Still Hesitating...please help!!!

[FlogWaffle]

Okay so heres the scoop...my Z was began to hesitate a while ago, and since i was lazy i let it go for a little bit. Also, ever since i bought the car it has noisy VTC gears. Just a week ago, i finally got around to tearing it apart a little and replacing the springs in the gears which stopped the rattling for good (yay!) and i also began to do some things to fix my hesitation. Here is what is happening

Whenever i drive, and am starting out the car stumbles and hesitates REALLY bad. It almost sounds like it isnt running on all cylinders (but i disconnected each coil connection 1 at a time..and they are all working)..this lasts up until about 3000 rpm and normally i can accelerate out of it. However sometimes it does not, and it will stumble all the way through the RPM band (but it mostly goes away after 3000rpm.) It only begins to do this after the car warms up a little bit...when i first turn it on and drive it cold it doesnt stumble at all, and its nice. Also, what i noticed is that the car idles high, around 1000rpm, and when it begins to back itself down at idle, the idle of the car becomes extremely rough.

Here is what ive done so far to try to fix the problem:

* Sealed off my EGR tube (i had cut it to get my old exhaust off...when it wasnt sealed it was giving me a LEAN reading on the console)
* Checked and sealed my vacuum lines going to the AIV's (i deleted them)
* 20 min ago i put in a new set of NGK plugs...
* New fuel Filter
* inspected my air filter to see if it was clogged up with s*** (it is still clean)
* set my timing to 15 degrees (it was around 18 when i checked it)
* the car is not giving any codes..the only thing i got was "system is ok" or whatever it says..


Can you guys please point me in a direction of what to look at next? Its just frustrating to drive my car like this, knowing what it is capable of.

any help is much appriciated!!!



*** Also, my car only has 65000 original miles on it..if that is of any use to anyone***

[marty1mc]

Well, ALWAYS the standard thing to do is clean all your connectors. Green corrosion will cause your spark plugs to misfire under load. Pull off each Coil pack connector and inspect it for green corrosion. Clean all of it off. I use some Radio Shack contact cleaner, emory cloth, wire brush, flat blade screw driver. After you have both the male and female connectors clean, shoot some brake cleaner in there to get the contact cleaner out, then fill it with di-electic grease to seal them.

Do this for the coil packs, injectors, PTU, CAS, Temp sensors, MAF, etc.

It is the easiest and simplest thing to do. It also will eliminate a lot of strange problems down the road. I have said this before so hear goes "most of the strange problems I have had on my Z have come down to a dirty connector"

[FlogWaffle]

That sounds like a good idea haha. I wish i thought of that while i had all of the coil packs off :P...oh well, ill check all of them tomorrow and try it out! anything is worth a shot at this point! Thanks man. anyone else have any other things for me to try?

[es.biggs]

While you clean the injector connectors, I'd suggest ohm testing them just to rule them out and verify they are good. Check fuel pressure, check the fuel dampener and regulator, check the PTU. Also, it wouldn't hurt to test the coolant temp sensor - procedure for that is in the FSM. That coolant temp sensor causes all kinds of trouble when it's not working, or when the connector is dirty.

All those suggestions after you clean your connections of course.

That's all covered in the FSM and guides on this forum and other resources. If you need help with any of them, let us know!

[1993zcandy]

Hi

My 93 NA did the same thing, I checked all the things you mentioned.

My solution was bad O2 sensors, I replaced them and the car runs like a top.

No more hesitation.

Okay so heres the scoop...my Z was began to hesitate a while ago, and since i was lazy i let it go for a little bit. Also, ever since i bought the car it has noisy VTC gears. Just a week ago, i finally got around to tearing it apart a little and replacing the springs in the gears which stopped the rattling for good (yay!) and i also began to do some things to fix my hesitation. Here is what is happening

Whenever i drive, and am starting out the car stumbles and hesitates REALLY bad. It almost sounds like it isnt running on all cylinders (but i disconnected each coil connection 1 at a time..and they are all working)..this lasts up until about 3000 rpm and normally i can accelerate out of it. However sometimes it does not, and it will stumble all the way through the RPM band (but it mostly goes away after 3000rpm.) It only begins to do this after the car warms up a little bit...when i first turn it on and drive it cold it doesnt stumble at all, and its nice. Also, what i noticed is that the car idles high, around 1000rpm, and when it begins to back itself down at idle, the idle of the car becomes extremely rough.

