swilson Posted October 23, 2007 Share Posted October 23, 2007 I am on my second comanche 4.0l now and both of them start the same. They crank for a longer duration and then fire up. Is this normal or is this something that can be rectified? Link to comment Share on other sites More sharing options...
Geonovast Posted October 23, 2007 Share Posted October 23, 2007 That's pretty normal for the renix system. Link to comment Share on other sites More sharing options...
carnuck Posted October 23, 2007 Share Posted October 23, 2007 Flick the key to on twice before cranking that helps with my '87 at @300,000 miles. Link to comment Share on other sites More sharing options...
Geonovast Posted October 23, 2007 Share Posted October 23, 2007 Flick the key to on twice before cranking that helps with my '87 at @300,000 miles. Yeah, that could help, since the pump would be priming twice before trying to start. Hadn't though of that. I just dealt with it on my 88 XJ cause it would always start, just took a few seconds. Didn't really matter. Link to comment Share on other sites More sharing options...
comanche 88 Posted October 23, 2007 Share Posted October 23, 2007 From what I understand these engines won't start until the oil pressure reaches a certain value, which makes sense since when I turn the ignition the oil lamp is on and remains on while cranking until just before it catches. Link to comment Share on other sites More sharing options...
Geonovast Posted October 24, 2007 Share Posted October 24, 2007 That comes on during ignition just to let you know the light works. Or at least that's what I think. Link to comment Share on other sites More sharing options...
Oizarod115 Posted October 24, 2007 Share Posted October 24, 2007 the engine's won't fire quickly because of the Crankshaft position sensor, it takes at least a full revolution of the motor to be sure when to fire and then fires... other cars start quickly (IE gm motors) because they either remember where it was, or guess and adjust quickly a new CPS with the replacement harness (runs the wires from the CPS directly to the computer instead of through the wire harness) will decrease time's a little but not much its still gonna take a few cranks Link to comment Share on other sites More sharing options...
Lewt2007 Posted October 24, 2007 Share Posted October 24, 2007 turn the key until you can hear the fuel pump a few times then hit the starter and it should light on the first try Link to comment Share on other sites More sharing options...
HOrnbrod Posted October 24, 2007 Share Posted October 24, 2007 That's pretty normal for the renix system. Not only Renix models, the HO's do it too, especially when they are warm. Had four of 1991 and up models, all did the same, even the 2001 XJ. Link to comment Share on other sites More sharing options...
Twisty Posted October 25, 2007 Share Posted October 25, 2007 Sometimes my MJ will start after 1 crank, and other times it takes 4 cranks. I don't know whats up with that. If my XJ is warm, it will always start after 1 crank. Link to comment Share on other sites More sharing options...
FxRacing282 Posted October 25, 2007 Share Posted October 25, 2007 is there someone who makes a conversion so that the start up is like a GM? Link to comment Share on other sites More sharing options...
clarence Posted October 25, 2007 Share Posted October 25, 2007 is there someone who makes a conversion so that the start up is like a GM? Something like this would be a waste of money. All of the 4.0 i have ever had took a while to start. Thats just the way they are theres nothing wrong with it and its not hurting anything. Link to comment Share on other sites More sharing options...
JOMJ87 Posted October 25, 2007 Share Posted October 25, 2007 is there someone who makes a conversion so that the start up is like a GM? Something like this would be a waste of money. All of the 4.0 i have ever had took a while to start. Thats just the way they are theres nothing wrong with it and its not hurting anything. Its a computer thing on GMs and others. Thats the way the programming is in it so that it happens this way. To do a conversion you would have to have some kinda source to send a feed to the ECU to trick it into thinking its time to fire or one that olds the memory of where the engine stopped so it knows it can fire first shot. I don't see any issues with a long start. The only time it might be a concern is if you are tyring to get away really fast from something and that 3 seconds might cause you harm. I wouldnt worry with it other then maybe upgrading your ignition so that when it does fire it is good and strong. You can get High output coils from ebay for 30 bucks and they work awesome from the two i have seen in use. Then go to the auto store and get heavy duty distributor cap and rotor and maybe bigger wires. With the new coil you can run a .65 gap on the plugs. See link for details Cole http://cgi.ebay.com/ebaymotors/Jeep-Wrangler-Cherokee-45K-Volt-Ignition-Coil-Upgrade_W0QQitemZ250178195911QQihZ015QQcategoryZ33689QQssPageNameZWDVWQQrdZ1QQcmdZViewItem Link to comment Share on other sites More sharing options...
jtdesigns Posted October 25, 2007 Share Posted October 25, 2007 those coils fit the renx too? Link to comment Share on other sites More sharing options...
JOMJ87 Posted October 25, 2007 Share Posted October 25, 2007 Nope sorry I wasnt thinking. I am running a 91 MPI motor in mine now and the whole renix thing slipped my mind. But I'm sure they make them for renix i can look later for you. Cole Link to comment Share on other sites More sharing options...
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