NEED SERIOUS HELP

[jschimms]

i am new to the forums but have been reading them for awhile. ive done ALOT of reasearch but cant figure out whats wrong.

i have a 1991 n/a z32 with 180,000 miles. oil has been changed regularly with high milage, spark plugs are the right ngk plugs and are only 11 months old. the car pops at idle and randomly idles either really high (1500 rpm) or extrememly low (600 rpm) i have tested injectors all at 13 ohms tps is set to .45 like it should be. recently clean all connectors in engine bay. cas is great, maf is newer, took off IAA module and air regulator and cleaned the hell out of all of it yesterday and nothing seems to fix it. power balance test shows all cylinders work as they should. PTU is newer one with pig tale harness and zero corrosion. timing is dead on at 15 degrees, all grounds are erfect and clean.

im am so close to gicving up and scrapping it cuz im fed up with it running like s***. any help would be so appreciated.

[nissanfreak12]

Sounds like you have a vacuum leak. Best thing to do is get a boost leak tester, works on an NA just the same. Just do not go above 5psi, that will guide you in the right direction. With your injectors running at 13, they might be on their way out, or at least one. It is very possible the injector test good, but it could be giving a higher reading at the ecu due to the old wiring.

I had a similar issue, replaced all the injectors with new style, popping was gone, just never had the idle change. Idle change usually means vac leak. That would be the first place I would start.

[Shoey2]

vacumm and injectors are usually the cause of these issues. you seem to have eliminated alot of the potential issues so your definitley getting close.

[jschimms]

Just an update on the progress of the z. Took off the IACV and Air Regulator, both ohm tested perfect took the regulator apart and the spring inside was off the vaLVE which caused the z to idle at 2000 rpm steady. fixed the spring and bought new vaccum hose for all of it. about to put it all back together and post the results.

[Ace2cool]

Good luck! That would definitely cause an issue like that.

[jschimms]

AH HA!!! idle finally down to about 950 with spring fixed in air reg thank god. vaccum hoses were a pita slightly but got them on all air tight. i was so closed to takin it to the scrap yard no joke if i couldnt figure this out haha. these cars are very aggrivating over the simplest things. still have the slight pop at idle and a hole in my driverside cat that i noticed when seafoaming the car just now. would that cause the popping? i know its not a timing/injector problem because its really random and not constant in the firing order. oh and last issue haha... the car shakes suuuupppppperr bad when releasing the clutch in first i read something about the driveshaft center support bearing possibly blown out in second and third etc its smooth driving. or my clutch is slipping when it heats up. any ideas?

[Ace2cool]

Just in first? Probably the clutch. Either that or you're letting the clutch out too fast and it's trying to stall. I don't know how long you've driven a manual. If you have the car in gear, clutch fully engaged, and accelerate in first, then let it decelerate, and accelerate again, does it shake?

The hole in the cat would cause the exhaust to pop as well.

[jschimms]

No I've been driving a 5 speed for years and I know when its gonna stall and I know how to dump the clutch. Starting in second is smooth the clutch pedal is adjusted. Its only after its fully warmed up and doesn't do it when I pop the clutch. Transmission and motor mounts are in great shape after 22 yrs. And basically it happens in stop and go traffic whenever im in it.

[nissanfreak12]

When was the last time you cleaned your throttle bodies? 22yrs on mounts, they may look good, but lift the engine up without disconnecting the mounts, guarantee they will separate. Rubber deteriorates after so many years, bad mounts will cause it to buck and /or shake, especially in first. This is when the most torque is place on the car.

I had another thought, does the shaking ONLY occur when you release the clutch? If it does, how old is the clutch? What brand? Did you have the flywheel resurfaced? I have seen and felt horrible chatter from a burned disk on a clutch, it will cause the whole car to shake, and would only do it in first gear. This normally happens to a clutch that is poor quality or from riding the clutch, it will glaze or burn the surface of the flywheel.

[nissanfreak12]

Yes, like Ace said, hole in the exhaust will cause a popping sound randomly. Injectors will do the same, the popping will normally be random when the injectors are on the last leg. Even a bad O2 sensor can cause the popping you may have, bad fuel/air mixture.

[jschimms]

Looks like ill be getting new injectors soon enough. Its weird cause the pop sounds like its in the cats hence thinking my cats were clogged. I really do appreciate all the help from you guys. The cars still runs a little rough but its slowly progressing. Once I restore the hp its supposed to have and the gas milage ill be satisfied. Hopefully I can post a video of how its running soon so you guys will have a better idea of the issues im talking about.