Here is what ive done so far to try to fix the problem:

* Sealed off my EGR tube (i had cut it to get my old exhaust off...when it wasnt sealed it was giving me a LEAN reading on the console)
* Checked and sealed my vacuum lines going to the AIV's (i deleted them)
* 20 min ago i put in a new set of NGK plugs...
* New fuel Filter
* inspected my air filter to see if it was clogged up with s*** (it is still clean)
* set my timing to 15 degrees (it was around 18 when i checked it)
* the car is not giving any codes..the only thing i got was "system is ok" or whatever it says..


Can you guys please point me in a direction of what to look at next? Its just frustrating to drive my car like this, knowing what it is capable of.

any help is much appriciated!!!



*** Also, my car only has 65000 original miles on it..if that is of any use to anyone***

[GerryO]

A lot of good info here:

http://www.mdsmarthome.com/z/Z%20Tech/Z ... 20Idle.pdf

Ever pulled the plenum and really cleaned everything thoroughly, replacing a few items at the same time?

[FlogWaffle]

Well, ALWAYS the standard thing to do is clean all your connectors. Green corrosion will cause your spark plugs to misfire under load. Pull off each Coil pack connector and inspect it for green corrosion. Clean all of it off. I use some Radio Shack contact cleaner, emory cloth, wire brush, flat blade screw driver. After you have both the male and female connectors clean, shoot some brake cleaner in there to get the contact cleaner out, then fill it with di-electic grease to seal them.

Do this for the coil packs, injectors, PTU, CAS, Temp sensors, MAF, etc.

It is the easiest and simplest thing to do. It also will eliminate a lot of strange problems down the road. I have said this before so hear goes "most of the strange problems I have had on my Z have come down to a dirty connector"

sorry guys ive been kinda busy the last few days, but I cleaned all of my connections under the hood and used dielectric grease on every one of them. It helped my hesitating a LITTLE bit, but it is still happening. Onto more testing i suppose!

[DCaff300ZX]

Do you have a mod front bumper?
If you have a large air opening like most aftermarket front bumpers and have and an upgrade cone filter, the airflow over the filter will affect the MAF and cause the hesitation- especially as the engine gets warmer, but that extra airflow keeps the MAF sensor too cold. The "Flower Pot Mod" is needed to correct this, basically you need to shroud the filter from excess air movement around it.
The rest of the info given above can also help, hope you fix that hesitation as I remember how annoying and wasteful (gas) this problem was...

[FlogWaffle]

Do you have a mod front bumper?
If you have a large air opening like most aftermarket front bumpers and have and an upgrade cone filter, the airflow over the filter will affect the MAF and cause the hesitation- especially as the engine gets warmer, but that extra airflow keeps the MAF sensor too cold. The "Flower Pot Mod" is needed to correct this, basically you need to shroud the filter from excess air movement around it.
The rest of the info given above can also help, hope you fix that hesitation as I remember how annoying and wasteful (gas) this problem was...

nope its got a stock NA bumper...well..atleast whats left of it :P hahah but my cone filter shouldn't be getting "too" much air, it has a stud on the top of it which is secured by a nut to the little plastic panel that is below it to shield it from water, so the only air that it is getting is from the stock ducts that piped air into the stock airbox.

Today i checked my car again with the scan tool, and a day ago it was running LEAN...however today it is again running right cycling from rich to lean and back and forth as the engine revs higher and lower..also everything else seeemed normal, but then again i have no numbers to compare them too. haha, could someone tell me what the pulse width/time/whatever you want to call it - for the injectors? Also, i was goingg to check the fuel pressure, but i was not told that the gauge i was trying to use was broken..so that reading will have to wait a few days but im checking it asap so everyone knows. I dont know if i said this above or not, but i did clean all of my electrical connections in the engine bay with the proper cleaner, and then put dielectric grease on them all to seal them all up. Hopefully this search will come to a close soon....its getting a little old at this point..

