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| Jeep chugs at cruising speeds http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=55469 |
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| Author: | bakersoil [ Wed Sep 08, 2010 1:29 pm ] |
| Post subject: | Jeep chugs at cruising speeds |
Anyone know what would cause the engine to chug or misfire while cruising at a steady speed. It will do it at any speed or any gear as long as you hold the accelerator to maintain that speed on a level road. If you let up the slightest amount or give it the slightest amount more throttle it completely goes away. When it chugs I can see little puffs of white smoke come out the exhaust which tells me it could be a misfire or excess fuel. Maybe an injection timing issue? Runs great all other times. |
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| Author: | Joe Romas [ Wed Sep 08, 2010 6:31 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Have you bled the fuel filter head and checked for air? |
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| Author: | bakersoil [ Wed Sep 08, 2010 10:36 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Yes many times and I have a lift pump. No leaks found. |
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| Author: | racertracer [ Thu Sep 09, 2010 6:27 am ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
One of the indication of White smoke out of the exhaust is air in the lines. Tighten down every fuel line, even the lines near the new lift pump. If you have over 12,000 miles on the filter then you should consider changing it. If you get it running, then report back and let us know what you did to correct the issue so that we can be aware of what to look for if this should happen to us. Thanks |
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| Author: | Glend [ Thu Sep 09, 2010 6:39 am ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Isn't white smoke a sign of water (or coolant) being burnt? Any chance of a head gasket leak? |
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| Author: | bakersoil [ Thu Sep 09, 2010 2:34 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Cant find an air leak. Lift pump should push fuel out if it had an air leak. Replaced cheap factory fittings on lines at tank. Fuel head is modified to use the Cat filter. Currenty has a Wix on it now. Jeep runs realy good except for the constant speed cruise. You have to hold the pedal very steady for it to start the chugging and puffing. Changing the throttle ever so slightly makes it stop. It will do it in first gear, 65 mph and everywhere between. I think I will rig it to draw fuel from a good clean one gallon can under the hood bypassing the filter head to test for any fuel or air issues. |
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| Author: | BiodieselJeep.com [ Thu Sep 09, 2010 4:20 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Curious how this worked out. I'm doubting air leak now because the chugging only happens at a steady speed, normally these air leaks are worse at quick acceleration (but a lift pump should hide that..). But there might be a disconnect on the flow rate with your lift pump! Tricky business, lift pumps. The bucket trcik should show you something. |
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| Author: | warp2diesel [ Wed Sep 15, 2010 8:40 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
Which lift pump are you using? In line pumps can leak between pump and tank or if the pick up tube is broken, it can leak internally. Another far fetched possibility is if you fuel is contaminated by Gasoline. Most Diesels need at least 40 cetaine to run and gasoline contamination will lower the effective cetaine. When I got some contamination from gasoline ~2 gallons, I had the same symptoms and only when I was under a load or low idle did it run right. If the gasoline contamination is possible, top off your tank and consider adding cetaine booster too. If the problem heals its' self, chances are that you had gasoline contamination and worked it out of the system. Octane is opposite of Cetaine. |
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| Author: | GreenDieselEngineering [ Thu Sep 16, 2010 11:39 am ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
This sounds related to the EGR system, the system may be borderline for setting a fault code. The misfire can occur when the EGR/FCV choke the engine too much at light throttle in order to achieve the proper EGR rate, this also tends to produce higher HC emissions (white/bluish smoke). You can try unplugging the MAF sensor and see if the problem disappears during a test drive. A CEL will most likely pop up, but it should heal after being plugged back in for a while. Let us know if it changes anything for you. |
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| Author: | danoid [ Sun Sep 19, 2010 10:07 pm ] |
| Post subject: | Re: Jeep chugs at cruising speeds |
GreenDieselEngineering wrote: This sounds related to the EGR system, the system may be borderline for setting a fault code. The misfire can occur when the EGR/FCV choke the engine too much at light throttle in order to achieve the proper EGR rate, this also tends to produce higher HC emissions (white/bluish smoke). You can try unplugging the MAF sensor and see if the problem disappears during a test drive. A CEL will most likely pop up, but it should heal after being plugged back in for a while. Let us know if it changes anything for you. Yeah, I was going to ask if he had my acceleration then steady state syndrome. |
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