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Rough idle until warm

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  #1  
Old 09-11-2010 | 08:05 AM
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Default Rough idle until warm

Latest problem, I finally finished my motor swap which consist of a used motor with new head gaskets,head bolts,head job, etc. Everything seems all well except the engine runs very rough and seems to be missing until it warms up which is about when the temp hand is half way up on the gauge, afterwards it runs very smoothly. I have to keep pushing the gas peddle about half way down rapidly to keep it running until it warms up. I can also keep it running by getting the RPMs up the around 2K. It is not giving me any codes and the SES light its not on.
Could I have overlooked something,possible an electrical plug or something.thanks for your help on advance. CW.
 
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Old 09-11-2010 | 08:23 AM
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If you are not getting a code then the sensors are all hooked up. Check the intake hose connections starting at the air box then up to the plenum for vacuum leaks, loose bolts or clamps. Clean out your throttle body and IACV also. Could be the MAF giving the wrong temp but that usually throws a code, do you have a scanner to check for a pending code? A scan tool would be helpful to see if it is running rich or lean when cold that will give a clue also. Did you get new wires and plugs during the install? Was the IACV from the new or old engine?
 

Last edited by lipadj46; 09-11-2010 at 08:28 AM.
  #3  
Old 09-11-2010 | 10:47 AM
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sounds like a vacum leak bro check all the hoses coming off the plenum.run the truck and listen for a hissing noise in the engine bay
 
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Old 09-11-2010 | 12:27 PM
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If you don't find it, send me your number and I'll call you and try and help.
 
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Old 09-11-2010 | 04:55 PM
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Originally Posted by lipadj46
If you are not getting a code then the sensors are all hooked up. Check the intake hose connections starting at the air box then up to the plenum for vacuum leaks, loose bolts or clamps. Clean out your throttle body and IACV also. Could be the MAF giving the wrong temp but that usually throws a code, do you have a scanner to check for a pending code? A scan tool would be helpful to see if it is running rich or lean when cold that will give a clue also. Did you get new wires and plugs during the install? Was the IACV from the new or old engine?
I do not have a scan tool yet but am planning on buying one as soon as I figure out which one that I need.
I reused the spark plugs which looked to be on good shape. The plug wires were replaced less than a year according to vehicle history.
Not really sure about the IACV but I think it is from the newer engine. I assume that that is the silver canister mounted to the upper plemium.
I will clean the throttle body tomorrow.thanks,Craig
 
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Old 09-11-2010 | 05:09 PM
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Originally Posted by ROVERTECH15
sounds like a vacum leak bro check all the hoses coming off the plenum.run the truck and listen for a hissing noise in the engine bay

Gotcha,will go over a hoses tomorrow.thanks,Craig.
 
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Old 09-11-2010 | 05:13 PM
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Originally Posted by Disco Mike
If you don't find it, send me your number and I'll call you and try and help.
Thanks a lot Mike,I am going to to over a few of the things listed above and if I still am having problems I will send you my number.thanks again,Craig.
 
  #8  
Old 09-13-2010 | 06:04 PM
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Finally got a chance to get to take another look at my LR this evening, started it up and it ran rough for around a minute or two then clears up and runs great. The SES light did come on while it running rough, the codes are P0304,P0733 and P0734. Also I did not have time to clean the MAF,TB and IAC yet,any ideas.thanks,CW
 

Last edited by cwood; 09-13-2010 at 07:30 PM.
  #9  
Old 09-13-2010 | 08:30 PM
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Looks like the MAF, you can try to clean it but these MAFs do not react well to cleaning. Since it is already dying it is worth a shot. Get a proper MAF from someone who knows LR's, don't go cheap. Call will tillery, PTSchram, etc.
 
  #10  
Old 09-15-2010 | 08:16 PM
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Problem solved....maybe.I decide to pull the #4 plug due to p0304 code"#4 cylinder misfire". After closely looking at the plug I found a crack in the porcelain which I thought I may have did while I was removing it, installed another plug,stated it and it ran fine. Went back today same thing started and ran great. Shut it down and cleaned the TB,checked for vacuum leaks. Will change plugs in a few days.

Now I need to resolve the issue of my battery draining down,after searching the site I think that it is the ABS module under the hood,it seems to run or to be humming all of the time.thanks again for all of the help.
 


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