How'd you stumble onto that?

 

I googled oxygen sensor simulator in an attemp to understand how it worked and recognized casperselectronics. The scary thing is that it just happened, they (EPA) should be cracking on the big offenders(petro) instead of the little guys...

Back On Topic; from reading the evo manual I did not see a connection between rear 02 sensor signal and the EGR activation. The documented inputs to the ECU to activate the EGR are coolant temp, MAF, crank angle sensor, and TPS.

from the manual
"When the engine coolant temperature is low, when
the engine is at idle or when a wide open throttle
operation is performed, the EGR valve is kept
closed, achieving no EGR.
After warming up of the engine, the EGR valve can
be opened by the engine control module (ECM)."

 

Thanks,

I need to do a test to see if it is indeed the egr not opening soon enough in 1st causing the knock, since it is the EGR that pumps the CO2 back into combustion

 

I just want to update this thread on the fix I found for the funky AFR. I know that some of you will think that this is not the proper way to do it, but I believe that each Evo is different and what one Evo likes, the next one does not like.

Let me also add that the first time the funky AFR happened was when I was testing a test pipe. At that time my intake was 100% STOCK. I have not even touched it. I suspect that it has been happening since I had the car from day one. The problem was that I was flashing the car daily and not allowing the fuel trims to build up. So I totally missed that behavior. Only after I drove the car for 1-2 days between flashes did I start seeing the funky AFR behavior.

I contacted Eric via PM and read his excellent posts in the injector scaling thread. I actually copied his two posts and saved them to a file on my computer.

Since my car was hit 10-12 LTFT_Lo and 8-9 LTFT_Mid, I went ahead and re-scaled the injectors from the stock 513 to 472. Then I monitored/logged the trims for almost three weeks now. My trims are now steady between +/-3 almost all the time. The AFR is rock steady and the graph is almost flat. I have not seen any negative side effects to the re-scaling. The idle is solid. The AFR @ idle and cruise is between 14.5-14.7, just as it was before.

Having fixed this problem, I was now able to finish the tune on my car. The boost is set @ 22 psi and holds to 19 psi to redline. Timing is set @ 2* peak and moves up to 10* by redline. AFR is @ 11.5-11.6 @ peak and holds to 11.2 by redline. The car puts down between 300-310 whp and 280-290 tq on DLL.

I have logged the car after driving it for 35-40 minutes from work with IATs in the 90s and it has only minor 1-2 knock counts in small rpm sections.

 

do you think nj that you need a fuel pump or maybe you have clogged injectors?

 

IIRC, a fuel pump is needed when you change your AFRs in the map and they do not change in the log. I have read in this forum that if you cannot richen the AFR in the log while making the AFR rich in the map, then you will need a fuel pump. I have had no problem leaning/ richening my AFRs in the log. Whenever I make a change in the table I get a change in the log.

Clogged? Myabe, since mrfred got used injectors with low miles on them and they were clogged. But my car had only about 2-2.5 K miles When I noticed this and I have always used Union 76 gas.

 

Nice job NJ,

I've personally seen Evo's that where tuned at 11.0-11.1 AFR with larger injectors that where not scaled properly. Later on putting the car on our dyno I have seen AFR's too lean from the same car, sometimes as much as 11.5-11.8. (on 91 octane).

After properly scaling the injectors and latency and tuning it back to 11.0-11.1 AFR, It would keep it's tuned WOT AFR and keep good trims.

It's absolutely important to properly scale injectors and, like you have seen, properly get fuel trims within range so as to not have a 'drifting tune'.

The stock scaling is for a stock car and as you have found out, sometimes needs to be tweak once you add flow mods.

 

See? I told you it was a fuel trim issue.

 

Yes, you called it correctly I never knew that fuel trims have an impact on the AFR @ WOT. I thought that trims were for closed loop operation and do not effect open loop operation. I learned something valueable. Now I log my fuel trims whenever I log the car.

 

Just wanted to share my final tune numbers. I am so impressed by how solid the AFR numbers have become after the re-sacle. They used to change so erratically before, but now they are within 0.1-0.2 AFR run-to-run. Attached are the AFR/boost and timing/knocksum. These are three runs. The first run was done on my way to work when the car was nice and cool. The last two was when I got home from work. I usually peel off the freeway when I am 4 miles from home, do two back-to-back logs on two on ramps @ around 2 pm (temps around 28-30*C), then go home.

What impresses me most about the 9 is its resistence to knock. Forget the big turbo and mivec. The most impressive thing to me is the better cooling of the cylinder head. That is the key to making the 9 better than the 8.

 

I saw one of those @ the LB meet. He had 720 injectors but the scaling was 513 stock. I checked his fuel trims and they were -11 and -8 on the LTFT Lo and Mid. That meant that the AFR was going lean on the car by about 0.7-1.0 AFR during WOT runs. A high negative fuel trim is more dangerous than a high postive fuel trim, IMO.

I told the guy to contact TT and have him re-scale the injectors, but he is not listening to me and thinks that everything is OK, since the car puts good power on the dynojet.

 

Since experiencing the funky AFR, I know have logged the fuel trims on two Evos.

The first one was an Evo 8. The LTFT_Lo was @ 5 and the LTFT_Mid was @ 2. So all is normal on that Evo.

Today I logged the trims on an Evo 9. The LTFT_Lo was pegged @ 8.9 and then backed down to 5.6. I did not get a chance to log the LTFT_Mid, but it was @ 3.6 while logging the LTFT_Lo.

I know it is too early to draw conclusions here, but I get the feeling that my Evo 9 is not rare in having high fuel trims.

I suspect if more people log the fuel trims on their 9s for an extended period of time over a span of two days, then they will see their fuel trims climb into the 8-10 mark.

This Evo had a TBE, drop-in and LICP.

I will keep on logging the trims of various Evo 9s to see if there is indeed a trend of high trims.