1998 VS Rough Idle Problem?
Hi All
Having some rough idle problems with my VS 3.8 V6. Have replaced injectors, cleaned upper inlet manifold, dissassembled and cleaned throttle body, new spark plugs, new leads and the idle is still pretty rough. Was wondering if it could be the coil packs. have tested with multimeter and seem fine. The ute has done 220 000km and the coils are original (still have cilinder no's on them). do they get worse over time or do they work righ up till they crap out completly? Just need some advice.
thanks in advance
A Memcal a Day Keeps..
could be DFI or a bad coil pack, is it only at idle? could just be the IAC not regulating correctly.
I am in a similar boat, I have replaced my coil packs and it made little difference to the idle, it did make the car more responsive and the rev's seemed to break up at high rpm (over 4k) and since replacing the coil packs they now dont. I've done new leads, plugs, coil packs and checked all sensors such as MAF, air temp and coolant temp and they are registering fine values.
Usually coil packs show physical signs of degradation, in my case one of them had a totally rusted terminal which due to high resistance on that terminal, means the coil would have most likely died... Testing with the multi-meter and checking for physical breakdown are about the 2 best methods to test them save swapping them out.
Have you checked your engine fault codes?
My understanding is that the DFI either works or it doesn't... ie it will either fail to start/stop the car when you are driving or it will work fine...
Drew
A Memcal a Day Keeps..
DFI connection between it and the coils can be dirty, check your IAC sensor and also check the airway that it blocks this might be full of crap.
The1, yeah, its just at idle. IAC valve seems to work fine. After reving the engine it returns to the correct idle position again and again.
astormsau, i checked fault codes and no problems. they physically look ok but i will pull them off and check the terminals underneath.
The 1, i'll check the connections but i cleaned the throttle body and got all te black gunk out of there. even removed the iac valve and gave it a clean. th was full of crap.
Have you checked al the vacuum hoses for any deterioration and possible air leaks?
thanks wortus. i checked the vaccume hoses off the manifold and the throttle body, no problems there. I noticed that one of the lines coming off my charcoal canister just slides on and off. should i have some hose clamps on these of should they do that?
A Memcal a Day Keeps..
i wouldn't be to worried about the canister connections as long as they wont fall off you dont need clamps on the hoses, the purge solenoid controls when it's in use anyway, check the line from the purge solenoid to the throttlebody as well.
checked all vaccume lines and lines to throtlle body. no issues there. starting to think it may be the coil packs. have ordered some MSD coil packs and will post results. I will need them anyway as i want to raptor the old girl a little down the track. if anyone has any other ideas on soloutions please post. has anyone installed an msd ignition? are they any good/work well??
A Memcal a Day Keeps..
a bad coil pack or dfi board yeh. Some swear by MSD some Dont, most will say though that stock coil packs are quite capable
Thanks The1. I had a look for new guenuine coil packs and they were the same price as the MSD's. Well, only slightly cheaper for brand new. quite a few people have the MSD's so i thought i might give Them a go. I don't doubt that the stocko's do the job, mine have been fine for the last 220 000km. so no complaints here. Thanks for the help. i'll trial these and if i have any further problems i might look at getting a new dfi board.
Have you checked the actual solenoid valve to see if it is closed properly? It may be faulty and stuck open.Originally Posted by lowwhite
Put the new coil packs in today. Great result. much smoother idle than before. Thanks for all the help guys
I still have a weird issue, when I got this VS (about 3 months ago) the IAC valve was totally sticky and hardly worked so I cleaned it out as well as the throttle body. I have cleaned it up and its much better, weird issue is, that sometimes the car idles smooth as silk, other times its rough... its always rough when its cold but when its warm its either rough or smooth and it can change from one set of lights to the other when pulling up... its annoying because I know it can be so good when its idling properly... even when its idling rough you dont see any real fluctuation of rpm's on the tacho and its sitting about 700rpm in drive...
the car performs flawlessly when driven, has new coils, plugs, leads, Torque converter, just serviced (penrite HP30 and new oil filter), cleaned MAF (which is working fine), cleaned plenum as well... removed all throttle body/plenum hoses and checked for leaks and no issues, all refitted correctly, coolant temp sensor is 100% fine as is the intake air sensor and TPS (operation has been checked by auto elec using computer). The IAC works - when the car is started it revs up to 1200rpm for 20 seconds or so and revs up to go into drive and when aircon is turned on and so forth... at a bit of a loss.... the only thing i can figure is that the IAC is lazy and isn't working quite as quickly or as accurately as it should and hence when I pull up at the lights its not always returning to the correct position and hence causing the engine to idle rough... when you look at the motor as the car is idling its almost as if its unbalanced and it shakes a bit...
any thoughts?
Drew
Thats a tough one Drew. I would have checked everything the same as you but i'm at a loss to what could be the cause. The only thing i could suggest is looking at the fuel dilivery side of things. I did have some issues once with a dirty fuel system and slightly blocked injectors, bit rough unless you were pushing the revs up high. I'm not sure about the IAC valve, maybe check your codes and se if there are any faults. Sorry i can't be of more help. Good luck with it.
Yeh im a bit stumped, have checked and no codes. Replaced fuel filter. Fuel pressure reg seems ok from the basic check of seeing if any fuel has gone up the line to the plenum... other than that it could be a leaky injector but no black smoke on startup and car is dead on the money for economy... you'd think its a vac leak but nothing showing that... The only thing I can think is that the IAC isn't returning to its closed position correctly some of the time because its buggered...
Drew
Yeah mate. i'de go with the iac valve. never heard of one wearing out but i'm sure its possible. all electrical moving parts have a limited life. try getting one from the wreckers and see how it goes. might be on the way out but not chucking any codes yet. Just a suggestion. seems like the only resionable explination left.
have you had extractors put on it recently mate
if you havent got extractors i would be leaning towards gear box mount . get back to me mate might be able to help you
I've not had extractors fitted, did have some rusted out exhaust bits replaced about 2 months ago. I had the gearbox mount inspected when the torque convertor was replaced and I was told its perfect as I was a bit suss about it.
Drew
A Memcal a Day Keeps..
you can get a brand new iac off ebay for $29, not sure what they go at holden for, but worth a shot at that price.
is there a vibration running threw the steering wheel in drive at idle...
v2Desire... its more through the whole car... ie my gps attached to the windshield even vibrates a bit.... its less noticeable through the wheel..
Drew
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