XJ_Nate

i have a 97 cherokee country and after starting it the motor sounds like a horrible missfire and sometimes dies if i dont give it a little gas. after it sits for about 45 seconds to a minute it is perfectly fine..i just did a full tuneup plugs wires cap rotor. any suggestions would be great

thanks

xjmuddigger

ur IAC

tjwalker

Welcome to the forum!

Cleaning the idle air control and throttle body is never a bad idea as they get carboned up over time and miles.

However, you could have a leaky fuel injector (or maybe more than one). If the engine "stumbles" or runs rough for a while on start up, that could be the engine burning off the excess raw fuel that has leaked into one or more cylinders.

Some comprehensive fuel pressure testing with a fuel pressure gauge and a factory service manual WILL tell the story here if that is happening. Here is a primer of how I would test for this...
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Some troubleshooting tips for extended crank times:

Hook up fuel pressure gauge on the schrader valve on the fuel rail

Start engine and bring to normal operating temperature.

Observe test gauge. Normal operating pressure should be 49.2 psi (plus or minus 5 psi)

Shut engine off.

Pressure should not fall below 30 psi for five minutes.

If pressure falls below 30 psi, it must be determined if a fuel injector, the check valve within the
fuel pump module, or a fuel tube/line is leaking. An adaptor tool/hose included with the fuel pressure gauge can help you with this. Consult gauge manual for more information on this but here is basically how it works:

*Turn the engine off and immediately clamp the fuel line at the adaptor hose. Watch the pressure gauge and see how long it takes to lose pressure.

*If the pressure remains at 49 psi for an extended period of time then the problem is in the tank - possibly the check valve. If the pressure falls below 49 psi fairly rapidly then the problem is probably a leaky fuel injector.