I have to hand it to you Web....nice write up...and a great project. This old guy has had to play catch up for years on all this computer, sensor, control crap...but, it is interesting. And I am learning. My big old cummins engine was losing power, slowly, and with 440K miles on her, I chalked it up to needing injectors or something...but, the other day, the altinator started to go, and I had noticed for sometime, the voltage was low, but that happens. Well, no it doesn't...in the old engines, not a problem, but in a computor, sensor controlled world, voltage is important. I found once the new altinator was installed and I had my voltage back, so was the power...so yes, I am learning....lol

 

I have seen that the addition of the boost signal to the fuel regulator works but the signal is so over kill that the car runs totally pig rich.

I developed a stand off regulator that gives an output signal that has a threshold of boost that is needed to give a boost output signal. Above the boost threshold the output increases 1 PSIG per 1 PSIG increase over the threshold, i.e. a 13 pound boost; it gives a 3 psig output if the threshold is set to 10 ; as an example.

Keeps the boost signal in control so your not boosting the fuel rail pressure without regard of the boost, in some area you are rich enough and more pressure will flood your a/f mixture.

Woody

 

Waldig,

I read your write up on this and from what I gathered the stock regulator looks like a 1:1; 1 PSI of fuel pressure increase for every psi of boost added. This is nothing short of Nirvana for an NA car going FI if it holds true. This is also the primary difference between your needs and mine.

You have an ECU that is designed for boost and a tune to match. I take it that you are trying to add more fuel above and beyond what the ECU is already programmed for due to your pulley upgrades, etc. Thus your need for a predefined threshold so as not to erroneously add fuel where the tune and fuel delivery is a known quantity. Even if you are increasing fuel rail pressure to get more out of your existing fuel delivery system like me, the same still applies in your case.

I on the other hand have an ECU that was not designed for boost and therefore have to hide it from the ECU and from every sensor. However, I also have what amounts to full control of fuel so I'm not relying on fuel pressure alone or trying to manipulate fuel pressure to achieve my target A/F.

The AEM allows me to tweak fuel via the MAP sensor, therefore my target fuel delivery is based on injector open time and achieved flow per rpm, per psi of boost. Therefore a change in boost will simply put me in a different cell with the proper injector time for that cell.

I couldn't use your setup as it would negatively impact me unless I could reduce the threshold to zero (which is effectively what I have now). In fact, it would introduce an interesting tuning challenge based on the perspective of my starting point versus yours. Having a nice linear fuel delivery based on manifold pressure is 100x better in my case as it is readily predictable.

The reason I would employee the 1:1 by adding a boost signal is to get more from my stock fuel pump and SRT injectors to support my ultimate power goals.

All things considered, I couldn't ask for anything better!

 

Thanks Doc!

Well, I have some great news to report! All of my partial throttle issues are solved and this baby runs with 100% stock like drivability!

Let's just say that my laptop was out of commission over the weekend so it gave me some time to reflect and come up with a new gameplan. I got started Sunday evening, came home after work today, tried it out and BAM! She is running 100% smooth. No hint of stutter, sputter, or spatter, and she pulls very nice under low to medium throttle positions.

So, now I'm going to put a few more miles on it to build up the fuel trims, then make sure that I have full control of the O2 sensors via the AEM, and then I can finally start bringing her up to full power!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! !!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

 

Great news! Cant wait to see how much power you make!

 

Interested to see what transmission mods your going to have to do! Is this a manual or auto?

 

It is an automatic.

 

I can't contain the excitement! I'm several days now into the fix that gave my car back 100% stock like drivability. I have "0" issues and that is saying a lot coming from me. I tweak everything and pretty much never stop as there is always "something" that I can play with and get a little bit better.

Don't get me wrong, I have some things I want to pretty up but as far as getting in, starting it up, and driving like a bat out of hell, and not knowing it didn't come this way, it is AWESOME!

But oh well. Today, I got the car inspected; 100% perfect. I have the Long Term Fuel Trims to +-2.3% with a basic straight line fuel map which means that I have the injector lag time set 100% right. So I changed the oil and adjusted the sensitivity on the knock sensor so that I can officially start turning up the boost this weekend!

I'm there, I am finally there with absolutely nothing else to hold me up. So now I finally get to see what kind of power she is going to make and which part of the system is going to be the first bottleneck to overcome

I just hope for goodness sake that I don't see some sort of catastrophic failure before the weekend is up!!!!!

