Arizona = Hot Temps - Running Rough in 100+ degree

[tomytum]

Hey guys.

Any input on rough engine conditions when the weather is 100+ degrees...

Symptoms:
1. Runs rough when AC is on
2. Idles rougher (@ red light)
3. At night when temps are in 90's and below, it runs alot smoother.

Car: 91 Accord
Mileage: 327k

Other note: Need to do: radiator and thermostat flush/replacement.
(Though thinking about replacing rad to Koyo Racing Rad and low temp thermostat to compensate for heat) - Good Idea?

[cloudasc]

First i'd clean your iacv if you haven't recently.

Second I would check your timing, and go through the procedure to reset your base idle.

Third, I would possibly replace all your vacuum hoses, as the excessive heat could cause the rubber to swell more turning the hoses from O to o.

Fourth, a good radiator is always a good thing, as for the low temp thermostat, it will do nothing but help your car warm up quicker. What you should consider is a low temp thermo switch, but if your running the a/c, your radiator & condensor fans are always running, so it wouldn't help keep the car cooler unless the a/c is off.

Hope this info helps!

[trickery]

327K ! thats alot of miles! I would check you fuel economy on a freeeway trip to give you another indicator of engine conditions. If you fuel economy is poor then you know its a result of needing a more general tune up. Cleaning it IAVC is super easy, id do this prior to resetting you idle as it tends to change the way the idle if they go from clogged to un clogged.

Ultimately you must be doing something right to have wrung that kinda mileage out of it !

[HondaFan81]

Make sure your cooling system is working properly and the fans are kicking on when they should.

If your radiator is deteriorated and not holding 16 psi of pressure, then replace. All you need is an OEM Koyo radiator, good quality. Race is not necessary.

Replace radiator cap as well, they can go bad and not hold proper coolant pressure needed to reduce boiling temp.

Replace thermostat, if not working properly.

Change your coolant if you have not. I'd use 50/50 ratio.

Make sure there are no coolant leaks. Check all heater hoses, intake manifold coolant hoses and radiator hoses.

Make sure coolant sensors are working properly. ECT sensor is located under distributor and is 2-pin. IAT (intake air temp) on intake manifold driver-side. Make sure both thermoswitches for radiator and A/C fan are working. Make sure your IACV is working properly as well, refer to DIY stick for setting base idle.

[pedroalcala]

Also, what type of oil are you using??

If you use 5-30 that can be a problem to....

use a higher grade oil....like maybe 10-40 or 20-50....especially in the summer when its over 100.

[foamypirate]

Also, what type of oil are you using??

If you use 5-30 that can be a problem to....

use a higher grade oil....like maybe 10-40 or 20-50....especially in the summer when its over 100.

No need to use anything heavier than 10w-30. I don't even use 20w-50 in my brothers 30+ year old 400 small block...