misfire issues which I can't fix!
#1
12-24-2016, 11:54 AM
misfire issues which I can't fix!
While coming home from work, my '02 SL sedan suddenly lost power and the service engine light began flashing. With any load it would barely run, and when codes were checked an 0300 random misfire came up. I have so far replaced the fuel filter, intake manifold gasket, plugs, plug wires, TPS, ECTS, MAP sensor, coil packs, and tried a different ICM. I also removed and cleaned the EGR and IAC motor. It still runs terribly under any load, and will not idle once warmed up. I will have to replace the thermostat soon as heater output is low and it takes a while to warm up. I tried running the car with the O2 sensor out to see if it was a plugged cat but it ran no differently. (This happened suddenly, not as a long-term thing. Was running great with no problems before this.) I am running out of ideas, and would appreciate some ideas! Thanks!
#2
12-25-2016, 01:20 AM
Well, that's one of the most severe cases of shotgunnning parts we've seen around here in a while....
1) How many miles on the car?
2) When you say it won't idle when warmed up, what exactly does that mean? Does it run from a cold start? If so. at what rpm when it first starts? Is it that as it warms up, the rpms continue to drop and drop until the engine just stalls out? Can you keep it running by holing the pedal down part way?
3) What happens when you clear the P0300? Does it immediately start misfiring as soon as you start it again? Do you get any addl codes?
4) How low on oil was it when this occurred?
5) Has the timing chain area of the engine sounded rattly or metal on metal lately?
From your description, without answers to the above, I'm going to GUESS that your engine was run down very low on oil, accelerating the wear of the timing chain, cam sprocket, crank sprocket, and tensioner. [Incorrect guess based on answers below] This has led to one of the sprockets slipping one tooth off from correct engine timiing -- the engine has "jumped time".[Incorrect assumption]
not relevant hereThis will result in misfires in all cylinders (hence the random code) as the timing of the intake and exhaust valves opening and closing relative to the piston position (hence crank position) is off. When the spark comes, if both valves are not closed, you will have very little compression .
A compression check across all 4 cyls should yield equally crappy results.
No real compression = no power.
Out of sync valves= rough running if at all
Hold off on timing check. see below After confirming crappy compression, I would recommend pulling the timing chain cover can rotating the crank by hand to see if the timing marks line up. I'm betting it's off.
>>>Analysis and future advice subject to change based on answers to above questions
1) How many miles on the car?
2) When you say it won't idle when warmed up, what exactly does that mean? Does it run from a cold start? If so. at what rpm when it first starts? Is it that as it warms up, the rpms continue to drop and drop until the engine just stalls out? Can you keep it running by holing the pedal down part way?
3) What happens when you clear the P0300? Does it immediately start misfiring as soon as you start it again? Do you get any addl codes?
4) How low on oil was it when this occurred?
5) Has the timing chain area of the engine sounded rattly or metal on metal lately?
From your description, without answers to the above, I'm going to GUESS that your engine was run down very low on oil, accelerating the wear of the timing chain, cam sprocket, crank sprocket, and tensioner. [Incorrect guess based on answers below] This has led to one of the sprockets slipping one tooth off from correct engine timiing -- the engine has "jumped time".[Incorrect assumption]
not relevant hereThis will result in misfires in all cylinders (hence the random code) as the timing of the intake and exhaust valves opening and closing relative to the piston position (hence crank position) is off. When the spark comes, if both valves are not closed, you will have very little compression .
A compression check across all 4 cyls should yield equally crappy results.
No real compression = no power.
Out of sync valves= rough running if at all
Hold off on timing check. see below After confirming crappy compression, I would recommend pulling the timing chain cover can rotating the crank by hand to see if the timing marks line up. I'm betting it's off.
>>>Analysis and future advice subject to change based on answers to above questions
Last edited by derf; 12-26-2016 at 05:29 AM.
#3
12-25-2016, 06:32 AM
Well, the answers are
1.109,000
2. Starts right up, even in our -15 temp we had last week, and idles at 1,000 rpm. After
it warms up, idle drops to about 500 rpm and will run when pedal held down.
3. Misfires after giving it gas.
4. No. Not low on oil. I check oil on my vehicles regu
ularly
and this one has not been low in the three years I have owned it. Can't say about former owner.( He bought it new.)5. Did not hear any noises and still don't.
I "shotgunned" parts because the shop manual and a mechanic pointed out that the misfiring my be due to electrical issues. It runs better after those parts were installed, but still bogs under load.
I will have to investigate the timing, hopefully that will solve the problem. It must have jumped suddenly as I was driving it.
