Black plugs, missing, whats going on?

[rightfoot]

About 6 years ago, I did the Stillen Stage III upgrade it's called. That's the jets, intake filer, ECU and exhaust.
I've put at most about 2000 miles on the car since the upgrade, doing Summer rally races and that's about it.
The rest of the time, the car sits a lot. I know that's part of the problem, I just can't get around to it.

About two years ago, the car started doing a bit of a stutter when I would start it. It lasted a few seconds then went to normal. That was the first time I noticed something weird. This went on until one day, it stuttered a lot and I decided it was safer to shut it down.

I checked lots of things, then for safety, installed new injectors, plugs (high heat cuz of the upgrade), new fuel regulator, cleaned a bunch of connectors I could see, stuff like that. Nothing changed.
I put a new air intake in because the old one was a little dirty, nothing changed.
I then bought a new oxygen sensor and replaced one which made no difference so put the old one back in and replaced the other and again no difference. Since I had to take it into the shop to do the second one, I left that new one on.

One day, it will run just fine, the next, I can barely hit the gas, it stutters, I have to quickly lift my foot off, put it back on so it doesn't stall, and eventually it gets to idle RPM and either runs well or continues to stutter.

One weird thing, which I know many of you won't believe, is that my brake fluid is disappearing. It is not going into the car and it is not leaking onto the ground, it's just plain disappearing. After I go for a cruise when it runs ok, I will sometimes have to refill the brake fluid container a LOT or it will be fine.

Yesterday, I took it for a ride since it ran ok when I started it. We had dinner somewhere, and when we got back into the car, it ran like crap the whole way home. It ran very rough as if it was missing on at least one cylinder.

The only other thing I can think of to mention is that the plugs were BLACK, very black when I pulled them out recently to check them again. I also see black smoke from the exhaust when I hit the gas sometimes. I believe it is running way too rich.

I contacted Stillen because I'm starting to think the ECU is messed up since after trying three different PC connections, I can never connect. They told me to contact Jim Wolf who says it's pretty much impossible that the ECU is at fault. I find that very hard to believe and they did say they would be willing to check it for $25.00 plus shipping and if found to be defective, would sell me another one for $600.00.

I'm rather peeved at having to buy another ECU if they tell me it's not good and I have no way to know otherwise.

Anyhow, I'm not sure what else to add but wanted to add all I could for now. Happy to provide what ever else I can if asked.

Thanks.

1993 Nissan 300ZX TT
Stillen Stage III Upgrade
No other mods

[Z31toZ32]

definitely sounds like it is running rich as hell. id start by seeing if your are spitting out any codes. have you ran them?

[300ZXttZMAN]

hmm i agree with them for saying the ecu is not the problem... Unless some how it happened to get wet or someone accidently kicked it... As for the brake fluid, either you havent looked good enough for the leak or its leaking at one of the calipers only when ever you brake hard. But since its leaking at the caliper it dries up quick from the the heat/friction on the rotor....

Ill tell you right now that im not very familiar with brakes im just telling you what my guess would be if it were happening to me...

As for the computer part i am pretty familiar with that.. I have a salvage yard and you wouldnt belive how many ppl buy an ecu for their vehicle and hook it up and nothing changes then bring it back and tell me or one of our other sales man that we sold them a bad computer ... We refund and charge a 20% restocking fee.. (keep in mind most salvage yards dont give any type of warranty on anything thats electrical)


Hope this helps...

to Nico

[RubyRed300ZX]

2,000 miles in 6 years. How old is the gas in your tank? Old fuel doesn't burn very well. And "old" is just a couple weeks. Added to the moisture from condensation inside the tank, and ...

[rightfoot]

definitely sounds like it is running rich as hell. id start by seeing if your are spitting out any codes. have you ran them?

Yes, I looked at that and it reads normal.

The one problem I've got is that I cannot connect to the ECU so can't use software to look at the bigger picture. Something isn't right there either. I need to find a way to test the connectivity of the ECU to see if it's serial input is busted.

[rightfoot]

>hmm i agree with them for saying the ecu is not the problem... Unless some how it happened to
>get wet or someone accidently kicked it.

It's never gotten wet nor mishandled in any way. I'm the only one who works on the car.

> As for the brake fluid, either you havent looked good enough for the leak or its leaking at one
>of the calipers only when ever you brake hard. But since its leaking at the caliper it dries up
>quick from the the heat/friction on the rotor....

I've looked at that one very closely because it's got me stumped. There are no leaks anywhere, no brake fluid on the ground, non in the car, none in the engine compartment. If it's leaking while I'm driving it, even that should leave some residue that would leak but I've never seen any.

