help, engine still running poorly ('98 LS)
10-30-06, 06:28 AM
#1
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help, engine still running poorly ('98 LS)
ok, here goes.
for a while now, i have noticed my 98 ls400 running rough, particularly on cold mornings. it felt like the car was running on 7 cylinders. it used to always go away once the car warmed up, but now sometimes it doesnt. i was told to start with a tuneup and here is what i did.
changed air filter, spark plugs, fuel filter, pcv
i also cleaned the throttle body.
now, not only has my problem NOT been solved..but i am idling all over the place... started cold, the engine may idle at 1300 rpm!!!!
any suggestions for both problems???
for a while now, i have noticed my 98 ls400 running rough, particularly on cold mornings. it felt like the car was running on 7 cylinders. it used to always go away once the car warmed up, but now sometimes it doesnt. i was told to start with a tuneup and here is what i did.
changed air filter, spark plugs, fuel filter, pcv
i also cleaned the throttle body.
now, not only has my problem NOT been solved..but i am idling all over the place... started cold, the engine may idle at 1300 rpm!!!!
any suggestions for both problems???
10-30-06, 04:31 PM
#3
Actually I don’t believe the 98+ models use an IAC valve, it has an electronic throttle motor to control idle speed. It does however use a throttle position sensor and if your experiencing fluctuations at idle then it could possible be the TPS. How many miles do you have and what spark plugs did you use when you did the tune up?? Also 1300 RPM during cold start is normal, it should drop to around 750 once warmed up and in park.
10-30-06, 04:54 PM
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i used NGK iridium.
could i have damaged the TPS when i cleaned out the throttle body? I am learning now that i probably shouldn't have sprayed the cleaner on the TB itself, instead use a rag that has cleaner on it...
could i have damaged the TPS when i cleaned out the throttle body? I am learning now that i probably shouldn't have sprayed the cleaner on the TB itself, instead use a rag that has cleaner on it...
10-30-06, 06:51 PM
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well, thats an easy replacement then... guess i'll swap off of my buddies 99 ls to see if that is the problem.
my bigger problem still is the rough running, can't figure it out.
my bigger problem still is the rough running, can't figure it out.
10-31-06, 10:32 AM
#7
Have you tried resetting the ECU? Try that.
My car went nuts after i cleaned the MAF without reseting the ECU for a few days.
And it may also be a vacuum leak, check all the hoses.
Last edited by GRAND_LS 4; 10-31-06 at 10:37 AM.
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10-31-06, 10:49 AM
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well, i did disconnect the battery for around 10 minutes after i did all of that. Im thinking now that the higher idle may be correct (because it does go down after the car warms), perhaps the clogged air filter i replaced may be allowing it to idle normal now.
still searching for a reason for the rough/misfiring engine though
still searching for a reason for the rough/misfiring engine though
10-31-06, 03:06 PM
#9
well, i did disconnect the battery for around 10 minutes after i did all of that. Im thinking now that the higher idle may be correct (because it does go down after the car warms), perhaps the clogged air filter i replaced may be allowing it to idle normal now.
still searching for a reason for the rough/misfiring engine though
still searching for a reason for the rough/misfiring engine though