Oh, and it had 60,000 on the clock when I bought it. Thanks for your help!
1.109,000
2. Starts right up, even in our -15 temp we had last week, and idles at 1,000 rpm. After
it warms up, idle drops to about 500 rpm and will run when pedal held down.
3. Misfires after giving it gas.
4. No. Not low on oil. I check oil on my vehicles regu
ularly
and this one has not been low in the three years I have owned it. Can't say about former owner.( He bought it new.)5. Did not hear any noises and still don't.
I "shotgunned" parts because the shop manual and a mechanic pointed out that the misfiring my be due to electrical issues. It runs better after those parts were installed, but still bogs under load.
I will have to investigate the timing, hopefully that will solve the problem. It must have jumped suddenly as I was driving it.
Oh, and it had 60,000 on the clock when I bought it. Thanks for your help!
#4
12-26-2016, 05:17 AM
ARE THERE AN OTHER DIAG CODES SHOWING UP?
THIRD ATTEMPT at a reply:
1) I expected very different answers back from you when I made my overarching condemnation of your issue as a timing problem. Usually I wait for the feedback, then make an intelligent guess.
Well, this time I did not wait -- and I'm pretty sure I'm wrong. Maybe.
----------------
I expected low oil high miles and difficult to start/run at all.
I expected constant misfiring.
I expected noisy timing chain area.
Nope.
------------------------------------------------------
----Let's back up on the timing thing and get back to basics first and work our way through like I should have done at the beginning.
1) What plugs are in the car?
Should be NGK 7755 {#BKR4ESA11) good ol fashioned copper. No platinum, iridium or whatthe****isthat-ium.
2) Do wires meet minimum Resistance spec?
3) is your cam cover gasket leaking oil into the spark plug wells?
If so, if the oil gets up to the bottom of the plug boot it can get "wicked up" (capillary action) to the top of the plug and redirect the current around the plug instead of through it.
If so, replace cam cover gasket with a quality one and do NOT over torque past the spec or it will leak. If you tighten it more it will leak even more.
Toy may need to replace the wires if the boots are all messed up due to oil exposure.
4) Have you checked for spark at each plug? I know this sounds redundant based on what you have replaced, but stranger things have happened.
With the fuel injector fuse pulled, hold the metal tip of a plug connected to a wire coming from the coil to an unpainted ground surface under the hood. Have a helper crank the engine a few rotations. Should get nice strong spark and between the the electrode and ground only. If you see other spark paths, we'll deal with that. DO the same with the other 3 plugs with their respective wires. This will confirm that the coils are doing their job and you should expect spark to occur when requested.
5) Do you have the plug wires connected in the right firing order. Firing order is on the front crossmember on one of those black and yellow stickers. Not trying to be insulting. Everyone except Andy has done it at least once in their life, including me.
6) Air intake. Did you perhaps acquire a bird on your last trip which is now dead and restricting the air intake? Air filter clogged, restricting airflow?
7) Throttle body cleaned lately?
8) V across battery when car is running? Saturns can be picky about operating V and the steadiness (regulation) of the V.
9) Have you checked the fuel pressure at the fuel rail up front? Loan tool at autozone should work for that. So should a compression tester (see below)
10) Have you ever pulled and cleaned the EGR wit choke/carb cleaner?
Usually you will throw EGR codes when it is truly gunked up but 100k is a good interval until it really starts burning oil.. If it were stuck closed, you'd get a stuck closed code, stuck open, a stuck open code, etc.
I was trying to think of what EGR condition could exist AND occur instantaneously without throwing a code that would affect your performance so profoundly, and the only thing I could come up with (this is a stretch) Is that the pintle itself is moving well enough but the pass through hole for the exhaust gases is so clogged up that the exhaust gases are not passing through. Though I think this should throw an insufficient flow code.
The valve is open when accelerating, and I think the PCM calculates in it's expected contribution to the Air/Fuel mix -- this air goes right into the manifold. If it's not there, then you are running an overly rich mix without meaning to and I'm sure that doesn't bode well for creating mixtures that just don't want to combust.
EDIT: If the EGR is not closing all the way, that can also lead to P0300 codes ( as it is leaking exhaust back into the intake)
11) The cold open loop idle sounds low to me -- seems like it should be more than 1000. DOHCs run at 1400 on cold startup, but this is an MPFI SOHC so I dunno. Someone else please chime in.
12)The fact that the rpms just keep dropping to the point that it will stall before idling tells me either the car's idle adjustment screw has been messed with, or, more likely.......
