Join Date: Dec 2001
Location: Belleville, Illinois
Thanked 22 Times in 17 Posts
Re: Strange detonation problem
Sorry; I didn't pay attention to your specs. There goes another star [img]images/graemlins/mad.gif[/img] Now NOBODY will believe me!
Here's my (25-year old) recollection of the way my engine was set up: It had a very lean mixture in the mid-range circuit to reduce unburned hydrocarbons. It had EGR to lower combustion temperatures and consequently lower oxides of nitrogen. It also had an air pump to oxidize more hydrocarbons in the exhaust manifold.
The EGR caused a very flat, maybe negative, throttle response. As throttle opening increased, EGR also increased, resulting in a loss - or a disproportionally small increase - in power. Disconnecting the EGR made the throttle response more linear, but then the engine would ping very easily in that range because the lean mixture was burning so hot. Raising the metering rod one notch took care of that.
If you want to keep the Jeep emissions legal, restoring the EGR might take care of the pinging. If emissions aren't a concern (who said that? [img]images/graemlins/wink.gif[/img] ) bag the EGR and richen the mid-range circuit a little, (by whatever means - I'm not familiar with the MC 2100) and the engine will be a lot happier. Who said THAT? [img]images/graemlins/shocked.gif[/img]
Of course, that's after eliminating the other possibilities everyone has mentioned, such as bad ignition advance, carbon buildup, and so on.