Car is missing at idle etc...
Car is missing at idle etc... Car misses throughout the rpm range, not bad but noticeable,no codes thrown though so im not sure, what are likely culprits? thanks. Besides plugs & wires as those are obvious.
Last edited by thatguy383; Jun 11, 2010 at 11:37 AM.
Joined: Nov 2001
Posts: 34,627
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From: Schiller Park, ILL Member: #317
Without having any codes, and without any scanner data listed, I would assume any of the following:
- plugs & wires (as you listed)
- MAF dirty
- Aging O2 sensors (probably wouldn't have much effect if not bad enough to throw a code though)
- Valvetrain related issue (bent pushrods, bent valves, loose/damaged rockers...do you hear any ticking or tapping?)
- Fuel delivery issue (poor injector spray pattern due to failing injector(s)/varnish deposits on tip(s), clogged fuel filter, poor fuel pressure due to failing pump)
- Weak ingnition coil(s)
- Several engine related sensors or internal PCM faults (again, not likely without throwing a code though)
That's a quick list off the top of my head.
If you could toss a scanner on there and see just how bad the misfires are, and whether or not they are cylinder specific (also things like O2 data, for a rough check of A/F ratio), that would be helpful to narrow things down.
- plugs & wires (as you listed)
- MAF dirty
- Aging O2 sensors (probably wouldn't have much effect if not bad enough to throw a code though)
- Valvetrain related issue (bent pushrods, bent valves, loose/damaged rockers...do you hear any ticking or tapping?)
- Fuel delivery issue (poor injector spray pattern due to failing injector(s)/varnish deposits on tip(s), clogged fuel filter, poor fuel pressure due to failing pump)
- Weak ingnition coil(s)
- Several engine related sensors or internal PCM faults (again, not likely without throwing a code though)
That's a quick list off the top of my head.
If you could toss a scanner on there and see just how bad the misfires are, and whether or not they are cylinder specific (also things like O2 data, for a rough check of A/F ratio), that would be helpful to narrow things down.
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Joined: Mar 2005
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From: Corpus Christi
with no codes or check eng. light on then I wouldn't say missing. if you do have a miss fire the check engine light would be flickering on/off. check your headers/exhaust system to see if they are hitting/bumping into anything. this can cause your knock sensor to reduce timing. and reset it's quickly then sens it again... did you by anychance removed or replaced knock a sensor? did you swap/replace/change anything prior to this "missing"?
'?' -would a slight increase in timing change the idle characteristics enough for me to think something was up?
my misfire code has been disabled through a tune, that explains no dash lights... havent gotten to the scanner yet
my misfire code has been disabled through a tune, that explains no dash lights... havent gotten to the scanner yet
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If you want to, get a scan to see what the 02 sensors are doing while the car is running. Not the cheesy code scanners, a real OBDII scanner like the dealerships use.
You could also buy two new 02 sensors and put them in and see if it fixes it. If not, return them for a refund.
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I changed out the o2s, plugs and wires on mine about 2 weeks ago when it started misfiring on me. Spent like $200 on all that, but it wasn't the problem. Took off the driver side valvecover and found a cracked valvespring.
Oh, make sure you buy Denso 02 sensors......not Bosch. And if you go to the dealership you will be getting Densos in the AC Delco box....but they will cost upwards of $180 each.
So go to Bennet Auto or if you can wait for them in the mail....$40.00 each at www.rockauto.com or amazon.com.
But you can go get some to try at the local parts store for now.
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So go to Bennet Auto or if you can wait for them in the mail....$40.00 each at www.rockauto.com or amazon.com.
But you can go get some to try at the local parts store for now.
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Just tell them that someone modded your ports for the 02 sensors and they won't fit...and that you could not install them....trust me, they will have no clue and they have to refund your money.
You can get other brands besides Bosch to do the check......if you have a Bennett Auto nearby, get the Densos.
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