[jschimms]

Well in the last few days the Z has been running better but there are still a few issues. Once i get a chance to drop the exhaust and see if its casuing popping and hopefully buy new o2 sensors that will fix that issue. The thing I am noticing now is a weird sound from the passenger side of the motor. The sound is just like when you shift to a higher gear too soon and it bogs out but its only noticeable from first, second, and third gear then you dont hear it in fourth and fifth. I know im not bogging out because i shift every 3000-3500 rpms unless i really get on it. I know its not the common water in the AIV's because recently i deleted the system and cleaned it all and put it back in hoping that it was the cause of my previous problems. To no avail during all my searching online i cant find anything about it. Is it possible that the PCV valves on that side if the plenum are either clogged or the hoses are cracked making that noise only happen on that side? And if I take the brush out of the PCV hoses will that have adverse effects on the motor or PCV system it self? We're almost done getting the z back to its original luster and all of the advice you guys are giving me is the biggest help ever.

[jschimms]

When was the last time you cleaned your throttle bodies? 22yrs on mounts, they may look good, but lift the engine up without disconnecting the mounts, guarantee they will separate. Rubber deteriorates after so many years, bad mounts will cause it to buck and /or shake, especially in first. This is when the most torque is place on the car.

I had another thought, does the shaking ONLY occur when you release the clutch? If it does, how old is the clutch? What brand? Did you have the <A class=vglnk title="Link added by VigLink" href="http://www.ebay.com/sch/i.html?_nkw=flywheel" rel=nofollow target=_blank vglnk_1360105726732="3"><SPAN>flywheel</SPAN></A> resurfaced? I have seen and felt horrible chatter from a burned disk on a clutch, it will cause the whole car to shake, and would only do it in first gear. This normally happens to a clutch that is poor quality or from riding the clutch, it will glaze or burn the surface of the flywheel.

Sorry I havent answered your questions I didnt even notice your post. I cleaned the throttle bodies sparkling clean about a week and a half ago. You are probably right on the mounts but the motor doesnt shakes much at all when reving. And yes its only when releasing the clutch in first gear. I had the same thought about the clutch and i have no idea how it looks or what brand it has. I am deffinately sure its not the stock oem clutch seeing as how the motor has 180,000 miles haha. I was really just hoping its not the drive shaft Center Support Bearing.

[Ace2cool]

Revving doesn't put any torque on the engine.

Also, Don't take crap out that's not supposed to be removed. If you're worried about it, unplug the PCV hose to see if there's a restriction. Are you sure there's not a vacuum leak somewhere?

[jschimms]

I should have worded that better, i didnt intentionally take it out... when i took off the driver side pcv hose connected to the accordian intake hose the goes to the vavle cover by the throttle body the bristles on the brush crumbled and im not sticking just the metal piece back in is all.

[Ace2cool]

If it's that bad off, get a new one.
http://www.z1motorsports.com/advanced_s ... ywords=pcv

[jschimms]

thats the plan i was just wondering if it would effect anything till they get in

[nissanfreak12]

Vacuum leak, possible oil leaking through the PCV system.

The shaking you speak of, I am really putting money on it being the clutch. The center carrier bearing will do it speed related, so more than likely its not that. If you really want to see how bad the mounts are, pull the e-brake, put it in first and slowly let out the clutch. It will torque the engine enough the see if they are separating, if you do it in reverse, it will show the other side.

Follow what Ace said, get the silicone hoses and replace. You will never have to worry about them again unless you cut them yourself. A suggestion, make sure you clamp all of them, even if the factory clamps do not fit, find ones that will.

[jschimms]

So today i had an interesting idea. i read on a post that n/a ngk plugs were supposed to be gapped to .044 to run right. so even though my current plugs only have about 6000 miles on them i bought brand new ones at autozone. I gapped the new plugs at .035 (tt specs for plugs) and the older ones at .044 (supposed n/a specs). after throwing in the .044 plugs i started the car and had residual exhaust pop as ive been posting about before. then after a few minutes and the aac let it idle down to normal warm idle it started running like garbage. so i swapped out the plugs... and BAM most of my previous problems disappeared!!! really made me feel so much better aout the z. so if you havent tried it before, get a spark plug gap gauge and try .035.

