1991 Turbo 306 coupe MS3/PiMPxs tuning adventure

[wiseguyk]

Maiden voyage and refueling complete!!!

Haven't looked at the logs myself yet but she made it down the street to the gas station and seemed to be running well. Before I got into traffic I was watching the AFR and it didn't seem to go any higher than 14.5 which is awesome.

Gonna do the first oil change now, but wanted to upload the first logs from the drive in case you have a chance to take a look while I'm still here at the shop

 

[wiseguyk]

I finally got a chance to look over the logs and as far as the idle goes, I see the same oscillation seemingly caused by the idle correction advance like before. In this screenshot it's oscillating between 850 and 1100 rpm (from Rev1.0.5_IACUnpluggedIdleSetting_2.msl):

Does this mean that we need to tweak the idle correction curve even more?

I also looked at the two first drive logs attached above but not really sure what I'm looking for there... I ran the VE analyzer against the driving logs like you instructed too but I haven't been back to the shop yet to try the changes it suggested.

 

[a91what]

I finally got a chance to look over the logs and as far as the idle goes, I see the same oscillation seemingly caused by the idle correction advance like before. In this screenshot it's oscillating between 850 and 1100 rpm (from Rev1.0.5_IACUnpluggedIdleSetting_2.msl):

Does this mean that we need to tweak the idle correction curve even more?

I also looked at the two first drive logs attached above but not really sure what I'm looking for there... I ran the VE analyzer against the driving logs like you instructed too but I haven't been back to the shop yet to try the changes it suggested.

I have a few ideas we can try, I will set you up with something.

 

[wiseguyk]

I have a few ideas we can try, I will set you up with something.

Thanks man, heading to the shop here in a few to work on cutting old crappy subframe connectors off. I might try to do a couple short drives using the VE analyze suggestions from the first driving logs I took the other day.

 

[wiseguyk]

Here is the current tune file and log from our idle tuning session with the testing of injector timing changes towards the end of the log. The RPMs would occasionally drop while idling and surge a little bit but overall was pretty steady.

 

[a91what]

Kyle i looked at the data-log and used a scatter-plot and histogram to see where the engine made best vacuum based on injection timing.
I really see nothing that points to an improvement. this tells me the injection timing may need to be reduced, we did not include the lower injection timing range in the test.
i made a best guess.

 

[wiseguyk]

Here's a fresh datalog from a cold start using latest and greatest Rev2.0.1. Idled real nice with occasional dips in RPM/surge but recovered nicely.

 

[wiseguyk]

Alright, so I swapped out the fowled plugs with new stock motorcraft ones and took an idling datalog from cold. I immediately started lowering a decent chunk of the idle section of the VE table to make sure the AFR leaned out from it's previously ultra-rich 11.5 it had been idling at.

I got it to around 13-13.2 AFR but above that it would start oscillating pretty badly and go between around 14 to very lean. I tweaked it back down to about 13 or so and towards the end of the datalog here you'll see that it idles pretty damn good for a bit

Now I'm just super paranoid about fowling out this set of plugs lol. I just don't want to have to pull the dang downpipe again if it happens again...

 

[wiseguyk]

New datalog with injector timing sweep from 200 to 370.

I did find I had to increase the VE idle cells a bit from what I had to stop a bad surging an I believe it was going pretty lean during that time too.

 

[a91what]

Very good, this looks much better. Most vacuum and most stable vacuum signal was achieved at an injector timing of 350.

Looks like we may be in a bit of a pickle.... Lets look at the PW you are currently idling at.

looks like your PW is sitting at 1.377 or there about's, problem is that is just below what the spreadsheet says the minimum pw is on this injector.

check the injector characteristics box, min pw 1.391 this usually does not become an issue with sequential injection, but this particular injector is.... problematic.

 

[wiseguyk]

Very good, this looks much better. Most vacuum and most stable vacuum signal was achieved at an injector timing of 350.

Awesome, were these numbers better than the higher range (375-550) we tested yesterday? Just curious because while removing the downpipe today I realized I had a loose clamp (like totally forgot to tighen) right before the elbow that connects to the throttle body and wouldn't want the numbers to be skewed now that I've tightened it down if it was leaking before...

I'm glad to see an example of using the histogram, very cool and I had been wondering what that feature could be used for.

looks like your PW is sitting at 1.377 or there about's, problem is that is just below what the spreadsheet says the minimum pw is on this injector.

Hmm, so does that mean that the injectors are not getting enough fuel or possibly bad in some way? Can we correct it somehow using the deadtime and voltage curve settings?

I see you enabled EGO control on Rev 2.1.0. Does this mean that the AFR table will now be taken into account and it will adjust to help hit those table values? Exciting stuff!

 

[a91what]

I dont think the injectors are bad, I think they suck at low pw values. I have used this spreadsheet for many injectors, for instance my bosch lu47 have a minimum pw of .695...
Your not the only person I'm helping having a hard time with these injectors @AUBURN1111 is as well.
I dont believe there is a fix with deadtime correction, the pw we see in the log is the actual injector time with the deadtime removed.
The ego correction will help keep the AFR at target this is important, however you may have to disable it if it tries to lower the idle fuel too much. I (assume) the car runs like crap when we try to lean it out further because we are trying to operate outside of the injector parameters.
There is a way to test this but it requires we swap the injectors.....

 

[wiseguyk]

Well crap, the ones I have were recommended by On3 and I got them along with the kit so that's pretty disappointing they perform badly like this

Do you think it's worth testing again at idle with EGO correction enabled and trying to lower the fuel and see how it runs?

I've already WAY overstayed my welcome at the shop so I'd hate to have to swap out injectors and prolong my stay even further...

Is it possible they perform ok at the non-idle RPMs and I might just have to settle for a slightly rich idle while I use these current injectors or do you think they'll be crappy at all RPMs?

 

[wiseguyk]

LIES!

 

[a91what]

I think they will work just fine at higher rpm, for instance a 950 rpm setpoint we could probably get away with 13.5
I will have to read a bit more about this issue, try and make them work. I hope I am wrong about this and they are just fine

 

[a91what]

LIES!

Lol they are controllable the issue is they have a large minimum pw... if you had a few more cubic inches this would not be an issue.
Oh idea! What fuel pressure are you running? Regulator? We could bump the fuel pressure down some and be just peachy.

 

[wiseguyk]

Haha, yeah and I'm sure "low pulse width" is a relative term. I have an adjustable FPR and I have it set to ~40psi with the vacuum line disconnected. I believe I see it running around 35ish at idle with the vacuum connected but not 100% on that...

We can definitely try tweaking it, I was actually wondering if while setting it with the vacuum disconnected if I have to plug the FPR or leave it open. I can't remember if I did or not so I can certainly "reset" it next time I'm down at the shop

 

[a91what]

Yes with the line disconnected set it to 35, this will work just fine. It will also tell us immediately if the minimum pw is the issue.

 

[wiseguyk]

Cool, I'll give it a try the next time I'm at the shop, not sure right now when that will be but hopefully at least a night or two this week.

Should I start a datalog before changing it? We should then be able to see if the PW changes as I make the fuel pressure adjustment?

 

[a91what]

The pw will not change, the ECU is not referencing fuel pressure in its equation. The only pw change you will notice is that which is modified by ego correction.