Curt Posted June 9, 2010 Share Posted June 9, 2010 I'm still fighting a too slow idle speed. I replaced the ISA and it does work, but it used to start at a high idle then throttle down, now I have to give it a little throttle to start. It will the idle ok til the engine get to operating temp, then it stumbles and sometimes dies when I stop at a light. I tested the TPS voltage output at WOT, and it was 4.5v. The manual says 4.6 to 4.7v. I couldn't adjust it any higher. Should I replace the TPS, or is 4.5v close enough? :dunno: Link to comment Share on other sites More sharing options...
Curt Posted June 12, 2010 Author Share Posted June 12, 2010 You guys don't like 2.5s, do you? :( I got the TPS to output 4.65v by bending the tab on it to give it a bit more travel. It starts better now, but still stumbles when warm. It will stumble for about 5 seconds when I stop, then the ISA extends enough to bring the idle up to somewhat normal. Any suggestions on how to proceed? Link to comment Share on other sites More sharing options...
jimoshel Posted June 12, 2010 Share Posted June 12, 2010 Thinks the 2.5 is a great engine. Reliable,efficient, dependable, economical,etc, Just don't expect V8 performance from it, Although mine has showed up a V8 now and then. Not familiar with the problems your having so unable to suggest anything, other than check all vacuum lines, fittings. Look for a vacuum leak. Give the guys a chance to respond. They don't live here 24-7. But they will help with good advice. Link to comment Share on other sites More sharing options...
Curt Posted June 13, 2010 Author Share Posted June 13, 2010 Just poking a little fun is all. :) I've already went through the vacuum lines. I did have a leak, but it's fixed now. Spraying all lines with carb cleaner doesn't do anything now. Link to comment Share on other sites More sharing options...
airspeed Posted June 13, 2010 Share Posted June 13, 2010 I want to follow this thread, my 2.5 has a simular problem. My engine starts and runs good when cold but will have a intermittent slow idle when warm. If that engine dies when I'm going around a corner, that's scarey, it takes an incredible amount of force to turn the wheel! I need to read up on how to measure and adjust my TPS switch. Link to comment Share on other sites More sharing options...
Curt Posted June 13, 2010 Author Share Posted June 13, 2010 This is what I used for TPS and ISA adjustment: http://jeepgarage.free.fr/OWN/2.5l%20cec%20system.pdf Link to comment Share on other sites More sharing options...
airspeed Posted June 13, 2010 Share Posted June 13, 2010 I was reviewing the 2.5L CEC System document located at jeepgarage.free.fr/own/2.5l, my 88 Comanche has an entirely different system than they show in the vacuum diagram. They also talk about a "knock sensor" located on the cylinder head? Their document is for a Cherokee, I can't imagine that the systems would be that different but maybe so. Link to comment Share on other sites More sharing options...
Curt Posted July 8, 2010 Author Share Posted July 8, 2010 How much longer should I wait? ;) I replaced the MAT sensor. It didn't help. :( Going in a different direction, the AC in my truck is an after market job. There is no AC relay, so the ECU doesn't get a signal to step up the idle speed. I can add a relay to feed it this signal, but looking at the electrical schematic, I am unsure what the signal voltage is. If I send 12v and it's supposed to be less, I suspect I will fry the ECU. So, does anyone know for sure what the voltage would be? Or is this another one of my many bad ideas? Link to comment Share on other sites More sharing options...
maddzz1 Posted July 8, 2010 Share Posted July 8, 2010 When the truck is first started it runs in an open loop mode until it warms up getting preset info from the ecu, then runs in closed loop mode getting its info from the sensors. Have you tried cleaning the IAC and throttle body. I would test the O2 sensor also. Not familiar with the 2.5 so just giving some ideas Link to comment Share on other sites More sharing options...
Curt Posted July 9, 2010 Author Share Posted July 9, 2010 I don't think the 2.5 has an IAC. The TB has been cleaned and recleaned. I'm not sure how to test the O2 sensor, other than it runs the same with it disconnected. The O2 sensor has 3 wires, while the ones I see online are only 1 wire. Link to comment Share on other sites More sharing options...
maddzz1 Posted July 9, 2010 Share Posted July 9, 2010 Look here for one: http://cgi.ebay.com/ebaymotors/ws/eBayI ... MEWAX%3AIT Scroll down on here for testing procedure: http://www.lunghd.com/Tech_Articles/Eng ... ostics.htm Link to comment Share on other sites More sharing options...
Curt Posted July 12, 2010 Author Share Posted July 12, 2010 Thanks, I'll look into that. Another question: Are the MAT and CTS the same? I noticed the wire connector ends are reversed. I was thinking of trying the new MAT sensor in place of the CTS. I can change the connector end if the sensors are the same. EDIT: never mind, they are different. :( Link to comment Share on other sites More sharing options...
Recommended Posts
Create an account or sign in to comment
You need to be a member in order to leave a comment
Create an account
Sign up for a new account in our community. It's easy!
Register a new accountSign in
Already have an account? Sign in here.
Sign In Now