New Owner, Need Help Working on Some of the Issues

[Black 93Z]

Hello everyone, So I finally got a Z .
Its a 93 NA with 175K miles, I know its a lot but I couldn't pass on it.

First, I didn't expect it to drive this well, it felt planted and solid for a 22 year old car. I really like it and its growing on me every day. However, it has kinks here and there.


1- After warming up, the car has a rough idle, I can feel it through the seat.
I've done some searching and I couldn't find something similar to my problem. I've changed the spark plugs, fuel filter and engine/gauge coolant sensor, and its still there. My next step is looking for vacuum leaks.

2- The car loses power when trying to accelerate under 2500 RPM, it feels like there is a delay before the power comes on or getting passed 2500RPM.
For this, I've looked at the MAF and throttle bodies and they were clean. I've also checked the O2 sensors operation and they were good as well. Also, Just recently I stepped on it, 50% throttle in 2nd and I heard a pop coming from under the hood, any ideas?

3- Oil pressure gauge is low, I know that oil pressure is good because the engine didn't go kaboom yet. I bought a sending unit so just need to install it but I don't know where it goes.

4-One day after driving for a while I hit traffic and we stopped for like 10 min and the car started to over heat, it didn't reach the H mark but it was close. For the rest of that day, whenever I stopped at a light it went up.
That is the one thing I cannot overlook, so I'm getting a new radiator and fan/clutch, it didn't do it again but I just can't let it go.

5- The car is eating the inside of my tires because its lowered and honestly it isn't to my liking, so first can an alignment shop fix it or do I need to replace some parts (i.e get an adjustable control arm). Two, what is a good combination of shocks/springs for a comfortable ride with good handling?

6- Cruise control doesn't work, it goes on but when trying to set my speed nothing happens. This isn't important but I'd like to fix it sometime.

I'm doing the 120K service, just need to see how much it would cost first.
I never did full throttle or go past 4K RPM, so there is more to explore but I like it so far.

Your suggestions and help is much appreciated.

[Ace2cool]

Hello everyone, So I finally got a Z .
Its a 93 NA with 175K miles, I know its a lot but I couldn't pass on it.
Only 5k away from needing a timing belt, just FYI. That is, if it is "on schedule."

First, I didn't expect it to drive this well, it felt planted and solid for a 22 year old car. I really like it and its growing on me every day. However, it has kinks here and there.


1- After warming up, the car has a rough idle, I can feel it through the seat.
I've done some searching and I couldn't find something similar to my problem. I've changed the spark plugs, fuel filter and engine/gauge coolant sensor, and its still there. My next step is looking for vacuum leaks.

What plugs did you use? The ONLY plug is NGK PFR6B-11 for N/A, 11A for TT. Vacuum leaks are likely, honestly. You can use a boost leak tester to diagnose if you suspect that. Also try a power balance test.

2- The car loses power when trying to accelerate under 2500 RPM, it feels like there is a delay before the power comes on or getting passed 2500RPM.
For this, I've looked at the MAF and throttle bodies and they were clean. I've also checked the O2 sensors operation and they were good as well. Also, Just recently I stepped on it, 50% throttle in 2nd and I heard a pop coming from under the hood, any ideas?

Could be tied in with ^

3- Oil pressure gauge is low, I know that oil pressure is good because the engine didn't go kaboom yet. I bought a sending unit so just need to install it but I don't know where it goes.

Common fail point is the sender, so you're good on that. It goes on the oil filter adapter.

4-One day after driving for a while I hit traffic and we stopped for like 10 min and the car started to over heat, it didn't reach the H mark but it was close. For the rest of that day, whenever I stopped at a light it went up.
That is the one thing I cannot overlook, so I'm getting a new radiator and fan/clutch, it didn't do it again but I just can't let it go.

Sounds like a coolant leak, or a bad fan. With the car fully warmed up, try to spin the fan by hand. If it makes more than a full revolution, it's bad. Also check coolant level. If it's any kind of low, that's a good cause for it.

5- The car is eating the inside of my tires because its lowered and honestly it isn't to my liking, so first can an alignment shop fix it or do I need to replace some parts (i.e get an adjustable control arm). Two, what is a good combination of shocks/springs for a comfortable ride with good handling?

Camber doesn't wear tires, toe does. But in order to correct camber, you will need adjustable arms.

6- Cruise control doesn't work, it goes on but when trying to set my speed nothing happens. This isn't important but I'd like to fix it sometime.

Either the cruise control relay or the module itself. Does the light come on when you try to set the speed or no?

I'm doing the 120K service, just need to see how much it would cost first.
I never did full throttle or go past 4K RPM, so there is more to explore but I like it so far.

