Thread: Need some advice

Hey! I would like to ask you guys for something I've tried to cope with. I have a euro P10 eGT engine with 8.5:1 det pistons and rods in it, Gtir T28, 370 cc injectors, top mounted gtir intercooler setup and nistune. During the time I have this setup I have gained some experience to tune at least basically my fuel and timing maps. Here is the case.. My afr at idle is 14.2 and slightly fluctuating around this having steady idle. Driving without boosting is good too 13.9-15 and when accelerating slightly it drops at low 13s. I have tuned WOT at mid 11s and over 6800 i drops low 11s. The problem is when i try to accelerate suddenly(meaning giving it more than 25-30% of gas) I am leaning badly. Low gears is worse than higher ones. If I am driving in second gear at 2500 rpm and depress gas pedal over 30% I am picking boost fast but my afr goes to high 16 even 17 despite I am on mid 12s on my fuel map, than suddenly it goes where it should be and the car is accelerating as it should. Interesting thing is that if i depress gas pedal smoothly it does not do that, i am moving through transition area, afr is going from 14 through 13 and 12s and if i continue to give it's moving to WOT tuned area. The problem is in all gears and i can't understand what is going on. Why under fast acceleration I am running extremely lean for a couple of seconds despite nistune is in the right cells and suddenly its burning right. Trying to drive responsively is like hell .
Sorry for the long post, but I just wanted to explain as much of the situation possible. What do You thing is going wrong? Thank You.

Is there any chance too much open IACV(because of close to turbo MAF) to cause such an issue?

I wouldn't think its the IACV. If you have already checked and cleaned your sensors, MAF, O2 ect. My question would be was your car originally equipped with the 370cc injectors?

No it was with stock 259cc. Sensors are working properly. One more thing is coming on my mind, but I am not sure if it can cause such condition - my restrictive exhaust

is your maf blow through (mounted in the pipe after the turbo) or draw through (mounted before the turbo)?

It's draw trough,but right now too close to turbo.

Do this: unplug your stock ecu o2 sensor, idle the car and monitor your afrs. what is it reading? I'm thinking your issue might be the k value on your injectors.

I don't have narrow band O2 sensor plugged and I'm also disabled O2 feedback so.. About the K value - why it is only leaning on fast acceleration? If the K value was so wrong it should've continue to lean out.

without a narrow band, yeah your right it would have continued to lean out. I had a similar problem with my nistune ve'd. Stock injectors were 259s, I ran the resize injectors function for the 333cc injectors and it did the same thing yours is. I found out as well it was leaning pretty bad with o2 feedback off at idle. I went back to the original map, adjusted the K value only and it fixed the issue. My problem was running the resize injector function was screwing with my TP tables as well.

Not sure if I'm helping any but its a thought!

These are my fuel and timing maps
2shared - download Fuel_Map.jpg
2shared - download TimingMap.jpg
It's starting doing this from 48 TP towards last columns. My current K is 23444 and 685 injector latency. Trying with original 580 latency just makes things worse. Increasing K value making offboost AFRs awfully rich. On this map I haven't used resize command, just change my K value. Also I am at full boost(9 PSI) by 2900 RPM giving it "2.8 volts" TPS If You see something wrong with maps please share with me.. will be grateful! Thanks.