[grk nickafis]

Same problem on my car a week later my PTU fried. Just buy one off ebay for 30 bucks and see if its fixed.

[FlogWaffle]

Same problem on my car a week later my PTU fried. Just buy one off ebay for 30 bucks and see if its fixed.

wasn't there a recall on the old style PTU's?? Because i thought i read there was...and if there was it was never replaced on my car. but if there was can i still get it replaced, does anyone know?

[AchilleZ32]

My car would stumble all the way up to 3k and then suddenly, it would just stop hesitating. I replaced the tps, ptu, and I cleaned all my connectors and still, nothing. I was getting power to all the coils and I could hear the injectors opening and closing. My connectors all had the correct voltage as well... So basically, I was like wtf? I am getting code 55 and am running hellarich. Then recently, it started stumbling all the way up and you can clearly tell theres a difference in the exhaust note. I ohmed my injectors and #2 is ohming at 200, lol. My injector showed up in the mail yesterday, which i'm going to install on Monday. I'll let you know if it fixes my problem. I don't know if all this is even relevant to your issue haha.

Also, if you have the older style ptu, it will be silver and have metal fins. The new ones are black plastic. If you have the old style, take it to the dealer and they'll run your vin. If the recall was never done, then they'll replace it for you for fffrreeeeee

[es.biggs]

Same problem on my car a week later my PTU fried. Just buy one off ebay for 30 bucks and see if its fixed.

wasn't there a recall on the old style PTU's?? Because i thought i read there was...and if there was it was never replaced on my car. but if there was can i still get it replaced, does anyone know?

LOL

From a thread I started a few days ago:

If you have an older PTU (the one with metal fins on the back) and if you can't get the recall (for some reason) you can put it under the nose panel to keep it cool which will make it last a lot longer. I relocated mine because there were wires everywhere after the recall and it was very ugly. Less clutter in the engine bay also.

I never put my cruise control back on because I never even used it anyways lol

Ive been wondering about this PTU recall. I just recently started to read about it, but i have a 90' NA too, and i have the older style PTU...so what should i do in terms of this recall??

I called my local dealership and told them I have the old PTU. I gave them my VIN - they ran the vehicle's history to see if the recall had ever been performed (which it hadn't), and then I set up an appointment to come in later that week.

I was probably in the waiting room for almost 2 hours. So I dunno what the book time is on it, but it might take a little bit. My service adviser said there was only one guy in the shop who had done that recall before, and he told her it was over 7 years ago when he last did it LOL

[dantesdoom]

as suggested above...ohm the injectors...i had almost the same problem and it felt like i could "get out" of the power band where i was losing power....three of my injectors were on their way out....replaced and wham...tons more power than anything i had before

[grk nickafis]

Same problem on my car a week later my PTU fried. Just buy one off ebay for 30 bucks and see if its fixed.

wasn't there a recall on the old style PTU's?? Because i thought i read there was...and if there was it was never replaced on my car. but if there was can i still get it replaced, does anyone know?

I tried, It was probably replaced. They erase records of cars after 10 years so you can't check and they dont even have the part anymore. I got my complete kit from conceptZ performance. its the original replacement that nissan used way back then. It's not really worth it just buy the PTU and not the whole kit, ebay. I threw my old one out. But I can guarantee that yours was replaced or else it wouldn't have lasted this long.

[es.biggs]

Mine had the factory one on it until May (and it worked fine), when I had the recall performed by my local Nissan dealership, just like I said in my above post.

So basically, that stealership gave you the run-around.

[BigTDogg (MA)]

OP, if you have a Consult or Datascan, check your airflow voltage. If it's below 1v, your MAF is bad.

If your PTU has the fins on it, it's the old one and needs to be replaced.

[FlogWaffle]

OP, if you have a Consult or Datascan, check your airflow voltage. If it's below 1v, your MAF is bad.

If your PTU has the fins on it, it's the old one and needs to be replaced.

Alright ill check it on monday and post back, about the MAF.

but I do have a PTU with fins on it....what do i need to do for a new one? just order a new one? or is there actually a recall on it??

