detroit evo

iTrader: (3)

I have experienced this issue as well. It occurs primarily in 5th gear but I have experienced it in 4th and 3rd as well. I sounds to me like a missfire and other times is sounds like detonation. The engine warning light has come on twice and it indicated detonation.

I am not too experienced with turbo cars but I think the issue can have several causes. Boost leak, I don't have a boost gage to study this. Something triggering the knock sensor causing it to jam up the works. I have even been wondering about over boosting. My merkur XR4ti had overboosting issues every once in a while. Also been curious about the spark plugs, when are they replaced for a hard working Evo.



Does anyone know if the engine computer goes into an open loop, set fuel/air/spark timing map when the car is at wide open throttle, WOT?

One theory is that in 5th gear the torque advantage of the engine is lost to the point that at low rpm it overpowers the stock partially used clutch. The stick/slip jerky action of the clutch causes an oscillation of the engine rpm up and down. This in turn causes the fuel/air/ignition map to choose the wrong cell in the fuel/air/spark table for the engine at any instant.

96_LXR

iTrader: (3)

I have the factory gauge and also a Defi boost gauge. According to the factory gauge I am peaking at 19psi, the Defi has shown a max of 20.3psi.

Also according to the factory specs, the 4G63 has 75% of peak torque availabla at 2500 RPM's.

If I want to get on it, I roll on the throttle a little and when it starts to spool at about 2800 then I go ahead and gas it.

On a crappy side note, my car got broken in to in a very nice, well lit neighborhood, in a cul-de-sac at about 6 PM.

The bastards used a pry bar between the window frame and the top, wedged it open and then probably two people yanked on the window frame and pulled it about 6 inches away from the door jam.

They stole the crappy factory gauges, the Defi gauge and controller, a radar detector and my cell phone (first and last time I'll leave that in the car).

The stupid part is they didn't get the sending units for any of the gauges so they are basically worthless.

The car has since been repaired, looks awesome but they still don't have the gauges for it yet.

Impulsoren

My car has been doing this lately as well. It is defenitely pinging when it happens. It is not any kind of a leak or boost cut, it is pinging from high boost and high timing at low RPMs, combined with bad gas. I always buy 92 octane Chevron, but depending on which station it comes from the car may or may not ping in this situation. Individual stations are franchises, so different stations of the same brand of gas may have different scruples as far as what they do with thier gas. I suspect several stations in my area are mixing lower octane with their 92 because 95% of the population will never know when they get cheated, and the franchise owner makes a bunch more money.