this has been going on for a while now i noticed when im driving and come to a stop the rpms drop slightly about 100rpms and go back up and car will vibrate. happens everytime i come to a stop or if im in park and i tap on the gas lightly and when the rpms come back to normal itll drop 100 and vibrate and go back up to normal again

happens in reverse also

any ideas? i seafoamed my car vacuum/fuel tank/crankcase. changed oil and spark plugs and did a coolant flush but that didnt help.

 

bad coil, clogging IACV, bad motor mount (vac boosted)
did you put the correct plugs in?

 

i asked my mechanic to check my mounts he said only my side mounts broken. and i put the right spark plugs this is the second time ive changed them because they were on sale for 10 bucks a pair so i thought might as well.

im going to try the iacv next whats the best way to clean it? deep creep?

 

5 bucks each for iridium or Iridium IX,,the right plugs for our car
heck of a price!

front and rear mounts can easily be overlooked as they dont fail in the normal way -like a side does
IF pass side mount broken I can almost guarantee you the front has been bad a really long time- unnoticed
the side takes extra load not made for and it breaks

Look under front and rear mounts for old signs of oil trail,,dust stuck on,,
not much fluid in there and very stange oil,,mine left 3 drops on the ground as signal of failure

USE a vacuum guage/suction tool, test for holds vac--the ultimate tell of a broken `boosted` mount

Unless your guy is a TL guru- I'd stick with ziner knowledge and double ck anything he told you!!

 

IACV is on bottem of TB-
remove TB from engine and flip it over
the tube that is the iacv= drops into a bore hole and rotates changing amount of air at idle
has a keeper tab you bend up to remove rod

clean the slit cut in side of that- remove grunge with dc or carb cleaner

buy a new TB to manifold and IACV `COVER` gasket

the egr passage/port cleaning is important to do too

 

EGR port cleaning

 

i would have my money on the mounts....I know the tech said only the side was broken but i would check the vac lines again....

 

Is there a steady vibration every couple of seconds while at a stop light?

 

care to share your thoughts?

 

yes sometimes

 

yup put the iridium ix they were on sale. the way we tested the mounts was i put it in gear and brake gas to see if theres alot of engine movement

 

i think the way you check the mounts is

1> put it in gear drive a bit and come to a stop as you do at a light....
2> check vibrations
3> put it in neutral
4> check vibrations

if there is a ton of difference....its blown

 

no- you look for fluid leak trail, compressed look to mount lower section,
and fails to hold vacuum!!
thats for the front and rear

others you ck by standing on the gas and brake together- giving it some rev and watch for engine motion
A prybar can be used to test other mounts= same as old cars

 

miles? done the egr service yet? if not start there
and clean IACV while its all apart

 

havent done egr service but my intake manifold is about a year old

 

I have the same problem actually happened after seafomaing and spark and oil change and everything is in correctly so idk...

 

Sounds like the same issue I have been trying to resolve for a while now.

 

do the gas with seafoam again
its always possible some small piece of crud is causing a problem

 

vac leak ck? whats the running vacuum read?

 

noticed the vibrations are getting worse i can feel them through the whole car now. and its happening every few seconds now when im stopped they go away when im moving

 

I had the same problem turned out one coil was failing but not bad enough to throw a CEL. I let the car idle for 20-25 minutes in the driveway and eventually it threw a CEL and a code. Replaced the bad coil and the idle is smooth again.

 

You may have the same problem; could have damaged one of the coils slightly from mis-handling them during the spark plug change.

 

I agree thats always a possible--treat coils like Grandmas finest china

kdawg can you get to a code reader to look for misfire codes?
or do the cheater method of removing the power lead to coil while engine is running
when you find one that doesnt drop the idle slightly you found a bad coil

since the manifold is recent and probably still clean, did you ck the egr valve itself- may need lube on the operating arm?

 

thanks i will try that cheater method

and i was having the issue before the spark plug change so i dont think it could be from mishandling the coil

 

could still be a dieing coil based on age

 

Remove the vacuum line from the front and rear motor mounts and plug them (a golf tee works well). There will now/still be a steady vibration but the engine idle and surging should go away if it is a bad vacuum motor mount.
Coils either work or they don't and testing them can be a lost adventure as at certian temps or vibrations they may fail but test ok under normal procedures.
Another test is to block the motor mount vacuum valve -upstream of the mounts vacuum lines- which may also be suspect.

 

my mechanic adjusted my idle speed to a lil faster so it revs at round 800-900rpms and it seems to have gotten the irratic idle out

 

you mean instead of fixing the real problem- he jacked with the system,,
adjusted idle how?
tightening the throttle cable freeplay does not count as fixing rough idle!!

 

he adjusted the screw on the top of the throttle body. its just a temporary fix im going to buy the xlr8 urethane mounts when they are done being fabricated

 

update xlr8 urethane mounts installed but idling issue is still there its getting annoying it feels like the cars gonna die when the rpms drop that low. i put a full can of seafoam in the crank case and drove it for about 150kms and changed oil to full synthetic 0w20. i always put 92 octane gas from shell

anybody help with my problems i dont think its the mounts. im going to try putting a full can seafoam in half tank of gas.

 

i think XLR8 mounts will cause some vibrations...

let the mounts break in, it will reduce....

just for my knowledge, these are solid mounts right ?

 

the mounts do have vibrations i understand that but my cars been idling weird even before i installed the new mounts