Odd sputtering at highway speeds

[rickgosk8]

Hello to all!! My name is Rick and this here is my ice breaking post to nicoclub, unfortunately it has to be a problem. Anyways let's cut to the chase, I have an 86 300zx non turbo, and amongst a million problems I've encountered since my recent purchase I now am having this weird sputtering loss of power problem almost as soon as I get it in fifth gear,. Recent things I've done include: putting in New tps pigtail,(double checked wiring) did a complete timing job as soon I got the car but it ran fine for a while afterwards so it's not timing related I don't think, replaced pvc valve with oil change, and that pretty much wraps it up as far as engine components go. Now here's the kicker, the problem started right after I sea foamed my car, which I poured half a can through gas tank and rest through brake booster vacuum hose,,,, so a week after that I did more through booster thinking it clogged some stuff up, I added a lot more and let it sit longer,, and still the same exact problem,,, the sputtering doesn't exist in first 4 gears no matter what rpm but as soon as I hit 5th, it starts acting like it's trying die out, and every gear below does the same thing after it starts sputtering until I cut the car off and try again, most of the time it runs fine back up until 5th after I cut car off and on,,,, so any help would be sooooo frickin awesome and greatly appreciated, let's get this solved for anyone else having similar problems,,,,, -Rickt

[evildky]

Have you checked the ECU for codes? You said it sputters in 5th gear, what mph? What rpm in 5th does this sputter occur? What happens if you do the same mph in 4th? Why did you put snake oil in the engine?

[rickgosk8]

Thanks for the quick reply evil!! So basically it doesn't matter what rpm I'm at when I Shift, I don't even break four grand unless it starts bogging and I try to just burry my foot in the gas pedal,,, lol I'm unaware of the snake oil comment, I know your talking about sea foam which I just used as a general name for what i actually used which is stp multipurpose treatment,,,
My highway speed leaving fourth gear is right at 55 and then the bog begins. If I never change and stay at 3500-4000 rpm in fourth gear it doesn't seem to happen, I haven't stayed on it that long because I was having thermostat issues that are now resolved I hope,, and I have checked the codes and first time pulled nearly six codes, including maf and tps,, I have gotten rid of the all except tps. My next step is probably going to be just unplugging tps and see how it rides,, any other suggestions?

[evildky]

So what happens if you run 4th gear all the way up to redline? I'm suspecting the fuel pump.

If you have a TPS code maybe you should try fixing the TPS?

Snake oil, referring to any number of products, such as sea foam, that people think contain magical powers to affect a physical problem. Why did you put it in your engine? That fact that you used it suggests you had a problem you tried to fix with a magic bottle.

[rickgosk8]

I honestly haven't tried redlining in fourth yet,, after doing a little work on it in a bit I'll go out and give that a try,,
And I just put a new tps on order so will be here Friday and hopefully that solves most of the problems, , I've noticed that a lot of the threads that had similar problems to this (bogging and sputtering loss of power) left their problems unresolved. Which I definitely will not.
And I see your point ,,, but the only reason I added it is because this car sat in a garage (thank god) for fifteen years, so I wanted to get the carbon build up and crap out. I work at an AutoZone and we had a buy one get one deal for 7 dollars,, which also is a big reason,, only problem I had with car before these problems is my water pump broke on day two of my ownership,, which is when I replaced timing components and chts, which we all know is a pita lol

[evildky]

Sitting does not cause carbon build up, granny shifting does. Actually it's still not as big a problem as the snake oil peddlers would have you believe. The plenum is pretty easy to pull and a flashlight will let you peak at the back of your intake valves, if there is a buildup, run some fuel injector cleaner so it slowly washes off and gets burnt.