Your suggestions and help is much appreciated.

Welcome!

[Black 93Z]

Only 5k away from needing a timing belt, just FYI. That is, if it is "on schedule."

According to the previous owner it was changed at 150K

What plugs did you use? The ONLY plug is NGK PFR6B-11 for N/A, 11A for TT. Vacuum leaks are likely, honestly. You can use a boost leak tester to diagnose if you suspect that. Also try a power balance test.

Those are the ones I got, bought them through concept z. I'm not familiar with a power balance test, can you explain it?

Sounds like a coolant leak, or a bad fan. With the car fully warmed up, try to spin the fan by hand. If it makes more than a full revolution, it's bad. Also check coolant level. If it's any kind of low, that's a good cause for it.

Coolant level is fine and there are no puddles under the car. The fan is always spinning when the car is running, so is the clutch bad or did you mean spinning it when the car is off?

Camber doesn't wear tires, toe does. But in order to correct camber, you will need adjustable arms.

Ok, what parts do I need exactly?

Either the cruise control relay or the module itself. Does the light come on when you try to set the speed or no?

It comes on when I turn on the cruise control on, but nothing happens when I try to set the speed

[DCaff300ZX]

Be sure to also check your injector connectors for corrosion, that will cause the hesitation and other issues as well as the spark plugs. Check your PTU harness connections as well for the green corrosion, clean/di-grease all connections as necessary. Also check any and all vacuum hoses you can reach, and all of your intake pipe clamp connections as well as the PCV system hoses (slightly larger hoses on sides of intake manifold) and replace the PCV's if they have not been replaced.

You want to spin the clutch fan with the engine off. Also in addition to if the fan spins freely it's bad, if it WON'T spin at all it's bad as well but will make a LOT of noise when frozen up. It's a centrifugal fan which is supposed to have the right resistance to "coast" at certain speeds, and if bad will cause issues with the water pump which leaks and can add/lead to cooling issues.

The sagging springs and worn shocks in your stock suspension cause the camber/toe tire wear issues, a very common age related problem with our cars, you need to either get new shocks and springs installed or buy coilovers and adjustable camber arms for front and rear. Powertrix is currently selling great coilovers and adjustable bits at group buy prices, the overall cost not too far out of line with stock replacement costs and FAR better and easier. Powertrix advertises on our site.

[Ace2cool]

According to the previous owner it was changed at 150K

Lol, Supposedly. If there aren't any records, I don't trust it that much, especially on something as important as the timing belt. That's the fastest way to "game over", if you know what I mean.

Those are the ones I got, bought them through concept z. I'm not familiar with a power balance test, can you explain it?

Cool, cool. With the power balance test, you pull one coil pack connector at a time, until you find one that doesn't make it "run worse." That will be your culprit cylinder, IF it is a dead cylinder issue.

Coolant level is fine and there are no puddles under the car. The fan is always spinning when the car is running, so is the clutch bad or did you mean spinning it when the car is off?

As Dcaff said, spin it with the engine warm but not running. It's got a heat sensitive element that is supposed to "catch" the fan and engage it when at operating temp.His other advice is also solid.

Ok, what parts do I need exactly?

Basically, upper control arms, if you just want to adjust back to zero camber, and an alignment. You may have to get new toe rods for the rear if there isn't enough left in the stock ones to adjust back into spec as well. If you want fully adjustable suspension though, definitely go the Powertrix Group Buy option with the coilovers and get all the bells and whistles. Best mod I've ever done to any car, hands down.

It comes on when I turn on the cruise control on, but nothing happens when I try to set the speed

So a couple things in that case. Could be the switch that the brake pedal contacts(more likely), could be the switch in the steering column (less likely). There's a diagnostic procedure.

1.Turn off the ignition.
2.Hold the cruise control stalk down or in the "Set" position.
3.Start the car while holding the stalk down.
4.The cruise indicator lamp on the dash should start flashing once you start the engine.
5.Go through all the components one step at a time. Step on the brake pedal, step on the clutch pedal (if equiped), hit the resume button, etc.
6.If that portion of the system is working correctly, the lamp will continue to flash. If not, that's your problem area.

Sidenote: I actually like responding this way. Easy to keep track of separate questions.

[Black 93Z]

Alright, you guys are vey helpful I really appreciate your replies.
It looks like I have a lot to do, so I'll do as much as I can this weekend and update this thread.

