slight shake at 2500rpm

[commodore12345]

Hey all I have a vt v6 auto, holding revs or making or slowly go past around 2500 rpm the engine can shake abit then clear up as more revs are incresed or goes away as revs are decreased, I have spent months trying to fix this slight pop in the exhaust system holding slight revs aswell, I am left with new injectors and a custom tune as im putting more air then the stock setup should be into the engine and have heard computer needs to be matched, I will replace my pcv hose as it could have hairline cracks aswell but thats all I got left to think thats causing the slight exhaust popping noise, it may be a valve but I have had them out and new guideseals, any ideas would be great, my leads, coils, plugs are good and I have had the car running with no air filter and still seems lik its doing it, I have extractors and I know there own noise but abit of revs nd this slight pop or miss is heard.

 

[Towcar]

Is it definitely a miss, or engine related vibration?

Could it be drive line?

 

[commodore12345]

It's a miss, I open the throttle body by hand listening carefully and its the same noise, , ill probs end up just replacing the knock sensors too and can do injectors easy, injectors lead to 15 problems out of 31 in engine problems, read lots of things to make myself learn, I am close to fixing the problem, I have heard having bolt on mods u do need to tune as car can miss fire, but im sure it was doing it before I put on bigger throttle body and extractors, soon enough ill have cold air intake and bigger ratio rocker arms, then I thought it would require a custom tune..

 

[Tsunamix]

MIsses are more likeley to be sensors than injectors. Injectors are pretty fool (fuel?) proof.

Coil packs also spring to mind though.

 

[commodore12345]

Ok it defs starts to run rough from 2400 to 3400 rpm after tht its clear as so im putting it down to miss through driving speed range, my spark is fine! All coils are good, im left with injectors dirty injectors and im 95% sure this is causing it, no leaking vacuum or egr valve leak so yeah.. but its fine to rev before and after those revs but during it its rumbling and shaking and its def not low cylinder compression lol, as I said I run it with no air filter so its basiclly left the the injectors 92 bucks for a new oem set nd will do the job easy my self, I just hope there the problem as there is nothing else unless a blocked fuel filter but ill have tht changed soon to.

 

[lout]

new injectors are closer to $90 each not a set
have a good auto elec or holden check your long term fuel trims at that rpm range
are all the mods you fitted compatible, i have seen too many mismatched parts in motors
i would be looking at electrical system CAS or coils

 

[commodore12345]

The 90 doller set are oem and do the same as factory, fuel trims r fine, I bet its a injector I have fixed everything on the car in the last 3 years but them, yes I know what parts match the car mate!. For #### sake!!!!! The coils are brand new msd coils, I said the coils are fine in the first mesaage, new dfi, was a mistake to waste my time asking here again havent heard anything smart from a regular on here, I'll have it fixed soon

 

[DJ_Cosmic_Fire]

OP. this could very well be the MAF playing up perhaps as it is one of the main factors in communicating to the PCM what happening in-terms of air intake

 

[lout]

well sorry for trying to help
but if you can explain how injectors can be a problem without a related change in fuel trims i am eager to be enlightened
only been a mechanic for 30 years, but what would i know

 

[commodore12345]

Thanks, Will look at it but have replaced it in the last year as I have had serious problems with it before, 5 mechanics failed relise it was a bad connection to the maf with took me 3 seconds to fix, either the maf will play up or it wont. I Laugh at the people who sprint out to waste 30 bucks on a can of maf cleaner, I have dumb f holdens and they said cant do much with there brains unless the tools are hooked up they use, but its down to injectors for me, I posted this incase anyone else suffers this problem.