TJ cranks but won't start

[Anger57]

Jeep cranks over but no start.
Fuel pressure is good. Removed boot off of the throttle body and sprayed starter fluid. Still no start. Checked for spark at coil rail. All had spark but 1. Replaced coil rail and spark plugs. Also replaced crank case sensor. Still cranks over good but no start. Im starting to think its my ecu. Removed negative wire from battery to reset and still no start. Only had 1 engine code before starting on this p1297 map sensor code. Which was first thing i replaced. Now i longer get codes. Any suggestions?
One other small detail. I drove jeep to airport and never had issue with this before not starting, i get back a week later and the park place said they had to jump my jeep but couldnt get it started.

 

[TJ4Jim]

What is the condition of the battery you are using and how do the terminals look, are they clean and tight.

 

[Chris]

First thing to do is always, always, always start with the simplest things. Have the battery load tested and see how it tests (even if it's a newer batter). Then check the condition of the battery terminals. If they are old, they should be replaced and properly tightened down. Once those are ruled out, then you proceed with digging deeper. My experience though is that it's almost always the simplest things first.

 

[Anger57]

What is the condition of the battery you are using and how do the terminals look, are they clean and tight.

New battery and conection is clean and tight.

 

[Anger57]

New battery and conection is clean and tight.

I will do a load test though to verify they are good next.

 

[Geep]

... the park place said they had to jump my jeep but couldnt get it started.

Wonder if the parking guys hooked jumper cables up backwards and blew a fuse.

 

[Anger57]

First thing to do is always, always, always start with the simplest things. Have the battery load tested and see how it tests (even if it's a newer batter). Then check the condition of the battery terminals. If they are old, they should be replaced and properly tightened down. Once those are ruled out, then you proceed with digging deeper. My experience though is that it's almost always the simplest things first.

Load tested complet. Battery didnt drop under 10.8v while under load.

 

[Chris]

It may be worth checking with @Wranglerfix. He likely knows of a way or two that you can rule out the PCM (ECU) entirely.

 

[Anger57]

Wonder if the parking guys hooked jumper cables up backwards and blew a fuse.

This is what im wondering also. Last summer i pulled off the doors and remove the key chim and dome light on while door open fuse. I never put fuse back. So when i dropped off my jeep for them to park it for about a week i think they left the key on partially and that killed the batt. So they jumped it while i was in shuttle heading back to park place from airport. Going to call jeep service department tomorrow to see if they can bench test my computer if i just bring it to them.

 

[afitzray97]

Since someone mentioned the jumper cables getting crossed I can vouch for that. Tried to jump a friend with my XJ and he hooked his end up backwards and it made the computer shut everything down. It was under warranty (imagine how long ago that was for an XJ) and the dealership just did a “reset” but didn’t have to replace anything. But if you’ve disconnected the battery wires and touched the cables together to reset I’m guessing that’s the same as what the dealership claimed to do. Unless someone else knows of a more complete reset method?

 

[Anger57]

Since someone mentioned the jumper cables getting crossed I can vouch for that. Tried to jump a friend with my XJ and he hooked his end up backwards and it made the computer shut everything down. It was under warranty (imagine how long ago that was for an XJ) and the dealership just did a “reset” but didn’t have to replace anything. But if you’ve disconnected the battery wires and touched the cables together to reset I’m guessing that’s the same as what the dealership claimed to do. Unless someone else knows of a more complete reset method?

I just removed the negitive off the battery. Im guessing they would flash the ECU with a program to do the reset.

 

[Painfultruth]

Did you verify the cam sensor is working?

Is your ASD relay activated, fuel pump running?

 

[Wranglerfix]

Here is a video from @Ozzstar that shows how to check the pcm. He’s great at diagnostic stuff!

I’m waiting to speak to my tech and will get back to you.

 

[Anger57]

Did you verify the cam sensor is working?

Is your ASD relay activated, fuel pump running?

No i didnt bench test old relay. I just replaced it with a new one. I swapped relays around. I did check for fuel pressure and have fuel pressure at the fuel rail.

 

[Anger57]

No i didnt bench test old relay. I just replaced it with a new one. I swapped relays around. I did check for fuel pressure and have fuel pressure at the fuel rail.

Also i replaced cam sensor with a new and didnt bench test old one yet.

 

[Painfultruth]

Do you have a JTEC or NGC controller?

you swapped the relays, but were they actually activated while you were attempting to start the engine?

 

[Anger57]

Do you have a JTEC or NGC controller?

you swapped the relays, but were they actually activated while you were attempting to start the engine?

Did not do this check. Ill check tonight after work. Not sure what you mean on the controller.

 

[Painfultruth]

JTEC’s were used in pre 05 vehicles, the NGC replaced it, and they operate slightly different. I didn’t see what year you have.

 

[Anger57]

JTEC’s were used in pre 05 vehicles, the NGC replaced it, and they operate slightly different. I didn’t see what year you have.

This would be a 2003 wrangler sport 4.0 manual.

 

[RMETeeJay]

Have you tried putting the old MAP sensor back in? What brand is the new one?