fendamonky

iTrader: (6)

So my tune has been slowly, steadily declining over the past several months. The problem was initially noted when I had my Aquamist system installed. The problem was then noted as a lack of power (lost 25whp, before W/I sprayed) and inability to hold solid boost. (The boost issue was a combination of solenoids, check valves and the stock BOV not being able to handle 16psi, that's understandable.)

What I don't understand though is how I'm making more/similar power at lower boost (10psi) in April than I am in July at higher boost (roughly 15psi).

The initial question my tuner asked me was if anybody had tweaked his map, which hadn't happened.

Since that day I've also noticed a LOT of stalling when cold (below 30 C) that I *don't* attribute to the water injection since I've got a 14psi liquid check valve in the line about 2-3 inches from the nozzle.. along with rough cruising/surging at low speed/rpm, almost like the standard 3krpm shudders (which I had tuned out).

The only other difference is my plugs... I've gone from platinum 9's across the board to racing 9's and 10.5's at my tuners suggestion.

So... is it possible for our ECU's to degrade the fuel maps over time?


Here is my dyno sheet with the comparison from April to July marked out. We didn't do a low psi run in July.. the July runs were done with 9's in lead and 10.5 in trailing with the car fully warmed up.






Any suggestions/clarification would be appriciated.

dradon03

iTrader: (2)

Your maps just don't change. However there is a possibility of different temperatures of either intake temp, or water temp caussing different timing.

fendamonky

iTrader: (6)

Yeah, we thought about difference in temperatures at the time. My water temp stays pretty consistent once warmed up (avg 85 C).

I *have* noticed that the cold stalling issue stops happening at 30 C. Up until that point I just keep my foot (lightly) on the gas, holding the revs at 1.5-2k.

As for the air temp, the ambient temperature in the shop only changed by 2 deg between April and July.


I'm kinda stumped...

I'll be having a V-mount installed and new mapping done in October, so hopefully the re-tune will sort alot of this out.. if not, well.... I'll be shipping the car back to the states shortly after, so I can have it all stripped, diagnosed, and fixed for a reasonable price then.

arghx

iTrader: (3)

when I switched my plugs from 9's to 10's I needed to change my idle tune significantly.

As for the power loss, have you pressure tested for boost leaks? I've never tried it on a car with stock twins, but you could use the pressure tester from www.boostpro.net/prodtester.html , the 300zx "dual pop" one, or just fab a similar one from home depot parts.

cewrx7r1

iTrader: (2)

Have you checked AFRs, or compression.

A badly tuned AIR TEMP vs. INJ map can cause AFR changes with temperature chnages that affect power.

fendamonky

iTrader: (6)

Unfortunately I can't give an accurate (current) AFR reading =/.. the Lambda sensor on my LC-1 is busted and needs replacing. When my compression was tested at the end of February my readings were:

Rear: 8.9, 8.9, 9.0
Front: 8.7, 8.7, 8.6

I rag it out regularly, but I haven't done anything stupid with it that would cause undue wear or knock... those reading were taken at one of the best specialist shops in the UK, so I have faith that they are accurate.


Are you suggesting that the colder weather may be causing the loss in power/stumbling?? The man who does my tuning is one of the most competent on the island, so I'd *really* hope it's not a case of poor tune in Air Temp vs. INJ Map.


Another thing I didn't mention before (the problem with power loss and harsh idle while cold was there before the problem arose) is that I have a fairly significant boost leak atm... both bottom bolts attaching my secondary turbo to the manifold have either walked out, or been broke off. I'm ordering new studs, bolts and a gasket for that. But otherwise... the problem was there before the boost leak

fendamonky

iTrader: (6)

For any/all clarification on what's been done. Here's a list of the engine mods:

GReddy dual intake
DP (Second bung for WBO2 sensor)
Free-flow Mid-pipe
Apex'i N1 Dual catback
BNR Stage 3 sequential twins
Efini Y-pipe
GReddy SMIC/hardpipes (stock ducting, cut to fit)
Koyo Radiator
PFS AST
Aquamist 1s Water Injection kit (has liquid check valve in line to keep water in under vac)
HKS Twinpower
Viton Check-Valves/silicone vac hosing
PFC/Commander/Datalogit
GM 3-Bar MAP sensor
Innovative LC-1 (broken sensor, only there to impress girls atm )
GReddy Profec B, Spec 2
Bosche 044 fuel pump
Aeromotive FPR (set to 50psi base pressure)
4x 850cc injectors (cleaned/flow tested)
Magnicore 10mm plug leads
NGK (racing) 9 and 10.5 range plugs
Tuned to 10psi and 16psi.

I'm pretty sure there's more... but I'm 'effin EXHAUSTED and can't think of any off the top of my head.

cewrx7r1

iTrader: (2)

For years many professional tuners were not using many PFC tables even though use of them were outlined here on this forum. Some tables require seasonal tuning to get them correct. How many people spend the time and money to have this done. It took me three seasons to get my AIT table corrected for the temp range I drive in.
Post you map and I can tell you what he missed!

Now for your setup:
(1) you do not need a 3 bar map sensor to run 16 psi. The stock is good to 17.5 psi.
(2) you should have gone 550/1200 injectors for ease of idle tuning.
(3) your base fuel pressure should be 38-40. 50 is too high for your application and is not required.
(4) WI is not needed for 16psi with your engine unless your fuel sucks.
(5) I made 347whp at 14.5 psi boost with the stock turbos running non-seq with mild exhaust porting.

fendamonky

iTrader: (6)

Thats really interesting!!! I honestly had no idea.. I'll have to check into that when I go back later in October for my V-mount/retune.

Thanks a bunch for the info =)

arghx

iTrader: (3)

INJ vs Air temp is not something you can just adjust once and then it's correct under all conditions. All the air temp correction maps require a lot of time to tune correctly. Just getting the cold start AFR's where you want probably takes half a dozen cold starts under different conditions.