I have an 89 se vg at. I have a tiny miss that I can feel through the wheel at idle to about 2100 rpms. The injectors are all 6 brand new from nissan. I changed the cap and rotor, fuel filter, seafoamed, spark plugs. Two issues, plugs are not yet verified to be gapped correctly, I have to re-check them and I have not yet changed pcv. I believe it is a miss, but it is definately less intense than a miss caused by injector failure. I listened to the injectors with a screw driver and they sound to be firing at different speeds. The rubber covers for the injectors are cut at the top, but the wires are not exposed. I think that covers all my attempts. If you think I can find the answer by searching (I didn't have much luck) feel free to delete my thread. 20mpg consistantly, so not a big miss. My vacuum lines are cracked and need to be fixed too.
Thanks for any help.

 

different speeds from each other? or you checked to see that they fire at various RPMs?

have you checked compression yet? mebbe you have one cylinder that isn't holding air as well as the rest of them.

 

Yikes, I have not checked compression, hasn't had any major issues and has been driven by my grandmother up to 114,000m. 118,000miles now, so I would hope nothing would cause compression loss. I listened with a screw driver at idle to the injectors and the clicking rate seemed to vary from injector to injector. Another thing to add is that there are no codes given from the ecu (not cel, i checked ecu) not that that means much.

Biggest thing is that it is not very noticeable, passengers cannot tell and I have to be rather still to notice it.

 

what about the wires and coil.
i have a crack around the coil and i found out the hard way, was filling r134 in the compressor and got one hell of a shock.

i think timing could also be an issue too....

 

could be motor mounts.

 

Mounts are going/gone bad, but I think that is amplifying the problem rather than being the single cause. Timing is a real possibility though (friend brought it up before), what would I check for that? Would it be something with the belt being off a tooth? Belt was changed 30,000 miles ago. I don't know how to check anything about timing. Also, not sure about coil, but wires are relatively new (could need changing maybe)
Thanks for the replies so far.

 

I would go and do a compression test, as suggested before. then post the numbers so somebody can confirm they are all ok.

 

not timing belt. you would know if it's off a tooth.
the ignition timing.

i just reread your 1st post 2100rpms is when it goes away.
eh...i had the same problem on my ve turns out the exhaust valve was burnt , not sayin yours could be like that.

but it is said that if that cylinder runs lean for quite sometime it'll burn out the rings, valves or something to that...

 

I have been experimenting with it and I do not believe it goes away entirely anymore. I just is less noticeable because it doesn't halt the engine or shake it as much as lower rpms. When I let my foot off the gas, I feel it much more, especially at near-idle rpms, it is like a bogged-down vibration feel that gets less and less as the rpms raise. like a tiny car-hiccup so small you can hardly feel it.

 

Compression checked the engine. 180-185psi on all cylinders...

 

I've had a similar problem when I was modifying my intake.

Injectors are all good seeing as I haven't had to replace them, I doubt compression being the problem, and I do have theories involving MAFs since it is an intake I was working on.

 

a healthy engine! so above 2100 rpms does it pull very well...

 

It pulls very well at all rpms. Most people (not too knowledgeable about cars) say it feels normal for an old engine, but that isn't satisfying me (I feel that helps describe the severity of the miss) after ruling out most posibilities I am left with the idea that it may be ignition timing. (I have no idea how to troubleshoot/fix that). The only other thing that confuses me was how the injectors sounded to be firing at different pulses (some click faster than others). That is about all I am left with, so any ignition experts around? Thanks for the replies so far.

 

it is 100% normal for a perfectly functioning motor to run a little "rough" that's why motor mounts aren't solid. they are there in part to absorb said roughness, and prevent it from being transmitted to the passenger compartment

 

Well then maybe I am just being obsessive. Thank you very much for that then, and when funds allow, I will purchase some new mounts.

 

if you decide to do the ignition timing, you can either do it by ear or get a timing gun....