1991 Turbo 306 coupe MS3/PiMPxs tuning adventure

[wiseguyk]

I had a few minutes free today so I updated rev 2.0.1 (unmodified version you sent me a couple pages ago) with the new injector deadtime and voltage curve for the 47lb'ers.

I just wanted to post it here in case anyone has a chance to eyeball it for me to see if there's anything else that should be tweaked before the new injectors arrive on Tuesday

 

[wiseguyk]

Woohoo!!!! 47lb injectors installed and just did a test run and datalog from cold to warm and holy crap did it idle so much better already!

It was super rich to start with but I slowly leaned out the idle cells and eventually got it up to 14.5 AFR!

So happy right now that it seems to have fixed the issue! The tune version I started with was the version I posted in my last post before this one. Attached is the tune with the tweaked idle VE table.

 

[5.0Thunder]

Glad to hear it helped! We all knew those injectors at low PW were likely the culprit so now the enjoyable tuning process can begin. Lol

 

[wiseguyk]

Glad to hear it helped! We all knew those injectors at low PW were likely the culprit so now the enjoyable tuning process can begin. Lol

Thanks man, me too! I can't wait to make some progress again, get the idle dialed in and then move on to tuning it for actual driving

One thing I wanted to mention real quick is that I started the car again right before I left the shop last night after it had cooled down a little bit but not full cool and noticed that the AFR was super lean. Like 17-18 lean. Does this mean I took too much fuel out of the VE table when it was fully warm? I didn't datalog it since I just wanted to hear it run one more time before I left haha

 

[5.0Thunder]

It depends on coolant and manifold air temps, heat soak, and whether any corrections were being applied. Hot starts get some tuning attention on their own so I wouldn't fret it much yet. the VE table will be refined with datalogging/tuning now that these injectors are installed.

 

[a91what]

easiest thing to do at this point is to enable "ignore mat ase corrections" this will help until you can get around to tuning the hot starts

 

[wiseguyk]

easiest thing to do at this point is to enable "ignore mat ase corrections" this will help until you can get around to tuning the hot starts

Ok cool, I'll be sure to do that. If you have a spare minute Steve, I'd really appreciate it if you could look at my most recent tune and smooth out the VE table to what you think it "should" be now that I have these kickass 47lb injectors. I guess that probably goes for the AFR and timing tables as well.

I'm just not quite sure where to start again with everything since we're kind of back to square one... If you think I should go back to an earlier version like your Rev 1.0.0 that you sent me back at the beginning I can do that, just looking for what you think is my best plan of attack here.

I like to be methodical when I can and I'm not sure exactly what things we did that were solely to try and make the 60lb injectors work. IE: the base idle setting with IAC unplugged, testing different injector timings to find ideal number, idle target curve, etc. Thanks man!

 

[a91what]

OK so the best advice I can give right now is to start over on the REV.3 tune. rather than try and correct the entire VE table that much lets make a global fuel adjustment using the req. fuel setting.
load the prior tune you used to create rev.3 then lower the req fuel by about 20%... your req fuel is at 8.5 now so lets drop that to 7 or so and see what happens. We want the car to idle at 13.8 AFR so it matches the AFR table

Once the car is idling away at 13.8 start the datalog and try and drive it some then I will show you what you need to correct and how.

 

[wiseguyk]

OK so the best advice I can give right now is to start over on the REV.3 tune. rather than try and correct the entire VE table that much lets make a global fuel adjustment using the req. fuel setting.
load the prior tune you used to create rev.3 then lower the req fuel by about 20%... your req fuel is at 8.5 now so lets drop that to 7 or so and see what happens. We want the car to idle at 13.8 AFR so it matches the AFR table

Once the car is idling away at 13.8 start the datalog and try and drive it some then I will show you what you need to correct and how.

Great, thank you Steve!

Just to clarify, when I lower the required fuel from 8.5 to 7, does that change the actual values in the VE table? I'm guessing it's some kind of multiplier or something that gets applied to the VE values since I tried changing it just now here at work and didn't see the actual cell values change when I changed required fuel.

Once I'm back on the previous tune (undoing my idle VE changes) can I simply play with the required fuel value and watch the AFR until I get it to the 13.8 target? Can this be adjusted in real time?

 

[a91what]

It is a global fuel multiplier.

 

[wiseguyk]

It is a global fuel multiplier.

Gotcha. Can I change this in real time while the car is running, watching the AFR as I do it until it hits ~13.8 at idle to match the target table?

 

[a91what]

Yes.

 

[wiseguyk]

Hey guys, I'm back at the shop and tested out tweaking the required fuel from the calculated 8.5 to 7. It idled pretty well but was quite high right when I fired it up so I loosened the throttle screw until it was in the ballpark of 900rpm.

