Misfire after build.

[JerzNick]

I finally finished the build. Installed the following mods:

XP-Cam
CompCam Lifters
Ported Gen 3
Ported TB
Ported Heads
AutoLite 104's
3.25 Pulley
Speed Daddy Headers
Wideband o2

Started it up and it idled perfectly! Opened HP Tuners and started Scanning while I drove for a half hour or so. Without boost the car seems to drive pretty good. The instant I make the slightest boost, it starts to misfire. Not only can I hear it in the exhaust but HPT sais "multiple random misfire". Again, it only seems to happen when throttle is 50% or more... I tried APP606's to see if the plugs would make a difference but to no avail. any ideas???

Thanks in advance

[Fivefingerdeathpunch]

Arent you suppose to delete the P0300 after putting a cam in?

[JerzNick]

Arent you suppose to delete the P0300 after putting a cam in?

[BillBoost37]

Yes...you are. Otherwise it'll often log a multiple misfire and run like crap.

Nick.. look at the how to setup an HPT file in the tuning section stickies and fix that stuff as well.

[88formula]

I finally finished the build. Installed the following mods:

XP-Cam
CompCam Lifters
Ported Gen 3
Ported TB
Ported Heads
AutoLite 104's
3.25 Pulley
Speed Daddy Headers
Wideband o2

Started it up and it idled perfectly! Opened HP Tuners and started Scanning while I drove for a half hour or so. Without boost the car seems to drive pretty good. The instant I make the slightest boost, it starts to misfire. Not only can I hear it in the exhaust but HPT sais "multiple random misfire". Again, it only seems to happen when throttle is 50% or more... I tried APP606's to see if the plugs would make a difference but to no avail. any ideas???

Thanks in advance

Your build sheet looks.... identical to mine. lol

[JerzNick]

Your build sheet looks.... identical to mine. lol

lol, And how is yours running?

I followed Bill's advice and turned off misfire/egr reporting but now I'm getting a knocking sound from my motor :\

I think it's coming from the supercharger, I need a mech stethoscope!

[JerzNick]

Yes...you are. Otherwise it'll often log a multiple misfire and run like crap.

Nick.. look at the how to setup an HPT file in the tuning section stickies and fix that stuff as well.

Followed both hpt guides Bill, nothing was mentioned about turning off those codes. Once I turned em off, it ran great for about 20 minutes then a knocking sound

Sounds kind of like the s/c rotors clacking... weird.

[BillBoost37]

You pulled the belt and checked the SC right?

[JerzNick]

Just pulled it today. Needs new bearings and seal... Fuggin money pit :/


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[BillBoost37]

Much better than the alternatives that can make knocking sounds.

Rollingperformance.com .... make it happen.

[88formula]

Mine is not put back together yet. Have a long ways to go.

[BillBoost37]

That's an hour away from being in a car..

[Sven the Sexman]

Bill, what are you doing? You can't be posting at this time of night.

[88formula]

That's an hour away from being in a car..

Check out my build thread, I got a little more too it then your typical L67 powered car. Plus I still need to buy bigger injectors, WBS fuel rails, fuel pump, and buy+install a shift kit while the cradle is removed from the car. Then once that is all said and done, and I have the motor reattached to the cradle I then have to fabricate a complete custom header back exhaust. Doesnt help I can hardly find the motivation to work on my car anymore... OH and I forgot to mention once it is all put back together I have to buy a wideband, and HPT then tune it myself. It will be quite the adventure!

[JerzNick]

Bro, that is one NICE looking engine so far

[BillBoost37]

Ok, so why is it going to take more than an hour to finish the engine assembly?

[JerzNick]

Bill, Vid here of noise... I re-did s/c bearings and it hasn't gone away... Sounds like valve train maybe?

It's only under throttle you can hear it, not idle.

Noise - YouTube

[Utter99]

Eek that doesn't sound to good .
Flex plate could be cracked hopefully.
Also sounds like my car . You don't wanna hear what's wrong with mine ..
Again

[BillBoost37]

Time to pull it back out Nick. That sounds like either a flex bolt or the bearings in the bottom end of the motor.

[JerzNick]

I'm getting very aggravated with this car. Every time I fix or replace something. Another piece goes bad. Wtf?!


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