Not starting correctly

[cardboard]

I have a 90 xj, 4.0 aw4, 242, Brand new optima, cap , rotor ,wires. Just recently the Jeep will just turn over , no start. It almost seems that if i turn the key off and try and cycle it again it will usually start. If not the first time always the second. Once it starts it runs fine, idles purrfect. Could this be my coil going bad or something else.
Thanx Digger

 

[Eagle]

CPS???

 

[cardboard]

OK Eagle i give up? What is "CPS"

 

[GSequoia]

Crankshaft Position Sensor. Common to fail. It's located on the drivers side of the bellhousing. What sort of manual do youhave? Look for CPS testing procedures..

 

[cardboard]

Thanx. Has anyone ever put all these abbrev. together so all us idiots can figure out what they mean?

 

[PaulJ]

Sure, they're all in the FSM or even the cheap manuals. It's tough to live without a manual anyway.

TPS Throttle Position Sensor
CTS Coolant Temp Sensor
MAP Manifold Absolute Pressure Sensor
02 Oxygen Sensor
IAS Idle Air Speed Motor
MAT Manifold Air Temp
CPS Crank Position Sensor
ECU Engine Computer
TCU Transmission Control Unit
NSS Neutral Start (safety?) Switch
There's also a hall effect sensor in the distributor that probably has an acronymn.
Knock Sensor - no acronymn

 

[cardboard]

Well i checked the CPS as my Haynes man. It said there should be no continuity, which i am thinking should read 0.00. When i checked mine it read 0.31, so i guess we areoff to Auto Zone tommarroo after work. Thanx for the help, Digger

 

[GSequoia]

Call them first, when I got my CPS AutoZone didnt' carry them...

That was a couple years ago though...

 

[cardboard]

No luck at Auto Zone but, Advance has one in stock $29.99
Does that sound like it will fix my problem?

 

[GSequoia]

If the test shows it as bad I'd say it's most likely your problem. CPS's go bad a lot lately (not that they go bad frequently for everybody...just that ten years down the line or so they're ready to fail.)

 

[PaulJ]

I think you should see about 200 ohms across the CPS. Chilton says 125-275 with a hot engine. I would be surprised if the engine temp makes a big difference.

 

[Manuel]

Another possibility is that you need new spark plugs. Worn spark plugs will give hard start symptoms.

Beware of Bosch Platinums. I had them for about 30,000miles. At about the 30,000mile mark I thought I had a fuel pump problem because the XJ would not turn on, on the first attempt or it would take long to turn on.

I replaced the spark plugs and the problem was gone.

Just something else to consider.
It is quite a bit cheaper to change the plugs too if you want to do some trial and error.

Hope this helps.

Manuel