The stock ECU doesn't prime the fuel pump when the car is keyed on, so the FPR solenoid is likely for bumping fuel pressure on initial startup to make it easier for the engine to fire. At least that's what I've always just assumed it was for. Definitely not a needed thing either.

 

Thinking about logging exhaust manifold backpressure.

Easiest way I can think of is through the EGR port. Years ago someone made a sandwich plate that you installed between the EGR valve and the engine that had a fitting for EMAP sensor tubing. To keep it simple I may buy a spare EGR valve on eBay and see if I can find a good spot to tap a fitting into the valve.

I suspect measuring through the EGR port will be a lot noisier because it's sourced from a single cylinder's exhaust port. Measuring right before the turbo would be ideal but I don't want extra holes in my exhaust manifold if I can avoid it.

Does anyone have throughs on measuring EMAP through the EGR port?

 

I was listening to one of the latest HP academy Podcasts with Robert Young. He didnt mention anything about EMAP sensor placement but they did touch on IMAP sensor placement. They described that there is a pressure drop in the intercooler system the best way to know how much pressure the turbo is generating is by putting a pressure sensor at the exit of the turbo before it goes into the piping.

On a single scroll setup that is easier to accomplish. The twin scroll setup presents an issue. Seems like the best place would be the o2 housing on a twin scroll setup. I have seen that Art Gennari placed his on the downpipe but I don't think I remember that detail 100%.

 

That's an interesting point. If I was primarily instrumenting the turbo then having pressure sensors at the inlet and outlet would be ideal.

I'm interested in EMAP for Speed Density tuning. Using manifold pressure and temperature is realistically fine. I'd like to experiment with using EMAP to calculate the pressure ratio across the engine for estimating load. Having EMAP logged is also helpful for knowing when you're asking too much from a small turbo.

In theory a tune that uses IMAP and EMAP to calculate pressure ratio would be much more forgiving of changes on the exhaust side: Driving to different altitudes (different atmospheric pressure at exhaust exit), swapping a catted DP for a test pipe on track days, or even changing turbos. The easy method of tuning with IMAP and MAT assumes that everything on the exhaust side remains constant, including atmospheric pressure.

I found some old conversations on another forum where someone logged EMAP from the EGR port as well as at another location closer to the turbo. His EMAP measurement from the EGR port was noisier as I expected. It also read a couple psi lower. Could be as simple as measurement error from different sensors, but now I'm wondering if there is some venturi effect due to the EGR inlet location. The difference looked small enough.

I'd be using an EMAP damper stuffed with steel wool to dampen some of the noise, like this:

 

In the downpipe would not be Emap. Emap needs to be in the collector. On a twinscroll setup you would just put it on one side, it's close enough.

I don't think in the EGR port would work well, port pressure is generally much different and has much more fluctuation vs in the collector.

 

just took a quick test drive of my car, fresh with rebuilt tcase, cusco 1 way front and cusco 1 way rear. snowy a bit but a little bit of gas and... total power understeer. my old car in the snow with the cusco and helical front, and it was like the car couldn't keep pointed straight, it was oversteering everywhere in the snow. any ideas? is it the front diff just behaving badly? I almost want to try the helical stock in the front again.

to be fair the diffs aren't broken in yet so they'll need some time but the same is true for the rear which absolutely wouldn't step out..

 

You should have the ACD ECU unplugged during tcase break in. They're a bit sensitive for the first 1k miles or so

 

It's just open when I unplug it right? Not quite sure what you mean by sensitive in relation to the ACD - the plates definitely do need to wear in a bit - they were shot-peened at TRE. I think the Cusco 1-way in the front is somehow just causing the power understeer. I never had this problem with the helical, and I think Luca even still runs the helical front diff.

I asked for 60% plates and 8 springs in the front I believe, it might still just be trying to lock too much on power.

 

The ACD is open when unplugged. The shot peened ring and pinion gear with Jon's set up is sensitive when new. Tuned ACD increases the load on the gear set, so it's best to have it turned off for break in

 

What type of Cusco diff did you go with?
MZ or RS?

 

RS for both front and rear, but the diffs are rather tight until broken in. Plates shot peened. 8 springs front and rear, 60% plates in front and 80% in rear.

 

Anybody got a 94mm Eagle crank for sale?

 

Jon never mentioned this to me, and we talked quite a bit over my rear diff and t-case builds. I followed the 100 mile break-in procedure in his documentation and then strapped the car into the trailer to go racing. No issues so far but it's only got 1k miles on it over the past couple years. Time will tell I guess.

Ope, party time for Vicious.

 

anyone ever do some injector testing?

I just bought one of those cheap injector cleaning and testing machines and decide to try it on several sets of injectors I had lying around.. After getting to know it a bit I threw in a set of ASNU 1000 injectors from I friends evo 9 that I am rebuilding and found that one injector was reading about 10 % higher... After some cleaning got other 3 to be within 2% of each other but one was still 10% higher... Luckily I had a brand new set of the identical ASNU 1000 lying around... so wanted to use that.. but decided to test those too.... and would you guess what.. all 4 were all over the place with one again 10% higher...
Now, I do not think it is the machine problem as it does not matter which trigger lead is connected to which injector or what their position on the rail is.. I have tried..

I was always happy with asnu but this is worrying me a bit..
Just to add.. the car did want to idle on 3 cyl lately, which could be caused by that rich injector..

 

Is that kit able to check at different duty cycles?