Now, here's something I'm sure you guys will laugh at. My father in law who is 70, who still to this day will take a car fully apart to rebuild it (he's working on a 56 t-bird at the moment) says that new techs will never know this but he believes the fluid is being sucked into the engine when it's running.

I've mentioned this to others before and they say he's nuts but like I say, he's been working on cars since he was 15, has rebuilt must be over 100 cars easily. He still has modern all the way to 1927's in his collection. So I have to consider what he's telling me.
I looked inside the hose connected to the master and can't really say if there is fluid in there but it is kinda oily, dirty if you will.


Ill tell you right now that im not very familiar with brakes im just telling you what my guess would be if it were happening to me...

As for the computer part i am pretty familiar with that.. I have a salvage yard and you wouldnt belive how many ppl buy an ecu for their vehicle and hook it up and nothing changes then bring it back and tell me or one of our other sales man that we sold them a bad computer ... We refund and charge a 20% restocking fee.. (keep in mind most salvage yards dont give any type of warranty on anything thats electrical)

>Hope this helps...

Appreciate all input. I'd love to get my car back to health, it's sad to see it doing this. Not one spot of rust and in very good shape, I want to enjoy it more often.

[rightfoot]

>As for the computer part i am pretty familiar with that.. I have a salvage yard and you wouldnt
>belive how many ppl buy an ecu for their vehicle and hook it up and nothing changes then bring
>it back and tell me or one of our other sales man that we sold them a bad computer

I believe that. Thing is, I've purchased three different ECU reading setups to date and none of them get a reading, let alone a connection. I asked in Z forums for recommendations on low cost home readouts that work for them and bought each one when the last didn't work.

All I can think of is that the serial port is dead on mine.

[rightfoot]

2,000 miles in 6 years. How old is the gas in your tank? Old fuel doesn't burn very well. And "old" is just a couple weeks. Added to the moisture from condensation inside the tank, and ...

I tend not to fill it and when I use the car, I stick a bottle of octane in it to help just in case. I know that's not a fix but short of emptying the tank completely each time I use the car, not sure what else I would do.

[RubyRed300ZX]

Product called "Sta-Bil" which you add to the gas while it's still fresh. Won't do anything for fuel that's already old. Use it for marine, lawn mowers, snow blowers, etc. Any auto store.

[RubyRed300ZX]

Also, in case you have moisture in the tank now, try some "Seafoam" in the tank if you can get it to somehow to mix in with the fuel in the tank.

[TTkickedin]

About 6 years ago, I did the Stillen Stage III upgrade it's called. That's the jets, intake filer, ECU and exhaust.


About two years ago, the car started doing a bit of a stutter when I would start it. It lasted a few seconds then went to normal. That was the first time I noticed something weird. This went on until one day, it stuttered a lot and I decided it was safer to shut it down.

I had a similar problem in my miata, turned out to be that the Harness going towards the MAF sensor kept coming partially out. Since you changed your filter, is it possible you could've damaged the connector and it gets loose?

[rightfoot]

So "Seafoam" and "Sta-Bil" but can I, should I, use them at the same time in the current tank?

[rightfoot]

>I had a similar problem in my miata, turned out to be that the Harness going towards the MAF
>sensor kept coming partially out. Since you changed your filter, is it possible you could've
>damaged the connector and it gets loose?

Yup, when searching around, that's one of the things which was mentioned. I made sure the connector is nice and tight and very clean. There's another connector on a cross pipe just in front of the engine that was mentioned which I also made sure was clean. I've tried to clean anything which might look obvious.

[RubyRed300ZX]

The Sta-Bil will do nothing for you right now. In the future, when you think your car will be idle for a period of time (month or more), put some in BEFORE you add fuel to the tank. As you add fuel, it will mix it in as the fuel splashes into the tank.

The Seafoam will help you now. Problem is getting it mixed into the fuel to "soak up" any moisture in the fuel. May have to rock the car a little, or drive it erratically, so as to try to slosh it around in the tank. You'll still have "bad" fuel in the fuel-line and the filter to burn off even if you get it mixed. Just have to try to burn off what's in there or drain it out.

I know all your symptoms would like to point you to something more complicated; however, it does sound like bad fuel (either too old or with water in it). It may not even be from letting the car sit too long. If you pull into a gas station, and you see the fuel truck there filling their tanks, drive off to the next station. When they fill the tanks, especially in the summertime, the warmer gas, mixing with the cold fuel in the underground tanks, causes condensation in their underground tanks, which gets sloshed around and mixed in with what gets pumped out into the vehicles during the first several minutes. Though the ethanol blended gas should compensate for this, ethanol will mix with water, it also will separate from the gas (the fuel floating on top of the ethanol and water).

