jaredjmoore89

I finally finished my Z and its idles great, runs strong and sounds good. THe main problem is when i give full throttle around the 3k rpm it starts to miss. Half throttle and anything less its not there just full throttle. Where sould i start. Im buying new spark plugs hopefully thats it.

ZLover4Life

Could be spark plugs, but also check your fuel injectors. Resistance across the leads should be 10-14ohms.

jaredjmoore89

You were right it is the fuel injectors. One of them is bad and im just going to get a wgole new set. Problem is what kind should i get. I thought might as well upgrade while im at it but i dont have the money to get nismoo 555. What else would you suggest thats a little cheaper. I was looking at the venom 550's but i heard they were crap. Also what do i have to do totune the ecu for the upgrade and how much does that cost.

ZLover4Life

Only get OEM injectors. If your Z is early model years (90-93), look into upgrading to the newer style, or you better get used to replacing injectors. When I replaced all 6, I stuck with the old-style (555) injectors... since then, I've replaced 1 every year.

300Degree rails + new style injectors (stick with 370 else you'll have to upgrade your ECU). Several vendors sell kits for the retrofit.

jaredjmoore89

You got me convinced lol, im going to go with the stock injectors, but the problem is i cant find a kit anywhere. I could probably just replace the bad one, but they are all really old and i wanna replace all.

ZLover4Life

You did not look hard enough.

http://specialtyz.com/fuel.htm
^ They don't show stock injectors as an option on their site, but you can get them if you call.

http://www.importpartspro.com/fuelcomponents.html
^ Again, call for stock injectors.

http://www.conceptzperformance.com/C...65.189.244.214

http://www.z1motorsports.com/index.p...34b69cf70f4a52

jaredjmoore89

With the pruce everything looks i think im just going to replace that one bad injector, because everywhere i see the stock injector kit its 1000 dollars and thats insane. Iv seen aftermarket 370cc injectors go for 300-500 and im sure they would work just as fine. I know stock is better on those im sure but i just cant afford that.

ZLover4Life

... for a few months.

Buy cheap, buy twice. Mark my words.

If you can't afford that kind of upkeep, then you're in for a HUGE surprise with an aging Z32.

91zxtt

....and how do you know they'll work just fine? Doesn't sound like you've done any research, so what you should say is, "I bet they'll work just fine."; to which we would respond by saying, "If you can't afford OEM, then sell your car instead of pissing your money away and ruining a perfectly good Z."

Merry Xmas.

jaredjmoore89

Just got new injectors and plugs put on and cone to find out it wasnt either one of them causing the miss, although i still needed to replace it all. My coil pack was completely broke in half im assuming from the last mechanic that i let work on it that dropped the bolt in my turbo. The last thing i need help with is that the EGR return tubes are blocked with some sort of really hard material. I think i read a while back that this is done for some reason but i wanted to be sure. If they are blocked and they are for a reason is it necessary to bolt them back up because those bolts suck. Had more trouble with those then the whole process all together.

KasbeKZ

doing an egr delete is fine if that's what you're asking. if you're talking about the black crap build up in the ends of the hoses where they go inside the upper plenum, that needs to be scraped out. yes, it's hard and almost looks like it was built in there. but it's just crap. scrape it out if you want the EGR to work.

jaredjmoore89

What does the EGR do because if i dont need it them im not going to worry bout it.

jaredjmoore89

NVM i know what it is now i found it but could this be the cause of the miss. I really dont think it could be but im not a genious and im wrong a lot.

ZLover4Life

EGR is very much not likely a cause for a misfire. But it is a good idea to remove it. While the EGR can cause poor performance, I have never witnessed it causing a misfire unless it actually destroyed the engine (which is possible, but only likely if the EGR was connected wrongly).

There are only three things needed for ignition - fuel, air, and spark. I'm pretty sure you're getting air in the cylinder (if you weren't, you would've started this thread with something like "my timing belt snapped..." or some other catastrophic problem), so that leaves fuel and spark. When you put in the new injector, did you install *new* o-rings? And if so, are you certain that you didn't pinch the o-rings (if you pinch one, it could cause too much fuel to leak into the cylinder, causing a misfire)?

