Jenvey ITBs

[SteinOnkel]

My older love is for my 1982 VW Derby and it has Megasquirt 3X and ITBs. I track and daily drive the car

Here it is in action:

https://www.youtube.com/watch?v=vK77SRrt9_A&t=70s

If you need any help with the tuning or want to take a look at my msq, let me know. ITBs like to be a little tricky.

Are you running batch semi or full sequential?

BTW your experience may vary, but my brake booster would disrupt everything if it was "connected" to the fuel pressure regolator or map sensor in any way. Now I run the Booster off of Cylinder 4 only and the rest on Cylinders 1-3. Try pumping your brakes at idle. Mine would fuel starve, sputter and oscillate.

[rug]

Somewhere I lost RPM input from my coil. Not sure what happened since I had it running except that I charged my battery. I got spark but the megasquirt isn't seing the signal anymore.

If you need any help with the tuning or want to take a look at my msq, let me know. ITBs like to be a little tricky.

Are you running batch semi or full sequential?

BTW your experience may vary, but my brake booster would disrupt everything if it was "connected" to the fuel pressure regolator or map sensor in any way. Now I run the Booster off of Cylinder 4 only and the rest on Cylinders 1-3. Try pumping your brakes at idle. Mine would fuel starve, sputter and oscillate.

I will be running batch. Future upgrade is 36-1 wheel on crank and also running spark of the microsquirt. I have run megasquirt before on a honda b16 powered classic mini but never had ITBs. We will have to wait and see what troubles I run into

/C

[SteinOnkel]

When you have the 36-1 wheel for tach in, use the distributor's hall pickup (I'm assuming you have a pertronix unit inside) for cam phasing. Trust me, you want full sequential. The idle quality will astound you.

[rug]

So I fixed my trouble with lost RPM signal. For some reason a resistor inside the Microsquirt died on me... Replaced it and now everything works fine. Got all fuel lines connected, new fuel pump is in so I figured.... why not see what happens? Put all fuses in, cranked the motor over and... STARTED RIGHT UP! It starts and idles better cold than it did on carbs! I used the wizard to generate required fuel number and the VE map. Nothing else has yet changed and this thing runs quite ok. The video bellow is the second start on ITBs. I always thought most of the "first start" videos online where motors start on the first try was fake, but I have reevaluated my thoughts on that

First (second...) start video

The old low pressure fuel pump which pumps fuel into the catch tank sounds like crap! Can't really hear it ones the car is running though. Computer connects via bluetooth so sometimes it takes up to 30 seconds to connect.

When you have the 36-1 wheel for tach in, use the distributor's hall pickup (I'm assuming you have a pertronix unit inside) for cam phasing. Trust me, you want full sequential. The idle quality will astound you.

That would be nice... Probably a project for next winter. Right now I just want to get driving I figure batch fire should not be worse than the webers?

/C

[SteinOnkel]

It kind of is worse. A carburetor supplies fuel constantly and it gets sucked in whenever the valve opens. On a batch injection, you are spraying at closed valves most of the time.

I think you should be able to run semi-sequential with your setup right away though. It's sort of timed batch.

[rug]

Quick update:

I finnished up the aircleaner. This is based on ITGs 30mm trumpet tray with a 65mm filter. My meassurements were a bit off. Acctualy I thought the 65mm filter had an external hight of 65mm but it has 65mm internal (95mm external)... The foam barely touches the hood when closed so It works, but a bit tight....





Slightly annoyed that the ITG logo is upside down... Sadly the tray will not fit the other way around without the tabs hitting the firewall.

Next is attaching the throttle cable, figure out what to do with the crank vent and then get the car to an exhaust shop to get the O2 sensor in. There is room to attach the crank vent to the trumpet tray but I will have to think about that before I go drilling another hole in it.

/C

[rug]

The car is running and driving again! I had a bunge welded this week for the o2 sensor.


Since the car idled OK all I had to do was set the AFR table where I wanted it and hit "auto tune". Worked like a charm... About 40 min of driving later, the car drives better than it did on carbs. Still have lots of tuning to do, but it works! I do have some resets of the megasquirt. I suspect this is because I have old spark plug wires (which I suspect are copper core?). I will replace these with newer resistor type leads to minimize noise.

The car had the stock steel wheels and a set of 18" modern monstrosities that I really do not think went well with the car. Sold those and invested in some 7x13" cromodora CD66 that looks much nicer Just waiting for the tires to come in.


/C

[SteinOnkel]

That is excellent news. What rubber did you pick? For 13s I like the Federal 595s.

Book a track day, fill it with 100 octane for insurance and run the laptop with auto-tune doing hot laps. That's how you really get it to nail the afr target in the fun parts of the map

[rug]

That is excellent news. What rubber did you pick? For 13s I like the Federal 595s.

Book a track day, fill it with 100 octane for insurance and run the laptop with auto-tune doing hot laps. That's how you really get it to nail the afr target in the fun parts of the map

I got Vredestein Sprint Classic 205/60 R13. I was looking at some R rated Nankang AR-1 tires... They were cheaper and since I don't drive the car daily they should last pretty good. Maybe next time Fereral tires are not readily available in sweden...

Tunerstudio auto tune is magic! Drove around for over an hour last night and the car runs great. It screams at 6500 RPMs! Earlier I collected enough log to set the curve for ITB mode (switch over from MAP to Alpha-n). Going to drive a bit more to get the VE table nice and then move on to acceleration enrichment and warm up tuning.

