I have an 84 Berlinetta that is idling really rough. I've done all the usual stuff (plugs,wires,timing,etc). Does the 84 LG4 motor have a temp sensor that controls air/fuel ratio on the carb? Wouldn't I get a check engine light if that fails? Just trying to figure out why the idle is so rough. Also, by the way the temp gauge in the car doesn't work. Are those two tied together?

Any ideas/help would be appreciated.

 

Back in the day when I had massive bog on accelleration, I checked several areas. I don't recall getting a check engine light though. good that you've already done "the usual stuff," so now you can move on. a mechanic told me that my temp sending unit could be crapping out on me. I'm not sure if it controls a/f directly, but it will make the engine fluctuate from open loop/closed loop. it doesn't cost much for a new unit, and the old one is easy to find. it's either mounted in the neck of the thermostat or on the intake manifold near the thermostat. when swaping units, watch out for spraying coolant

edit: that didn't solve my bog problem, but it did make things a LOT more tollerable. it has since been decided that a stretched timing chain is the culprit.

 

Thanks for the information. I do see a sensor in the water neck housing. The is also a sensor in the drivers side block. I'm assuming the block one must be the sending unit for the gauge. I've also found out my EGR valve is bad. Would that cause it to run rough at idle?

 

YES, a bad egr WILL give you a bad idle. I couldn't tell you if one sensor was for the guage and the other was for the comp. Deffinately fix your egr problem, regardless

 

Temp sensor in the intake (2 wire) is for the ECM.

Temp sensor in the driver's side head (one wire) is for the dash temp gague.

An EGR valve that is stuck partially open (leaking for any reason) will send the idle to heck in a handbag pretty quick- definitely fix it.

 

Most excellent. Thanks to both of you. I'm changing both this weekend.

Take care,

Devin