[rickgosk8]

Gotchya thanks for the info, , and yeah I know carbon doesn't spontaneously appear, I just wasn't sure how well the previous owner kept up with the engine so decided to make sure lol,,, I'll stay away from that carp from now on and stick with Lucas injector cleaner or some other trustworthy brand.
As for an update on sputtering problem, I drove to work and back this morning with tps unplugged and was able to shift and drive in fifth like it should, however the sputtering is still present at random times during the drive but seems to drive a whole lot better and sputters only half as bad and tends to be able to go away when I start hitting 75 to 85 mph

[rickgosk8]

So I've put the new tps on and if anything it got worse,,, so I'm not even sure where to look at this point, I see so many threads with my same exact problem but were all left unresolved except one guy found his problem to be a cracked wire on his chts, , can someone tell me how this would cause my problem, also on another test run today I discovered it isn't mph related but either temp or time related. It semi resets if I cut car off and try again. . Anymore help is greatly appreciated before I throw money at a shop that may not be able to fix it either lol

[evildky]

CHTS and O2 both have the same effect on running just to different degrees, both cause a rich condition, the chts can cause ti to run so rich it floods and won't restart. This is only a problem once the car warms up as a cold engine should run rich. Warm restarts are the tell tale sign of a chts issue. You presented us with a sputters in 5th gear issue, This is why I suspected the fuel pump and was asking about rpm and speed. The ecu doesn't know how fast the car is going or what gear you are in, it knows air temp , density and engine temp. It's tough to diagnose a car on the interwebs as all we have to go on is your interpretation of the issue at hand. So if your problem is warm start i'd start at the CHTS. If it's a drivability issue the ECU r MAS would be the next items to check out.

[rickgosk8]

I see,,, yeah I'm pretty terrible at telling what's wrong with it I'm sorry.. I can try an upload a video, but there is one that seems to be doing same thing if I can find it instead. If I'm having maf or chts problems there should still be a code right? Last I checked it only threw tps code,, but when I first got it it had all three of those codes plus some other.random codes yet the car never had this problem. I did add a mushroom air filter,, you think it's too high flow? I'll disconnect maf and o2 just to see what changes on test drives, Until I find my multimeter and can test connection and continuity at sensor connections and ecu connections

[evildky]

The air filters only serve to lean the mixture a touch it won't hurt anything as long as it keeps the crud off your MAS. These OBD0 systems aren't always great about throwing codes, they don't throw false codes but don't always throw the codes of whatever isn't working.

[rickgosk8]

Okay cool, thanks again man, I'm going to dive in a lot deeper this weekend and recheck all associated sensors with fsm I downloaded if it cooperates on my phone lol

[rickgosk8]

UPDATE*
I've done a few things since last I posted. My problem has gone away but I did three things and am not sure which worked until I go and start undoing them lol,, basically I removed my catalytic converter, unhooked o2, and readjusted tps,,, so I have know idea which lol... a bit more good news is a buddy of mine just bought an 86 300zx as well so now fixing things will be so much easier with another close by,,, however I do have to say that when compared, his car is a lot quicker and they're both na. With that being said I still haven't changed my plugs, cap, rotor, plugs, and coil,,,, I'm waiting on my msd blaster 2 coil to come in and will do that and see what she rides like then,,, quick Question (forgive me if this is already answered in this forum) does anyone know the amount of gap I can increase my new ngk platinum plugs in correspondence to the msd coil I'm getting,,, I know our gap is originally
.44,,, thanks in advance. Also if anyone wants to give me some pointers on becoming less of a newbie I'd love to dive deeper into our community

[evildky]

Stock coil is good, changing to a blaster won't improve anything and doesn't change the needed spark plug gap. If your cat is out and your exhaust is wide open and the O2 unplugged you can will run poorly. I'd start by plugging the O2 back in this will fix the rich condition you caused by unplugging it. Then I'd reconnect the cat, if having the cat is in worst than having it out then it's clogged and needs replaced, you can gut it for the time being but you will have a suitty bumper and if you have emissions testing you obviously won't pass.

[rickgosk8]

You I love read the stock ign system is good up until around 400 or more right?, I just decided to get one with my coupon code so got it relatively cheap lol,,, and yeah I'll definitely do that next,, I have leak to address on my brake hose used for clutch damper delete. And I'm thinking of just gutting the cat either way, which mufflers sound best on our cars in your opinion? I'm tempted to leave it how it is,, I likely!! but yeah I'm in a small Georgia town, no emissions for me.

[evildky]

certified muffler has a great deal on Z31 exhaust but they make the systems to order so plan in advance.