Couple of side notes, I've been checking coolant level so I'm sure there are no leaks, I'm leaning towards the cooling system is just isn't efficient enough so I'm replacing water pump, T-stat (since I'm doing the 120K), fan/clutch, radiator and new fluid.
I'm almost certain the car is lowered, there isn't much clearnce between the wheels and the body, unless the stock shocks exploded and dropped it that much.
Not sure if I'm going with coilovers, I have a lot to do on the car like tires, besides this isn't my main project , however I won't leave stock either

[The Silent Genius]

most likely the tstat that failed. I went through this myself a few years back. good call replacing the water pump while at it, it's a cheap part anyway.

[Black 93Z]

Here is what I did today.
Checked the coils by disconnecting one at a time just like Ace suggested, that revelad the middle cylinder on the driver side (is it #3?) to be dead. Nothing changed when disconnecting the coil.

Tried spinning the fan by giving it momentum and let go, it hardly went ¼th of a revolution I suppose that mean the clutch is fine.

I decided to familiarize my self with the vacuum lines and inspect them visually until I replace the dead coil so it'll be easier to hear any hissing. They all appear to be good to my eye, however I couldn't find any lines going to the AIV solenoid.

Red box = EGR solenoid
Green arrow = line coming from intake pipe
Yellow arrow = vacuum line should continue to AIV
Blue line = vacuum line going to EGR



Does that mean AIV was deleted?
There weren't a vacuum line coming from the balance tube either, also I'm curious about what was plunged in the yellow box.

[DCaff300ZX]

You probably don't have a dead coil, the pb test points out that either the spark (wire/connector, plug itself) isn't correct or that the injector (wire/connector, injector itself) aren't functioning. Yes, the coil COULD be bad but you can test it, and normally these do not fail although not unknown. Focus on the injector connector (corrosion) and wire (short) first, then check plug connector and if no help then ohm the injector and inspect/gap correctly/replace the spark plug.

Your questions regarding the plenum and balance tube- the plug you asked about is a normal plug in all Z32's as far as I know, both mine have the same so nothing to worry about there. The AIV's operate from a solenoid just like the EGR solenoid on both sides of the motor and a with host of vacuum hoses and a wire involved, the AIV's live in the fender wells and these hoses/wire all connect to it...or if missing, then the AIV's have been deleted or deactivated. If AIV has been removed completely, there should be a big screw-in metal plug in your exhaust collector where the previous AIV hose connected. You will want to ensure if so that ALL vacuum hoses and connections have been capped/dealt with appropriately as vacuum problems can mimic some other problems in our cars. It seems like you are in the classic position of deciding whether you have corrosion/connection problems, or failure of control devices/solenoids (or BOTH!) to determine.

Regarding cooling issues, we have left out a potentially important step- that being bleeding the cooling system for ALL air. The OEM radiator has a screw-in bleeder plug on top of the return hose connection- you'll want to have the engine warm, then start the engine with the rad cap open and top off the rad with coolant as well as the overflow, then go into the cabin and turn on your heater on the highest heat setting possible and full fan. Go back under the hood remove the bleeder screw and cap the rad, then being VERY CAREFUL TO NOT GET TOO CLOSE TO THE SPINNING FAN, pinch the return hose nearest to the rad as possible for finger/hand safety to make the coolant "rise" into the bleeder screw area and ensure that as the coolant flows past, you see NO air bubbles. It is possible you may need to add more coolant if there's a lot of air in the system as air bubbles escape- just use a funnel and pour some in through the bleeder screw area or shut the engine down and refill, start over. When the coolant is finally flowing past with no bubbles or surges, keep it this way for 10-20 more seconds of no bubbles, then still holding the hose until the bleeder screw is completely set and pinching until the coolant is RIGHT at the top of that opening, replace the bleeder screw. This should result in an air-free environment in the motor and best cooling possible with an OEM system that is working correctly- further issues will need a pressure test and more to find where air is getting in, if no obvious problems. BTW, also inspect the rad cap for correct operation or replace, and check rad coolant hose mounts for cracks/failure as with rad being plastic/ABS, the connections can crack/fatigue due to age and be the air entry point- this happened to me so I know by experience.

Hope these things help you move along!

[Black 93Z]

Todays findings:

Did the cruise control test, and the light continued flashing with every component, breaks, clutch, set, cancel and accelerate.
I bled the cooling system, with the car warm, opened the rad cap and the little screw, turned the heat full blast and waited a couple of minutes. There were no bubbles coming and I can see the fluid circulating. I really think its just an old radiator and it can't dissipate heat well enough. Because it only overheated once after sitting for a long time among other cars, so "cool" air wasn't going through the radiator.