[es.biggs]

^^This guy must have hit the "ignore user" button on me or something. Seriously dude, are you kidding?
Follow this link and it will direct you 5 or 6 posts up in THIS thread:

still-hesitating-please-help-t513880.html#p5870253

All USDM cars were subject to the recall; here is my invoice (the recall was performed on June 30, 2010, not in May like I said earlier, oops)
I blacked out my address and phone number for obvious reasons



Right click the image and open it up in a new tab or window, so you can zoom in and read the information. It looks like the recall number was P4120, and it should still be an open recall. This was less than 5 months ago.

[FlogWaffle]

^^This guy must have hit the "ignore user" button on me or something. Seriously dude, are you kidding?
Follow this link and it will direct you 5 or 6 posts up in THIS thread:

still-hesitating-please-help-t513880.html#p5870253

All USDM cars were subject to the recall; here is my invoice (the recall was performed on June 30, 2010, not in May like I said earlier, oops)
I blacked out my address and phone number for obvious reasons



Right click the image and open it up in a new tab or window, so you can zoom in and read the information. It looks like the recall number was P4120, and it should still be an open recall. This was less than 5 months ago.

holy s*** dude im sorry! haha i completely missed your post above. my bad on that one..i honestly didnt even notice.. but thanks a lot for the info man, ill stop by my nissan dealer tomorrow sometime and kick some stones over there to see what they can do. Hopefully if they can fix it, my problem will go away!...i guess we'll see!!

[es.biggs]

Haha don't sweat it man. It might, but it might not fix the problem - at least that will be one thing you can cross off the list. It's a good idea anyways cuz the old PTUs always fail at some point.

If they give you any trouble about it, feel free to print that invoice out and show them that you're not taking any BS

[AchilleZ32]

I replaced the injector in my car and the miss went away completely. It feels great to be running good again

[FlogWaffle]

I replaced the injector in my car and the miss went away completely. It feels great to be running good again

rub it in....rub it in as i stumble around.. but my PTU is getting replaced (woohoo for recalls!) tomorrow...ill post back after i get it back.. at this point i learned not to expect a single thing to change no matter what i try, i always just got let down haha

[es.biggs]

Any updates?

[FlogWaffle]

Any updates?

hey man. Still no luck...it still has a stumble up to about 2500rpm. I got the PTU recall done after an ordeal with my dealership...which resulted in me calling corporate nissan to get them to b**** them out haha. But i got the new PTU, and it didnt do jack. So i went back to testing the electrical components under the hood. I checked the TPS again and it was .44v, where it is supposed to be. Then i ohm tested the injectors and they were all within the 10-14 range. I also cleaned all of the connectors (i forgot them last time!) I scraped off some corrosion on all of them and sealed them up with grease, test drove my car.....and it still stumbles. It seems to have improved...but it still has the issue. I have been getting 92 octane gas at the pump so that shouldn;t be a factor. However i did notice that my timing crept itself up to like 24 degrees btdc...so i set it back to 15, and it made it slower...and still didn't fit my issue. Any more ideas? I am nearing a point where i want to sell this car for a WRX... haha

[GerryO]

A dirty MAF element caused my F150 pick-up to engine stumble ever so slightly at each shift point and buck violently when in OD at freeway speeds.

[es.biggs]

Check out this thread. I had similar problems when I bought my car and it turned out there is a problem with the alignment of the CAS to the camshaft.

1990-300zx-na-hesitation-t475118-80.htm ... a#p5547780

There is a technical service bulletin (TSB) Nissan released about the problem, but they never recalled it, so it's not a free fix. The link above has a copy of that TSB that I put up there for future reference (aka right now)

Basically, check the production date of your car and see if the TSB applies to your car. If it does, pull the CAS off of the bracket (mark the spot it is in right now for when you re-install it). It's like 3 bolts and a connector - not difficult at all. When you get the CAS off, look at the peg that meshes with the camshaft and see if it is worn or rounded out at all. It should be a sharp, half circle shape on the tip. Mine was worn down a lot and it was rounded a bit around the edges. Also check the end of the camshaft for the same wear.

Read through that whole thread though if you get the chance to; it might help. Holler if you have Q's, and let us know the results!

