thewird

iTrader: (8)

Last night while I was leaning out my AFR's in the vacuum cells. I noticed that when I do a full 16 PSi pull now, my AFR's go to 14!!! That is dangerously lean and I only let it run for like a second. Thinking that I may have edited the wrong cells by accident, today I loaded up the laptop and loaded the original map that was tuned before. Unfortunately its still doing the same thing...

Also, a bit after this test my air intake temps went to -25C and stayed that while for 10-15 minutes which made my vacuum AFR's rich and my 16 PSi loads roughly normal (~11 AFR). After about 10-15 minutes, it jumped back to normal (55C) and the 14 AFR problem under boost came back.

Ok, so theres a few things that I think this can possibly be. My air intake sensor obviosly needs to be replaced or wiring fixed. Now there is a possibility that the wideband sensor (Bosch) is almost dead and giving bad readings, however it can read rich AFR's still. I'm thinking since it only does it under boost and WOT, that it could be the fuel pump or fuel filter. Although when the air intake sensor died, I had proper AFR's so it might not be the pump so I'm leaning towards the filter. Also, could the TPS be a possibility? It might not be reading my full WOT position and therefore not putting enough fuel. It can also be the injectors but I'm hoping it isn't.

Has anyone ever had something similar or have other possibilities? I regularly track the track (almost every week) so I'm pushing it to the limits for prolonged periods often. Also the fact that I run 16 PSi at the track also pushes it even more.

thewird

mdpalmer

iTrader: (24)

You might want to post this in the PFC forum... are you logging PIM and injector duty? Notice anything strange there? If you have a map watch running you can see what's going on while you're boosting, it's possible that if the map sensor is not responding like it should you will be in perhaps a P row that you really shouldn't be in (as in you're boosting but the PFC thinks you're in the vacuum region which is leaner).

You should check the voltages with the commander to make sure the sensors are working correctly. Keep us posted. BTW, your car looks amazing, I've seen all of the cool pics of it in the "pics" thread

thewird

iTrader: (8)

The map sensor is fine since it does read 1.1 bar of boost on the commander (that was actually the first thing I checked). I didn't have the laptop hooked when testing, only to change back to the original map since I thought my tinkering could have done something. So I don't have any logging. I'll do some logs tomorrow and see if I see anything funny. (or maybe tonight lol)

thewird

thewird

iTrader: (8)

Ok, so I took some logs, I can't really see anything wrong though. TPS seems fine so my only other guess is the fuel filter? Here are the logs if anyone can see anything that I can't... I removed the meaningless cruise parts.

http://www.wdservers.com/Log_20080718_0104.txt
http://www.wdservers.com/Log_20080718_0130.txt

thewird

Dudemaaanownsanrx7

iTrader: (23)

is the air sensor still screwing up?

is it possible the car was tuned with the air temperature screwed up and when the sensor intermittently works it goes lean from it finally seeing the real air value?

Have you tried remapping and adding fuel?

mad_7tist

did the iat read in the neg?? checking fuel pressure is a good idea. is the pump still dual speed? a dodgy speed relay or control could cause lean boost issues

thewird

iTrader: (8)

The air temps seemed fine when I ran the logs and the car was tuned with a working air temp sensor. I have a Walbro 255lb fuel pump but im not sure if its dual speed. What is IAT?

thewird

moconnor

iTrader: (14)

IAT = intake air temperature.

Do you have any way of comparing your previous injector duties with your current duties? If they are almost the same then the AFRs should be the same (everything else being equal) and your wideband sensor is likely the fault. Do you have it mounted near to the turbos or further away?

thewird

iTrader: (8)

I've checked the injector duty cycles and it they seem to be about the same at same loads and RPM. Here's a log from a dyno pull after tuning was finished (by me)...

http://www.wdservers.com/Log_20080508_1939.txt

Would injector duty cycles stay the same even if less fuel is getting to them from the tank?

thewird

thewird

iTrader: (8)

I forgot to mention the o2 sensor is in the stock location.

thewird

mad_7tist

the duty cycle would change if there was some form of feedback from the o2 sensor, which there is not. the ecu does not know it is running lean. if you were tuned for 16psi at 45 psi of fuel pressure and for some reason the fuel pressure drops the duty cycle will stay the same but you will be lean. that said the O2 may be faulty also. It is never a bad idea to look at your fuel pressure under boost. which ever is easiest for you swaping the o2 for a known good one or hooking up a FP gague i would do first.

the 2 speed fuel pump is in regards to the stock set up of running fp voltage through a resistor at low loads and bypassing it with a relay at high loads(battery voltage) if the relay failed the pump will not put out enough volume and you will run lean.

moconnor

iTrader: (14)

Yes - they are driven blindly by the ECU based on the injector tables with no feedback in the boost part of the table. If fuel pressure drops, less fuel will be delivered so (as the other poster suggested) you should check that too.

