GrayWolf Posted June 28, 2017 Share Posted June 28, 2017 1990, with basically stock 4.0. Recently upgraded to Volvo 4 hole injectors. Runs great, better gas mileage. Most of my driving is sea level to 1000 feet. Went to Eastern Washington and crossed one pass at 5400 ft and into a back-country lake at 2200+ feet. On both I noticed a definite loss of power and overheating. The route into the lake was only 2200 to 4000 feet, but was done slowly on a rough, rocky road. The initial 1000 feet was very steep and overheated to boiling over. The pass was highway speeds, 60 mph, and overheated, but not to the red-line. Dropped off as soon as I started downhill and dropped rpm. I noticed a definite lack of power each time. I reset the ECM after adding the new injectors, and it's been running great, but wonder if I could be running lean, particularly at altitude. Reset ECM again, other suggestions??? Next step will be upgrading to a open (real radiator and cooling) system. Link to comment Share on other sites More sharing options...
Eagle Posted June 28, 2017 Share Posted June 28, 2017 You "reset" the ECM? The Renix ECU doesn't need to be "reset" -- it resets itself every time you turn off the ignition. I think you have a radiator problem. Link to comment Share on other sites More sharing options...
Ωhm Posted June 28, 2017 Share Posted June 28, 2017 At Key ON the MAP will take a barometric pressure (BARO) reading for the ECU. This BARO reading will be updated during any WOT condition after the initial reading is taken. BARO reading - actual vacuum reading = plays a major part in the fuel calculations. Your "loss of power" should've taken your vehicle to the WOT zone for a BARO re-read. I'm with Eagle on this one: Radiator. Link to comment Share on other sites More sharing options...
GrayWolf Posted June 28, 2017 Author Share Posted June 28, 2017 Thanks, this is my first Renix Jeep and in the past one of my go-to fixes for ignition or fuel problems was an ECM reset. Like I said, top of my list of priorities is to replace the closed system. Link to comment Share on other sites More sharing options...
87MJTIM Posted June 28, 2017 Share Posted June 28, 2017 Do you have an auxiliary fan? If so, does it turn on when the temp rises? check the radiator temp switch or the cooling fan relay. Link to comment Share on other sites More sharing options...
GrayWolf Posted June 29, 2017 Author Share Posted June 29, 2017 Electric auxilary fan seems to be working fine. I did just replace the air-conditioning/fan mount, after the fan shaft started to work it's way forward. When I did that I got one at a WR and a clutch fan was already on it. I did not take it off and replace it with my original clutch fan. You've got me thinking that maybe the clutch fan that I put back in there is not working as well as it should? I'm going to do some trial and error to see what works. I have an aluminum expansion tank and I also replaced the radiator cap. I have an appointment for next Wednesday to have the system backflushed and refilled with coolant. I'm going to keep working on it while I'm looking for a 92+ header and order a high end radiator. Anyone have suggestions on radiators. Last one I bought was for my YJ over 8 years ago. Link to comment Share on other sites More sharing options...
87MJTIM Posted June 29, 2017 Share Posted June 29, 2017 How old is the lower rad hose? It have an internal wire/spring to keep it from closing/collapsing in on itself. If the hose is spongy or the spring has rusted away, the water pump can cause the hose to close, thus restricting the flow of coolant. The low speed and higher RPMs of climbing could increase the vacuum of the water pump. If you are not sure of the age/condition of the hoses, it may make sense to change both hoses when you have the system serviced. Link to comment Share on other sites More sharing options...
johnj92131 Posted June 29, 2017 Share Posted June 29, 2017 1990, with basically stock 4.0. Recently upgraded to Volvo 4 hole injectors. Runs great, better gas mileage. Most of my driving is sea level to 1000 feet. Went to Eastern Washington and crossed one pass at 5400 ft and into a back-country lake at 2200+ feet. On both I noticed a definite loss of power and overheating. The route into the lake was only 2200 to 4000 feet, but was done slowly on a rough, rocky road. The initial 1000 feet was very steep and overheated to boiling over. The pass was highway speeds, 60 mph, and overheated, but not to the red-line. Dropped off as soon as I started downhill and dropped rpm. I noticed a definite lack of power each time. I reset the ECM after adding the new injectors, and it's been running great, but wonder if I could be running lean, particularly at altitude. Reset ECM again, other suggestions??? Next step will be upgrading to a open (real radiator and cooling) system. My semi-educated guess is that you have cooling system problems. First, replace your radiator cap with a new one with the proper pressure. See that you did that - GOOD. Next get your radiator pressure checked. When did you last replace your thermostat? My guess is that it has been a while and it may be stuck, restricting the flow. As long as you are replacing the thermostat - may as well replace the water pump. BTW, be sure you get the correct water pump.. Hoses are also relatively cheap, so replace them too. Don't forget the temperature sensor, replace it and save the old one. Even with everything refreshed on my truck, the temperature still gets to about 215 on a 4000 ft climb. Last year I had cooling issues going from Seattle to Spokane. Doing all of the above resolved my cooling problems. Not cheap, but it worked! Link to comment Share on other sites More sharing options...
GrayWolf Posted June 30, 2017 Author Share Posted June 30, 2017 All good suggestions!! I've replaced all the hoses, but the lower hose, will do that this weekend. Thermostat is relatively new, but not expensive, I'll probably replace that also as long as I'm at it. Called a couple of parts stores no one has hoses with the spring. I remember them being as gray as I am. Can you buy the spring separately or do they come with a certain hose? Also, when I go to the open system, can anyone recommend a particular upgrade radiator? A step at a time!! Link to comment Share on other sites More sharing options...
Crash Posted June 30, 2017 Share Posted June 30, 2017 I have parts store 'spectra' rads in my heeps. No issues. For heater Hoses you can vo one of two things. Either get HO molded hoses or get adapters and cut in splice mid hose. Universal reservoirs available at local parts store. Most times you can remove spring from old hose and put in new Link to comment Share on other sites More sharing options...
GrayWolf Posted July 2, 2017 Author Share Posted July 2, 2017 Thanks for the ideas! Pulled the lower radiator hose, soft as butter, and even worse, almost worn through where it was resting on the steering box. Replaced that. As long as I was pulling things apart, I replaced the thermostat. Whatever the problem was, it's fixed, running substantially cooler all the time, and no overheating on hills. Seems to be fixed. Also, has anyone cut the bottom out of the fan shroud? It is a royal pain having to work behind the shroud to unbolt the fan, and pull both out together. Link to comment Share on other sites More sharing options...
GrayWolf Posted July 7, 2017 Author Share Posted July 7, 2017 Cut the bottom center out of the fan shroud and it is much easier to get to the fan and other things. Does not seem to effect the cooling at all. Had the cooling system back flushed and refilled and that really had no obvious effect, but always a good thing. Down side is that the person doing the back flush had never seen a closed system. Came back and found my windshield wiper bottle full of antifreeze. When will I learn to do simple things like this, myself!! Link to comment Share on other sites More sharing options...
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