Thread: L67 engine block

Okay, so I am giving it another try at getting my car to run right. I have had it modded for a couple years now and just quit messing with it because I couldn't ever get it to run right. It has excessive amounts of knock (up to 10*). I only have a 3.4 pulley and you can see in my sig I should be very safe with this setup. If the engine is still cool (160-170...not cold) and I get on it... it hauls butt without misfires or knock. However, once it gets up warm (running temp-185ish) I can barely get on the gas without it trying to knock or misfire. This leads me to wonder if my car somehow had the higher compression engine block (L36 I think) put in it. That's the only thing I can think of that would cause so much knock when it's warm... unless I just have an extremely special car that needs methanol to run a 3.4 lol. Anyways... Is there a dead giveaway difference between the L67 and L36 engine blocks? Thanks for any help guys.

1.) They're the same blocks..

2.) quit beating on the car when it's not up to temp. Knock sensors don't kick on till op.

3.) I think you need it scanned if you can't do it yourself.

yeah, your knock sensors dont read until 160. are you using a tuned pcm or did you have a custom tune?

He's got a tune from Brian.. Idk if Brian changes the on temps or not.

**not custom... canned**

Its not cold... I don't get on it until its over 160 probably close to 170... a 160 t-stat would keep the engine colder than that. I promise I'm not a stupid teenager tearing up their car... lol

I thought I read the knock sensor kicked on before OT... maybe not. But I thought you could get away with a 160 thermostat and not have to mess with knock sensor values. Just what I remeber reading somewhere, no backing to it at all. Lol

Okay... so there is literally no way for me to tell if its had an L36 (I'll be more specific) "long block" put in it?
And yea, its a custom tune from Brian. The issue has nothing to do with tune though. This is the 3rd pcm this car has seen and the issue has been persistent.

I appreciate the input

Any block is gonna say series 2 on it.

You need to get it scanned. And possibly put the stock pulley on if you have it. A custom tune is gonna be best.

I just wanna know what you have done to try and rid the misfires?

Plugs, wires, coils, ICM?

Any of those?

Also, and this may be related to the problem, what keeps the fuel pressure up when the fuel pump isn't running? I know the fuel pressure regulator, but what about on the feed side? After I replaced my fuel pump the fuel rail looses pressure after sitting for a minute. Oh, its not the injectors leaking either.

Its had a few sets of plugs, couple different sets of wires, and all new coils. No ICM... yet! Lol

Btw, it does not misfire at all until it starts knocking. So I don't know if maybe misfires are causing the knock or if it is misfiring because of the pcm pulling timing... the later would be my guess.

A stock pulley would do zero good... it hits 5lbs of boost at half throttle and bam... like 6* of knock. A stock pulley will put out that much boost no problem. I stay out of the boost when I'm just driving. I only get on it when I'm messing with it trying to fix the problem.

FPR will control the pressure in the fuel system.

if you do KOEO the pressure should stay around 40ish for a long while.

Yea.. I know... and it doesn't lol.

The fpr controls the return side, but what about the feed side. For example, if I cut the feed line in half would it not release all the pressure? What keeps the fuel from leaking back out of the feed side? Is it something in the pump assembly?

The feed line in the assembly is leaking... just checked that out. Its only dripping so whether or not that's affecting WOT performance I don't know yet.

That's why your knocking bro. Your leaking pressure.

I sure as heck hope so! That would make my day. Only problem is I now need to pray some two part epoxy will seal it up or its a new fuel pump assembly for me...

Bit the bullet and bought a whole new assembly. I'll post back when I get it in. Hopefully it fixes it, but I'm doubtful.

It didn't help... I didn't figure it would, but my car starts the first time I turn the key in the morning now lol
This knock will never go away... guess I'm gonna have to make the drive up to Brian to get it custom tuned because I don't know anyone locally I can trust. Something has to be different about my car, and I'm really starting to believe it has the higher compression L36 long block in it. If I stay under 5lbs of boost I'm golden. Any more and it wants to knock and misfire like crazy.

I don't know how fast a l67 is with my setup... But this thing pulls hard and will screech the tires at 40 around 3/4 throttle (only boosting about 6lbs). Is that fairly normal or does that sound like the engine is putting out a little more power than normal (as the higher compression L36 will do with less boost).

It's real... If I take the s/c belt off I can beat on it with zero KR. And as long as I don't let the boost get over 5-6lbs the KR is at or close to zero. I'm seriously considering buying a 4.0 pulley for it... lol

Now has new fuel pump assembly and a known good ICM... same problem.

Is there an actual compression difference between a L36 with the L67 top end components? I know compression ratios are different, but what about the actual compression? Will it be higher? I really want to know if my car has an L36 lower end... I saw that a bolt was missing out of the transmission bell housing, which leads me to believe either the engine or trans was pulled at some time...