My guess is that the sensor fried because it was too close to the turbos (though it may just have died because of age too).

thewird

iTrader: (8)

Well, hooked up a portable wideband to the tailpipe and it gave the same readings. So the wideband is working fine and its definitely going lean.

thewird

moconnor

iTrader: (14)

Do you have an air pump? If so, post cat reading will show leaner than they actually are because of the injected air.

dradon03

iTrader: (2)

Did you change any PIM voltages?
Shouldn't his pressure be about 51 psi....
If you have a wideband, have you not turned off O2/FB?

thewird

iTrader: (8)

Air pump and cats are gone. I didn't change anything. Did you notice something in the logs? 02/FB is off as well.

thewird

Dudemaaanownsanrx7

iTrader: (23)

Dirty clogged injectors , dirty fuel filter, pump not supplying enough fuel. These are possibilities. Can you just richen up the maps or does that not effect the afrs?

arghx

iTrader: (3)

Rewire the fuel pump. Cut out the resistor relay completely, it is useless if you aren't on stock ECU.

thewird

iTrader: (8)

It does affect AFR's, read below...

I have a Walbro 255 pump, not stock.


Well, I went to the track today. On the way there I put in some fuel injector cleaner in case it would help. I brought my laptop with me to change some the fuel maps. Ok, so I increased the fuel cells for boost starting at 3% increase to 25% increase at 16 PSi. So I did a few laps. Low to mid boost was rich but full 16 PSi was about right 10-11 AFR. After a few laps I noticed it was getting richer and richer to the point where the wideband would just say "RICH" (less then 10 AFR). So I start thinking, "Great! The injectors were clogged and the cleaner has done its magic". Cooldown and PIT.

But wait, thats not the end of the story... Pull out the laptop and lean it out some. Not back to it was since you should never jump a lot without testing first, but about 8% reduction in fuel at 16PSi as well as some at lower PSi. So out again I go. AFR under boost was about on the money 11.5 AFR. Then after a few laps again, it started going rich again. What the hell I say? Cooldown and PIT.

So I leaned them out again, roughly the same thing (12 AFR) and then RICH. Cooldown and PIT.

Ok, so I'm getting frustrated. I load up my map before increasing fuel. Go out again and it starts at 14 AFR under full boost. I just said screw it, it will hold with my 94 fuel. After a few laps it starts getting richer and richer until its about 11.5 AFR (the sweet spot) and held there. So after a few laps it was 11.5 AFR stable again like I tuned it.

A few more sessions later, still exactly the same symptoms. Lean, then perfect. So now begs the question WTF? I started noticing a pattern eventually. The AFR's seemed to richen up as the intake temps went up. Start at 50-60C IAT which would result in 14 AFR and then move up to 80-100C which would result in perfect AFR's.

Ok, so now it seems things are pointing to the intake temp sensor that is probably dieing and not reading the correct temps. Would this be the right conclusion? I also thought that possibly it might still be the injectors, as they warm up, they release more fuel for some reason and I might need to replace them.

I'm gonna try replacing the IAT sensor and test, if it doesn't fix it, I'll try fuel filter. If that still doesn't fix it maybe flow test the injectors.

Idea's/comments?

thewird

mad_7tist

the type of pump is not the important question the wiring set up is. that is not as important as establishing if you have correct fuel pressure to begin with. even if the iat is dodgy and reading super high during the lean runs it will not cause the car to lean out like that.

thewird

iTrader: (8)

After replacing the AIT since it needs to be fixed anyway, we'll install a fuel pressure gauge to see.

thewird

arghx

iTrader: (3)

doesn't matter. My car habitually leaned out with a Supra TT pump until I rewired it.

RotaryBuddha

iTrader: (4)

thewird, listen to what he is saying. Until you rewire your fuel pump. You are not getting the proper voltage back their. If your resistor pack is still installed. You may be losing voltage to your pump.

Some useful threads.

https://www.rx7club.com/showthread.p...wire+fuel+pump

https://www.rx7club.com/3rd-generation-specific-1993-2002-16/more-proof-fuel-pump-rewire-improves-fuel-pressure-565645/#post5956883

https://www.rx7club.com/showthread.p...wire+fuel+pump

Dudemaaanownsanrx7

iTrader: (23)

80-100C (176-212F) is pretty high for intake temperatures, if the temperatures are accurate that could be a dangerous situation.

The stock base map continues to lean the car out as the intake temperatures rise due to a lower air density requiring less fuel. under boost the base map starts adding a little more fuel above 70c. The base map also retards the ignition at these levels for added protection. I think the afr's would be effected a little bit under these conditions but from 14afr to 12 seems excessive. Unless you changed some of these settings yourself. If not, i would think comething else is going on.

Also i dont know that i would trust the 94 octane at 14:1 under 16lbs of full boost.

dradon03

iTrader: (2)

^

Are you saying 14.1 because considering an 94 octane to have 10% ethanol the stoic value is 14.1 AFR?

Doesn't more fuel cool and less fuel heat?

Sorry for being lazy b4 and not following the links at all.