MicroSquirt.com read only forum (Jan.15,2018)

I haven't been on these forums in a while - I've been having so much fun finishing up my car and driving it around! The engine is still very tight - only 450 km after tonight's little rip. Here's some details:

1993 VW 4-cylinder water-cooled 2L ABA engine code (in 1989 jetta)
punched out, forged JEs, lightened+balanced, headwork, big cam.
38mm Honda ITBs
Very open exhaust
60-2 crank wheel VR triggering, with single coil and distributor
Innovate LC-1 WBO2
V3, MSnS-E 029s, RPM-TPS (Alpha-N)

Latest MSQ is attached, most recent datalog is here (6.5mb)

Biggest issues I've been having:
*Off-the-line is hard to control. I get too many revs, which leads to lots of clutch slippage or tire squeal. This may be because the motor is new.
*Luffing, popping, whatever on closed-throttle decel. I have been playing with the spark and fuel, increasing the advance seems to cure the problem, but not all the time.
*hesitation on low-rpm accel.
*at some rpms, it surges while cruising.
*idle is rough and high. what AFR should i be aiming for here?

Minor issues:
*Warm starts are made a lot easier by opening the throttle a bit.
*o2 gauge seems to jump around a lot.

Half the time driving, i'm in the passenger seat with the laptop telling my friend what to do, and playing around with fuel and spark. the other half, i'm driving around, just to see how it drives.

I talked to ValveCoverGasket on VWVortex, he said to tune Alpha-N with TPSaccel turned off until the car runs good, then fine-tune everything with the AE. This is what I've been doing, and TPSaccel is still off (no AE at all).

So there, any input you guys can give will be appreciated muchly.

Just wanted to chime in, I also have an old VW with a new (2001) 2L motor. Mine is the AEG, similar to the ABA, without the distributor.

I don't have too much to suggest as your motor's alot more built than mine is, but I'll give it a guess.

For your decel issue, just sounds like theres too much fuel. Try using the fuel cut feature, or just lean out your map. Don't go too far or you'll get decel surging.

I think as for the tire slippage, welcome to the unleashed VW 2L motor. VW seriously de-tunes these motors, the amount of low rpm torque you can get with aggressive tuning is incredible. My motor came out of a lofty Mk4 jetta automatic 2.slow, but in my rocco it eats 350Z's for lunch. The slightest throttle movement in low gears can break the tires loose, an effect I can only imagine must be devestating with your ITBS! If its out of control, maybe backing off your timing will help.

Your hesitation with low RPM accell is because you haven't tuned the accell enrichment yet. Your friend is right, you should get it as close as you can using the fuel MAP first. Try to richen up the areas right above idle kpa and just above idle rpms, see if it helps. When those throttle bodies open up your engine will take a huge gasp of air and obviously will need an instant blast of fuel to respond quickly. Accell enrichment is just that!

I also experienced the surging. Make sure your AFR and Spark map are fairly smooth and flat around your 'cruising' area. If there are big jumps in spark or fuel, the engine may hunt around a bit. The other big thing is your O2 correction. Is it on? I'm assuming it is, since you're using a wideband. Since I use a narrowband, mine swings up and down constantly at stoich, and I find it causes the O2 correction to swing up and down along with it. My solution was to tune the VE table more and more so that I wouldn't need so much correction, then turn down the authority on the O2 correction to 5%. Also playing with the step size and speed can correct the issue.

I have a shrick 268 and my idle is rich and high as well. I don't use a warmup air regulator, so when its cold, my engine runs at 800 rpms, then when it warms up, it runs at 1100 or so. I would tune it so that it runs as good as possible, who cares what AFR that happens to be.

Since you have a cam and ITB's, I imagine you've used the tricks to stabilize your map, like using a fuel filter and/or restrictor? If you haven't, it would very likely help you out.

Sounds like fun!

thanks for the reply.

on decel i have tried leaning it out, it's currently at 9-ish VE, i guess that has to come down some more. also, it's when i'm decelerating, say in 4th gear, closed throttle, 4000rpm, it goes pop huff pop pop huff huff pop pop pop until i release the clutch or press on the gas.

if you look at my spark table you'll see there's a small area where the timing is backed off a little bit before the revs get any higher. i heard that this emulates what points do, which is why it's there.

i'll keep tuning the map until low-rpm accel is smoother, then turn on AE. a few hundred more miles and i can start really opening it up which should make tuning AE easier. I've been pretty gentle

cruising part of the table will be smoothed.

O2 correction is off. i was tuning while my friend was driving to get the tables i have now. i think there is some kind of divider in the LC-1 to slow down the rate the data changes, maybe that'll smooth it out.

no fuel filter in the map line - this is alpha-n!