13) the car is not entering closed loop control. This would make sense especially if the front O2 sensor or was giving bad or no readings
it is constantly monitoring the Oxygen level in the raw exhaust---once it is warmed up! If it is not warmed up or defective, it cannot dynamically control the air fuel mixture in real time, and it seems the car would just keep running super rich as it is programmed to do open loop. Incorrect coolant temps inferred from a NON GM ECTS /pigtail also are known to cause problems, as the temp vs resistance behavior is not the same, leading to an even bigger mess w r t the air/ fuel mix.
14) Compression test: Look up on the internet how to PROPERLY perform a compression test (there are too many wrong ways to list) loan a tool from autozone and go for it. It should give you an overall idea on the state of health of your engine. I'd probably do this after checking the basics, as the results won't change throughout all the above testing, and if you have awful compression then you need not spend all the extra time.
Please go through this list of checks, one at a time, to see if one of them can be traced to the root cause of all evil. If you change 3 things at once and it works properly, NO ONE will ever know which fixed it.
Please post as you go -- it'll give us more to think about along the way.
Apologies for my bogus earlier leap to the worst case scenario--there's a lot to rule out first.
THIRD ATTEMPT at a reply:
1) I expected very different answers back from you when I made my overarching condemnation of your issue as a timing problem. Usually I wait for the feedback, then make an intelligent guess.
Well, this time I did not wait -- and I'm pretty sure I'm wrong. Maybe.
----------------
I expected low oil high miles and difficult to start/run at all.
I expected constant misfiring.
I expected noisy timing chain area.
Nope.
------------------------------------------------------
----Let's back up on the timing thing and get back to basics first and work our way through like I should have done at the beginning.
1) What plugs are in the car?
Should be NGK 7755 {#BKR4ESA11) good ol fashioned copper. No platinum, iridium or whatthe****isthat-ium.
2) Do wires meet minimum Resistance spec?
3) is your cam cover gasket leaking oil into the spark plug wells?
If so, if the oil gets up to the bottom of the plug boot it can get "wicked up" (capillary action) to the top of the plug and redirect the current around the plug instead of through it.
If so, replace cam cover gasket with a quality one and do NOT over torque past the spec or it will leak. If you tighten it more it will leak even more.
Toy may need to replace the wires if the boots are all messed up due to oil exposure.
4) Have you checked for spark at each plug? I know this sounds redundant based on what you have replaced, but stranger things have happened.
With the fuel injector fuse pulled, hold the metal tip of a plug connected to a wire coming from the coil to an unpainted ground surface under the hood. Have a helper crank the engine a few rotations. Should get nice strong spark and between the the electrode and ground only. If you see other spark paths, we'll deal with that. DO the same with the other 3 plugs with their respective wires. This will confirm that the coils are doing their job and you should expect spark to occur when requested.
5) Do you have the plug wires connected in the right firing order. Firing order is on the front crossmember on one of those black and yellow stickers. Not trying to be insulting. Everyone except Andy has done it at least once in their life, including me.
6) Air intake. Did you perhaps acquire a bird on your last trip which is now dead and restricting the air intake? Air filter clogged, restricting airflow?
7) Throttle body cleaned lately?
8) V across battery when car is running? Saturns can be picky about operating V and the steadiness (regulation) of the V.
9) Have you checked the fuel pressure at the fuel rail up front? Loan tool at autozone should work for that. So should a compression tester (see below)
10) Have you ever pulled and cleaned the EGR wit choke/carb cleaner?
Usually you will throw EGR codes when it is truly gunked up but 100k is a good interval until it really starts burning oil.. If it were stuck closed, you'd get a stuck closed code, stuck open, a stuck open code, etc.
I was trying to think of what EGR condition could exist AND occur instantaneously without throwing a code that would affect your performance so profoundly, and the only thing I could come up with (this is a stretch) Is that the pintle itself is moving well enough but the pass through hole for the exhaust gases is so clogged up that the exhaust gases are not passing through. Though I think this should throw an insufficient flow code.
The valve is open when accelerating, and I think the PCM calculates in it's expected contribution to the Air/Fuel mix -- this air goes right into the manifold. If it's not there, then you are running an overly rich mix without meaning to and I'm sure that doesn't bode well for creating mixtures that just don't want to combust.
EDIT: If the EGR is not closing all the way, that can also lead to P0300 codes ( as it is leaking exhaust back into the intake)
11) The cold open loop idle sounds low to me -- seems like it should be more than 1000. DOHCs run at 1400 on cold startup, but this is an MPFI SOHC so I dunno. Someone else please chime in.
