I have a DE-K motor in my 98 Maxima and I took it to get dynoed yesterday. I knew that it would dyno some low numbers because the bigger DE-K injectors but I didnt expect it to be this low. I put down 158hp/174tq and the curves look terrible and the a/f is rich.

I have a S-AFC and I will get my own WB02 to tune the a/f to around 13.5 across. They guy at phillydynoworks.com- great place, said that the a/f is reading leaner then it really is due to my stock exhaust, cat and the a/f reader is a tailpipe sniffer. Would leaning out my a/f fix my problem?

Heres the dyno chart of mine and a friends to compare (MEVI was not opening):

Blue- mine
Red- MEVI, stock ecu
Green- MEVI, TS ecu

 

It looks like you need to be tuned badly. The VI seems to be working, kind of hard to tell.

 

have you check the KS in this car?

 

Have not checked the knock sensor, but there are no codes for it. The engine had only 7k miles on it so I didnt think there was a need to. VI is working for sure because I did a run with nitrous, and when it opens, it can be clearly seen. Im hoping the tune fixes it and there is nothing else wrong.

 

I am not sure if the DEK KS works with the 4th gen ECU. In 2000 they switched to a differ type of KS but I dont remember if it worked with the 4th gen ECU or not. It may have(I would have to dig up some old VQ35 swap threads)

 

the other dyno was mine and we watched the car as it was dynoed and the mevi wasn't opening correctly. the acuator would not move till after the we let go of the throttle. hoping to fix this and get closer to 200 whp

 

Hmm, Im not sure but I thought I read somewhere that they were interchangeable. Im going to look into the knock sensor but it seems a lot more difficult to change on the DE-K motor, there seems to be a large coolant line in the way, so I will have to remove the manifold.

 

I read that the 5th gen plug doesnt fit w/o some modification. Is it plugged in?

 

Well, im not going to say yes but im almost positive that it pluged in fine. I didnt actually see the knock sensor when I had the manifold removed, but I plugged it into the sub harness of the knock sensor and not directly into the sensor. I did not get any ghost codes for it so it should be plugged in but im going to check tomarrow.

 

I was searching for threads of cars dynoed with a knock sensor problem. I came up this dyno chart where the knock sensor ended up being unplugged and it seems like the curve is similar to mine. Does anyone remember that thread where someone did a dyno to compare with the knock sensor plugged in then unplugged? When I get some time, ill try to see if I can get to the knock sensor without removing the manifold.

 

I looked into it some more and the harness and sensor is the same. I think the problem might be a ground problem with the sensor.

 

So then it would be related to the harness then ... it's 15$ from most online Nissan stores.

 

I dont think it would be the harness, I have 2 right now anyway, the one that came with the engine (8k miles) and my old one which has around 100k. The knock sensor only has one wire which goes to it. If you look at the side of the main harness, there is 2 wires but the sensor side only has one. I believe it recieves it's ground from the lower intake manifold (correct me if I am wrong). I bought some 4 gauge wire and ring terminals to make a grounding kit so I will make sure I cover that point.

 

Clean the LIM GND points.

 

(My thoughts in my head as I look at this thread)
Like Kevlo said, the VI is opening when it should... but wow. Your power just takes a plunge right when the ECU switches into open-loop mode. Although you do need to tune that A/F, its not really bad to the point that it would cause anywhere close to THAT much of a power loss.
-I doubt it's got anything to do with your fuel system, since your a/f is mostly where it should be for an untuned stock ECU setup. Even with the larger injctors being taken into account)
-The lines become VERY jagged after open-loop switchover (even with a Smoothing of 5 on the graph). Did you hear any pinging while they did the run? Because it really seems that there was timing being pulled.
-You say you HAVE an SAFC, is it hooked up already or its ready to be installed? If its installed already, make sure all the sensor types/inputs/ouputs are what they should be. Not having that setup properly can make the ECU go
Best of luck with this man. When you fix it, it'll run like a beast, just think of that

 

I changed the 00+ KS that came with my VQ35 and replaced it with a 4th gen KS. Also remember to change your KS harness along with it. It does make a difference.

