Trouble Starting Cold

[rtitteri]

96 Cherokee Sport, 4WD, Auto, 112K

When starting from cold (say sitting overnight) it will start, but it is not smooth at all. I have to keep the key turned, and it cranks and rumbles for a second before it fires up. Once it is running, it's fine. If I start it up after running it, it fires up with no problem.

Have brand new plugs, wires, cap and rotor that are firing fine... any other thoughts?

Thanks!

[denisond3]

My jeep is a throttle body injection, but in your case I would suspect the Throttle Position Switch, or the Idle Air Control Valve.

[rtitteri]

denisond3

I have heard TPS from a few people... What would be involved in checking this, and if that is the case, is it a difficult/expensive repair?

Thanks again!

[denisond3]

The only way I know to check one would be to compare its resistance (across its range of positions) with a new one just out of the box. But if the old one tested good I would likely replace it anyway - and keep the old one as a spare. At www.rockauto.com they list them from $27 up to $43 dollars, plus shipping cost. I dont know that I would buy the cheapest one though.
They list the idle air control valve (in the fuel/air parts listings) at $34 & $51, plus shipping cost.
Good Luck....