Hey guys, I’ve searched far and wide on the web and can’t figure out what’s wrong with my Z. So basically whenever I’m between 2-4K revs my car will stutter as if it’s going to stall. Sometimes it’ll stop but majority of the time it’s constant stuttering like it’s misfiring or losing power. The thing that’s strangest to me is that my car is showing no codes whatsoever. I’ve looked at multiple forums and people say it’s a bad coil. So I checked all the coils and they’re all reading perfectly fine on my multimeter and also no oil on them whatsoever so the gasket seals are fine. While I was at it I changed all my spark plugs. Some people said it might be the maf sensor so I cleaned that and made sure there were no holes in the air intake when I was changing the part plugs and tightened everything back up and that didn’t change anything either. I checked the cam sensor and that was perfectly fine and clean too. Checked the o2 sensors and they were fine also. Lastly I changed my oil because people say that might be the issue but low and behold that didn’t do anything either. Anyone have any ideas on what it could be?

 

Welcome- how many times have you scanned the ECM for codes?

 

about 6 times. Nothing shows up. I unplugged a few things on the engine and tested it again to see if my device is broken but codes showed up so it’s not that and then I plugged everything back in and the codes cleared and nothing is showing up again but my car is still misfiring, stuttering, jerking, whatever you wanna call it

 

Did you pull all the coilpacks off at same time, or individually?

 

I disconnected the sensors from each coil individually while the car was on to see if the idle stayed the same and it only stayed the same when I unplugged coil 5 so I took it out and there was on oil on it so the seal on the rocker covers are fine and I tested the ohms on the coil and it was reading 1.5 which is what it should be reading and the spark plug was worn out so I took that out and changed that and decided to change all of them and test all the coils and they all were reading 1.5 ohms so I don’t know what the issue is.

 

Sounds like it could be a fuel issue if none of the things you tried have worked.

 

I put my odb scanner in and tested the codes again and these 4 came up. P2135, P0123, P0223 and P1122 which is all throttle position codes. Would these codes be the reason for the misfiring or stutter or is it more than likely bad fuel injectors?

 

I’ve also looked up the codes and people say bad throttle body and people who get these codes have trouble starting their car but my car starts and stays on perfectly fine it’s just when I’m driving it misfires and stutters bad. Like imagine you’re in 4th going 10mph and your car jerks and stutters really bad that’s what it’s like but in any gear and any speed except sometimes it’s not intense or goes away for a few seconds but I don’t have any engine light or codes that tell me it’s a bad fuel injector. Am I just going to assume they’re clogged?

 

If the codes are saying throttle, why are you dead set on injectors? The gears in the TB are pretty finicky if/when the butterfly is manually opened

 

I posted a few days ago but got some new information. My car stutters bad when driving, imagine you’re in 4th gear going 10mph and your car stutters and jerks trying to pick up power and speed. My car is doing that in any gear at any speed, sometimes it’s not intense, sometimes it goes away for a few seconds but it comes back and my car misfires and shakes while idle or in neutral. I plugged my obd2 in a few times and nothing came up but I plugged it in again and the codes P0123, P0223, P1122 and P2135. I cleared the codes and they didn’t return again. All those codes have to do with the Accelerator Pedal or Throttle Body according to other forum posts and people who experience these codes either have trouble starting their car or keeping it on but my car starts and stays on perfectly fine. People have been saying bad fuel injectors but how exactly do I tell they’re bad? And shouldn’t an engine light be coming on or a code telling me what fuel injector is bad? or could it just be clogged and not getting enough fuel?

 

as i said last night, if the computer (which is made to control the systems and tells you what is wrong) is saying it is throttle related, why do you keep wanting to touch the injectors?

 

Just bring it in. Seems like you want to fix things that are not broken. Ever think it may be the throttle body going out?? Opinions. Every one has one. Spend the money. Get an opinion that will
fix the issue.

 

More than likely an issue with the throttle body. Start there.

 

+1 on the throttle body.

Perform the throttle close/position and idle-air relearn operations. Retest and see if that sorts it out.

If you manipulated the throttle butterfly by hand at any point, there’s a good chance it’s botched. As mentioned above, the gearing is very fragile in the throttle bodies.

Someone can correct me if I’m wrong here, but while the fueling on the Z33 is calculated predominantly from the measured air volume, the ignition tables first respond to changes in throttle position before taking feedback from the knock sensor, etc. I think this particularly applies during injector cut when the TB snaps closed on decel. So if the problem is on acceleration, AND your TB sensor signal and actual TB position are out of alignment, you could potentially end up with a timing problem that causes the misfire.

TLDR: Reset the TB, test, replace with new TB and gasket if reset doesn’t work.

 

I’m saying is it fuel injector related because everyone I’ve asked has said it might be. I’m saying it’s not the throttle body because as I said I’ve taken the throttle body off and tested the resistance and it’s getting the power it should be and I’ve done the throttle reset everytime ive touched it. Haven’t tested the harness yet and another reason I’m saying it’s not the throttle body is because my car doesn’t stall or having problems starting like it does with every other person that has the same codes on this site. I tested the pedal harness and it’s getting the power it should be and the pedal sensor itself is getting resistance from pins 1 and 4. Also 3 and 6 but none in 2 and 5 but I can’t find the specs on it anywhere so I don’t know where the problem is

 

hard to take it in when you live out of home and pay a mechanic absurd amount of money to find the issue. Why take it in when you can try to fix the issue yourself from people who have had similar experiences and similar problems? The reason I don’t think it’s the throttle body is because A). I’ve checked the power on it and it’s getting the power it should be according to specs. If it were the throttle body would it not be stalling and having trouble starting like it has with every other person who’s had these codes on this site?

 

have checked the throttle body and it’s getting the power it should be according to specs. Haven’t tested the harness though. Pedal harness is getting the power it should be and pedal sensor is getting power but I’m not sure what the specs are for it as I can’t find it anywhere

 

I’ve tested the throttle body with a multimeter and it’s getting the resistance that it should be according to specs. I’ve done a reset on it and it’s still continuing with the problem. Would you still think I need to replace it? You seem like the most knowledgeable person here

 

Good luck kid.....the onboard computer is smarter than you are,

 

The advice is to perform the throttle body relearn procedure, if by "reset" you mean you tried that then you could try replacing the throttle body completely but you should probably just take it to a mechanic. You have codes from the car now that should lead a mechanic to the right place.