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Re: 4.6 stroker in 00' xj need help with pcm tuning and misf
Posted: June 26th, 2013, 9:57 pm
by Retlaw01XJ
bandofthHawk wrote:You can tell when you take a listen its a consistent ticking sound. Is detonation usually more erratic / spontaneous?
Detonation typically occurs only under certain conditions when engine is under a high load.....part throttle going up a hill, or full throttle blasts. If you hear it while not moving, it's something else.
The injectors will make a light ticking sound. You'll hear it when you put your ear near them.
Mine had a tap from under the valve cover which turned out to be the rocker hitting the underside of the cover!
Re: 4.6 stroker in 00' xj need help with pcm tuning and misf
Posted: July 11th, 2013, 11:31 pm
by bandofthHawk
Ok as far as that tapping / clacking sound i mentioned i found out its not my engine. I had a loose piece of plastic behind my cd player...doh..so nothing from the engine there. Pretty sure what im hearing is a slight exhaust leak coming from the header. I believe what happened is the previous ownee would over tighten the bolts every month or so in attempt to stop the leak but i think he probably deformed the header enough so where it cant sit in there correctly. O well. Could that exhaust leak solely be responsible for causing a misfire? Would that affect vacuum as well? I have always had a slight whistle during acceleration and when i step on the gas I have a rather slow return to idle. I always thought that was the split duration cam. im thinking typical vacuum leak now. Also i remember speaking with the engine builder and he said 87 gas is fine. I ran a few tanks of premium and it made no differrence. Once again you guys have been so helpful.