TJ starts but then dies

[kyro]

Hey TJ'ERS brain trust.
I brought a 1998 TJ which didn't crank or run, suspected fried PCM.
So I brought a PCM from the USA with it being coded to my VIN.
Installed it and it started first go but would not stay running.
What I've do so far
Checked fuel pressure 40psi at key on and when started and when stops.
Changed CPS
Changed complete throttle body from running TJ, still no change
Checked all fuses and relays all good and no change.
So I got my son who is the owner of this tj to start it and I can keep it running if I spray carbon cleaner etc in throttle body not well but it will keep going till I stop.
Been checking wires but nothing looks out of place.

Cheers for any help

 

[rlinares40]

Hi Kyro,

any engine codes come up?

 

[kyro]

Hi Kyro,

any engine codes come up?

Sorry should of put that in as well
No engine code from key test or from scan gauge

 

[rlinares40]

Sorry should of put that in as well
No engine code from key test or from scan gauge

I see you tested the the fuel pressure, what about the spark from the coils?

 

[rlinares40]

I see you tested the the fuel pressure, what about the spark from the coils?

Also the immobilizer feature wasn't implemented until 98, what color is your key? grey or black

 

[kyro]

Also the immobilizer feature wasn't implemented until 98, what color is your key? grey or black

Grey key and the light on the dash of the key with circle around it and line though the middle comes on when first turn on key to run then turns off before starting

 

[kyro]

I see you tested the the fuel pressure, what about the spark from the coils?

Wouldn't there be spark if it starts to run but then dies. I don't have a tester for plugs.

 

[rlinares40]

Grey key and the light on the dash of the key with circle around it and line though the middle comes on when first turn on key to run then turns off before starting

If it starts and dies shortly after then I want to say this is likely your problem, The SKIM sensor is a known point of failure. Do you know if they removed the SKIM from your PCM when they redid your PCM VIN?

 

[kyro]

If it starts and dies shortly after then I want to say this is likely your problem, The SKIM sensor is a known point of failure. Do you know if they removed the SKIM from your PCM when they redid your PCM VIN?

No I don't think so they said it was programmed to my vin number

 

[rlinares40]

No I don't think so they said it was programmed to my vin number

it can be programmed to your VIN but if the SKIM receiver is failing/malfunctioning then your vehicle still won't turn on. I would ask them if they did a SKIM delete on the PCM or not.

if not then that would probably be your cheapest option.

 

[kyro]

it can be programmed to your VIN but if the SKIM receiver is failing/malfunctioning then your vehicle still won't turn on. I would ask them if they did a SKIM delete on the PCM or not.

if not then that would probably be your cheapest option.

Can you swap the SKIM module from tj to tj or are they coded as well.
I have another tj here a 99

 

[kyro]

it can be programmed to your VIN but if the SKIM receiver is failing/malfunctioning then your vehicle still won't turn on. I would ask them if they did a SKIM delete on the PCM or not.

if not then that would probably be your cheapest option.

I unplugged it and the light on dash disappeared but its still does the same thing. Plugged in or not still starts but then dies after a rev

 

[rlinares40]

I unplugged it and the light on dash disappeared but its still does the same thing. Plugged in or not still starts but then dies after a rev

Correct if the SKIM is unplugged it still won’t start because the PCM is expecting that signal from the module.

I don’t know if they’re interchangeable but there’s some good threads on this site over the SKIM topic.

 

[kyro]

Correct if the SKIM is unplugged it still won’t start because the PCM is expecting that signal from the module.

I don’t know if they’re interchangeable but there’s some good threads on this site over the SKIM topic.

Ok the programming dude said they always delete the SKIM on them.
I swapped pcm and SKIM module to my working tj and it did the same thing.
So has to be computer again yeah?

 

[tr21triton]

Ok the programming dude said they always delete the SKIM on them.
I swapped pcm and SKIM module to my working tj and it did the same thing.
So has to be computer again yeah?

sorry you wasted your money with that PCM ! contact @Wranglerfix and he'll get you running again ! who did you get your current PCM from ?

 

[kyro]

sorry you wasted your money with that PCM ! contact @Wranglerfix and he'll get you running again ! who did you get your current PCM from ?

Module madness who have been great with there communication and are happy to refund me but its the time of a dead car blocking driveway that get me.

 

[rlinares40]

Sorry Kyro we had some holidays last week. Without any PCM codes the last thing I can think of is the Cam Sensor and the Crank Sensor aren't synced. When you switch the PCM over to your working TJ did you try it without moving the SKIM over? if the SKIM was really removed then your other vehicle should start up without having to move the SKIM.

 

[SCMatt]

Going through this myself on my 97... Sounds like SKIM is your issue - best bet would be to remove the SKIM module, reflash the PCM with SKIM disabled and off you go - unless you particularly care about the secure key integration.

Problem is - if you have the SKIM module plugged in and they disabled SKIM - I'm told it will automatically re-enable it. So if you get an RMA or Re-flash the computer make sure you remove the skim module before reinstalling the computer.