Lean spot, cannot resolve

[Matt]

I'll have a look through these files etc tomorrow

[Delox]

EDIT: just saw the other thread, Email sent.

[Matt]

@ 00:11:762 in the log is major spike showing lean (16:1 AFR) whilst the injection time is still climbing

This means that the engine is getting unmeasured air from somewhere since injection time basically follows MAF measured air in the same curve, but AFRs are going haywire

Base image is compatible with the ECU being used 41P60 (MT) in 41P70 (AT)ECU

Regardless if the maps came from a different base image (48P01) wont make any difference here. The maps are very similar when comparing against the 41P60 base image

[Delox]

Resolved!

Received this email from Matt:

Hi Rich



Might be best to go through this via email. I haven’t had a chance to look closely between the 5 images and various log files in the two threads which were posted on the forums in enough detail to work out exactly what was going on until now. Did briefly comment at the end of your forum thread:



viewtopic.php?f=8&t=2390&p=17750#p17750



So your ECU is the following (AT model)



Z32 VG30DET 300ZX 91 USDM 41P70 (late) T A F A18-A77 MC1

Your board is programmed with the following (MT model)

Z32 VG30DET 300ZX 91 USDM 41P60 (late) T M F A18-A76 MC0


Your board is currently fine and matches your ECU for the transmission type. As such unless there was a major issue (like corruption which Eric was mentioning) would there be a need to reprogram the board

However after further examination of your last log I think there could potentially be a vehicle issue:


Earlier log files show an obvious hesitation which caused early leanout in the 3000-4000ish range making the load get ‘stuck’ in a lean patch until it came out of it

This latest log file 910v3.1.5MOD_2012-07-19_1544_37.csv shows a separate issue

Eric was looking at the AFRs which as you mention are not correct. The red line above shows 16.21:1 AFR whilst its ramping up (see AFR trace window on right). The main thing showing the fueling the ECU is commanding is the Injection time. You will notice that the injection time (green line) is increasing in proportion with blue line MAF (airflow) which is correct. However the AFRs lean out whilst the amount of fueling is increasing

This seems to indicate to me that there is another issue with the vehicle where due to plumbing or otherwise there is air getting in causing the lean patch you are seeing. It may also be related to your idle issues. So you are using 910CC injectors with latency at 1200uS? It seemed a bit high but should be okay as long as its not masking an airleak issue which can be made obvious at idle. I would suggest going over the plumbing. AFRs should reflect injection time and not spike like they are (nothing in the ECU is spiking only the output from the engine)


Regards

Matt Brown
Managing Director

I took some time and rigged up a fuel pressure gauge I could see whilst driving, and saw a weaning off of the fuel pressure right at my trouble spot (~40psi), then it'd spike up to right where it needs to be (~60psi) and the car would launch forward as its thirst was quenched.

A big thank you to everyone who took the time to help me assure myself that the issue was not tune/ECU/nistune related, especially Matt who has made it a point to stay involved with every customer! I recommend Nistune (and the community) to everyone I talk to, cannot beat it!