MSPNP2 Injector Change (230cc to 550cc) snafu - terrible idle?

So I'm getting ready to rotrex the exocet - I converted my 1.6 to sequential injection, that facet seems to run well with the stock 230cc injectors. I have a set of flow matched 550s that I got for free and then sent to RC injectors, they all checked out/etc installed new seals. I know they're not the best, but I figured for my track only car that they would work fine.

After the physical install I followed these instructions for the base settings, the required fuel setting roughly halfed (which seemed correct for doubling the flow rate)

https://youtu.be/zybmfDslKp0?t=674

I then found a ballpark for the injector dead time so I could then calculate it on my own (the internet says 1.2-1.5ms ballpark)

After burning it in and starting it, it runs like absolute crap, it sounds like when I've switched up plugwires or something, the engine jumping around (i.e. not just bad idle). I double checked with a multi-meter that these are high impedance injectors and they came back with 15 Ohm (http://fuelinjectorclinic.com/faqs/#3) 

These are the 550cc in question (Denso 195500-2020):

https://www.ebay.com/p/550cc-195500-2020-High-Impedance-Oval-Plug-DENSO-Injectors-Honda-Toyota-MAZDA/1033337416


I would think they are bad injectors, but I literally just had them tested and rebuilt.... It got to the point it wouldn't even start so I swapped back in the 230s to make sure I hadn't damaged something. It wasn't happy, but started back up. What's the best way to start about debugging this???

Are the injectors too big for idle?  Idle just takes a little fuel.  550CC injectors are going to have a problem giving just a little fuel.  You might be better off with smaller injectors there and putting a couple bigger injectors standing off some further away from the head in the intake as a secondary for boost, if you can. 

I have the same 550cc injectors in my 1.8 turbo Miata, they are definitely not too large to idle well. 

I can try to pull up my settings tonight if that would help. I'm running MSPNP1. 

Edit: looking at your post again mine aren't actually the same. I have the RC Engineering 550s. 

Even when you give it revs it runs un-even/very poorly. I.e. it's not just stumbling/falling. The whole engine is shaking - it sounds like it's not firing correctly. 

Plugs 1 and 4 were straight black (maybe a bit wet, hard to tell), 2 and 3 looked normal/dry.

What is your wideband 02 sensor reading? I run 700cc injectors in my blown 1.8L and it idles fine on those, but even with MegaSquirt's required fuel setup, I still had to pull a ton of fuel out of the tables at idle.

Did RC Engineering check the dead time when they flow tested the injectors? I'm guessing you may have set the dead time too high.

Are these banked?  1 and 4, 2 and 3?  Is there a problem with the injector driver for the 1 and 4 circuit?  Can you put a scope on it or even a volt meter?  That is, compare the voltage across 2 and 3 v. 1 and 4 while it is running.  An analog meter is more handy for things like that.

I was going to go with the dead time suggestion.

Til I read this, "Plugs 1 and 4 were straight black (maybe a bit wet, hard to tell), 2 and 3 looked normal/dry.".

It sounds like you have 2 injectors overfueling or 2 plugged.

You could juggle injectors and see if the problem moves?

Test injector wiring (with all injectors unplugged)?

Post your MSQ over on the MSExtra forum for analisys?

Have you done something like staging or some such with the injector config?

Possible you just have fouled the plugs, but strange that just 2 plugs.

That's a lot of things to check! Let me go through and see what I can find out - I will report back tonight.

Also, can you send me a data log of what's going on and a copy of the tune to support@diyautotune.com?

MadScientistMatt said:

Also, can you send me a data log of what's going on and a copy of the tune to support@diyautotune.com?

Will do so, right now it has the 230cc injectors in it - and I didn't have my head together enough to be logging as I freaked out at how bad the car was running. I'll have to swap them back, etc. I'm running the mspnp 1.6 basemap with minor adjustments by VEAL at idle (just playing with it), but there are so many settings, etc I may have screwed something up while trying to learn it all....

Is it possible that you accidently unplugged the coil for cylinders 1 and 4 while you were installing the injectors?

APEowner said:

Is it possible that you accidently unplugged the coil for cylinders 1 and 4 while you were installing the injectors?

Now THAT I triple checked ;) - after checking all the connections, etc I assumed I screwed something wiring up (I did just switch to sequential injection) or on the fuel side and switched back to the 230cc - everything ran fine after that. Fortunately it takes 5 minutes to switch injectors because I have an exocet with braided fuel lines, so I just lift up the fuel rail and pull out the injectors.

Is there an easy way that won't damage the injectors that I can "bench" test them? They were just rebuilt a few months ago, but they've sat in the garage in their packaging for a while. 

I don't see any mention of deadtime? 

Sidebar Judge Ito:

What does that service cost to have performed?