# Intermittent overheating/misfire



## himilefrontier (Jan 21, 2003)

I have a 1998 Nissan Frontier 2wd/KA24DE/FS5W71C(5spd) and am having 2 problems with it. First off, it has a problem with overheating, especially on hot days in stop and go traffic, but on rare occasions it will also overheat at speeds of 45 mph or greater. I have a broken fan shroud which I plan to replace, but this does not explain the overheat at speed. I have replaced the fan clutch, thermostat, water pump, and coolant hoses in the last year. It does not boil over, just peg the gauge at the end of the "normal" range. It will do this if I sit in traffic with the A/C off too, if it is for too long.I ran a compression test and it was 160PSI in all 4 cylinders ( not bad for 264k miles). It uses no oil or coolant either ( well..1/4 quart of oil between changes). The coolant is green, not rust colored either as I pulled the block drains when I flushed it to be sure to get all of the old coolant out. Now for the misfire. It does it only at idle, and throws either a code P0303 or a code P0300. P0303 is cylinder 3 misfire, P0300 is intermittent misfire across multiple cylinders. I have replaced: Plugs, wires, distributor, cap, rotor, Crank angle sensor, O2 sensor, a cracked exhaust manifold, etc but to no avail. I tested the TPS and it was within range as was the closed throttle switch and the IAV motor/harness. I am baffled and can only think of it being a intermittent leak in the head gasket that's maybe related to specific temperatures, but it seems unlikely that this is the case.


----------



## frontera99 (Jul 3, 2005)

i had the same problem on my old 1996 Chevy truck. Same codes and I replaced pretty much everything too.

These trucks had a design flaw in the intake manifold that made them leak coolant into the combustion chamber. The chevy tech pressure tested the cooling system and found the problem.

New sealant and $400 later, the problem was fixed until it came back again 30k later.

Unlike the Chevy crap, Nissan trucks will rarely have this problem, but at 270k, anything is possible.


----------



## nissanmadness (Sep 18, 2006)

himilefrontier said:


> I have a 1998 Nissan Frontier 2wd/KA24DE/FS5W71C(5spd) and am having 2 problems with it. First off, it has a problem with overheating, especially on hot days in stop and go traffic, but on rare occasions it will also overheat at speeds of 45 mph or greater. I have a broken fan shroud which I plan to replace, but this does not explain the overheat at speed. I have replaced the fan clutch, thermostat, water pump, and coolant hoses in the last year. It does not boil over, just peg the gauge at the end of the "normal" range. It will do this if I sit in traffic with the A/C off too, if it is for too long.I ran a compression test and it was 160PSI in all 4 cylinders ( not bad for 264k miles). It uses no oil or coolant either ( well..1/4 quart of oil between changes). The coolant is green, not rust colored either as I pulled the block drains when I flushed it to be sure to get all of the old coolant out. Now for the misfire. It does it only at idle, and throws either a code P0303 or a code P0300. P0303 is cylinder 3 misfire, P0300 is intermittent misfire across multiple cylinders. I have replaced: Plugs, wires, distributor, cap, rotor, Crank angle sensor, O2 sensor, a cracked exhaust manifold, etc but to no avail. I tested the TPS and it was within range as was the closed throttle switch and the IAV motor/harness. I am baffled and can only think of it being a intermittent leak in the head gasket that's maybe related to specific temperatures, but it seems unlikely that this is the case.


Are you sure the temp gauge circuit is good? You may have a weak temp sensor or gauge or a resistance problem in the wiring. Can you check the temp with a laser thermometer to see what its actually reading. Also check your grounds, make sure they are clean and tight, especially the cable from batt/frame to eng block.


----------



## smj999smj (Jan 1, 2006)

Wouldn't hurt to do a cylinder leakdown test...especially at #3 cylinder. Done with the radiator cap removed, if there is air pushing past the head gasket, you will be able to see the air bubbles come up through the coolant in the radiator.


----------



## himilefrontier (Jan 21, 2003)

Well, I did check the radiator with the cap removed and the engine running, no bubbles to report. The gage seems to be functioning normally due to the fact that it has linear response in both the up and down directions and it works in a predictable fashion. For example, when stuck in traffic for 15 minutes with the A/C off , I watched the gauge gradually raise over that time, and when I got out of the traffic jam, it took 3 minutes to lower itself into the normal range-not the way a short performs.I also pulled the harness grounds and re-tightened them as a precaution. I have heard of the ground being faulty in the IAV motor in 240's, which causes the engine to misfire at idle. While the Frontier uses a different engine management scheme than the 240, it is possible that it is the same issue as Nissan may have used the same IAV motor in multiple applications. The engine in my truck is squeaky clean as I believe in keeping the engine bay like new so that any leaks can be found easily, and the oil does not deteriorate the wiring and other rubber components.I regularly scrub out any grease with a toothbrush and 2-3 cans of degreaser whenever I repair anything, and every 2-3 months otherwise. I am the original owner and have always cared for it this way. I even re wrapped the wiring harness when the tape became old and brittle. I need it to last 500k miles and will be disappointed if I get less than that from it. After all, I spent $11,500 for this thing and I will feel ripped off if it does not give me a good return on the investment.


----------



## golfer (Aug 21, 2006)

It's possible the two issues of overheating and misfire are related.

The rad cap may be faulty or the neck of the filler tube may also need cleaning with emery cloth , the rad it self may have restriction of flow. 

[URL=http://imageshack.us][/URL]


----------



## himilefrontier (Jan 21, 2003)

The radiator cap was just replaced, and it did help to quell some of the overheating, but it still does it on occasion. I was stuck in traffic today and it was going over, so I just whipped out a 12mm and pulled the hood off, threw it in the bed, and it stayed steady at just below half way on the gauge. Then it started to rain, so I had to put it back on...lol


----------



## joefrontier (Apr 26, 2007)

@ himile..

You are not expecting much from your frontier 500000 miles? Don´t buy a chevy cause I didn´t even get to 100,000 miles before the 4x4 broke twice, water pump, alternator, bearings, ball joints and my wallet.

Anyhow, is the thermostat you installed a genuine OEM part or after market? Did you temp test the thermostat before installing it? Thermostat maybe flaky still and it may cause it to overheat while. Also does it overheat when parked and engine running?

cheers


----------



## nissanmadness (Sep 18, 2006)

himilefrontier said:


> The radiator cap was just replaced, and it did help to quell some of the overheating, but it still does it on occasion. I was stuck in traffic today and it was going over, so I just whipped out a 12mm and pulled the hood off, threw it in the bed, and it stayed steady at just below half way on the gauge. Then it started to rain, so I had to put it back on...lol


Ever think of having the radiator core rodded out or having it flow tested at a radiator shop? Just a thought.


----------



## himilefrontier (Jan 21, 2003)

I have replaced the cap in the last month, I also decreased the amount of antifreeze in the coolant mix.

As for the reliability, I replaced the A/C clutch at 125k, water pump at 180k, alternator at 190k, original starter at 260k, trans was rebuilt at 243k, first clutch at 203k, sway bar endlinks several times until I upgraded them, Steering wheel, driver's seat, door strikers and window seals at 246k.


----------