 

Hmmm, this makes me wonder what sort of problems I'm gonna run into when I get around to dynoing....I had a feeling I was gonna run rich due to the 290cc injectors, but I sure hope I don't have as many issues as you do. Before you dynoed, did you notice the power loss on the street?
I wish I could offer some input, but I am interested to see how you resolve your issues.....

 

I didnt really notice the power loss on the street. It actually felt fine but I knew that it was not going to put down 190ish. I thought more like 180whp but I wasnt even close to that. Im going to install my 2.5 exhaust without cat, UDP, SAFC, 4th gen knock sensor w/ harness and see what happens.

 

That probably won't help nearly as much as the others you mentioned.

 

I think the exhaust would help out a bit, and removing the cat will give me the piece of mine that its not clogged. I also have a NX 75 wet shot so going from the stock catback to 2.5" should give me some reasonable gains.

 

I'm still not convinced the VI is operating properly. The cup might be turning, but that doesn't necessarily mean the rod is turning. The only way to tell is to open it up and check.

 

VI is definitly working properly. I have already checked the cup before putting the motor in and the VI has 8k miles on it anyway. I can distinctly hear when it opens and it was also noticable on the dyno chart with the nitrous run.

I have so far removed my cat and installed a PLX M300 wideband. Wideband shows that A/F is around the 10s and up top when the manifold opens, it hits 11s. It might actually be richer then that due to an exhaust leak. I have a consult scanner on the way so I can log and see if anything is wrong. Im debating whether I should install the S-AFC I have now or wait and buy a Emanage Ultimate.

 

Oh ok.

Well the exhaust leak wouldn't hinder WOT performance since the ECU ignores the O2's at open-loop. But yea, that's rich as fawk. I'm sure you could pick up at least 10 HP just from tuning it to 13.5 or so.

On another note, where did you install the WBO2? Did you weld in a new bung close to the collector or did you use one of the stock bungs?

 

The WBo2 is right after the test pipe where the cat used to be. I just used have it where the stock o2 after the cat is.

 

Did you fix this problem?

 

I have been busy with a lot of things so I havent put in much time getting this fixed. I did buy a Consult Interface data logger. I only scanned 2 short runs because I was just checking to see if it was working okay and it wasnt my laptop. Heres the results, I was pulling the data out as it was replaying:

RPM MAF TPS IGNITION TIMING

3625 3.66 4.04 13
4525 3.98 4.12 18
5500 4.28 4.12 23
6025 4.38 4.10 24

4050 3.94 4.14 15
4513 4.07 4.14 18
5000 4.19 4.14 21
5550 4.32 4.12 23
6000 4.41 3.98 24

From the results it seems like everything is okay, TPS should be around 4volts at WOT and my timing gets up to 24deg so my knock sensor must be fine. Im not too sure what the MAF voltage should be at. Next thing will be tuning with the S-AFC or just go ahead and get the Emanage Ultimate.

 

Are you still running the 00 KS? I havnt dynoed my DEK setup but I am hoping I dont have to go find me a 4th gen KS

 

Just curious, but how is your Infiniti an I35 if it's a 2000?

 

Just by looks

 

Job well done .. Would have fooled me .. from the pics anyway.

 

It will fool you in person too unless you open the hood. But then you open the hood of my 97 and find a DEK lol

 

I finally put in my S-AFC which didnt really take long at all, should have done it sooner. I street tuned using my PLX M-300 WB02. AFR before was around the 11s and hit high 10s around 4500 RPMs, it was worse when it was warmer out. Its street tuned to 13.2-13.8 across and it feels much better but some of it may be just the placebo effect.

I plan to go to the dyno very soon but I need to weld together my 2.5" exhaust and put my UDP on. After my first dyno, I would be happy with around 185whp. Then the turbo can go on

 

you need pipes first