Now, more importantly, I checked the injectors. First by listing for each one through a screw driver. All were ticking consistently and as loudly except the dead cylinder which is the middle one on the drivers side (again, is it #3 or #4??), it was ticking but it wasn't as audible.
Secondly, by measuring the ohm readings, I didn't do the injectors under the balance tube cause they were difficult to get to, but I figured they would be ok since they were ticking like the others.
The dead cylinder's injector read 34.x while the others read 11.4 and since I had the ohm meter with me I measured the coil and it read 0.4 or 0.5 Not exactly sure because I did it with no idea whether this would reveal anything. Further investigation revealed that coils should read 0.7

So, I know I need to replace the injector but pulling the plenum looks like a lot of work, not to mention other stuff I need to do. So how long can I drive the car like this? and is there any consequences? Also what about the coil, is bad too?

Lastly I looked at the PTU but I don't know if its normal compared to what is shown in the photo guide.

[DCaff300ZX]

PTU is new style which is good, looks solid although there still can be corrosion inside those connectors. I checked mine today and they both were corroded badly, despite the fact I'd cleaned them a year ago so do yourself a favor and check/clean them as this can be an issue. They are sealed at the junction, but as you can see the wires are not and the corrosion enters there.

The cooling system work sounded good, from what you said about the overheat you may well be OK there.

As for the coil it probably is OK, as you found the injector is not and is the problem you have in that cylinder. There is a method where you can use a dremel to ease access to the injector plate screws and with effort remove the injector without a plenum pull, but it makes a mess that must be controlled and still takes some time to do and has difficulty for an amateur and even relative veteran who is not familiar with the VG30DE. Replacement is the only solution unfortunately, and driving it a lot is never a good idea and may well cause a cooling issue on a long trip because of the constant misfire.
Treat your Z with respect and fix her first...

[Black 93Z]

Lol, well, I don't intend on leaving it like this, after all I want to enjoy the car.

We have a saying, stretch your legs as long as your blanket. My blanket can barley cover the 120K service, so it'll be a while before I replace the injector. Of course, there is always doing it myself, however the guys that made this engine did't make it easy. I'm still playing with the idea of doing stuff myself, I've done a timing belt before and I'm mechanically inclined.

For now I'm gonna pursue other things like the cruise control.

[DCaff300ZX]

Sounds good, if you have tackled the tbelt then you understand what you are up against...and we can help a lot with the DIY. I DEFINITELY understand the financial burden, it took me almost a year just to accumulate the parts for my work done and it would have taken two more years+ to afford all of the labor that was thrown at the car.
I honestly think you should do your best to get that injector nearer the top of your list- check the Nico classifieds for a used but good injector and read up on the dremel method- IIRC you also are in the "easier" area for injector work (mid engine) and may even have not much dremel work to do to get to those PITA cap screws...which you will replace with bolts to ease future work!
I also had some luck years ago limping along a failing injector by using Lucas upper cylinder lubricant in every tank fill, it lubes the injector to help it and also help other areas which seemed to really help early, but less later as the injector neared it's end and was eventually replaced. All in all I went about a month that way, so if it isn't missing badly try that and maybe that gets you a few more weeks until you are more ready for that work.

Good Luck and keep us posted!

[Ace2cool]

So how long can I drive the car like this?

Not recommended. At all.

and is there any consequences?

Blown piston rings, loss of compression, diluted oil leading to excessive engine wear, knock, do I need to continue?

Don't drive it like this. You will end up needing a rebuild. I guarantee it.

I understand the blanket quote, but this is a guaranteed issue. Fix it or don't drive it. Or deal with the consequences down the line.

Sorry to be blunt, but you're treating it like a small issue, and it really isn't.

And as far as doing it yourself, it's really the only way to go if you think you're capable, otherwise you'll get raped on labor charges. Things take a while on this car, and the shop will make sure to charge you every cent they can, because this car is a pain to work on.

[Black 93Z]

I didn't expect to see all those scary words
Alright, I'll do it myself using the dremel method. DCaff, I will try the stuff you recommended as well.

On a side note, I don't drive it that much so you don't have to worry

[Black 93Z]

I checked ebay to see how much I might be looking at. I saw a couple of brands, Nissan, GB remanufacturing and others.
So what do you guys think about other brands? are they worth it or should wait until I can get a used one?
GB Remanufacturing have them for a good a price.

[Ace2cool]

Never heard of them, and I've heard horror stories with remans, with the drilling pattern being absolutely horrendous. If I was going to get remans, I'd at least get a reputable brand such as Deatschwerks.

And I don't mean to pile it on, but just know if you've got one gone bad, chances are at least one is close behind. It's a good habit to, especially if this is your DD, to have at least a thousand dollars set aside for repairs.

