Rb25 neo wont start after maf and injector change

[godzilla_753]

hello,

I finally got the car put together and was hoping to get it running to baby it to the tuner. As of right now I used the drop down list for the AFM change to the Z32 maf, and went from 370cc to 630cc injectors. Changed the injector latency to 1.14ms as well. Car doesnt want to even catch, no start no idle. Anyone have any clues?

Im making sure to synchronize the maps, and burn them after every change btw.

Also have got an ignition fault DTC and CAS code but doesnt show up everytime, and checked all the spark plugs, all have good strong spark, running LS2 truck coils currently, have not modified any dwell times yet.

Havent checked timing but was vehicle was running prior to the turbo/maf/injector upgrade and timing was good at that point.

I do have to mention that on the stock base map we did get it to crank and idle but ran roughly. Only after messing around with the injector resizing and maf drop down menu did we basically get stuck with nothing.

Thanks in advance for any help

[unreal-]

Did you have Nistune modify the cranking tables during the injector resize? Those can result in a no-start if they are injecting too much fuel.

[Matt]

Post your current map. Also wondering if you ticked the crank resize tickbox during injector resize

[godzilla_753]

Matt when yous say to post my map, thats the Bin file correct?

I am 100% sure I didnt check the cranking table box when I did the resize.
After messing with it over the weekend, I realized my K constant was retardedly high, like 2200..
It flooded the engine after multiple attempts at cranking, and fouled my plugs. I started with the fresh stock map again and redid the injector resize and maf changeover and my K constant ended up being 351. Also I changed the injector latency to the specs given to me by the manufacturer.

At this point it still wouldnt start but I think thats due to the flooding and fouled plugs. I also noticed that my coolant temps were fluctuating wildly from 200 to -49 degrees C. I would be able to get it run kinda if I held the pedal to the floor but it would die immediately after I release it.

I will get the map posted, and also I am going to change my coolant temp sensor and plugs. Anyone by chance know of a USDM CST that will work?

[godzilla_753]

Ive got the CST and plugs ordered should have an update this afternoon.

When I tried to find the map, I cant find anything at all, and I still get that error where it says rom pack not found, and then once Im in nistune, it says the file needs to be repaired and I have to pull up the stock .bin. As of now in my PC there is no saved tune even though Ive saved, and autosaved numerous times.

I know I can download the modified bin from the ECU, but why isnt it saving to my PC?

Sorry if Im missing something obvious, thanks for your help

EDIT: I was able to find the "autosave" bin but its just the stock map that autosaved a few minutes after I opened up nistune, no bin file is saved in the PC. I will try to download the modified map from my ECU and save it.

[godzilla_753]

So replaced the spark plugs and CST, nistune still seeing -49 to 200 degrees on the CST, so left it unplugged. No change, still not starting or idling.

I am posting a bin of the most recent attempts to get it to start.

After looking at the injector latency on the seimans website, it shows the ON time at 1.14 ms, off time at .85 ms. Injector rehab shows the LAG time to be .28 ms. Very confused as to what is what now...

Im running the deka 107962 injectors. When I tried the .28 value (280 in nistune) it seemed to want to start a few times, but never reached an idle.

after a few attempts I checked the spark plugs and they didnt seemed fouled again, but were getting there so I stopped. Really could use a nudge in the right direction

Thanks

[Matt]

I also noticed that my coolant temps were fluctuating wildly from 200 to -49 degrees C

You need to fix this immediately! The coolant temps affect a lot of parameters in the ECU. Find your coolant temp sensor and trace it back through your ECU loom

After messing with it over the weekend, I realized my K constant was retardedly high, like 2200..

Not sure what you did there. K constant not used during cranking, only afterwards (well with most ECUs)

Cranking tables are used when cranking to determine initial fuel enrichment. These are normally pulled back when increasing injector size

Also have got an ignition fault DTC and CAS code but doesnt show up everytime, and checked all the spark plugs, all have good strong spark, running LS2 truck coils currently, have not modified any dwell times yet.

You will need to halve the well table. LS2 coils will raise the fault DTC because they dont feedback the same as stock ECU coils

I am 100% sure I didnt check the cranking table box when I did the resize.

You needed to adjust the cranking during the resize by ticking the box

I cant find anything at all, and I still get that error where it says rom pack not found

Did you install the ROM pack? Refer to the software manual. Install the ROM pack. It is why you are getting file errors afterwards

Latency about 0.85ms would be a good starting point

Okay I've done the changes here. After you have installed the ROM pack, restart the software and load the file. Upload to the ECU and try it out. Once cranking over then adjust your K until it runs smooth again

[godzilla_753]

Thanks for the help Matt.

I tried the new bin file and still having the same issue. Turns over, seems to catch for a second and then dies again. Is is possible the computer is fried?

Originally when I first started messing with nistune, we had base fuel pressure at 60 psi, without touching the stock map (no injector/maf change), it started and idled, but was rough. I shut it off myself. Since then I changed the base fuel pressure to 43.5 psi, and been messing with it and has never since started again.

I also got the CST figured out, looked like a wire was loose, fixed it and dont have the wildly fluctuating temps anymore, this morning the CST showed temp at 27 c.

I didnt mess with K at all since I never got it to run, I did play with latency a bit, but didnt see any change. Should I try to move K even tho its not running? Really at a loss as to what to do now.

I am going to pull the fuel rail off to make sure all the injectors are firing, and one not stuck open or something.

[godzilla_753]

After pulling the fuel rail off we realized that the first three injectors werent firing at all, and the last 3 were very weak. Fuel pressure was at 43psi at this point.

I checked with a node light, and all injectors are getting a pulse, but extremely weak. At this point we were using a battery that had been sitting for awhile, with a jumper box attached to give it extra juice. Im thinking maybe that the starter is pulling so many amps, the the injectors arent getting enough juice to fire correctly.

I ordered a new battery, now their firing equally as well, still no start.

I pulled the plugs out, and their clean, makes me think they are maybe not getting enough fuel? I looked in nistune and there are some table for cranking, cold/warm cranking etc, should I mess with these?

[Matt]

You should have probably got everything running right with the original 370CC/ER34 MAF with the stock maps in the ECU before doing the upgrades. Becoming difficult to determine what the exact problem is now

Light is difficult to measure a proper 12V pulse from the injectors so difficult to know what is going on

More background on the vehicle? Is this a transplanted engine? Have you traced back and secured all the grounds? Difficult to work out if an electrical issue...

You can move K around to get your fueling better, once the vehicle is started of course. Before this you are only running injection from the cranking tables (whilst the start input is seen by the ECU)

Log of it starting during cranking would be useful

[godzilla_753]

I had the vehicle running properly before doing the upgrade, literally all I changed was the MAF, injectors, and turbo/hotside. Even with the stock map and fuel pressure at 60 psi it ran.

I checked with a multimeter and all injectors had 12v.

At this point I think I can only revert back to the original injectors and maf and see if it starts with the stock map. If it does, I can rule out the ECU being toast, and any other weird things. From there if its running, Ill add the z32 maf and injectors back in and diagnose it from there.

Ill get a log it cranking for you.

Thanks alot for the help so far, I appreciate your time.

[Matt]

Try just the injectors firstly with the factory MAF reinstalled and see if that starts.