All right,

My dad has a very odd acura legend to say the least and no one can figure out what is wrong...

It is a 1993 legend L sedan with 100K miles.

The problems are this;

The car starts fine and idles decent for about 3 minutes when cold at which point it proceeds to bounce the idle between 1K - 2.5K RPMS. It just bounces up and down. This will eventually stop after the car is driven and gets warmed up.

The second problem then occurs, once it is warmed up sometimes, not all the time and not predictably, the car will spike the temperature guage for a few seconds. This seems to happen more in colder weather but it has happened in the heat as well. When this happens the heater stops working and no heat comes out no matter what the dials are set at. The guage will gradually come back down anwhere from 10 seconds to 2 minutes. It just gradually fluctuates, as in not rapid changes.

This has been ongoing for about 3 years now and no technitian has been able to solve it. This car has been through numerous thermostats, radiators, radiator flushes, and even the head gaskets on two occasions. The last time this was taken to the acura dealer and they pronounced it fixed after about a month, but the problem started happening again recently.

I was hoping one of the tech guys in this forum may have a suggestion as to what this may be as we are all pretty much stumped. My guess is its electrical related but thats just a guess.

Thanks a lot for any input in advance.

 

For the first problem, check for cracks in the exhaust manifold. If that is not the case, look replace the IAC.

The second problem, I didn't see any mention of replacing the ECT?? If not then that would most likely be a starting point. But I suspect it is just a worn wire which is a PIA to track down and fix.

 

Ok, ill have my father look into the first one.

But I dont get your abbreviations IAC and ECT?

Sorry im not a huge technical person when it comes to that.

Thanks for the help to this point though.

 

IAC = Idle Air Control Valve
ECT = Engine Coolant Temperature Sensor

 

IAC is your idle controller (little servo motor which controls a small air valve) "Idle Air Control"

ECT My guess "Engine Coolant Temperature". He's saying to check the temperature sending unit. Might be a electrical problem. However I might be wrong with his use of ECT.

 

Doh, I see Scalbert answered while I was

 

www.acura-legend.com

Search the forums, there have been similar problems with the surging idle. Also, the overheating sounds exactly like the blown head gasket problem.

 

I'm sorry to say but it defenitaly sounds like a Classic case of the headgasket blues . Air in the cooling system is causing idle fluctuations and erratic temperature guage operation.

It happened on my 91 and it has happened to many others.....a hairline crack or leak in the rad will cause the 'flawed' (acura knew of a mathematical head to gasket design flaw during production) head gasket to blow around the 3-6 cylinders.

I almost spent the price of a head gasket trying to diagnose the overheating.....99% of the time it is the HG.....hopefully it can be fixed soon before it has a chance to warp/crack the block (like my 91 ).

Good Luck! and defenitaly go the the www.acura-legend.com forums for more info.