[Ace2cool]

Curious, what made you try .035?

[jschimms]

I looked forever for n/a spark plug gap info but the tt .035 came up everytime. finnally i found the n/a gap size but it didnt help anything. so i said it couldnt hurt to try the .035 and it is better, atleast for me. more deffinate spark due to shorter distance im guessing. im still trying to figure out this hesitation/exhaust pop issue. today i changed the fuel filter hoping that the fuel pressure was just low. totally made no difference. ive listened to the motor by ear and hear no misfires what so ever. i did the screw driver te the ear on the injectors and cylinders/valves and they all sound good and the same both sides. its really really bothering me that i cant figure this issue out. if i tap the gas really quick it hesitates and the exhaust goes pop,,poppop...pop but not loud. its actually not notice able to anyone that doesnt know aout it. when driving it doesnt do it until i downshift and it sounds like an old v8 idleing.

The timing is perfect (just used the timing light on #1 coil pack wire, ptu ground, and high tension extension wire) at 15 degrees everytime. with 180,000 miles is it possible that the cats are plugged? also when i rev an excessive amount of h20 comes out of the exhaust. ANY IDEAS????????

[jschimms]

So just some updates for the z people. After being a dumbass and putting a phase 2 injector in a phase 1 fuel rail and flooding the #2 and #6 cylinders then trying to start the car without removing the spark plugs and blowing my starter off the transmission and destroying the clutch slave cylinder and almost blowing up my whole damn car because i was pissed off and a total dumb a**. I know i did almost everything ompletely wrong and feel retarded no additional comments needed haha. I got everything drained new slave cylinder, starter, correct injector and o rings. I got the car started and running. i re wired a few injector connectors and its running alot better. My issues still lies with idle being slightly retarded so to speak.

I cant for the life of me find any vaccum leaks. The ptu is great, coild packs perfect, injectors perfec tohm test, cas and timing are exactly where they need to be. The only thing thats killing me is when the car is running and i unplug the iacv (yellow) connector the idle doesnt go down until i restart the car. Then i adjust to 650 rpm and plug it back and idle idles up as it should and setteles at 900. regular for my car. Then after a good 30 seconds it goes down to 650 then back to about 800 and back down to 650 back and forth. i tap the gas and the car shakes a little hesitates then revs up. I ohm tested every possible sensor/module under the hood and there perfect. Im at a brick wall still.

I was wondering if any of the gaskets go bad in the motor could cause and vaccum leaks causeing it to run roughly. please help me figure this out cuz i will end up lighting it on fire haha.

p.s. clutch slave cylinder bleeding was a b**ch

[Ace2cool]

Yeah, there is most likely a vacuum leak somewhere. What you can do is spray some starter fluid around the engine bay to localize the leak. If you spray somewhere and the idle changes, there's your leak.

Is the idle stable when you have the IACV unplugged? Sounds like there might be an issue with the IACV itself or the gasket.

[jschimms]

So i took your advice ace and used the starter fluid trick. Totally worked haha. The balance tube on the passenger side o ring was nearly destroyed and on of the bolts actually strippied out of the plenum. Got a new o ring and bolt and fixed that issue. The air regulator to balance tube hose had a vacuum leak as well so i got that taken care of. I am nearly complete with getting her running up to par. I have found out some things recently as far as the TPS. It is supposed to read .45v/.50v when adjusted properly with the hard idle switch on. When the hard idle switch isnt on and the car is at idle it will idle at 1500 rpms steady, which it does... sometimes. Sometimes it idles ust fine. So i unplugged the TPS with the car running and it stalled which I figured was normal. Plugged it back in and restarted it. Idle still at 1500. unplugged the 3 pin connector to the tps and it didnt chnge anything. plugged it in and unplugged the TPS connector and this time the car stayed running. Pretty weird I thought. I cant seem to find a way to test the TPS without an interface device because i dont have one and financially cant afford one. Is there any other way to test the hard idle switch with the TPS?

Next issue is the IACV system. With the car at operating temp I unplug the connector (yellow) to it and the idle doesnt change. But if I restart the car it idles down to 650 like it supposed to but only sometimes. I ohm tested every component an connector involved with that system and EVERYTHING is getting the correct ohms/volts that it is supposed to. Could the gasket be the issue even though it doesnt have a vacuum leak. If i can figure these 2 things out i am 100 percent sure i am done fixing the issues i am having haha.

Any ideas from the z lovers out there?