Engine rough at Red light, also hesitates from dead stop

03-26-2011, 08:54 AM

#1

aschutz

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Engine rough at Red light, also hesitates from dead stop

n/a

Last edited by aschutz; 03-04-2015 at 01:12 PM.

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03-26-2011, 09:29 AM

#2

Mazurfer

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Pure guess......................possible motor mounts?
Would need to know alot more, including service history.

Might want to start by reading these!

https://www.rx8club.com/new-member-forum-197/new-potential-owners-start-here-202454/

https://www.rx8club.com/new-member-forum-197/congratulations-you-got-8-a-202548/

https://www.rx8club.com/new-member-forum-197/rx-8-faq-please-read-before-posting-959/

https://www.rx8club.com/showthread.p...&highlight=FAQ

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03-26-2011, 12:29 PM

#3

Mazurfer

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That's a decent list. Be careful with the MAF.
How long since plugs have been changed? Coils?
Not saying it needs those at, all just thinking ahead if it continues or gets worse.

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03-26-2011, 12:55 PM

#4

lilring

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Motor Mounts. I am sure of it. I had this same problem with my auto 8 that i use to have.

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03-26-2011, 02:00 PM

#5

EDZRIDE

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Quote:

Originally Posted by aschutz

I also noticed some hesitancy when starting from a dead stop but once the rpms rev up, lots of power. Any ideas or suggestions?

That's normal, especially for the autos.

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03-27-2011, 06:48 AM

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PeteInLongBeach

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Quote:

Originally Posted by EDZRIDE

That's normal, especially for the autos.

Low rpm hesitancy is not normal....

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03-27-2011, 09:32 AM

#7

tj7723

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x2 on Motor Mounts i have the same issue

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03-28-2011, 08:14 PM

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eyangx

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try using a bottle of fuel injection cleaner by stp. i had the same problem and after i used it, the idle seems to be smoother. (not so rough anymore)

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03-29-2011, 08:28 AM

#9

987HYS

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If you are still under 50,000 miles the motor mounts will be covered under warranty. just saying..

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03-29-2011, 08:31 AM

#10

Bigbacon

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does it get worse when you turn on the fan or A/C?

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03-29-2011, 12:20 PM

#11

eyangx

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Quote:

Originally Posted by aschutz

No change if I turn on or off fan or A/C. I did put some STP Fule injector cleaner in and it may have less lag when starting from a dead stop but will monitor for a day. So for clarification besides the lag discussion, the rough idle only occurs when in D or R, runs smoother in P or N.

some or whole bottle of stp? let me know the results. cause if the stp really does work, imma get more!

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04-05-2011, 08:26 AM

#12

Swampdonkey

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i would take the broken motor mounts to where you bought the car from show them and tell them they need to hire a real mechanic

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04-05-2011, 03:03 PM

#13

DocBeech

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^+1 lol

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04-07-2011, 07:39 AM

#14

shakeyourbrakes

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hey are the mounts just covered under 50k, or are they under the 100k warranty?

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04-09-2011, 01:00 PM

#15

rocketman1045

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I am totally confused, I am having the same problem with my 8, rough idle and stalling at a red light. I'm able to restart after a little cranking. the funny thing is it idles fine when its cool temps outside, I've noticed when it gets hot out like 90-100 deg is when the trouble starts. It will start fine cold but after the engine gets hot, the troub starts, have had no problems in the winter mos, just the summer,I have an 06 auto with the bhr coils, 75k miles I've just changed the plugs and the MAF... runs a little better but I really haven't put it thru its paces yet. any sugg. would be welcome....but I am dying to know how a motor mount affects idle!! other than allowing the motor to move around a bit more but dont u have to have the rough idle first? I"m 54 yrs old and I have done competitive auto and motorcycle racing and wrenching, so I at least know which end of the plug goes into the motor....but I am stumped by this motor mount thing.

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04-12-2011, 06:56 AM

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PeteInLongBeach

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Quote:

Originally Posted by rocketman1045

I am totally confused, I am having the same problem with my 8, rough idle and stalling at a red light. I'm able to restart after a little cranking. the funny thing is it idles fine when its cool temps outside, I've noticed when it gets hot out like 90-100 deg is when the trouble starts. It will start fine cold but after the engine gets hot, the troub starts, have had no problems in the winter mos, just the summer,I have an 06 auto with the bhr coils, 75k miles I've just changed the plugs and the MAF... runs a little better but I really haven't put it thru its paces yet. any sugg. would be welcome....but I am dying to know how a motor mount affects idle!! other than allowing the motor to move around a bit more but dont u have to have the rough idle first? I"m 54 yrs old and I have done competitive auto and motorcycle racing and wrenching, so I at least know which end of the plug goes into the motor....but I am stumped by this motor mount thing.

Perished/collapsed motor mounts lose their isolating / cushioning properties, so the engine transmits more vibration to the body.

Hot starting / running problems can be a classic symptom of low compression.

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