Skip the auto shop - Our mechanics make house calls

Q: No idle after ignition, unless holding the throttle.

asked by on

My 99 WJ 4.0 will not stay running. I had an ignition coil bank b code come up. I replaced the coil with a BWD coil and autolite single platinum plugs. Now the truck will not relearn its idle. Since replacing above mentioned, I have replaced the IAC valve, TPS, new battery and load tested the alternator. Before this issue I replace the CPS and CKS, 3 months prior and the cat, post o2 and muffler, a month ago.

Before this issue happened, my WJ would run rough / hesitate at idle, once the engine was hot, but ran fine while giving it throttle.

Here's exactly what's happening now.

The WJ will crank and fire normally now, but will die out with no throttle after 5 - 10 seconds. While holding the throttle after ignition, the WJ will run smooth for about 20 seconds, then it will run rough. Every now and then on a start up, either the gas gauge or the volt gauge will drop down to nothing, but is not consistent.

Where do I go next?

My car has an automatic transmission.

Hi there. I can see how you’re stuck; as this one is tricky to diagnose. There are three things I would do first before removing anything else. First, download all OBD-II codes with a professional digital scanner; perhaps they will show an electrical fault with the TPS or other fuel system component. Second, check for any vacuum leaks. Although in many cases a vacuum leak will cause a high idle, it can also create similar symptoms you’re indicating. Third, when was the last time you cleaned the fuel injectors or throttle body? It’s possible that this is also a possible cause. Try these three things and if you still can’t resolve the problem, contact a local mechanic to assist you.

Was this answer helpful?

Need advice from certified mechanic? Get help now!

Over 1000 mechanics are ready to answer your question.
The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

Ask a Mechanic
(100% Free)

Have a car question? Get free advice from our top-rated mechanics.

Ask A Mechanic
Over 10,000 questions answered!
  1. Home
  2. Questions
  3. No idle after ignition, unless holding the throttle.

Get an instant quote for your car

Our certified mechanics come to you ・Backed by 12-month, 12,000-mile guarantee・Fair and transparent pricing

Get a quote

What others are asking

Q: Won't start

Hello. This is often times a sign of a faulty starter relay. This is a small unit near the starter that directs power from the battery to the starter allowing it to engage the flywheel. When this is faulty, it...

Q: Loud clicking behind the AC controls

Hi there: If you unplug the system and the noise goes away, it's possibly the actuator, but I wouldn't count out other AC systems including the blower motor or compressor that are causing the ticking sound. To avoid any unnecessary...

Q: I have a ticking noise in the front axle in my 99 Jeep Cherokee 4x4.

Hello, thank you for writing in. The ticking noises you are hearing may be coming from the actual axle itself. The CV joints on both sides of the axle can click or tick as they wear down. You would hear...

Related articles

How Do Power Car Windows Increase Passenger Safety?
Power windows are responsible for approximately 2,000 emergency room visits every year. When a power window closes, it exerts enough force to bruise or break bones, crush fingers, or restrict an airway. Though...
P0052 OBD-II Trouble Code: HO2S Heater Control Circuit High (Bank 2 Sensor 1)
P0052 code definition HO2S Heater Control Circuit High (Bank 2 Sensor 1) What the...
P2103 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit High
P2103 means there is a fault with the throttle actuator control motor circuit, likely due to a defective electrical component or part.