jewbacca

iTrader: (5)

Been trying to figure this one out for a while now. Car runs fine in open and closed loop, but in closed loop I get a ridiculous amount of spark retard. I can get as much as 12 degrees at idle. WOT shows 4-7 degrees all throughout the RPM range. But in open loop I don't get any spark retard. When I am cruising I don't see spark retard that often, but when I do it's usually at lower speeds. The car doesn't throw any codes, nor does it run bad at all in closed loop. I picked up some 101 octane and logged it yesterday, and am still seeing the same problem. The car has ported heads and intake, a hotcam, 58mm TB, and hooker long tubes. Stock MAF, no cats, and a mail order tuner. I'm currently running stock injectors, but I have a set of 30lbs ones to go in when I get a retune for them. I've notice the car does tend to run slightly on the rich side (hovering around 14.3), but I always chalked that up to the spark retard. I'll try and upload one of my logs tonight if anyone wants to take a look, but I thought I'd see if anyone has any ideas.

shbox

What is the knock count register doing?

jewbacca

iTrader: (5)

It seems to be going up at a steady rate. It increases sometimes without showing actual spark retard (which I've read is ok, but not sure). It increases in open loop as well.

jewbacca

iTrader: (5)

Just to clarify real quick, you're talking about the knock counter? At least that's what it's called in TunerProRT.

Ed Wright

iTrader: (1)

First, if your knock sensors aren't over torqued, you have an engine noise setting them off.
Second, if you have a bigger cam that lowers manifold vacuum, you have a tuning issue if it actually shows knock retard, not just the spark advance backing off.
Spark advance moving around at idle is perfectly normal, the PCM varies spark advance to stabilize idle speed. Actually showing knock retard is not. That is a tuning issue.

jewbacca

iTrader: (5)

Ok, I'll have to talk to my tuner about fixing the knock retard at idle. I've logged with both TunerProRT and with DataMaster. Both are showing actual knock retard at idle, as well as all over the RPM range. The guy who helped me put the engine together really knows his stuff, so I don't believe the knock sensor is over torqued. Can things like RR and long tubes cause that much spark retard at idle due to false knock? I also forgot to mention that I do have an LT4 KM and roller rockers.

Ed Wright

iTrader: (1)

Any engine noise can cause it, as well as the exhaust system in a bind. If the exhaust system pops a lot cooling down after shutting the engine off is a clue to that. Solid engine mount cause it too. Solid roller engines are bad to do that, if the tuner doesn't know how to stop it.

bufmatmuslepants

iTrader: (3)

Could be something as simple as your header touching your k member, under acceleration the engine is torqued to one side, at idle it shakes to both sides. Just something to check that's easy and common.

jewbacca

iTrader: (5)

I'm wondering if that's my problem. I do notice a bit of a tapping sound especially at idle. I think it's the passenger side header that is really close to the k-member on my car. I can't remember which way the engine torques, so it might be hitting some of the primaries on the k-member. I might try and stick my jack under the passenger side header collector, and see if I can move it a little bit more away from the k-member (no I don't plan on jacking up the entire car from the header collector).

jewbacca

iTrader: (5)

Found my problem. Looks like the header is contacting the k-member a lot more then I originally thought. Two of the passenger side primaries are basically resting on the rear lower a-arm mount. I tried putting my jack under the collector and carefully raising it to maybe bend the header upward some. Went as far as I felt comfortable, but I didn't want to do something stupid like break a weld. I'm going to probably try and pull the header and "clearance" it some more (hammer). Also trying to figure out whether I should swap in poly mounts to keep the engine from moving as much. I know they cause more vibrations, but I'm not too concerned with that.

bufmatmuslepants

iTrader: (3)

Boom. Inspect your mounts, if the rubber is cracked and sagging going to poly could gain you a little room. Otherwise a BFH works.

jewbacca

iTrader: (5)

I looked at the mounts when the engine went in last year. They didn't look all THAT bad, but they are 120,000 miles old. I didn't see any cracks, but I'm sure they're sagging. I think you have to remove the headers anyway when you replace the mounts, so I'll probably give the passenger side mount a little persuation while it's out, just to make sure it doesn't contact the k-member anymore!

mcalus

iTrader: (14)

How'd it go? I may also have a false knock. I want to get this figured out.