Cant get it to idle and driving issue

[louis123]

Hi guys!

I finally got the engine to run somehow, changed the battery for one with more power and changed to bigger starter, engine fires up well. Worked on the tune yesterday and today.

First thing is that i cannot get it to idle. Today i tried different settings for a few hours and never got it to idle by itself. If i keep a slight throttle like 5% it can stay running but as soon as i let it go it goes down to like 400-500 rpm witch is way too low. Even when the engine started to warm up it was still an issue. Is there not somewhere in tunerstudio to set a min rpm? Maybe i missed a setting somewhere? I tried playing with the wue, different idle control setting (i am not so sure what they are but i tried them to see if they make a difference or not...)

This is annoying because on the road test, going to a stop the engine dies as soon as i put it in neutral because there is no idle.Even while shifting gear it could die down if iam not quick enough. So i did not get to drive very far.

Another problem i got on the road test was that in first gear at higher rev it did like a fuel cutoff but a hardcore version. I had the rpm limiter set at first (6000rpm) but i know for a fact i did not make it that high into the revs (10mph in first gear stock transmission), i was maybe a 4000rpm and the whole thing just gave a big kick back and slowed down. So i parked and set the rev limiter algorithm to none and left it at 6000rpm. Drove again and made sure to rev it in first gear and samething happened.. Again i was no where near the 6000rpm mark. I had the log going so maybe someone here can help me understand what is the cause. I dont know if this is something wrong with the engine or with the tune but its was very strange. Never had this issue before and drove my stock 1600 at that speed in first gear hundreds of times in the past...


Here is a log of the driving issue and idle problem. (seems like i cant attach these files here...)
Looking at the log i think the problem is around record 318 of 1619 and rpm was at 3687 at that time...
https://drive.google.com/open?id=0B85O9 ... 2lnZDZqeG8

That is another log of the idle issue with out driving
https://drive.google.com/open?id=0B85O9 ... FF2OUVjNWc

Here is a copy of my tune, its the closest i got it to something that could almost idle but its still boggs down as soon as i let the throttle go. CLT might seem low but its oil temp, engine was warming up.

https://drive.google.com/open?id=0B85O9 ... DYzSDhoWVE

Here are my engine specs 1971 vw bus
2276
webcam 86a
1.4 rocker
5.4 hbeam rods
ms2 with crank trigger, german plenum, 51#injectors from the dub shop

Hopefully i can get some help from you guys to get a decent idle that way i can drive it more. The little bit of driving i did today was fun, had good power so far!
Thanks folks!

[Clonebug]

What do you have for throttle body/bodies???
I adjusted my stock VW German TB with the idle stop screw first. I made it stop just before it wanted to stick.
After that I adjust idle with the air bypass screw built into the TB for setting idle speed.
You should be able to do one of the two if not both depending on your TB.

[louis123]

Its a german plenum tb with cb end castings.
I only see one big screw it the front of it. it is set all the way in.


And before someones ask, no its not an oil bath filter, has regular a paper filter with some added holes at the back for more air to get in the filter.

[Clonebug]

Start the engine and screw that big screw out until it idles.
That is the idle air bypass screw.
First set the throttle plate by backing the stop screw out and then turning it in until it moves the plate just a little...I move it until it doesn't feel sticky. After that the idle speed is adjusted with the big screw. If I remember correctly it allows more air as you turn it out.
You should have your idle advance set at somewhere between 8-18 degrees before TDC. I run mine at about 12 degrees BTDC.
I used the stock plenum and TB for a year on my turbo 1679cc engine. It gave me a really sticky throttle and drove me nuts. I ended up building my own intake after one year and it is SO much better for pedal feel.

Here is the intake I built. I also bought a new alternator stand from CB Performance since my filler/breather was all rusted out. It cleaned everything up nicely.

[louis123]

Thanks for you help clonebug!!! Got it to idle in just a couple minutes move the throttle screw just a little bit and now it purrs like a kitten!!! Amazing! Did not have the laptop on but i will connect it later on and fine tune it.


Now iam wondering if anyone has an idea what could be the driving issue i had.

Here is the picture of the log where it happened while driving. Has you guys can see, iam still quite new to all of this but since it happened more then once it the same conditions i want to investigate and correct this before taking the road again.

[miniman82]

Your first clue should be your 'lost sync' graph jumps up at the same instant the engine cuts out and loses RPM...

When mine had this issue it was ignition noise related, fixed that by going to a crank trigger system to avoid the ignition coil noise. Depending on which style ignition you have, I'd bet you either have a noise issue (if you're directly driving the coil or currently don't have resistor plugs installed), or if you have a crank trigger it doesn't have the correct gap on the sensor or some other setup problem.

[louis123]

Iam currently running à cranktrigger system with resistor plugs. I played with the gap between vr semsor and wheel today and it got à little better but not much... What should I try?? Makes driving aweful, so much power left but I try to shift before 3600rpm before it happens....

[miniman82]

Are you VR or optical sensor? If VR and you're running the sensor directly to the MS, you probably need to play with the conditioning circuit or pots to get a clean signal. This usually means looking at the signal with a scope to get clean triggers from the sensor, or the ECU resets when it loses sync with the wheel from noise. If you're optical I really don't have a suggestion since I've never tried one before, but noise immunity should be much better with one of those than a VR.

[louis123]

Iam running a vr sensor, could a swap to optical be possible and use the same toothed wheel?

I dont have a scope but ill look to find the pots and see how they are adjusted..
In tunerstudio there is a noise filtering, could that help?
Thanks for your help!

[louis123]

I read a couple of sites online regarding electrical noise on 12vdc systems.

Iam confident that my setup is correct except one little thing. The vr sensor cable is shielded but pass right next to a sparkplug cable and them passes behind the shroud and the cables are there aswell. Iam thinking these cables could create enough noise at high rpm to trouble the readings...

Tommorow i will disconnect this cable and have it pass in a different route away from these cables to have all the chances on my side.

Fingers crossed!

[Clonebug]

Are your wires twisted pair???

Mario's harnesses all come as a twisted pair or twisted triple depending on how many wires on each sensor.
See the pic.



As you can see each sensor and injector is a separate piece and twisted together to cancel out any noise.
I separate the twists when I hook it to the relay board.



When I was getting some sync losses I bumped up the filter settings as follows. You can try them if you want.

Noise filter = on
Tach period rejection = on
Time (ms) = 0.2
Percentage (%) = 12

This was the max I could go.....any increase made it worse.

If I were you I would adjust the pots on the ECU first and then try the noise filter.

If no luck try twisting your VR sensor wires like Mario does and see if that helps.

[louis123]

My whole efi setup comes from the dub shop, so the wires are twisted and shielded. But my installation is not as nice as yours clonebug...Maybe if i get a place to store the bus inside next winter ill get to work on this...

I passed the vr sensor cable away from sparkplug cables and used your setting for noise reduction.

Made it much better now! Shifting at 4500 and more. Still a little noise in the signal but atleast its driveable.

Had a fun drive on Thursday night. Today i will play with the timing to see if a can get more out of it.
Makes the bus feel like a rocket!

I will flush the oil and maybe reinstall my deep sump this weekend.
Next weekend is a long one and we have a local vw camping event, should be good to hit the road by then!

Thanks everyone for your help!