Mudderoy
01-31-2012, 08:51 AM
A year, or more, ago I was in the midst of trying to figure out a running hot on the highway problem. One of the many suggestions was that due to the increased capacity and flow rate of the high flow components that the coolant was passing to quickly through the system and the radiator wasn't having time to cool it.
Digging around I found there was an easy solution that could be put in place and taken out. Great for testing. It was a restrictor. Basically a nylon cutting board and a 2" (I don't recall the size now) disk cut out of it. Then a 3/8 to 1/2" hole in the middle. You just take off the upper hose at the thermostat housing and place the restrictor in the hose and let the housing push it back down the upper hose. The idea being that the coolant coming out of the radiator would have to slow down to fit through the 3/8" to 1/2" hole. This was much quicker than changing out all the high flow stuff.
http://www.go.jeep-xj.info/Restrictor6.jpg :link: (http://www.go.jeep-xj.info/HowtoRadiatorRestrictor.htm)
I made the restrictor and placed it in the hose. Fit great! I started up the 1998 and I had one hell of a miss. If memory serves correctly I believe it even through a code! I do not recall the code, it was so long ago. I removed the restrictor and reset CEL.
Fast forward to me picking up my beloved 1998 Jeep at the radiator shop. It had a miss! It's had a miss (off and on) since. I've tried various things but it has not resolved the problem. When I get out of idle it seems to run fine, at idle is sounds bad and at times has even shook.
I've noticed since picking up the Jeep that the coolant temp hasn't been very high, no where near it used to be. I figured this was do to the cooling system working MORE correctly since the transmission shop replaced a rear freeze plug. Still it seemed a big change.
Finally (Sunday night) I replaced the thermostat with a 195 degree Stant. I broke my high flow thermostat housing in the process, so I had to go back to the original. I would have changed the thermostat sooner, but I was having issues trying to get another RobertShaw.
The results have been remarkable. There is no miss. It was just like what happened with the restrictor.
I was getting a P0301 after driving about 50 miles. Occasionally I would see a P1281, which says to CHANGE THE THERMOSTAT when you look it up. :rotfl2:
I'm only into the 2nd full day of driving it but so far none of the knocking or jerking is there. I had some slight knocking yesterday, but it was about 10% what it had been. Today, nothing.
Does anyone have any idea why a restrictor or a thermostat stuck open (I'm assuming open since the engine was cooling MUCH better than normal) would cause a miss-fire?
Digging around I found there was an easy solution that could be put in place and taken out. Great for testing. It was a restrictor. Basically a nylon cutting board and a 2" (I don't recall the size now) disk cut out of it. Then a 3/8 to 1/2" hole in the middle. You just take off the upper hose at the thermostat housing and place the restrictor in the hose and let the housing push it back down the upper hose. The idea being that the coolant coming out of the radiator would have to slow down to fit through the 3/8" to 1/2" hole. This was much quicker than changing out all the high flow stuff.
http://www.go.jeep-xj.info/Restrictor6.jpg :link: (http://www.go.jeep-xj.info/HowtoRadiatorRestrictor.htm)
I made the restrictor and placed it in the hose. Fit great! I started up the 1998 and I had one hell of a miss. If memory serves correctly I believe it even through a code! I do not recall the code, it was so long ago. I removed the restrictor and reset CEL.
Fast forward to me picking up my beloved 1998 Jeep at the radiator shop. It had a miss! It's had a miss (off and on) since. I've tried various things but it has not resolved the problem. When I get out of idle it seems to run fine, at idle is sounds bad and at times has even shook.
I've noticed since picking up the Jeep that the coolant temp hasn't been very high, no where near it used to be. I figured this was do to the cooling system working MORE correctly since the transmission shop replaced a rear freeze plug. Still it seemed a big change.
Finally (Sunday night) I replaced the thermostat with a 195 degree Stant. I broke my high flow thermostat housing in the process, so I had to go back to the original. I would have changed the thermostat sooner, but I was having issues trying to get another RobertShaw.
The results have been remarkable. There is no miss. It was just like what happened with the restrictor.
I was getting a P0301 after driving about 50 miles. Occasionally I would see a P1281, which says to CHANGE THE THERMOSTAT when you look it up. :rotfl2:
I'm only into the 2nd full day of driving it but so far none of the knocking or jerking is there. I had some slight knocking yesterday, but it was about 10% what it had been. Today, nothing.
Does anyone have any idea why a restrictor or a thermostat stuck open (I'm assuming open since the engine was cooling MUCH better than normal) would cause a miss-fire?