Rough Idle
Overdrive Member
Joined: Apr 2010
Posts: 3,354
From: Spanaway, WA
That does raises another question. How hot should the cat be? Mine runs at 572, which seems a little cold, but maybe I'm wrong? It is a new cat, but I also know that don't always mean a thing. Just got back from a 30 mile test drive, got 1801 misfires on cylinder 3 and 1353 on cylinder 6. AND, how can it register that many cylinder misfires and not turn on the check engine light? It did give me the PO300 code, but it says that the MIL light was off. Fuel trims look good. Changed the PCV valve and gasket. And by the way, how does that thing work? I mean, I know its a valve that opens and closes with the vacuum. But the way it just sits in its little hole with the cap on it, with nothing going to it, just don't understand how it can do any good.
You may be reading shadow codes. Those are the codes that were tripping the CEL but are now cleared. The computer usually stores those for a while before dropping them. It is good for a tech to know what was going on in the engine before the next set of codes. Not all readers can see these codes. Usually an engine will miss every now and then on any cylinder, this is normal but I would like to see the timeframe of all those misses, if it is over a few months then no biggy (but it should be all cylinders missing and showing in the record) if the miss is in a few minutes time then there is an issue.
Massey
Overdrive Member
Joined: Apr 2010
Posts: 3,354
From: Spanaway, WA
The only code I get is the PO300. And, I must admit, that tells me it is a bad coil. But Ive swapped out the coil with another one I had, and swapped it out with another coil on the car. Neither one had any affect on the misfires.
New plugs
New wires
changed and swapped coils
New ICM
two cans of Sea foam
Fuel system cleaned
New MAF
New PCV and gasket
New plugs
New wires
changed and swapped coils
New ICM
two cans of Sea foam
Fuel system cleaned
New MAF
New PCV and gasket
Low/too high Fuel pressure,
Oil consumption
low compression
Corrosion on sensor, computer or ICM
burnt valve
broken rings
Improper plug gap
improper plugs
I wish you luck in finding the problem I really do. This is my least favorite code to track down.
Massey
Thread Starter
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In the Staging Lanes
Joined: Jul 2010
Posts: 52
From: Park Hills, Mo
Just an update, I checked the compression in all the cylinders they were all 210 except for number 4 and it was 215. I'm also holding steady at about 18.5 pounds of vacuum at idle. And I'm getting 50 lbs of fuel pressure with the K.O.E.O. and it drops down to 42 with the K.O.E.R.
Last edited by Barkat; Aug 1, 2010 at 07:05 PM.
Thread Starter
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In the Staging Lanes
Joined: Jul 2010
Posts: 52
From: Park Hills, Mo
No, the plugs looked real good. Just a hint of a light tan color on the insulators from the spark. I took it to a shop. He said it could be the injectors or it could be burnt valves. He recommended taking the injectors out and swapping them out with the other cylinders. OR doing a "running compression test." Said to take compression readings of off each cylinder while it is running. I had never heard of that before.
Thread Starter
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In the Staging Lanes
Joined: Jul 2010
Posts: 52
From: Park Hills, Mo
Just got done swapping the injectors. Sad to say I still got the miss on 3 & 6. Which leads to the burnt valves. It still strikes me odd that it is on cylinders 3 & 6 though. Just seems odd the the ones with the burnt valves share the same coil pack. And it also seems odd that the car seems to be getting better. If it was a burnt valve, it would still be running the same way now as it was when I got it. Maybe its just wishful thinking but I swear it runs better now.
Just another quick question, this cant be right, can it?
http://shop.advanceautoparts.com/web..._1136909870___
http://shop.advanceautoparts.com/web..._1136923716___
I can buy both heads for $520? Brand new, complete?
Just another quick question, this cant be right, can it?
http://shop.advanceautoparts.com/web..._1136909870___
http://shop.advanceautoparts.com/web..._1136923716___
I can buy both heads for $520? Brand new, complete?
Last edited by Barkat; Aug 2, 2010 at 05:14 PM.
Overdrive Member
Joined: Apr 2010
Posts: 3,354
From: Spanaway, WA
you would not get those comp #s with burnt valves, you can thow that idea out the window.
OK I cant remember right here but did you ever change the ICM? How about the pins on the ICM connector and plug? also moving the coil does not help right?
Now if this was me, my contact are good on the ICM, and changing the coil does not move the issue I would be looking at my wiring harness to make sure that my plug for the ICM is not got alot of corrosion on it. Clean off what is there if any and use a dielectric grease to prevent farther damage. It may also not hurt to check the plugs on the main computer as well just in case.
There is nothing else I can think of, Coil or ICM would be the only cause left since there is new plugs and wires, unless the wires on those plugs have burnt through.
Massey
OK I cant remember right here but did you ever change the ICM? How about the pins on the ICM connector and plug? also moving the coil does not help right?
Now if this was me, my contact are good on the ICM, and changing the coil does not move the issue I would be looking at my wiring harness to make sure that my plug for the ICM is not got alot of corrosion on it. Clean off what is there if any and use a dielectric grease to prevent farther damage. It may also not hurt to check the plugs on the main computer as well just in case.
There is nothing else I can think of, Coil or ICM would be the only cause left since there is new plugs and wires, unless the wires on those plugs have burnt through.
Massey
Overdrive Member
Joined: Apr 2010
Posts: 3,354
From: Spanaway, WA
OH and a running compression test is pretty simple, you use a computer diagnostics machine to monitor the idle speed then kill one cyl at a time and check how the engine reacts. The more the RPM drops the more compression the cyl has. This is a good way to get the idea of how much one cylinder actually works but not so good on the actual comp #s. It is a great diagnostics tool, I miss having access to systems that use it.
Massey
Massey