86z28iroc-z

iTrader: (1)

Not to sure if it's a misfire or what but, when holding a low speed around 25 30ish i'll get a little blip in the exhaust note, and I can feel the car very very slightly surging, it's very minor but very annoying. Not sure if it's a misfire or what?

During acceleration it runs fine and holding highway speeds of 55+ it's not there. Only crusing around town.

Specs are in the sig (only about 700 miles on her so far), and I've got a pretty decent tune, I've attached a log, but I don't see anything out of the ordinary when i'm holding 28ish mph, but maybe I'm missing something. Which leads me to believe that it's something mechanical...but with most everything being new, I don't' know where to begin to look...

It was more noticeable when my timing at cruise was around 31, and less when i progressed up to 41. If that means anything?

Thanks!

Supervisor42

Are the injectors the original ones?
A dirty fuel injector will cause what you describe.
If they are 20 years old you might want to run some injector cleaner thru them. Shouldn't hurt anything...
(you'll get some replys nowwww)

AlkyIROC

The TBI in my truck did the same thing. I always noticed a slight miss while sitting at a light. I changed the injectors and the miss went away.

86z28iroc-z

iTrader: (1)

Hmmm, they are pretty new 24# SVO injectors, I purchased them from a member on this site. They looked almost brand new. They all ohmed out too....

I'm not sure if it's even a misfire though, it's very very small whatever it is. It only happens every 5-10 seconds it'll run nice and then blip run nice for 10 seconds and then blip runs nice and then blip.

Hope its not the injectors...

AlkyIROC

That's what mine was doing.

Injectors wear out. Electrically they can be fine but mechanically, they still wear. When I'm working on a diesel engine and the driver complains about lack of power, I check the hours on the engine. If it has a lot of hours then it's suggested that the injectors be changed. It normally fixes the problem.

Buying used injectors is no guarantee that they're "almost new"

86z28iroc-z

iTrader: (1)

Sweet odins ravin....

Do you think that they might actually just be dirty? Running some injector cleaner thru them as someone else suggested won't screw anything up? Being a new engine and all?

**** me off....

Supervisor42

...and your ZIP file is corrupt.
Anything else we can help with?

86z28iroc-z

iTrader: (1)

I'll re-zip it when I get home, not sure why it's corrupt.

Is there any test that I can do to see if it is indeed the injectors?

When I get the log setup, you can't see any blips in the BPW or anything? Or does that not show descrepincys when the injectors go bad?

Sorry bout the pissed comment, just kinda frustrating when you pay big $ for something that possibly doesn't even work right.

Thanks for your help though, appreciated.

Also, does running injector cleaner thru an engine harm anything? I guess i've never been the type that runs anything other than gas and oil and antifreeze, stuff that was intended to be there, kinda scepticle about off the shelf products.

86z28iroc-z

iTrader: (1)

Was just thinking, this all started to happen after I put headers on the car...Wondering if maybe the spark plug wires are getting to warm?? Would that cause a misfire? I tried pushing all the boots on to see if they were all tight and they were way to hot to touch.

Just thinking.

Thanks!

Supervisor42

It could. Mostly it will cause a cylinder to drop out completely during WOT and acceleration. You can usually hear it snapping if you don't have open exhaust.

86z28iroc-z

iTrader: (1)

Well, it doesn't blup at idle or when acceleration, only when holding a constant speed of 25ish mph and when decelerating or in gear and just letting the engine pull along around 10mph, anything above 30 it's fine. And as long as I keep my foot slightly on the gas and accelerate very very slowly from 25 to 30 over a period of 10 minutes it won't do it, just when constantly at the speed. Which is kinda weird if you ask me...

Another way to explain it, i'll be going along burrrrr and then it'll burrruhbuuuuruhbuuuuuruh, kinda pulls a little bit and you can see it on the tach, it'll go down 40-50rpm. And then it'll plub.....plub..plub on light decel.

If that helps any?

Here's another try at the zip.