It was still a little rich and off from the 13.8 target AFR so I slowly decreased the required fuel until I got it pretty close to 13.8 with a required fuel value of 6.15. Overall it was pretty steady but still had a bit of surging.

See attached for the tune and log files. The cold start one is from 4.0.0 and for giggles I did another short log with EGO correction enabled just to see how it would do so both tune and log files are attached.

I'm going to do another log while varying the RPMs and see what VE Analyze suggests for it. As always, thank you so much for looking at these and for all your help!

 

[wiseguyk]

Ok, one more set of logs before I go for the night. I did several short drives around the neighborhood around the shop. Only ever getting the RPMs up to maybe 3k max. I was being careful because I was seeing the AFR shoot up occasionally to 16+.

I did several short drives, each time running VE analyze (difficulty hard, lambda 3, > 1200 rpm) and applying the table changes before the next drive. The first drive, it would buck a bit in 2nd and third gear when trying to accelerate a little at lower RPMs. That smoothed out after a couple VE analyze sessions and applying the suggested changes.

I noticed that it seemed to want to stall unless I gave it a bit more gas when getting it rolling, I'm not sure if that's useful info or not but wanted to mention it

I just want to be cautious and not hurt anything so I'm hoping for your guys advice on these logs as to whether you think they look ok to do some more driving the next day I can get down here. Hopefully that'll be this weekend sometime. I thought about trying a drive with auto-tune running but I don't know if that's a good idea or not...

Man... I won't lie, hearing the turbo even just beginning to spool up is pretty damn satisfying! I'm gonna be in trouble when I can actually start feeling the boost mwahahaha!

 

[wiseguyk]

I took a stab at adjusting the VE table after looking at my driving logs. I worry about the lean AFR spikes that happened in certain spots while accelerating through the gears so I added fuel in the areas where I saw the spikes. After that I adjusted the other cells such that they are always increasing when moving up or to the right.

New table:

From my reading it sounds like it's recommended to have things too rich and then let VE Analyze lean it out rather than the opposite which makes sense. I'm hoping to do some more tuning and testing at the shop tomorrow.

If you guys think this looks bad or needs to be tweaked before I try it out please let me know

 

[a91what]

Your thinking is correct, let it help you pull fuel out. You can replace plugs easily but an entire engine is difficult.

 

[wiseguyk]

Just did a quick cold start idle log with 4.0.1. I tweaked the idle cells a bit more to try and hit 13.8 and also lowered the PID gain to try and calm down the surging.

We're gonna be at the shop for a few hours (putting on new hood ) so if anybody has a chance to take a look and give advice that would be awesome! Once the hood is on I'm planning on doing a short drive or two to test my VE tweaks and see if it helped with the lean spikes I was seeing in the last logs.

 

[5.0Thunder]

It looks like it has the immediate surge after first firing then smooths when the AFR leans out a tad toward mid-high 13s. Maybe decrease some afterstart and cranking fuel to keep it from punching rich AFR's right off the bat. This being a sequential system, it might not need AFR's as rich as 12.5 like the batch fired systems.

Kudos for familiarizing yourself with the tuning process. Sounds like you're getting the hang of it. Your fuel table appears to have a better transition than it did earlier.

 

[wiseguyk]

It looks like it has the immediate surge after first firing then smooths when the AFR leans out a tad toward mid-high 13s. Maybe decrease some afterstart and cranking fuel to keep it from punching rich AFR's right off the bat. This being a sequential system, it might not need AFR's as rich as 12.5 like the batch fired systems.

Kudos for familiarizing yourself with the tuning process. Sounds like you're getting the hang of it. Your fuel table appears to have a better transition than it did earlier.

Thanks man, I'm really trying to get the hang of this whole tuning thing It's been a lot of fun and I feel like I'm definitely getting a better grasp of how everything works together.

I tried tweaking the ASE like you suggested to add less fuel and it seemed to help me get to the target 13.8 AFR along with tweaking the idle VE cells a little lower. I'm still seeing a bit of idle oscillation though so I'm wondering if there's something I'm still missing there. It seems to idle pretty well for 20 seconds or so and then surge for 5-10 seconds. Here's the log and tune for a semi-cold start with the tweaked ASE settings.

I think I mentioned this previously, but when I start the car up again shortly after it's been running, the AFR seems to be leaner (15-16) than it was just a few minutes earlier. Is there some time based setting or something that would cause it to read 13.8-14 when warm and then go lean after stopping and starting the engine again? I'm also wondering if the target AFR table might need some tweaking too... I think Steve says he runs his around 15 at idle but I might be mis-remembering

Sadly it rained the whole day so I didn't drive it but definitely looking forward testing the VE tweaks I made based on the previous driving logs to see if the lean spots are any better. I did get the new hood on though.

 

[a91what]

Yes i idle closer to 15afr, however every car is different and you have to give the car what it wants. When my internet comes back up I can take a look for you.