.

 

Sharif, what happens is that on the second run (and all subsequent) the boost never gets to the correct level. Here's exactly what happens:

(1) I set the desired boost level (leaving the gain at factory default of 10) and the AUTOP light comes on.

(2) I do a WOT run starting at 2000 rpms and as soon as I reach the desired boost level I let off the throttle.

(3) The AUTOP light begins to flash indicating that I've completed Phase 1 of the learning process and need to do one more full throttle run.

(4) I do another WOT run but this time the boost never gets to the desired boost level. For example, if the desired boost level is 8psi then the boost won't go above 5psi before I run out of RPMs.

--Steve

 

Your problem is the gain is way to low! Try 50 and you should get it. Thanks for the updates. Some thing is up though with your power.
Good luck,
Gary

 

Gary, thanks! I'll try increasing the gain to 50 later this evening.

Power is indeed fairly low--but keep in mind that I'm pulling about 6-8 degrees of timing (TS reflash) and that my exhaust isn't nearly as free-flowing as it should/will be. Even so, HP seems lower than expected even with those considerations.

--Steve

 

Oh, one more thing... My Profec only reads -10.0 at idle whereas my analog gauge (and the dyno reading) show -22 hg. Is that because the units of measurement are different on my gauge under vacuum?

--Steve

 

Steve,

Your profec is most likely reading in PSI where the other gauges are reading in metric.

 

About the Vac reading: yes Profec stays in psi even in the negative range unlike any other guage I've seen

As for your power, I feel it's directly related to your boost curve. Once you fix the gain you should see 400rwhp or more with the test pipes at 8.5psi.
Gary

 

zimbo...you shouldnt let off once the desired boost is reached...that may be why you are having issues. You just need to do about 3 WOT throttle runs from 2500rpm to redline...or as fast as you dare. Usually, on the third run, the "autop" will stop flashing, and you should be good to go.

In auto mode....I never set the gain beyond 10. The gain is essentially the "sensativety" of the boost solenoid. The higher the number, the more likely you are to overshoot the boost level. Play with it some more. Believe me, once you get it set, it's a lifesaver. The manual boost adjustment is scary as *****...seriously. you'll think you got it right, lets say at 20%, but then in 4th gear, the boost will be WAAAAY higher than you want.

 

GQ, If you look at Page 19 of the Profec manual you'll see that you are suppose to lift once you reach constant desired boost.

The reason you have to do several WOT run is because you have the gain set too low. If you increase your gain to 40 for 5.6psi or 50- 55 for 8 psi you will see it learns much quicker and the response is quicker.

By setting the gain so low you have to do run after run so the Profec can slowly raise the computed gain to achieve the target boost.
HTH,
Gary

 

7-Eleven...thats good..I will have to try it out. I usuallly just hold it WOT as long as possible, so the Profec as more time to learn how much and when to release boost pressure.

Maybe I should shut up until I get my car back from the shop. sob..cry..weeping...

 

OK more info. Joenismo just reminded me that with his set up he uses alot less gain than me to get to his target boost. I think that's due to where he taps his vac source. He has his before the throttle body while I use the vac source from right behind the TB (For the Evap system).

So I should state your results may vary. As with any time to mess with the big three (Air,fuel,timing) Your should do it slowly from safe i.e. rich to dangerous i.e. lean.

Zimbo, Where does the PE kit take it's vac source for the stock actuators?

Gary

 

I tried again tonight with the gain set at 50 w/o any luck. It gets past the first phase but does not ever reach the target boost in the second phase despite multiple attempts.

BTW, the PE kit takes it's vacuum source from the tube that goes into the throttle body. It's above the MAF.

--Steve

 

Zimbo I had the same problem you are describing. My problem was that I was loosing boost pressure before it entered into the plenum. Check for boost leaks. My leak was at the maf housing. One of the bolts had backed out and boost was leaking. I turned up my gain just as you did but couldn't reach my desired boost level. Just a thought. It is hard to do without a dyno. What I did was drive next to wall or median with the windows down and go into boost. You shouldn't hear boost escaping. Did you check your BOV to make sure it isn't opening to quickly?

 

Joe, thanks for the ideas. I may well have a boost leak. I'll check the BOV and such tomorrow and report back.

--Steve

 

Here are the preliminary dynos with the boost problem.







BTW, You can also see that I'm having some sort of misfire issue or something at around 5400 rpms. I don't think it's pinging, but feedback is welcome. I'm planning to check the gap of the plugs (they are Iridium one-step colder than stock). What should the gap be?

 

I think we've got the fumes problem taken care of. Now I can focus on the boost decay. I am going to try adjusting the BOV (HKS SSQV) later this evening, but one thing I noticed is that if I loosen the lock nut on my BOV, I can easily turn the tightening bolt by hand through several rotations. Is it supposed to be that loose?

My plan is to tighten until I hear flutter and then loosen it back up until flutter goes away.

BTW, I was expecting the BOV to be significantly louder than it is. It's barely audible in the cabin. Is that another sign that it's too loose perhaps?


--Steve