Anyway, before you get to anything expensive to fix, try to eliminate this as a potential cause of your problem.

[rightfoot]

I'll give this a try this week. I'm just nervous about running it when it seems to be missing. I'm not sure if that would cause any problems. What ever the problem is, the car was always a very strong runner until this slowly started to happen.

[McShanks]

Maybe you have a bad master cylinder leaking fluid into the engine causing your engine to lag. Maybe? It is most likely however that you have a bad electrical connection if the lag is intermittent. I know that is vague, but everything I looked at points to that. I am dealing with 2 dead injectors atm and have looked into lag issues a lot lately. About brakes... It might be a good idea to pay someone $70 at a shop to check them out for ya. Sometimes, if I am so stumped, I will just take it to a shop to diagnose the issue before I dump money into something. I had a 2000 Buick Lesabre that was making a ridciuclous intermittent screech/squeal, and I replaced everything I could think of and find on the forums. Spent alot of money. Still squealed until my dad bought it off me and took it to a shop where they replace the f*$%ing idler pulley. I could have fixed that myself, but I should have brought it to someone else to diagnose to pinpoint the issue. Learned my lesson then, and I go to the shop now if I can't guarantee I have the problem figured out. On my Z, I know my injectors are bad, so I will replace them. However if I still have lag issues, it's going to a shop for further diagnosis... Bottom line, don't spend more money than you absolutely have to!!!

Good luck!

[marty1mc]

Have you tested the compression? I would start there and make sure you aren't having ring or valve issues that are causing it. Put fresh fuel in it after draining what is in there and don't add octane booster to it. Put in new plugs, clean all your connectors for CAS, PTU, coil packs, injectors, TPS.

[rightfoot]

>Bottom line, don't spend more money than you absolutely have to!!!

Thanks for your input. I also tend to think it might be a bad connection somewhere but other than the obvious visible ones, I have no clue how in the world to get at most of them.

As for having it checked out, I did that, twice. I brought it to a Nissan dealer and each time, they told me it's a great car, it doesn't need anything, it's running fine, etc. Yet I can't connect to the ECU with three setups? That's kinda weird.

I'm leaning towards finding a good shop in the area that does Z cars but this year is a tough one so can't spend on toys right now so trying to figure it out on my own in the meantime.

There is one other thing I forgot about that I'll post in a moment.

[rightfoot]

>Maybe you have a bad master cylinder leaking fluid into the engine causing your engine
>to lag. Maybe?

I just re-read this and forgot about this. You're the first person that has ever said this could be a possibility.

[rightfoot]

Have you tested the compression? I would start there and make sure you aren't having ring or valve issues that are causing it. Put fresh fuel in it after draining what is in there and don't add octane booster to it. Put in new plugs, clean all your connectors for CAS, PTU, coil packs, injectors, TPS.

One reason I've never bothered is that when it decides to run well, it runs very well, and very strong. If I was having compression problems, that would not happen right.

[rightfoot]

So I had forgotten something I wanted to add.
When we changed the injectors, we had to disconnect the intake so we could lift it high enough to get the rear injectors out/in. There was something holding the intake to the motor which we never did find or see, so left it in place and just lifted it.
We were very careful when we put the new intake gasket back to make sure it was seated right as well.
Now, something that I noticed right after this job was the following.

When we started the car up, it didn't make one damn difference which was VERY discouraging but worse, it sounded like we might have disconnected something. When I put my ear close to where the battery is, I could hear what sounded either like an air leak or an exhaust leak near the back of the motor, by the battery.
Since you can only hear it when the motor is running, it's hard to hear it well since the motor IS running so it's kind of a catch 22. I tried using one of those stethoscopes but wasn't able to pin point anything.

Another thing is that when it starts to do that missing thing, it sounds kinda like a putting sound, almost like you'd hear when there is an exhaust leak. I don't believe the exhaust is leaking since when it's running well, there is no leaking exhaust sound but when it's putting, then that's what it sounds like.

Also, when it does that, at idle, you would believe it's missing because the whole car moves, you know, as in rough idle. When I hit the gas, I have to very slowly sorta tap, release it so that it can rev up as it seems to want to stall. I don't think it would stall but that's how it acts. Once it revs up, the roughness goes away (of course) but it's still got no power of course and you can still tell it's not running right.

Haha, it's so hard to explain such things in text .

[rightfoot]

>Put in new plugs

I ordered new ones from Stillen about a month ago and they are installed.

