1999 Chevrolet Lumina Logo
Ot Tap Posted on Mar 12, 2014
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1999 chevy lumina rough idea after warm up

Rough ideal after warm up temp sensor and coolant sensor new no coolant leaks new coil packs plugs wires. no vacuum leaks and crank sensor plus cam sensor new. Still rough ideal after warm up. New map and idela control sensor new maf also. wires check out OK. compression OK fuel OK.

1 Answer

Allen Stewart

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  • Expert 71 Answers
  • Posted on Apr 11, 2014
Allen Stewart
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Joined: Dec 01, 2012
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It could be several different things causing this, my first guess would be to look at the EGR port going into the intake. Most times it will clog up and can cause rough idling. You must know how to clean it properly, the EGR valve will have to be pulled as well as the throttle body in order to clean it properly. Also, check for vacuum leaks. It could be other things as well but this is where I would start. Hope this helps. Thanks, Allen with Morgan's Auto Repair 912-282-1602 Waycross, Ga.

5 Related Answers

Anonymous

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  • Posted on Mar 23, 2009

SOURCE: 1995 lumina cranks but will not start

Sounds like it has jumped timing, dont know which engine you have so could be chain or belt.

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Anonymous

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  • Posted on Apr 26, 2009

SOURCE: 89 Corsica: no power, hesitates in drive, idles

Check your fuel pressure, and or injectors. You may have too much fuel getting into the engine causing it to burn rich and overheat the converters.

6bta

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  • Posted on Dec 18, 2009

SOURCE: 98 Chevy Tahoe 5.7 liter engine cuts out and

Have you checked for vaccume leaks?
You've got lots of parts in there, Has the problem been the reason you have replaced all of those, or did it come up while doing some of the repairs?

Anonymous

  • 819 Answers
  • Posted on Feb 28, 2010

SOURCE: I have a 2002 TrailBlazer with the straight

did you replace only one spark plug? that can cause issues because of differences in resistances between cylinders. also, did the map code stay off after replacing
?

Anonymous

  • 834 Answers
  • Posted on Sep 27, 2010

SOURCE: how are the spark plugs wired up on a 1990 chevy

Make sure that there are no dis-connected wire connectors or vacuum lines, and the spark plug wires must be in the correct order, here is a firing order diagram for that engine and vehicle, and let me know if you need any help to understand this firing order diagram of if you require any further assistance.


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I need the easiest possible directions to replace the coolant temperature sensor in my 1999 Chevy Lumina ltz 3.8 v6 car please.

The coolant sensor temperature is usually found just beneath the cylinder head, on the engine block.

You just disconnect the 1-2 wires and then undo it with a wrench.
The sensor will look like one of these:
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Just be aware .. you may have TWO such sensors on your vehicle.

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If it's a running fault .. speed .. rough running .. fuel. It may look like this:
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Rough ideal after warm up have new map, maf coolant sensor wires, plugs and coil packs. no coolant leaks, no vacuum leaks. fuel pressure OK. runs great except for ideal cam sensor OK compression OK. Even...

Try the tps, throttle position sensor, and the idacv, idle air control valve. Even sometimes the temp sensor could be bad, telling the motor its cold when its really hot..
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check that the EGR valve is not sticking or has a vacuum leak. This valve will not operate until the engine is warm.

check also the engine coolant temp sensor (ECT). This sensor tells the engine computer that the engine has warmed up, so if it is faulty, it could be sending wrong information to the computer. If the sensor is disconnected, wires to it broken, or faulty in full cold mode, it will tell the computer that the engine is very cold, like -40F. The computer will schedule fuel for cold conditions. This is usually way too much fuel for a warm engine and it will rich misfire, idle rough, and be difficult to start warm.

The ECT has two wires going to it and is dedicated to sending information to the engine computer. It has nothing to do with your dash gauge that shows coolant temp. That sender has only one wire and is dedicated to the coolant temp gauge.
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