Iīve tried to search, but didnīt come up with anything.

The problem is, that Iīve got lots of exhaust detonation. Iīve tried to set the FP from 41-52 PSI and the base timing from 6* to 12*. I got more detonations the lower base timing I had.

Now I donīt know where the timing is, but I guess itīs round 18* or so. The engine doesnīt pull as good as before, but Iīve got a decent idle and the detonations are gone.

Am I really meant to have that high base timing? It feels rather high to me.

My setup and other problems are discussed here: http://web.camaross.com/forums/showt...hreadid=142040

/Andreas

 

By exaust detonation, are you refering to the "Cackling under deceleration?" I have some Ideas, but I need more info. when was the timing chain replaced? was it replaced?

 

I have done a complete rebuild of the engine (didnīt need to bore the cylinders) during the winter, so the timing chain where replaced then.

What I mean, is when the engine gets warm and been idling for a few seconds and I hit the gas, there is a large "bang" coming from either the somewhere around the heads or either in the catalyst. Not when decelerating.

Hope I explaind it good.

 

Sounds to me like a valve is sticking.

 

I gone through your pervious post not totally but most of it and it still seems that it is a programming issue.
I have no idea what the heads are or what they flow but the basic back fire that usually indicates a rich condition or the fuel not burning totally up in the heads.
I personally think the ARAP bin is a joke and if you burn your own chips I have a good bin that you could start with just email me and I'll email it to you.

 

Ski89Z28, Youīve got a mail

 

Several things can cause detonation.

Too high timing.
inductive crossfire
hot spots
fuel contamination(oil, water, etc.)
poor gas
too much compression
plugs are too hot
motor is too hot

It is hard to believe that more timing would cause less detonation.
You really need to find out why. Take a look at those things and eliminate what you can.

 

Ski89Z28--> I tried Your bin (changed the injector constant and base-timing first). But I got some heavy knocks when I hit the pedal, so I saw You had put Power Enrichment Mode Spark Advance to Zero. That was a huge Advance table You used then.

Too high timing - the higher, the less detonations for me
inductive crossfire - there should not be, no wires cross eachoter hot spots - donīt understand what You meen with this
fuel contamination(oil, water, etc.) - nope, checked that
poor gas - You meen the quality? Iīve tried with 3 diffrent "brands", and also tried with some fuel-adder
too much compression - what Iīve understood, not with these heads
plugs are too hot - hmm, Iīve isolated the heads, and rerouted the wires
motor is too hot - 160* termostat and lowered the temp. when the fan starts, so it should not be

 

Glimmer, If it is knocking you may want to play with the injector constant. BTW what did you set it to? Work with this till basic acceration is obtained with out knock. Then you may want to decrease the Power Enrichment vs rpm. Especially between 1200 rpms to 4000rpm area.
Oh do you have any backfire still?
Remember only adjust one thing at a time and see the results this way you can narrow things down to the adjustment of the one thing you did.
Hope this helps.

 

Oh, I also realized You locked the BLM.

Iīve tried 25, 27 and 28. It still runs to rich, so Iīve tried to lower the FP without result. Dont get it.

Hmm, Iīll try some more.

 

inductive crossfire - there should not be, no wires cross eachoter
It can also be caused inside the cap.

hot spots - donīt understand what You meen with this
Hot spots are carbon deposits inside the combustion area that heat up and stay hot and can cause pre ignition

poor gas - You meen the quality? Iīve tried with 3 diffrent "brands", and also tried with some fuel-adder
Ok. I assume you are using 93 octane.

plugs are too hot - hmm, Iīve isolated the heads, and rerouted the wires
I meant the heat range of the plug itself. The hotter the plug, the more chance of knock.

motor is too hot - 160* termostat and lowered the temp. when the fan starts, so it should not be
At what temp. does the motor run at?

 

Inductive crossfire - how to check with the rotor and cap? I use the big red MSD rotor and MSD cap.

Hot spot - heavenīt checked that. The car has not been driven too far since rebuild

Poor gas - We donīt have the same specification of the octane as You do, so I really donīt know. But I do use the highest available here.

Plugs too hot - Oh, sorry. I use 2* lower than stock. AC-Delca something (donīt know the name of them)

Motor too hot - Itīs about 180* misc. and a bit lower on the highway

 

[QUOTE]Originally posted by Glimmer
[B]Inductive crossfire - how to check with the rotor and cap? I use the big red MSD rotor and MSD cap.
That probably isn't your problem then.

Hot spot - heavenīt checked that. The car has not been driven too far since rebuild
This probably isn't either since the rebuild was not long ago.

I really don't know what it could be. Are you POSITIVE it is knock from pre ignition?

 

Well, nocks really isnīt my big problem, itīs the exhaust detonations. I havenīt been able to check the car last two days now.

The thing is, that if I raise the timing to like 16*-18* I get rid of the detonations, but the car wonīt pull the same. And what ever I do with the prom, it still runs rich. Iīm only a beginner with the promīs, so I really donīt know where to proceed right now.

About the plugs, do You think I should buy new plugs to test with? If thatīs the case, should I go even lower, or should I chose a higher?

 

What do You guys think about these heads?

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2423446753

http://cgi.ebay.com/ebaymotors/ws/eB...tem=2423867416

Iīm really not sure about what type of heads to go with. How much more expensive are AFR?