>clean all your connectors for CAS, PTU, coil packs, injectors, TPS

Are all of these in the manual by these terms? I've checked all of the injector and coil connections and the MAF sensor connector, but not sure I know what the other ones are above.
CAS, PTU, TPS, any others I can get at easily which I could make sure are clean?

[300ZXttZMAN]

MAF! ^^

[McShanks]

Rightfoot, that sounds like a vacuum or EGR leak to me. Could be wrong as I am not an expert, and it may not be the only issue, but I had a similar issue when I tested my #5 injector as I forgot to reinstall a small vacuum hose. Mine was a constant hissing sound though that got louder with higher engine speed. Maybe, just maybe, you might wanna remove the intake plenum and check/swap your vacuum lines. Do the TB jacket delete too while you're at it. It could also be your EGR line if it is more of a putt-putt than a steady hissing sound. Pulling the plenum properly and checking everything very carefully and reinstalling carefully may be your best bet with this issue. Some also do the EGR delete though it is not legal. There are many threads and tutorials on plenum pulls and what to check.

About the possibility of a leaking master cylinder through the vacuum line into the engine... Not very probable but anything is possible with a 21 year old car. As an aspiring Engineer and former Navy mechanic, I have learned that sometimes just "throwing things out there" can often lead to great solutions to problems.

Good luck!

[rightfoot]

MAF! ^^

Guessing you're saying you think it's the MAF?

[rightfoot]

>that sounds like a vacuum or EGR leak to me.

I tried to peek into the spot using a small mirror, even a small camera and could not see anything loose or obvious yet there definitely was a leaking exhaust sound after we put the intake back on.

Does anyone know what would have been holding the intake back from our pulling it fully off? There wasn't anything holding it back on the sides or top, but there was something holding it back from underneath and we could not see what it was. It makes me wonder if we puled something loose underneath?

>I had a similar issue when I tested my #5 injector as I forgot to reinstall a small vacuum hose.

Which one? If you mean the ones on top, rear, we got them all.

>Mine was a constant hissing sound though that got louder with higher engine speed.

Mine was more of a leaking exhaust sound but only on the passenger side, listening by putting my head near the engine, by the battery.

>Maybe, just maybe, you might wanna remove the intake plenum and check/swap your vacuum lines.

That's a big job. I'd love to cover all of the bases before pulling that apart yet again .

>Do the TB jacket delete too while you're at it. It could also be your EGR line if it is more of a
>putt-putt than a steady hissing sound.

I'm not sure what a TB jacket delete is. I'm assuming the EGR delete means removing the EGR valve or something?

>There are many threads and tutorials on plenum pulls and what to check.

I looked around for a bit of a howto on pulling the intake and was never able to find one which showed images of things to look for, especially what ever is holding the intake in from underneath. We didn't want to pull too hard on it since we were not able to see what was preventing it from coming up.

>I have learned that sometimes just "throwing things out there" can often lead to great solutions to problems.

I work in technology and the same thing applies .

Thanks for the input.

[300ZXttZMAN]

MAF! ^^

Guessing you're saying you think it's the MAF?

Absolutely not but while your in there cleaning other connectors you mine as well clean it in the post above mine you say

any other sensors i can easily clean

You said something along the lines of that^^^^^^^^^^

[300ZXttZMAN]

>Put in new plugs

I ordered new ones from Stillen about a month ago and they are installed.

>clean all your connectors for CAS, PTU, coil packs, injectors, TPS

Are all of these in the manual by these terms? I've checked all of the injector and coil connections and the MAF sensor connector, but not sure I know what the other ones are above.

CAS, PTU, TPS, any others I can get at easily which I could make sure are clean?

Just make sure its clean i see that you looked at it but did you clean it... It may look clean but it doesnt hurt to put some electrical cleaner in there because it can be corroded on the wiring that you cant see.

I had the same problem with my PS blinker... I looked at it the bulb was good so i took the bulb out the contacts looked clean not green at all plugged it back up still didnt work so i just popped the bulb back out and sprayed white lithium grease into the bulbs socket and *wola* fixed

[rightfoot]

>Just make sure its clean i see that you looked at it but did you clean it... It may look clean
>but it doesnt hurt to put some electrical cleaner in there because it can be corroded on
>the wiring that you cant see.

Yup, I did clean it. It looked ok but there was some grudge around it so when I took the MAF out, I carefully cleaned it's connectors, then cleaned the other end attached to the car. I used battery cleaner and a wire brush and tried to get right into the little contact holes.

[rightfoot]

I got the seafoam but the store guy says not to use the whole can, he says just use a little first.
What is the opinion here? I have at least half is not a 3/4 tank of gas.