[Black 93Z]

And I don't mean to pile it on, but just know if you've got one gone bad, chances are at least one is close behind. It's a good habit to, especially if this is your DD, to have at least a thousand dollars set aside for repairs.

I figured as much, thats why I was going to leave it for now and replace them all when I have a chance.
But since its going to lead to more headache if I leave it like this I thought I should at least get this one going, I do intend to replace them all eventually.

[Ace2cool]

Oh, by all means. I was just letting you know just for your personal information. Don't want you to get in over your head, y'know?

[DCaff300ZX]

I didn't expect to see all those scary words
Alright, I'll do it myself using the dremel method. DCaff, I will try the stuff you recommended as well.

On a side note, I don't drive it that much so you don't have to worry

My apologies as I didn't make it as clear as Ace did, and agree with him that you really should not drive it at all, or beyond a short trip to the repair shop.
OK, maybe I did by saying "Do the right thing and fix it right" just also said it could be driven some...contradictory, sorry.

Carry on!

[Black 93Z]

I didn't expect to see all those scary words
Alright, I'll do it myself using the dremel method. DCaff, I will try the stuff you recommended as well.

On a side note, I don't drive it that much so you don't have to worry

My apologies as I didn't make it as clear as Ace did, and agree with him that you really should not drive it at all, or beyond a short trip to the repair shop.
OK, maybe I did by saying "Do the right thing and fix it right" just also said it could be driven some...contradictory, sorry.

Carry on!

Lol, I don't think you made it clear enough, not to me at least
Don't worry about it though, Ace pretty much covered it

So I received the "remanufactured" injector from GB, it just looks like a used one.
ohms are within spec, and it looks good to me.






So, I'm changing it in a couple of days. Expect some questions

[NolimitZ32]

Remans are usually new guts in old shells so it wont look brand new. hopefully they didn't screw with the spray cap and you get a matching pattern. GL

[DCaff300ZX]

Hmmm, good call Anton. When I got mine replaced Doug used an OEM replacement which would ensure a similar operation.

[grayman_TT]

There weren't a vacuum line coming from the balance tube either, also I'm curious about what was plunged in the yellow box.

JDM Z32's have a fitting there that supplies the brake booster.

[Ace2cool]

Oh. You know, that should have been common sense, but I guess I'm lacking that.

[Black 93Z]

Remans are usually new guts in old shells so it wont look brand new. hopefully they didn't screw with the spray cap and you get a matching pattern. GL

Well, no use worrying about it now.

At any rate, today I got the fuel damper off, and got myself a nice cut on my left hand palm removing one of the fuel lines of the hard lines near the balance tube.
Tomorrow I'll start grinding, hopefully that would go smoothly.

[Black 93Z]

Good news!
New injector is in, and it wasn't that bad actually. At first I had doubts about doing it, it just needs caution.

So the first time I fired her up, it wasn't smooth as I expected it would be, and for the whole 10 or so minutes it idled, I heard a thumbing sound.
It went thump thump, every 4-5 minutes, so turned it off, back on and its gone. Once it reached operating temps it smoothed out, no rough idling like before.

I didn't get a chance to take it out yet, it was getting dark and started raining, I'll update tomorrow.
Now I just need to get the 120K service and new tires, the rest is trivial compared to this.

[DCaff300ZX]

Congrats! Be sure to get some Ramey idler studs with your 120K and replace your accessory belts plus don't forget a thermostat with the waterpump, and if you can spare the extra bucks go with a quality tbelt as well

[Black 93Z]

Finally took her for a test drive and its a lot better than before.
Idle is smooth, no hesitation under load.

Still, I have some concerns. The thumbing sound is still there, only when the car is cold, I assume this is knock?
I've put the Lucas stuff and it says on the bottle its an alternative for octane boosters, that makes it strange for the car to knock.

Secondly, there is a delay in power, not like before it happens at any gear at any RPM, mostly below 3K. It feels like the car is holding back, or maybe I'm just used to my other car.

I got a quote for $650 for the 120K service, which include the cam and crank seals, waiting on the parts to arrive next week.

[DCaff300ZX]

I assume you mean "thumping" like a sound, as in a "plump...plump" kind of sound during high idle? If so this is a misfire, and caused by either the injector itself or the connector to the injector having corrosion (more likely) that becomes less of an issue as it warms up and swells up with heat for a better fit and connection. Also among the possibilities if the injectors ohm out correctly and your connectors are all clean (no green residue) is your Idle Air Control Valve (IACV) which is notorious for idle issues- both the valve and it's connectors. All definitely worthy of being checked and fixed, even if this doesn't solve your issues as this all falls under the maintenance end of Z32 life.