armedwithturtles

hey all, I was getting horrible mileage in my 00' sport and it turns out the MAP sensor wasn't good. I got the part, changed it out as well as cleaned out the throttle body since it's been a while and ever since then the Jeep won't start. The first time I reinstalled the throttle body, the car would start but idle low ~300 RPMs - it would accelerate but very sluggishly. I figured I got a bum part so I threw my old one in there in which the car would start but idle would be even lower near the 0 mark. Came back to it and now the car won't start at all and just cranks. I tried boosting it, no luck. Fuel pressure is all good and had no other issues previously. I was driving a bunch today to do errands and she'd start up with no issue until now. no codes as well.

Is this the famed CPS failure? I have no idea what else this could be.

thanks

Idunno

A dead CPS will kill the ignition so no spark could mean a dead CPS. Take one of the ignition leads off a spark plug, insert a Phillips screw driver into it and, with an air gap between the screw driver shaft and the engine or other ground point, see if a spark jumps the gap. Obviously, you'll need someone cranking the engine when you do this check. If there's no spark across the gap then there's a resident evil in your electrical system.

If you do have spark, then no fuel is on the rail. With the key in the ignition-on position (not cranking), you should hear the electric fuel pump and there should be evidence of fuel at the valve on the injector rail. Momentarily depress the valve core and see if any fuel pressure is released.

armedwithturtles

thanks for the reply. i'm not sure I understand how to test the spark, I remove a spark plug and stick a screw driver into the engine and ground it? do i use the coil pack in all of this? sorry i'm fairly new to all of this

fuel is good, I checked that and the valve sprays out fuel

Idunno

Sorry, I did not realize you have coil packs. Yes, remove one spark plug completely and reinstall the coil pack onto it. Then hold the exposed threaded end of the spark plug against the engine block or another ground where you can see. Do not touch the spark plug. Hold it by the coil pack. With someone cranking the engine you should see the electric arc jump across the center electrode of the spark plug if the ignition system is functioning. The CPS, when bad, disables the ignition.

dave1123

I ruined my TPS by getting solvent down the shaft past the seal, trying to clean the throat with the throttle body still on the manifold. It would run raggedly above 1500 but not idle at all.

00t444e

Did you pull a battery cable to reset the computer after you did all of this?

dave1123

D'oh! No.

MXDNJSport

What brand is your replacement MAP sensor? Recheck to make sure the little L shaped rubber fitting from the MAP sensor to the throttle body is on securely. Did you also clean the IAC motor? Make sure the electrical connections are tight.

armedwithturtles

great thanks. I won't have time to deal with it until thursday but I will report back!

​​​​​​​I took it off the manifold to clean it, I had that issue last time haha, lesson learned

​​​​​​​stupidly I did not. just pulled off the cables and tried a reset, still no luck

MAP sensor is a 'Standard' brand. Rubber fitting is on solidly. I did clean the IAC and even put on a new o-ring (the old one was flat and cracked).

​​​​​​​question regarding the IAC - is the pindle suppose to move in and out manually? the sleeve moves, but the whole pindle does not. could that be an issue?

Ralph77

I might have missed it but I am not seeing anything about the throttle body gasket. You did say you removed the throttle body to clean right?

armedwithturtles

yes, removed the entire assembly. everything including the gasket is back on correctly

Ralph77

A new gasket?

armedwithturtles

no, i reused the same one. i bought it about a month ago so it's not too old and still looks good

Ralph77

Thinking that might not be an issue then. Hopefully.

Cummins93

Test tps voltage. You will a voltmeter or scan tool with live data.