I got the car tuned thursday. Ran like a champ! It was a cooler night weather wasnt above 70 degrees. Drove the car all day no problem pulls here and there. The day after im driving to work car runs perfectly fine 55miles. Throughout the day it got really hot about 85degrees or so. turned it on. Started to pull out and the car sputters exactly at 2600rpms. drove the car about 40 miles and it always sputtered at 2600rpms every gear. Got the car scanned it said misfire in cylinder 3. Swapped out the coil in 3 to 1 to see if it was the coil. Then I had a misfire in 1 and 4. and it would misfire only during low rpms..about 3.2k and under. Drove the car home from a friends around 1:00am it was chilly out ran home like a champ NO MISFIRE! I was confused. Went to a meet still backfired and this was around 11pm or so. Cruised home no problem going through low rpms. I did a highway pull WOT, SMOOTH AS A BABIES BOTTOM! when I got on residential streets again. It would sputter around 2500-2600 rpms on and off. Cleared the codes at autozone since the car was driving normal. When i got to my house there was no cel light so i thought him maybe it was the weather. I didn't do any pulls from autozone to my house. Went to bed woke up the next morning and took my dad for a ride pretty hot out. Was driving normally until I got on the highway gave him a pull("HE SAID HOLY SHIT ITS FAST!") Coming up to my first light its start misfiring again. NOW IM Worried? CEL light came on so I headed back home. I thought the heat of the engine bay may be messing with the coils. Causing a misfire or the spark plugs blew the gap out when I did a pull. But it turns out all of the spark plugs are gapped to spec. Check the Resistance on the coils. Everything seems alright. I have no clue what is going on? Anyone have an idea what could be causing my misifires?


Mod list


Inlinepro Stage II street Kit.

Borg Warner S366


Tial Waste Gate

Inline pro Chain tensioner

Inline Pro oil filter relocation kit
Stage III competition Clutch

ID 1000cc injectors

Aeromotive Fuel pump

Aeromotive Fuel Pressure regulator

4 Bar Map Sensor

Hondata KPro(with all the sensors)


Mishimoto Radiator.


Dual 3 Inch Turbo Back .

Turbo blanket and other MISC heat wrap.


454whp and 327lbs of torque.

Could it be a bad sensor?
Could the heat in my motor caused something to malfunction? My hood it not vented yet.

 

running lean? whats the afr's? whats your plugs gap? heat range 8?9?7?

 

How many miles on your motor/coil packs? (though it seems very unlikely they would all go bad at once)

Misfires are usually (in order of cheapness): spark plugs, injectors, coil packs, head.

Since everything but the head is new, when did you have your last valve adjustment? You have an ap1?


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Also, we are sure wires are tight, coils are pressed down (screwed down) on plugs etc right? The obvious things have been checked?

 

Yes, for about 30 seconds when i turn it on it sits at 14.8 then I down slowly all the way til the end of the red were it stops reading numbers then it starts misfiring. The plugs are gapped to .024. I bought 2 step colder spark plugs im not sure of the heat range.

Sparks seem okay. I did blow the gap out at one point. I regapped them and the gap has not changed since. Injectors are brand new. Coil packs, I would be suprised that they would go just like that too, I did a resistance test on them and they seem okay. The car has 24650 miles on it. I have not done a valve adjustment since the miles low and im not sure if the people before me have done it I bought the car with 16600miles. It is a AP2. Is it possibly I messed up a retainer/value/springs in my head? I don't here any ticking or anything like that. It just misfires.

 

Yes, when it first started misfiring the gapp was off. Fixed the gap the see if it was the problem. It cured the problem for about 4 miles and while at the car wash it started up misfiring again.

 

Start with new plugs honestly. The same plugs though so your tune isn't affected of course.

 

Aside from the obvious checks, where was it tuned?

 

update: Did a compression test everything checked out good. Coils were good. Spark plugs were good. Noticed that there was gas leaking on my fuel rail. It was coming from my fuel pressure gauge. That was retightened. The car hasnt misfired since. It definetly was not the tune. I got it tuned at AMS. The car drives like butter! I also got a new map sensor just be on the safe side. Yesterday at WOT the afr was 12.1(scared me) now it is 11.3 so I can sleep peacefully!

 

Could the cause of this be when my engine bay gets extremely hot on a hot day(the last 2 days have been cold and it hasnt done it) it messes with my coils or sensors, causing the misfire? I don't have a vented hood yet.