I can't make a fare comparison with the stick IDFs. All I know is that it was running very rich with the IDFs (based on all the carbon buildup on the spark plugs). It does run smoother/better with the jenveys than what I had.

Here is my VE table. It has an interesting peak around 3400 RPM but it runs good, and AFR is tracking the table perfect around those points.


Already looking at having a trigger wheel made up so I can control spark. Maybe even make a new crank pulley for it if I can get an OK price... Already started making a pulley and trigger wheel in CAD
/Carl

[SteinOnkel]

Good stuff, Carl.

Ah, you are in Europe, where there are more options for 13" tires. AFAIK the Federals I mentioned are not sold in the EU at all. Which is a shame, at $40 a tire you can't beat them for sheer grip. Wet traction could be a bit better, but you're gonna light up 185s in 2nd w/ a 140hp engine any way you slice it.

How's the throttle response on tip-in? That has always been a sore point on my setup. As for ITB mode, I spent so much time tuning with alpha-n that I don't want to basically rethink the entire map for ITBs.

Crank trigger is the way to go, and then use your dizzy input for full sequential. You'll love it.

Make sure your crank trigger is bullet-proof! I had a homemade one at first (no idea why, my engine has an oem crank trigger out of the box) and it hit the framerail in a turn on the racetrack. The result was something like this:

Downshift
Turn in
Floor it
Hmmm feels like I lost a cylinder

Turns out the crank trigger was feeding the ecu garbage information and the megasquirt decided to just keep going. Tore a chunk out of Piston #2 It's kind of stupid but the only thing you can do when "sync loss" goes above a threshold x is turn on a check engine light. I'd love for there to be a setting that says if that happens, turn ignition off immediately, but there isn't.

Cheers
Manuel

[rug]

Throttle response is pretty good even though I have no acceleration enrichment at all yet. When I had a MS on my old hond motor I never got acceleration enrichment right... Tunerstudio is way better/easier than the old Megatune though. So far I have the idle well tuned (motor likes it pretty rich, around 13.3), VE table is ok. Might be able to get it a bit better in some areas but it drives great. Started tuning cold start today. Had to turn cranking pw way down from the base settings but now it's easy to start. Once I get starts and VE really nice I will start tuning acceleration enrichment/tip in. Sooo many things to tune!

Had a problem where it would lose power exactly at 5400 RPM. Almoste felt like a rev limiter but RPMs dropped to around 3000 every time. Turns out I had the noise filter configured wrong and it filtered trigger events above 5400.

Shouldn't you lose RPM sync and the MS stop fueling/sparking if the signal from your trigger wheel gets lost?
It's all fun and games until you loose a piece of a piston...

I have found a machine shop that takes on smaller jobs. They have CNC machines, watercutters etc. Figured I could CAD a new pulley and trigger wheel and see how much they want to make them.

For now I just want to go driving and get the car ready for some meets. Need to save some projects for next winter...

/C

[SteinOnkel]

"Shouldn't you lose RPM sync and the MS stop fueling/sparking if the signal from your trigger wheel gets lost?
It's all fun and games until you loose a piece of a piston... "

That's what I thought. However, VR sensors are pretty damn resilient. The impact shaved the first 2cm off of the sensor, but it was still delivering impulses to the ecu. Due to the sensor being hit, what the ecu thought was TDC was probably more like 30* before TDC.

So the sync loss in the logs look something like this: no sync loss, sync loss count jumps to 45 in about ~2 seconds, no sync loss.

Pretty dumb coding. There is no plausible scenario where that much sync loss is acceptable.

[rug]

Had some time to spare so I made a pulley and trigger wheel in Solidworks (CAD). I 3d-printed them and I will test fit them on the car to se if they clear everything. Kind of a pain to test fit them though since the radiator has to come out... Hopefully I can then have a pulley and trigger wheel made up from a local machine shop.
Pulley is made 3mm smaler in diameter to give room for the teeth on the trigger wheel. This is that they look like in plastic



/C

[SteinOnkel]

Solid work.

I would loctite the four screws that you put in.

Keep us posted please, very interesting project.

[rug]

Ok, time for an update.

It has been a long winter with many updates. I have replaced the stock exhaust manifold with an abarth copy. Looks really nice (I'll try to get some pictures of this next time). I also replaced the whole exhaust with a custom stainless one. I bought a cheap TIG welder in the fall and this was a good project to learn som TIG. Came out pretty good too . I'll get some pictures of this as well for next time... Also had the tranny out and replaced bearings, synchros, 4th and 5th gear (5th missing a tooth, 4th kind of worn). This thing still makes a lot of noise compared to what I am used to but I have figured this is noise from the gears engaging and not bearings or worn parts.

What I am really excited about is that I finaly had the pulley and trigger wheel made. The 3D printed dummy part was really good. I found I needed to make the hole in the front bigger so the socket fit over the nut for one. I have yet to fit this piece to the car and I hope it fits as nice as it looks . I always expected an aluminium pulley would be lighter than the stock cast one. This is not true for the one I made... It is almost exactly the same weight (think 20 grams difference). This is due to the factory sliming the cast part down a whole lot. The aluminium pulley I had made could probably have had some more material removed from it. You learn new stuff every day



After I get this fitted comes making a mount for the sensor, mounting the coil pack etc etc...

Oh... I've had the jenveys on for about a year now I think. Tune is really nice. There are no issues. Idle is a bit low on cold start but I hope I can tune this a bit better when I have control over spark.

/C