5 seconds to start

[1eliminator1]

My 4.0 in my comanche now takes 5 seconds of cranking before it starts. Sometimes even longer, and when it starts, it idles so low that my whole cab rattles. Anybody have an idea of what might be the cause?

[1eliminator1]

 

here's my mj

[kyleag89]

What year is your MJ? Does it idle low all the time or just for a little while upon start-up?

[1eliminator1]

89' and no, it idles fine about 30 seconds after i start it

[HOrnbrod]

What year is it? Renix era?

 

EDIT: Not abnormal for a Renix. You might look at the distributor cap for corrosion on the rotor contacts, plugs and boots are tight, plug wires, the normal HV ignition stuff.

[1eliminator1]

i am not sure. i bought it about 2 months ago. i need to replace the filter

[kyleag89]

Ok since it is an 89 it has the RENIX controlled motor. It is usual for it to take a long time to crank. My 89 takes between 4-6 seconds to start.

 

The idle issue could be an idle air control valve..

[1eliminator1]

yeah. alright, it sometimes takes 10+ seconds. but as long as it eventually starts, i will be ok

[1eliminator1]

thanks

[jpnjim]

Try turning the key forward for a few seconds first (into the 'run' position, to get the fuel pump up to pressure), then start.

 

It works for my 98 XJ (sometimes i forget, and it takes 5-6 seconds).

 

My 89' MJ is also a slow starter (5-6+ seconds), and the 'key forward first' trick does not work.

 

Cleaning the CPS might help you.

Tho it didn't help me,

neither did a new cap & rotor, plugs, wires, fuel filter, etc (<--- it needed that stuff anyway, but didn't help with the cranking issue)

[88pioneer]

Check your vacuum lines also, my 92 had a broken line to the MAP sensor and it idle real rough for the first 30 seconds

[1eliminator1]

alright thanks

[Pete M]

you can try both cleaning the CPS as well as unplugging it and cleaning up the terminals inside the connector. the CPS sends a pretty weak signal anyways and anything that degrades that signal will cause the computer to wait longer until it's absolutely positive of the location of the engine before firing.