Hello all,

My car seems as it is detuning itself from time to time.

In the Morning, the car runs normally and after about 15 minutes of driving, it feels sluggish.

I also have the CEL come on every so often, but when I pull codes, it gives me an 05 05.

I just changed the front 3 spark plugs and need to get the rear 3.

My Car is supercharged by the way running standard pulleys.

I am guessing it may be the knock sensor but I get no ghost codes for it, MAF, or coilpacks?

Any help is greatly appreciated.

Sorry I didn't do the install so I don't have much info on the supercharger set up. Redline Max installed it so Addae should have the info. I'll see if i can't get it.

The mods I have are:

V2 supercharger kit with FMIC, blowoff valve, custom 3" exhaust from headers back, ground kit, exedy stage 1 clutch, fidanza flywheel, and a bunch more.

 

It's my understanding that only a Scan tool will show the knock sensor ghost code. Checking codes via the ECU will show nothing. That's how it was for me as well.

So you're saying that at WOT, your car doesn't quit feel as fast? Have you checked for any obvious vacuum/boost leaks?

 

How do you know its "detunning" itself?

 

I haven't check for boost leaks but it only happens from time to time.

I'm not sure if it is detuning itself but there is a loss of power. For example, on a level road going 50mph in fifth gear I accelerate and the car quickly moves to 60mph.

10 minutes later, I try the same thing on the same stretch of road and it feels like a freaking geo metro, crawling its way to 60. I think it may be the knock sensor.

 

I've always been able to get the KS code out of a 4th gen ECU via the screwdriver method, (and scanners of course). It's only a ghost code because it won't turn the light on, but if it's stored in memory it should be readable by any method that pulls codes...

 

^^Guess my car is special??

OP, what your describing could be the coilpacks. How does the car sound as you go WOT? When I had bad coilpacks, I heard strange noises coming from under the hood (at WOT). Can you swap coilpacks with a friend and recheck? When I swapped coilpacks with Ptatohed, my car became alive and became consistently fast.

 

I try that and see what happens.

 

Hmm.. so you're saying you couldn't get any codes at all out of the 99 with a screwdriver? Or you could get codes but never the KS?

99 could be a bit different since it's kind of a hybrid year between the 98 and 00 when the 5th gen came in. I've tested each year 4th gen except 99 so perhaps my statement applies only to 95-98?

Anyways, sorry to go OT a bit... got that EU in yet?

 

i thought that getting the codes from a 99 was different from the rest of the 4th gens.

 

You can get the ghost codes(knocksensor) from a 99. I have pulled them myself from a 99SE-L

 

I have a 98, I guess I'll have to find someone with a OBDII reader

 

Dude, you don't need an OBII reader. Just use the screw driver method.

 

I did and it showed 05 05 and I reset the CEL. It hasn't come back so I hope it just fixed itself.

 

Every time you reset your ecu is will take 40-50 miles of driving before the code will reappear.

 

So the CEL came back on and I am still pulling 05 05. Does anyone know what causes the CEL to come on without any problem codes?/

 

I could get codes from the ECU, but never the KS.


Nope. I'm slacking, and have learned some bad news with regards to the patch harness I was going to make. I figured that the wiring harness and connector to the ECU would be the same for 95-99's, while only the ECU is different from year to year. Now, several members have told me that the 95-98 connector won't plug into my 99 ECU. I have not verified this yet, so it seems the 98 wiring harness (16") I bought (with connector) and 96 ECU (to rape it's connector from) is all for not. In the end, I need to start comparing what I bought to what I have....


OP, any luck solving your problem?

 

The physical connection is the same. They have to be, otherwise how would members like Zack242 and others run JWT modified 96 ecus in their 99s with no re-wiring?

The pinouts are different though, but everyone knows that..

 

so I had my car check and I have a severely clogged EGR valve and Evap system is leaking. I should hopefully have these fixed by next week.

Codes
P0400
P0440
P0325
P1448

 

I spy a knock sensor code

Evap system code is the same one that I got. Unscrew your gas cap and it should let out some air. Put it back on and the code will be gone.

 

I've tried that and no dice there. I had Nissan pull a report and the ECM logged 11 EGR codes events and 4 EVAP, and 4 Knock Sensor Codes. I'm going to get all of these fixed this week.

 

You originally stated you only had 0505, but now you have 4 new codes? What changed in the last week?

 

I pulled the 0505 code last week after the ECU was reset. The light came back on 1 hour later. Those codes were pulled by goodyear and today by nissan via OBDII and nothing has changed in the last week. I guess the codes were hiding?

 

I don't really see how codes can hide?

 

Yeah, the codes are either there or not. Sounds like the original check did go through as you thought.