1999 4.0

Every now and then when I start my Jeep, it feels like it's running on 5 instead of 6... with no power.... Then after 30 seconds or so, it "springs" to life and runs on all 6 and things are fine. Have any of you see this problem?

Going to do a tune up but would like know if anyone else have seen this.

Al

 

This happened to me just this past weekend. I was giving a coworker a ride home Friday afternoon, and he said that it seemed like something wasn't firing right. I didn't notice what he was noticing before, and even when he pointed it out, I didn't realize it. I guess because I only had it for a month now.

Anyway, I did a tune up, and it's fine now. Much smoother, too.

 

Lucas oil and seafoam in the gas tank, does wonders for the old 6 cylinders

 

The importance of fresh tuneup hardware CANNOT be overstated.

Start with fresh Champion copper plugs gapped to .035, new quality plug wires (not el-cheapos), new distributor cap and rotor with brass contacts.

See where you're at after that.

This is money "well spent".

 

Ok, did the above... the engine runs nice! The old rotor was pretty rough by the way.

But once, after starting up and driving maybe 50 yards, I felt like the engine didn't have any power for maybe 5 seconds... after that... all was well.

I think my next check will be to make sure the connections to the control module are ok and then I guess the next replacement part would be the ignition control module.

What do you think?

Al

 

If you have a symptom only once, I wouldn't recommend chasing it. If you have repeating or consistent symptoms, describe them in detail here.

BTW, you don't have an ignition control module on a 99. That went away after 1990.
You do have an ignition coil though, which can be easily tested for primary and secondary resistances with a manual and a meter.

If you've never done so, it wouldn't hurt to add a bottle of QUALITY fuel system cleaner. My favorite is BG44K, followed by Techron (by Chevron), followed by Seafoam.

 

Did the 44K before the tune up... ( love that stuff ). Took another look... I guess that is a small coil... mounted on the engine block... just didn't look like the standard coils that used to be on older cars. <g>.

The symptom does repeat... normally 1st start up of the day.... engine starts perfect...but as you're driving off, you loose power... like it's either not getting fuel or spark... you limp along for maybe 5 or 10 seconds max and the engine springs to life. After that all is well. It always happens at low rpm / low speed.

It kind of reminds me of driving an english car through a deep puddle and the elec spark goes away till it drys out... but like I said it only lasts a few seconds.

Hope my description makes sense.

Al