Extremely rich under boost

[kaptainkool]

Hi Guys,


I'm having a puzzling issue. After about 9psi my AFR's go from 11.8 to 10.8 and then around 11-12 psi they drop to ~9:1. The ecu isn't tracing over cells that would cause this change. I even tried leaning out my high load columns to the same values as the low load ones. The engine isn't knocking and there are no boost leaks I can find.

Here's some info on my setup

KA24E
550CC rx7 injectors
aeromotive FPR @ 28psi (idle) Mani Vac is -22psi (idle)
z32 maf
China's best POS turbo with a 1bar spring.
Innovate MT-XL
O2 input is still disabled
TPs was replaced and re-calibrated

I've kind Frankenstein this tune from a jimwolfe ecu (off an L13 turbo), a local tuning shop's early attempts at tuning my car, and lots of illicit street tuning. Under low load operation (up to 8psi) the tune is pretty sweet.


Thanks!

[Matt]

Would like to see a log captured containing the injection time and the AFRs so we can see if they deviate. Also copy of the tune

[kaptainkool]

Hi Matt,


I'll get you the logs and rom soon. I also figured out how to make cell values negative . Is it normal to have it wrap around to negative values after 127? The tune is a bunch better now, however in 4th gear afr's still dump to 9:1 whilst on the same group of cells in the previous gears (at 12 psi).


Thanks looking into this!

[kaptainkool]

Hi Matt,


Here's the log and rom. I couldn't get my serial adapter to play with my laptop so I couldn't get logged AFR's. However when the injection time goes off the chart so do the AFR's (9:1). Nothing else logged seemed to explain why this is happening. I'm going to set the max pulse width inline with the other gears and watch the afr's.

[bachig24u]

Is the battery voltage normal for that ECU?

[kaptainkool]

I guess that does seem a bit low. I'm only seeing .5-2 ohms on the ecu grounds so that seems ok. I did find something odd however, one of the three power pins (pin 47) was measuring 1.2 volts. Also, imposed a max pulse width of 16ms and it still went up to 20ms+ in 4th gear.

[bachig24u]

.5 to 2 ohms is no good. did you exclude the test lead resistance?

.1 to .2 would be acceptable depending on the cable cross sectional area and length.

the battery voltage can affect pulse width (inj latency change) in nistune from memory.

[kaptainkool]

I pulled out the harness and went through the whole thing (fixed grounds, and removed unused wires). Everything measures out to within .1 ohms. The car runs exactly the same as is did before. Also the pin 47 issue was due to a sudden drop in IQ. Any other ideas?

[bachig24u]

post another log with Lamda and we'll have a look.

if you change of update nistune in the mean time, include the bin and address file.

[kaptainkool]

Here's the new log file. I haven't changed anything since the last run.

[bachig24u]

it looks like the ECU is jumping to Knock map fueling.

grab the timing, fuel, gear and knock maps from the tune attached,
then if the car behaves properly,

then copy the remaining;
cold start, warm start, throttle enrich, max Tpulse, min Tpulse.

if the lamda is still on the rich side by around 10%,
copy the inj constant value, expect to increase base fuel pressure up at least 5 psi.

Let us know how you go.


Not much else I can see at this stage apart from confirming the ECU model with the Rom used as the tune you posted looks really messed up when I open it here.

[kaptainkool]

It does indeed appear to be jumping to the knock maps. I don't have the logs on hand but it doesn't get as rich now. Thanks for cleaning up the fuel maps they were pretty bad. Unfortunately a whole other problem as re-developed again and its left me completely demoralized. My car is eating ECU's it seems like. My last nistune'd ecu worked well for a month or so until it developed an inconsistent A/F under low load. It eventually lost it's ability to maintain idle (was idling really high). The whole time nistune wasn't showing anything to explain these behaviors. I've replaced the TPS/TVS (re-calibrated), the temp sensor, and the MAF (another stock, then the N62) no change. I then replaced the ECU and all the problems went away (same nistune module, same tune). I ditched the tune and went with this current Frankenstein one. Very recently my ecu stopped cold enriching on cold starts and now warm/cold idles at either 14:1 or 16-17:1. I must be missing something stupid but I really can't figure it out.

[bachig24u]

possibly missing a fuel pessure issue by the sounds of it. also the idle control motor/solenoid could be sticking.

[kaptainkool]

At first I thought my rich under load issue was FPR related too so I added the aeromotive fpr. During these lean conditions the fuel pressure doesn't change. The ecu shows the unusually low injector open time. I also thought I had a sticky idle control valve so I took it apart and cleaned it then later replaced it. All these issues immediately went away with the new ecu.

[kaptainkool]

Well, I've finally got some time to work on this some more this weekend. I'm going to try burning the rom to a 27c256 and running with out the nistune board. If that doesn't solve it I'll do some more head scratching and see if I can't find other potential causes. After that I guess I'll have to go standalone and eat the time and money I spent thus far.