Vitesse STEALTH MAF/MAP Kit

[NCGermerican]

When did you purchase it?

End of September 2023

[NCGermerican]

**Update. I'd like to thank @Fast951 for his help with my issue (suggesting vacuum leak). Since I had a long weekend I installed the Vitesse MoMonitor that I purchased from John. Before I fired the car up, I decided to replace my oil pressure sender (what a pain) and while I was under the car, I noticed a small amount of oil on the bottom of the alternator cooling hose. Upon inspection, it was dripping from the bottom of my brand new Evergreen Turbo housing!

From the top, it looked as though the j-boot was sealed correctly on the turbo inlet. HOWEVER, underneath it was not. Since it was letting the small amount of oil (condensed from the AOS) drip out, that means air can get in. I have a feeling that vacuum leak was the cause of my warm start sputtering/lean issue. I'm hoping to have some time to start it up and use the MoMonitor to see how she runs!

[Jotronic]

**Update. I'd like to thank @Fast951 for his help with my issue (suggesting vacuum leak). Since I had a long weekend I installed the Vitesse MoMonitor that I purchased from John. Before I fired the car up, I decided to replace my oil pressure sender (what a pain) and while I was under the car, I noticed a small amount of oil on the bottom of the alternator cooling hose. Upon inspection, it was dripping from the bottom of my brand new Evergreen Turbo housing!

From the top, it looked as though the j-boot was sealed correctly on the turbo inlet. HOWEVER, underneath it was not. Since it was letting the small amount of oil (condensed from the AOS) drip out, that means air can get in. I have a feeling that vacuum leak was the cause of my warm start sputtering/lean issue. I'm hoping to have some time to start it up and use the MoMonitor to see how she runs!

How did this wind up working out for you?

[NCGermerican]

**Update. I'd like to thank @Fast951 for his help with my issue (suggesting vacuum leak). Since I had a long weekend I installed the Vitesse MoMonitor that I purchased from John. Before I fired the car up, I decided to replace my oil pressure sender (what a pain) and while I was under the car, I noticed a small amount of oil on the bottom of the alternator cooling hose. Upon inspection, it was dripping from the bottom of my brand new Evergreen Turbo housing!

From the top, it looked as though the j-boot was sealed correctly on the turbo inlet. HOWEVER, underneath it was not. Since it was letting the small amount of oil (condensed from the AOS) drip out, that means air can get in. I have a feeling that vacuum leak was the cause of my warm start sputtering/lean issue. I'm hoping to have some time to start it up and use the MoMonitor to see how she runs!

How did this wind up working out for you?

Unfortunately, I ended up returning to the stock AFM system (still with the Raptor X turbo) for now. I just couldn’t get the car to run properly without having intermittent hesitation issues. Therefore, I didn’t have confidence in taking the car too far from the house.

While John’s support was exceptional, having to go back and forth with questions and issues all the time just lead to extended periods of time where I could not drive the car. If I could do it all over again, I would opt for the traditional setup and not the “stealth” setup.

By having the factory AFM and F9 Tech DME, it’s much easier for me to diagnose issues on my own. I’m using the Lindsey Racing DME/KLR chips for now, that I had purchased previously with their “instant HP kit”.

[chrischrischris]

Update - I'll split this into 2 parts.

Part 1 - Fuel Pressure Regulator
I don't know if this is the issue or not, but after doing a fuel pressure test, I found out that the 3.0 bar FPR I installed with the "Instant Horsepower Kit" I purchased last spring is NOT 3.0 bar. I've been running it since April or so and never thought to do a check until I had the issues with the new MAF kit. Here are the numbers:

Pump Prime (F9 Tech DME Relay): 2.6 bar / 38 psi
Car running: 2.4 bar / 34 psi
After car shutoff: 2.6 bar / 38 psi
After 20 minute leakdown: 2.4 bar / 33 psi
After 3-4 hours: 0 psi

Now I need to find a 3.0 bar FPR. I've reached out to Emanuel at 944store and I'm going with a Delphi since Bosch units are NLA.

Pretty strange that lindsey sent you a 2.5FPR instead of the 3.0 bar. Did you ever get the stealth MAF installed?

[NCGermerican]

Pretty strange that lindsey sent you a 2.5FPR instead of the 3.0 bar. Did you ever get the stealth MAF installed?

I did but unfortunately, I couldn't get it to run without intermittent hesitation issues. One time it almost resulted in me being rear-ended at a stop light. The light turned green and I hit the accelerator pedal. The car started to move but then immediately cut out and the car behind me had to slam on their brakes.

I ended up reverting back to the stock AFM with the Lindsey MAX chip (in my F9 DME) and sold my Vitesse kit. I'm pretty confident that the issue was probably with the 37 year old wiring harness harness. So many items depend on very specific electronic signal parameters that I just think even what looks to be a "good" harness probably has internal wiring degradation, just out of age and heat cycles.

My other issue was due to me having the "stealth" kit from Vitesse. I just could not install the MAF tube without the MAF touching the coolant manifold. There are posts in this thread describing the issue. John was very responsive in trying to help get it sorted. The issue there is my Raptor X turbo has a larger inlet (27/6) and therefore I needed the larger diameter, LR J-boot. I have a feeling the vitesse kit was designed for the factory J-boot, which would have probably solved that problem. I wasn't about to resort back to my factory turbo for that.

It's also much easier to diagnose issues with as many stock pieces as possible using the FSM, Clark's Garage, CARPOKES!, etc) Once you get into modifications (especially electronic), it makes figuring out issues....especially intermittent issues....so much more difficult and time consuming.