To test for spark, pull the plug out, insert it into the coil pack (make sure it's touching the lead), touch the threads of the spark plug to a ground (the plenum works, just make sure it's not near fuel - touch the corner of a throttle body or something), and crank the car. The spark should be both visible and audible. If you don't see it, try a different coil pack first (coil packs can go bad). If a coil pack from a working cylinder doesn't get it to fire, you probably have a wiring problem and we'll cross that bridge when we get to it.

While the spark plug is out, listen for the injector firing. You should be able to hear it while cranking (and smell it, of course).

mayitin

Zlover4life you really are an Encyclopedic Knowledge I just enjoy reading the answers an learning from them. Were you or are you a mechanic? or you just learn it as you worked on cars? Thank you for answering on the posts I learn a lot. your saying about the worse kind of advise... is so true. I remeber when I had an olds diesel wagon and I wanted to put ona a 350 gas motor verybody gave me advise how easy it was, so when I had problems and I asked all these gurus no one had every done the swap and it was not that easy, it was not a take out put put other back on no sir it was not. in provers reads " even the fool is seen as wise when he keeps his mouth shut"

ZLover4Life

Thanks for the compliments. And that's a great quote.

I was once a technician specializing in Nissan Z cars (not certified or anything), but most of my experience comes from my own car. Most of the ones I worked on at the shop were basic repairs and aftermarket part installations (and most of the diagnosis was done by the shop owner). When I've had a problem with my car, I'm the one to do the research and figure out what's wrong with it... and my cars have had a LOT of problems, hence my experience. lol

ZLover4Life

Back to the subject at hand... one other thing... I forgot you were the guy who was planning on buying cheap injectors. If you went this route, I would NOT be surprised if the brand new injector you bought is, in fact, dead. Test its resistance (again, should be 10-14ohms). And if you even think about coming back here and saying you bought another cheap replacement to replace a bad new injector, I want you to re-read this thread and look at those words that I told you to take note of. ;p

jaredjmoore89

Thanks for the help but the injectors are working great , but the main problem is that my coil pack was broke in half and a wire was put in there to make it work and im sure that still didnt make it work. The last thing i got to ask is that if my egr valves are cut off and blocked do i still have to bolt them back up because those bolts are the worst things i have ever had a problem with on that car. They are in the worst spot. Thanks

ZLover4Life

What do you mean the EGR is cut off and blocked? (And you don't have multiple valves, just one valve that feeds both sides of the plenum.)

I'd recommend a legitimate EGR delete kit. (You say they're cut and blocked, but if you have a TT, I'd be willing to bet it could blow off whatever you used to cap the tubes.) And no, you don't have to put the EGR valve back on if it's not going to do anything.

jaredjmoore89

What i mean by blocked is they put someting in the ends of the pipe thats really reayll hard and its red feel kind of like jb weld but red. Also i just got the coil pack on and it still misses so i played around for an hour and theres a hose that comes off of a sensor that connects to the balance tube thats kinked and when i squeeze the kink out it idles up a lil higher and actually sounds like it runs better. Any ideas on that.

jaredjmoore89

Oh sorry its the larger hose that connects to the balance tube in the back.

jaredjmoore89

Its the hose coming from the iaa unit. Seems like this could only cause idle problems but could it cause a miss when u get on it.

rtmorgan

some pics might help

the bigger black tube coming from your air inlet duct on the divers side that goes back to the iac is what your car runs on at idle.

ZLover4Life

2nd rtmorgan. That hose should not be kinked.

And it should not be able to cause a miss. How do you know the injector of the cylinder that's misfiring is actually working? Did you test its resistance or are you just adamant that "because it's new, it must be working"?

You swapped coil packs with a working cylinder and that didn't solve the problem? Check the spark plug itself (swap with another cylinder if you can't tell if it's good, or you can use the way I detailed earlier in this thread). Let us know the results.

jaredjmoore89

The injectors tested fine and the spark plugs are all new, i replaced them when i replaced the injectors. Im really not sure what else it could be. It runs perfectly fine if i only give it half throttle and it idles just fine with no missing sounds at all. It only does the missing noisewhen i get on it and if im taking a corner lol i know that sounds weird. I thought a lot bout it and could that mean my fuel pump is mayb bad. All my ideas are out. Thanks for all the help because this is really getting frustrating. I also i havent checked the fuel filter but thats most likely not the cause unless it was reall stopped up.