Believe me, the thought of that has been haunting me since I read that Rcompart had blown his motor with the SRT SC on the first pull on the dyno and with the very AEM I am using now. I had stretches where the car seemed good but there was always some nagging issue that would crop back up every time I tried to tweak things to my 100%. In fact, the closer I got to perfect the worse the little problems became. It was really weird..

Oh well, armed with the knowledge that something might not have been quite right has forced me to be very persistent in tracking down every single little anomaly and not trusting anything until proven safe. I can honestly say that I now have 100% confidence in my setup and the supporting systems. All that remains to be seen is how well the stock motor will hold up to the abuse I throw its way starting this Saturday!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

Yeeeehaw!

 

Haha!! That is awesome!!!!!!!

 

Congratulations on the fruits of your labor. I will be looking forward to an update this weekend. I hope you are all smiles and giddy with excitement after your Saturday run.

 

Congratulations! I have a pretty good understanding of what you experienced and how you must feel now!

 

Looking forward to some positive posts this weekend!
Good luck!

 

I spent yesterday making runs and tweaking fuel. I had the cruise perfect, but ran back into fuel cut when I started flooring it. So, I had to spend some time adjusting my maps and working that out.

I had to pull a TON of fuel from what I had calculated and the changes I made to correct fuel cut caused me to have to correct fuel even more in certain areas. Once set, I spent time getting the A/F out of the 10's and then circled around with getting my favorite logging software to display a dyno of the logs from the spd.

I accomplished both for the most part. I still have a whacked out A/F that needs some TLC to smooth out, but I did get at least one decent run to 5k with 1-5 psi (low to high end) with no sign of knock.

However, she still wasn't making anymore than 5 psi. This was very odd so I had to stop and investigate because I had no visual signs of belt slippage. Looking further I found a boost leak at the EGR valve! From the quick look I took, it is vacuum operated and one side has an electrically operated solenoid. When the valve is off on one side, boost from the other side (manifold) forces it open enough to leak. It is sort of like a built in pressure release valve

So, this morning I am going to have to map out a strategy around it. I'm looking to not disable it completely as I don't want a constant check engine light. We'll see, but that is probably going to consume my day today.

 

anychance your going to build a custom intake manifold for your boost set up? maybe relocate or get rid of the egr completely, just trick the ecu into thinking it's still there..

 

No custom intake manifold needed as far as I see. Pretty much everything is stock except my bolt-ons.

 

Well, well, well. Finally some progress and some good progress at that!

Today, I disabled the EGR by removing the pipe from the IM to the EGR valve, capped the valve, and made a block off plate for the IM. I've thrown an EGR code twice at random times so I'll end up revisiting this with a more in depth fix later to keep that light from going off on me.

Once I did that, boost went up a bit. Right now I am set for 8-8.5 psi at redline.

If you look at the charts below, you will see that I am making some nice power while still working on cleaning up the A/F. It is around 12:5 at the beginning and end but has a dip in the middle, then it goes lean suddenly on me so I had to let off the gas.

Keep in mind, these charts represent RWHP. If you extrapolate up the curve, it looks like I am set to make around 270 RWHP at redline at 8.5 psi. That is putting me in stock SRT territory and a bolt on 100 hp! The great news is that there is more on tap, so whether this holds true or I have to turn her up a bit more, I'm on track to at least match a stock srt on the top end. They will have a better torque curve of course but that is the nature of the rotrex. It is what makes it so fun to drive. I can tell you this, the low first gear in the NA makes for some fun at kick down! I'm going to need some new tires soon!





Well, more to come soon. I'm going to keep working on the fuel and clean up my A/F under all circumstances. I'm also going to be spending some time seeing what I can do to get some more wrap around my drive pulley. I'm probably going to have to add another idler pulley so that I can improve the wrap as I think I am getting some belt slip. We'll see. One little thing at a time!

 

that is impressive...and you just might surprise a few srt's out there...now, as you perfect this, it might be time for a kit, to make some that $$$$$$$ back...and make these N/A's non N/A's....

 

Great work and results. A very interesting read. Look out guys the N/As are coming.

 

It is really fun to suprise people who don't expect a wingless Crossfire to blow their doors off!

 

And in my case, people refuse to race me because OF the wing.

Buahahahahaha.