Rough Idle Around 1000 RPM
08-09-2008, 08:48 PM
#1
Racer
Thread Starter
Rough Idle Around 1000 RPM
I have had this problem ever since I have owned the car. The engine idles as it should between 600-700 rpm and is smooth. The engine only is rough between around 900 rpm through 1100 rpm. That also coincides with my intown driving with the overdrive, so it makes the whole car vibrate when the engine is within this range, and it does it in park as well as in gear. I have checked all the vacuum lines, compression check, new plugs, wires, cap and rotor and this has me stumped. The car is reletively smooth in all other ranges. Could I be starting to loose my balancer? As I said before, idle at 600-700 rpm is pretty smooth, and revving the engine or driving it through the 4000 range is fine also....just between 900-1100 rpm is rough. Any thoughts???
08-10-2008, 08:03 PM
#4
Le Mans Master
Shot in the dark....this doen't work on all balancers though. If you think the balancer is going or spining draw a line on the face of the balancer from the crank shaft to the outer part of the of the unit. Start the car and rev it up a few times or drive it hard a day or 2 the pop the hood and check to see if the line is still lined up or if it has spun. I've seen bad balancers they are pretty noticable when the engine hits higher RPMs.
Good Luck!
Good Luck!
08-10-2008, 11:41 PM
#5
Racer
Thread Starter
Shot in the dark....this doen't work on all balancers though. If you think the balancer is going or spining draw a line on the face of the balancer from the crank shaft to the outer part of the of the unit. Start the car and rev it up a few times or drive it hard a day or 2 the pop the hood and check to see if the line is still lined up or if it has spun. I've seen bad balancers they are pretty noticable when the engine hits higher RPMs.
Good Luck!
Good Luck!
08-10-2008, 11:50 PM
#6
Safety Car
Member Since: Oct 2007
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We're assuming you've lit up no codes?
Does it idle well when warm?
Try to do a fuel pressure test - static, idle with vacuum on FPR, idle with vacuum off of FPR, and pedal down (tape the guage to the windshield).
You have to do each to rule out specific problems. Post back up with results.
Does it idle well when warm?
Try to do a fuel pressure test - static, idle with vacuum on FPR, idle with vacuum off of FPR, and pedal down (tape the guage to the windshield).
You have to do each to rule out specific problems. Post back up with results.
02-05-2009, 06:14 PM
#8
Racer
Thread Starter
Ok, I have pretty much replaced the whole upper end of the engine from the intake up....taken the distributor out and apart and cleaned so the shaft spins smoothly and the gear looks good. I get some kind of whining at the back of the engine around where the distributor is and it cant be heard until I get about 900-1000 rpm. I beleive this is the source of it, but I am afraid of what it might be. Is the cam gear machined into the camshaft? I thought the noise was the tranny pump for the longest until I took the bolts of the torque converter to make sure. Noise was still there. So what would make this noise and cause a misfire/balance problem. I am thinking something is wrong with the cam?? I have plenty of oil pressure....since the distributor drives the oil pump. Something? Anybody?
02-05-2009, 09:17 PM
#11
Racer
Thread Starter
Both new.
It idles fine...I guess I misused the word 'idle'...idles fine at 625 when warm and closed loop. Its when I ease on the throttle around 1000rpm is when I get the vibration, slight miss maybe, and when the whining noise starts ..
It idles fine...I guess I misused the word 'idle'...idles fine at 625 when warm and closed loop. Its when I ease on the throttle around 1000rpm is when I get the vibration, slight miss maybe, and when the whining noise starts ..
02-05-2009, 10:09 PM
#13
Le Mans Master
I can't imagine what would make a whine noise back there. Small exaust leaks can make a whistle sound. Maybe check the vacuum hoses in the area for leaks....seems like weird problem. Does the car whine when cold at 1000 RPM? Failing/blocked injectors can cause an engine to miss....maybe check the injector coils for the proper resistances.
02-05-2009, 10:49 PM
#14
Racer
Thread Starter
Remove the valve cover emblem see if the whine goes away
I can't imagine what would make a whine noise back there. Small exaust leaks can make a whistle sound. Maybe check the vacuum hoses in the area for leaks....seems like weird problem. Does the car whine when cold at 1000 RPM? Failing/blocked injectors can cause an engine to miss....maybe check the injector coils for the proper resistances.
I can't imagine what would make a whine noise back there. Small exaust leaks can make a whistle sound. Maybe check the vacuum hoses in the area for leaks....seems like weird problem. Does the car whine when cold at 1000 RPM? Failing/blocked injectors can cause an engine to miss....maybe check the injector coils for the proper resistances.
02-05-2009, 10:59 PM
#15
Racer
Thread Starter
The tuner told me for the program he uds I needed to have my tps set at .61v at idle...thats what I have it set at.
This noise has been there ever since I purchased te vehicle. Its mechanical. All the new parts I have put into it hasnt solved anything.
This noise has been there ever since I purchased te vehicle. Its mechanical. All the new parts I have put into it hasnt solved anything.
02-05-2009, 11:07 PM
#16
Team Owner
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Need to pin down the whining sound.
It's not the air pump is it?
Check the vacuum advance unit on the distributor, see if it's smooth in motion.
It's not the air pump is it?
Check the vacuum advance unit on the distributor, see if it's smooth in motion.
02-05-2009, 11:08 PM
#17
Le Mans Master
Just a guess:
Well I guess your injectors are not the problem then.
I know you said you inspected the distributor gear but perhaps the intake's distributor deck is at a different height than the one you had on there before and the distributor gear is striking the cam at a little different spot than what it was use and worn to and that is producing the whine noise. If this is the case the noise may go away with time as gear wares.
Good Luck!
Well I guess your injectors are not the problem then.
I know you said you inspected the distributor gear but perhaps the intake's distributor deck is at a different height than the one you had on there before and the distributor gear is striking the cam at a little different spot than what it was use and worn to and that is producing the whine noise. If this is the case the noise may go away with time as gear wares.
Good Luck!
02-05-2009, 11:15 PM
#18
Racer
Thread Starter
Air pump got deleted with the new intake setup. I have no vacuum advance for the distributor...its controlled by ecm. Its not an air whining or whistling...its mechanical because I can feel it when I put my hand on the intake. This was doing this before I changed the intake setup.