HELP! Large number of CEL codes thrown intermittently..

[nsxotic911]

Need help! I'm getting the following CEL codes thrown intermittently. It starts with a blinking CEL and can't quite figure out why..

P1201
P1202
P1203
P1204
P1205
P1206
P0300
P1399
Mil ON
Monitors
1 inc
Evap
7 ready
Misfire
Fuel
Comp
Catalyst
o2 sensor
02 htr
EGR

Car configuration:
-AEM FIC installed by DA. Previously converted from AEM EMS 1 and it's VERY possible, if not most likely, existed prior, though with the CEL disabled, it never popped.
-Engine sounds "solid" (as per Shad). Made 38r3 RWHP. Compression and leakdown numbers were good. Fuel trims looks good. Car runs strong off and on boost.
-New spark plugs, coils, fuel filter. 650 CC injectors. Walborod Fuel pump.
-Idles well on startup, although SOMETIMES / OFTEN (?) it dies after it's warmed up at idle. 20 - 45 minutes into drive.
-Car runs strong, no strange engine noises even with CELs on.
-"Used" O2 sensors (I put Shad on a time crunch..) but they seemed to work just fine for the tuning.
-Comptech high flow cats.
-Whipple Supercharger. About 7 PSI.
-A/F in the 10 - 11 range (iirc..). Basically, tune looked really good!

When this started happening:
-The CEL first clicked 100 miles from Sacramento at night. Shad cleared the codes, ran the car hard for 60+ miles (during the day) and could not reproduce error. I ran the car off and on boost for 100 miles and did not repro.
-I drive the car home at night to Seattle and 400 miles later and same thing. This was towards the end of going through the I5 mountains in southern Oregon (ugh.. I hate I-5)
-Then in another 400 miles and it clicked, about 50 miles from Seattle.
-About 100 miles later, it clicked again..

I want to say that it seems to 'stutter' under light throttle (not on boost) but it's hard to say because with the exhaust.. it's hard to really make sense of it. You move the throttle to about 50%, and vroooom.

One of the things that is different about when it reproduced and when it did not was that it was 10 - 30 degrees colder (at night vs the day). I'd like to say that it flips after a few runs on boost.. but it's hard to say. It's inevitable that I'll hit a couple of pounds of boost just by virtue of driving it around.. and driving 50 - 400 miles before this clicks to eliminate boost, is hard to do.

At first I thought it could be the EGR valve, so I removed it, made sure the flapper was working, and cleaned it with a carb cleaner (lots of carbon build up..) and it looked good.
Shad suspected it might be ground/electrical issue. We checked all the grounds and they looked good. I had no "other symptoms" that might indicate an a electrical issue - e.g. dying battery, headlights, stereo, anything else flipping.

Confuzzled because the car runs solid.. and it seems to happen intermittently. Shad spent hours on it and couldn't reproduce.. )
The "best" lead I have seems to be the fact that it dies SOMETIMES AFTER it's all warmed up. Short somewhere, where??? 02 sensors, maybe? All components listed faulty?? Hard to believe..

I'd like to try and investigate based on cheapest first...
Any ideas?

 

[RYU]

What year car?
How's your voltage?
Did you clean or replace the map sensor?

 

[docjohn]

I was under the impression for obd2 cars ....."blinking bad".....best of luck sorting it out.

 

[Valhalla]

Uh oh. Follow my thread on this. Check your engine wire loom especially around the injectors. Don't replace anything until you do this. Ask me how I know.

 

[bngl3rt]

Uh oh. Follow my thread on this. Check your engine wire loom especially around the injectors. Don't replace anything until you do this. Ask me how I know.

As in ECU wire harness?

 

[Valhalla]

No. More so the engine wiring harness. Once it was finally diagnosed (after spending a ton replacing everything electrical on the engine) I contacted Shad and he had an engine harness laying around for my vintage of NSX. Cured everything. Check the harness for any brittle or cooked wires.

 

[nsxotic911]

Well, I talked to Shad today and he suggested I unplug the TCS.. in case it's screwing things up. The TCS is off a 97 which (should) be the same P/N, since I didn't initially have it.

I did so and took the car for a nice spin around town for about 75 miles. So far, so good. It did die at idle though after being warmed up. It feels like it's "dropping" the idle and then car dies. You can see the idle drop to 250- 1000 RPM as it tries to stabalize it. If it fails, it dies, or starts dying. Doesn't always do it, and I've been trying to 'catch' it by 'letting her down slowly.'

Also, apparently the "7 ready" codes afterwards is a good thing. It says all of those components are working well.... e.g it would pass emissions. Wierd, but good news I suppose. It's the P12x that are questionable.

