Engine Hesitation and Loss of Power

I was driving up to Crossgates yesterday when out of nowhere, I notice a loss of power when I step on the gas. The engine sounds odd too, the exhaust note is “pulsating”. I headed home and popped the hood and I found that a radiator hose wasn’t secured and I was leaking coolant a bit. I checked the coolant and the level and color is fine, so I just slipped the hose back on and tightened the clamp. I also checked the MAF and cone filter and both seem to be fine. So my next guess is either fuel delivery or spark. I’m going to check the fuel filter and swap the spark plugs for NGK iridiums today. I’m curious though as to what you guys think the problem is.

I had a similar issue when I was running on 5 out of the 6 cylinders, made a pulsating WRX sound. Turned out it was a broken wire in my injector harness.

Did you clean the MAF?

My car did the same thing when my coil packs were shitting the bed. I kept telling VW service that my car would jerk or fall on it’s face out of no where… Their answer: make sure you have the clutch all the way let out. (AKA - You’re a girl and obviously can’t drive.) So I would say yeah probably check the plugs…

Im going to lean towards a head gasket for following reasons.
-loss of compression or power on 1 or more cylinders. hence the exhaust noise and lack of power
-compressin leaking to coolant system. radiator hose blowing off due to higher than normal system pressure.

check your fuel/air/spark stuff first especially the ign. but if everything is fine try a coolant pressure leakdown test first (cause its easier) and then a cylinder compression leakdown.

Dont drive it cause if this is the problem coolnt in your oil will wash out your bearings… ask me how I know… :idiots

is your exaust white and smell sweet?

Yeah, I cleaned the MAF and air filter. The mesh on the MAF is all intact and looks good aswell. I’m hoping its not an injector but it does sound and feel like its not firing on all 6. I can get a video clip up once my phone stops tweaking on me. I’m going to OHM test the injectors as well.

Doubt its a head gasket. The exhaust is fine and the color of the fluids is normal, they haven’t mixed.

I had a bad ECU and it did the exact same thing you are talking about…

I hope Johawk is wrong.

Check the coolant. You can get a coolant tester too to look for hydrocarbons.

There are 20420909249 ways to explain this but the coolant thing trigged my head too.

What would I be looking for in the coolant? Oil?

edited post above ^

Alright, I’ve made some progress. Did a cylinder balance test a few minutes ago. I copied my reply from my post on the Z forum.

I only had to pull two coil packs before I found the misfire. Its cylinder #1, (passenger side closest to the front bumper). I pulled #3 first and the idle changed. Pulled #1 and it stayed the same. I did get a spark though when I pulled #1, it jumped and contacted the plenum. Does this rule out spark plugs and coil packs?

Edit-I should probably add that I got a somewhat strong whiff of gas from the tailpipe. Also in the weeks preceding the misfire, when I would go to start the engine, it wouldn’t really crank. It would just kind of start right up instantly. I always thought there was something strange about that.

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Got it figured out, my injector is dead. It OHM’ed at 0.lol

Changed plugs, tested coilpacks, cleaned air filter and MAF. Even pulled codes from the diagnostic comp. and got nothing. Hopefully tomorrow I can get that new injector in. I’m gonna need to grind the plenum to get to the injector screws though, I hate Nissan. lol

let us know after you install the new injector is the misfire is fixed…

Good job going through the analysis.

Thanks, I’ll post up when I’m finished

sweeeeet dont u love engineers !

Seriously, wtf is with the plenum design on the VG30DE’s…

Its either grind the plenum to get to the bolts or pull the plenum all together to replace one bad injector.