No start, or randomly shutting off - CPS? Or something else?

[JoshNZ]

Hi all,

About a month ago my Jeep quit on me while on my way home from a trip. Conveniently, it wasn't far from my parents place, so I towed it there and got home.

I "knew" the fuel pump was on its way out, the check valve was on its way out, always needing a few key turns to prime it
However I wasn't convinced that was the only issue, it felt more spark/ignition, and I knew the CPS was old, from the previous owner, and I know he wouldn't have sourced Mopar parts here in New Zealand

So, I went back this weekend, replaced the CPS (with a NTK sensor... I know, all I could get local) - It fired right up, idled for about 1 min, then died.
It kinda spluttered, like it ran out of fuel - cool - new Delphi fuel pump module went in.

Started up, then died again shortly after - wasn't getting any spark. I started wiggling wires, unplugging and replugging in the CPS, coil etc.

I noted the fuel pump and ASD relays were hot, so I replaced them too (all of them actually) and it fired up and ran well - better than ever.

To add, no codes throughout this

I took off for a few laps around the block to build up confidence before the trip home... and it died again.
This time with a bit of a pop, and now I have the following codes

P0108 - MAP sensor high input
P0351 - Ignition coil circuit
P0138 - O2 sensor high voltage.

Where to next? Its hard to troubleshoot and diagnose as its a 5 hour round trip.. but it can sit in Mum's barn as long as it needs, so happy to get some quality parts ordered before I head up again

I'll get a Mopar CPS,
New O2 sensors - NTK/NGK
New MAP sensor - Brand?

Coil/distributor cap and plugs are all ~ 12 months and maybe 5,000 miles old

Camshaft position sensor?

I don't want to replace things unnecessarily,
But I also want to have the solution next time I head up...


Any other ideas?

Thanks in advanced!

 

[JKP]

What brand coil? I was blowing coils all the time. Mopar, MSD, BWD, are all made in China. Some would last a few yrs, others a few weeks. Finally found a Blue Streak by Standard that seems to be a good coil, not made in China.

 

[TJ4Jim]

Hi all,

About a month ago my Jeep quit on me while on my way home from a trip. Conveniently, it wasn't far from my parents place, so I towed it there and got home.

I "knew" the fuel pump was on its way out, the check valve was on its way out, always needing a few key turns to prime it
However I wasn't convinced that was the only issue, it felt more spark/ignition, and I knew the CPS was old, from the previous owner, and I know he wouldn't have sourced Mopar parts here in New Zealand

So, I went back this weekend, replaced the CPS (with a NTK sensor... I know, all I could get local) - It fired right up, idled for about 1 min, then died.
It kinda spluttered, like it ran out of fuel - cool - new Delphi fuel pump module went in.

Started up, then died again shortly after - wasn't getting any spark. I started wiggling wires, unplugging and replugging in the CPS, coil etc.

I noted the fuel pump and ASD relays were hot, so I replaced them too (all of them actually) and it fired up and ran well - better than ever.

To add, no codes throughout this

I took off for a few laps around the block to build up confidence before the trip home... and it died again.
This time with a bit of a pop, and now I have the following codes

P0108 - MAP sensor high input
P0351 - Ignition coil circuit
P0138 - O2 sensor high voltage.

Where to next? Its hard to troubleshoot and diagnose as its a 5 hour round trip.. but it can sit in Mum's barn as long as it needs, so happy to get some quality parts ordered before I head up again

I'll get a Mopar CPS,
New O2 sensors - NTK/NGK
New MAP sensor - Brand?

Coil/distributor cap and plugs are all ~ 12 months and maybe 5,000 miles old

Camshaft position sensor?

I don't want to replace things unnecessarily,
But I also want to have the solution next time I head up...


Any other ideas?

Thanks in advanced!

Your good with the NTK crank sensor, it is one of the preferred brands.

 

[JoshNZ]

Your good with the NTK crank sensor, it is one of the preferred brands.

Good to know. I’ll order a Mopar one as a spare anyway, but I thought of all my options here that would be the best.

The mounting hole is slotted, and I wondered about setting the depth correctly, is there a consensus on how much of a gap between the trigger wheel and sensor?

 

[JoshNZ]

What brand coil? I was blowing coils all the time. Mopar, MSD, BWD, are all made in China. Some would last a few yrs, others a few weeks. Finally found a Blue Streak by Standard that seems to be a good coil, not made in China.

Delphi if memory serves.
I'll check the resistance etc, but does seem to be more of an issue when the engines warm, so could be the coil breaking down?
I’ll test it with a known good one before I buy another for the sake of it

 

[TJ4Jim]

Good to know. I’ll order a Mopar one as a spare anyway, but I thought of all my options here that would be the best.

The mounting hole is slotted, and I wondered about setting the depth correctly, is there a consensus on how much of a gap between the trigger wheel and sensor?

Pretty sure the Mopar CPS was produced by NTK as many others were.

Head over to the resources section and download the manual for your Jeep, any CPS requirements for your year will be well laid out.

 

[Kiwi TJ]

Hey mate sorry to hear of your troubles...have you tried calling Izzy at Central Motors. I called him for some advice about a year ago and he helped me narrow down the problem.

 

[JKP]

Yes, they typically break down after they get hot and will run fine when cold.

I did not try a Delphi.