 

[Valhalla]

The P12x and P13x are cylindar misfire codes. Since you have all of them going off, I would look at one source, possibly the ignitor or the spark plug detection module. Ignitors are expensive so if you have a local Primer that you could just swap these parts with, it would be easy to eliminate the need for new parts. If you do need an ignitor, I'll give you a great deal on a slightly used one.

 

[arny213213]

if the car is not running bad and all the monitors are set I would consider the spark plug detection module. I would also check the coils (look down inside for white trace marks or corrosion) for your idle issue i believe for the aem stand alone there is a setting for engine rebound that the tuner should set for idle setting between shifts. I had to play with my settings for my drag crx running hondata s300 to get it right without dying.

 

[nsxotic911]

Could main relay be at play, particularly in the diying at idle scenario? I just reproduced it again after letting the car idle for 10 minutes in warmup, started her up, popped it out of gear at a stop sign and shut down. Restart, drive stop and go for the next 30 minutes and runs no problem.

The CELs have not appeared as of yet.
Arny, I went from the EMS 1 to the FIC now and don't believe the rebound is adjustable.

The last symptom I may be hitting is that it tends to hesitate at lower rpms.. I 'hesitated' (pun intended) of sharing this because it's hard to tell and could just be placebo... Seems to be most prevalent around 3000 - 4000 RPM.

 

[nsxotic911]

Update: I bought a new main relay, cleaned and separated the grounds for the ECU, aftermarket fuel pump relay (Shad installed), and a miscellaneous ground within the cabin. I also added dielectric grease and in addition, replaced the alternator which seemed to be weakening.

Well, didn't fix the issue.

The "good news" is that if I drive it around and stay off the boost (100+ miles tested) it doesn't reproduce. The CELs only came on only after I started hitting boost in the 20s - 30s F (every day in Seattle). The "bad" news is that it's not consistent. I can be WOT on and off multiple times in a day and it doesn't reproduce... and the next day, I get on 'er once and she starts throwing a fit

In fact, one of the times I stepped on it, my brother who was behind me said a lot of black smoke (rich?) came out, but only the first time. Stepping on it afterwards didn't result in black smoke. Surprisingly, the CELs didn't come on that night, it came on the next night.... but he wasn't behind me to see if the same condition happened.

What seems to be consistent is that the CELs come on only AFTER I'm on the supercharger, but NOT always, and this is more likely to happen when temps are cold. I say this because in Sacramento when it was in the 40s and 50s during the day... we drove the crap out of it on and off boost for 100s of miles...

I also read that vacuum issues could cause similar problem? How do I check for that? Note: I have the Dali oil catch/breather tank installed.. Might it be in play?
I'm thinking of replacing the aftermarket relay (should be a few bucks..) Shad installed in case it is failing intermittently.

 

[shawn110975]

boost.. nothing last longer than stock.

 

[nsxotic911]

boost.. nothing last longer than stock.

Not all that helpful. Car had solid compression and leakdown test numbers (3%) and produced great power at conservative A/F. Car doesn't knock and otherwise idles and runs very well. There's something triggering a CEL. Either a faulty part in the system or possibly, require a re-tune under colder conditions... Before I drive it down to Sac town and ask to do a 1 AM run.. I want to rule out all possibilities.

 

[Valhalla]

Have you looked at your engine wiring loom?

 

[nsxotic911]

I looked at all the wiring loom and didn't notice anything suspect.
I also took out the spark plugs and could to see what they may tell me.

All the coils resistance tested good. They should since they were brand new...
5 of the 6 spark plugs looked normal... Except for one of the plugs had a bit of corrosion on the read end of the plug.. I swapped it with a new plug. I didn't replace the other five because they were all supposed to be < 1,000 miles old..

Next, I plugged in the stock fuel pump resistor that Shad said I didn't need to have plugged in, but clicks on/ off when I get on/off the boost.

After I did these two things, I didn't clear the CELs and in about 25 miles, they went away! They haven't been back for at least 100 miles and I have been on and off the throttle! Car hasn't shut off either...

Crossing my fingers but we are looking good..

 

[nsxotic911]

Just to provide an update - after many months of banging my head, and burning battery.. KR Motorsports suggested to seafoam the engine and the fuel system. I was skeptical, but had tried much by this point to no availa.
I ok'd to have it done, and what do you know, the codes went away and car hasn't stalled. I had talked to a couple of others on PM that had similar resolution, and a couple of odd Prime posts that referenced smoother behavior or CEL code fixes from seafoaming, particularly on supercharged cars.