[FlogWaffle]

hey man! Well i have some positive news atleast...haha today i cleaned my MAF and my throttle bodies (ROGUE DIRTY!!) and it helped a lot. somehow it didnt strike me to clean them when i did everything else..but atleast its done now haha. but my throttle response = now, but there is just the slightest stumble underneath it now. same as before, low throttle, however it doesnt sound like im making popcorn anymore, and it doesnt nearly keep me from moving forward from a stop. I found a piece of vac line that had a split down the side of it, and put a new piece in. I thinkkk there was another that was split but i didnt have another piece to stuff on in its place. So once i get that fixed up, hopefully it will help a little more.

but of course that TSB applies to my car! what doesnt.. :P haha. ill check my CAS once i have some more free time, and ill get back to you about that.

hopefully this time of running nice wont go away on me again. the last time i thought i fixed it, lasted all of 5 minutes. my car likes to play mind games with me aparently..

but i have a quick Q for you..(pardon me if this is a n00by) but i pulled my vacuum balance tube off to get my fat fingers to my injector connections to check the rear 2, and when i pulled it off there was some oil in my intake manifold?? and a little on the balance tube itself. could you hit me with a reason for this?..unless there is some amazing feature of the motor im misunderstanding here, i dont think you are supposed to see oil in an intake mani...


also, my car still has a bit of an idle issue. I need to adjust it down, because it idles at 1000rpm right now, but when i am say..sitting at a red light..it will happily and smoothly idle for a little bit, but then it will slowly start dropping down..900...800..750..and as it is doing this it becomes hella violent and the whole car, including myself gets shaken to death. It will do this for a little (i didnt give it gas..i wanted to see what happened once) and it lowers itself to around 650rpm?? and then hops back up to 1000rpm and idles smoothly for a few sec, and the cycle continues... could you point me in a direction for this?

[es.biggs]

The oil in your plenum is probably from bad PCV valves - have you ever changed them or do you have a record of them being changed? It's normal for them to fail over time. And if they are factory PCV valves it's definitely been time lol. I put Purolator PCV valves on mine (from Advance) - they are like $3 a piece. I decided against OEM because its a very simple product...no reason to pay 3 or 4 times more for OEM in my opinion. This is one of those rare cases. If you change the PCV valves, you will probably run into some very hard rubber hoses that you might have to destroy to access the valves. Lots of people use the silicone PCV hoses to replace the old, hardened factory hoses. Import Parts Pro, Z1, and I'm sure a few others offer the hoses. I use them on mine

Sounds like your idle is "bogging down." There are a few guides to help troubleshoot that type of problem...it could be a million things. One cure-all (sometimes) fix for idle problems is spraying some WD-40 into one of the Idle Air Control Valve hoses. That valve is on the back of the plenum and it has a large hose that runs up to the balance tube - you had to take the hose off to remove the tube. It is coming from the rear and it attaches to the balance tube basically on the back center and it has a hose clamp. Spray some WD-40 into that hose. You decide how much to put in there; I can't really describe the amount lol...just put enough to get it wet. The WD-40 cleans the valve and lubricates it, and basically performs a magic trick where it makes the car run better lol. I did this and the results were immediately noticeable!

If you are planning on removing your CAS, you might want to mark it so you know about where to put it back on so you can keep the timing close to 15. Make sure to double check and verify that the timing is set right after you put the CAS back on.

Here's a couple of articles that have some info about bogging, and lots of info about hesitation. Not sure if you've seen these, but they are definitely bookmark worthy haha

http://www.twinturbo.net/ttnetfaq/FAQpa ... tate2.html
http://zhome.com/ZCMnL/PICS/hesitation/hesitation.html

The second link is long but has a lot of good stuff in it! Def look into that

[JayShep1]

Its just frustrating to drive my car like this, knowing what it is capable of.

This is exactly how I feel. Took my car in for a "tune up" and when I got it back, hesitation starts. It seems that when I start her up she doesnt want to run like she should be. Feels like im driving in sand until i hit around 3000rpm, or 4th gear. The "tune up" consisted of new spark plugs, timing belt, and others. Im going to pull the plugs tomorrow morning before I go to work, I dont think the shop put NGK's in, but Im not sure if this is the issue. Any ideas would be greatly appreciated.