Stoich idle on 1.6 with ID1050x and Ms3pro?
 

Hi, my inspection is coming up and i am wondering if i am idling to rich. According to what i have read on this forum you are supposed to be able to idle at stoich (14.7 afr) on ID1050X With sequential injection?
I currently have a pretty stable idle around 850 rpm With an AFR of 13.0 to 13.5. But around 13.8 the idle is getting rougher and abow 14.0 the engine will start to popp and misfire. Can this be a tuning or mechanical problem, or is the engine/ injectors just not capable of idling that lean?



My current specs.
1990 na, 1.6 rebuilt to sequential injection.
Ls 2 coil kit from Flow Force
Ms3pro Diypnp
ID1050x injectors.
Walbro fuel pump. Dont know if it's 190 or 255

How's your o2 sensor? Does your wideband need to be calibrated/is it due for such?
Bosch specifies that their sensors can start to deviate pretty wildly after a couple hundred hours (IIRC).

I've had this problem on mine since I installed my MS DIY (first on MS2 and then upgraded to MS3). I have nearly the same setup, but a '96 1.8: FF LS coils, ID1000s, stock fuel pump. Idle is stable and smooth at 13.1-13.5 AFR and 900 RPM with maybe a +/- 10 RPM swing, but any more lean and it pops and misfires something awful. Compression and leakdown tests are great, no exhaust or vacuum leaks, and I've checked, set, and rechecked the mechanical timing and timing offset in TunerStudio multiple times with no changes. But I don't have to worry about inspections or emissions testing though :)

I dont know how old the wideband sensor is, It was in the car when i bought it. I will try to borrow a new sensor to se if it changes anything.

Have you tried to change the injection timing? i changed it from 90 in the base map to 400 and it It did wonders for my idle. I now have a pretty stable idle around stoich.
watch from 1:16:00

I don't have OP's issue but i do have some AFR instability down low. Thanks for this video, has a ton of useful tricks.

I watched the video and have been setting injector timing via the method shown and have had great results. I've got the best idle I've ever had at 14.5/850 RPM. Still dialing it in, but it's been a huge improvement. BG Calibrator (the log viewer software in the vid) has been a great tool too. Thanks for the help.

I've had an excellent idle on my 1.8L w/VVT on ID1000. Didn't have the same idle on FIC 1150. But this being a 1.6L, it may in fact be a problem. You can install an adjustable fuel pressure regulator and lower your fuel pressure at idle to help it a bit.

Last night I took the time to adjust the voltage compensation for dead-times on my FlowForce 640's.
Yes, I know the values Nigel supplies are actual-factual, and I trust them. But what I do not trust is the accuracy of voltage read by MS vs the voltage received at the injector.

I had to flatten the curve (eyyyyyyy) a good bit, but sure enough - forcing my alternator voltage by hand and adjusting AFRs worked incredibly well. I have much less variance now.

Rev, can you comment on doing this on an NB2 by chance?

In another thread I detailed some metal found in my oil. I swapped a donor engine in and have yet to do a tear-down, but I suspect that a big part was that I tuned my cruise cells with too much injector heat-soak. The AFRs were often in the 13's at cruise timing instead of the mid 15's...

If so, that's entirely my fault. But if it's practical to adjust NB2 rail pressure lower to compensate for heat-soaked deadtimes, wouldn't mind it. Thinking mostly about blips.