12)The fact that the rpms just keep dropping to the point that it will stall before idling tells me either the car's idle adjustment screw has been messed with, or, more likely.......
13) the car is not entering closed loop control. This would make sense especially if the front O2 sensor or was giving bad or no readings
it is constantly monitoring the Oxygen level in the raw exhaust---once it is warmed up! If it is not warmed up or defective, it cannot dynamically control the air fuel mixture in real time, and it seems the car would just keep running super rich as it is programmed to do open loop. Incorrect coolant temps inferred from a NON GM ECTS /pigtail also are known to cause problems, as the temp vs resistance behavior is not the same, leading to an even bigger mess w r t the air/ fuel mix.
14) Compression test: Look up on the internet how to PROPERLY perform a compression test (there are too many wrong ways to list) loan a tool from autozone and go for it. It should give you an overall idea on the state of health of your engine. I'd probably do this after checking the basics, as the results won't change throughout all the above testing, and if you have awful compression then you need not spend all the extra time.
Please go through this list of checks, one at a time, to see if one of them can be traced to the root cause of all evil. If you change 3 things at once and it works properly, NO ONE will ever know which fixed it.
Please post as you go -- it'll give us more to think about along the way.
Apologies for my bogus earlier leap to the worst case scenario--there's a lot to rule out first.
Last edited by derf; 01-01-2017 at 10:13 AM.
#5
01-01-2017, 02:44 AM
[QUOTE=derf;56451]ARE THERE AN OTHER DIAG CODES SHOWING UP?
THIRD ATTEMPT at a reply:
UNQUOTE
I just stopped by to say Happy New Year and saw the unhappy post. And the very first and only question I have had on this is a repeat of Derf's question. Are there any other codes showing up.
I ask because I really did not see any listed and that is where I would go to in the first place.
So Happy New Year and I hope everyone has a good year.
THIRD ATTEMPT at a reply:
UNQUOTE
I just stopped by to say Happy New Year and saw the unhappy post. And the very first and only question I have had on this is a repeat of Derf's question. Are there any other codes showing up.
I ask because I really did not see any listed and that is where I would go to in the first place.
So Happy New Year and I hope everyone has a good year.
#7
01-01-2017, 07:57 AM
I see you replaced the ECTS. Where did you get it and did you also replace the connector? Aftermarket ECTS are not correctly calibrated. Hopefully you got it from a Saturn friendly GM dealership and it has a brass tip. The rosin tipped ones are crap. I ask about the connector (pigtail) because the one on one of my SC's was cracked and the ECTS didn't make any difference. Once I got into the wiring, it turned out to be a cracked connector on the ECTS. I replaced it and the car started running great. Take a close look at it.
#9
01-02-2017, 08:20 AM
Dan
I will chime in on the ECTS also. And in doing so I am acknowledging that here it is some 25 or so + years and the company is now out of business the one single thing that over those years have caused a whole bucket full of problems simply because when aftermarket reversed engineered the thing, GM had installed the wrong part on the engine so all of the auto parts supply places developed the wrong piece to replace it with, in essence another bad one. Saturn (AKA GM) sent out a service bulletin acknowledging that things were wrong, 10 years after the fact and way too late to fix the screw up and here it is 25+ years down stream and it still ain't fixed leaving one with the only solution to fixing problems caused by the ECTS is to purchase one from a GM dealer along with the replacement socket it gets plugged into. And it seems to be getting harder to find a GM dealer that will sell Saturn parts.
What kinds of problems can this thing cause? I am reminded of a Red Buttons record from the same era "strange things are happening" Almost anything!
So entertain your self by listening to the record (
) and find a GM dealer to buy one with it's pig tail. A Chevy dealer around the corner from where I live sells GM Parts for my 1994 Saturn. Good Luck.
I will chime in on the ECTS also. And in doing so I am acknowledging that here it is some 25 or so + years and the company is now out of business the one single thing that over those years have caused a whole bucket full of problems simply because when aftermarket reversed engineered the thing, GM had installed the wrong part on the engine so all of the auto parts supply places developed the wrong piece to replace it with, in essence another bad one. Saturn (AKA GM) sent out a service bulletin acknowledging that things were wrong, 10 years after the fact and way too late to fix the screw up and here it is 25+ years down stream and it still ain't fixed leaving one with the only solution to fixing problems caused by the ECTS is to purchase one from a GM dealer along with the replacement socket it gets plugged into. And it seems to be getting harder to find a GM dealer that will sell Saturn parts.
What kinds of problems can this thing cause? I am reminded of a Red Buttons record from the same era "strange things are happening" Almost anything!
So entertain your self by listening to the record (
#10
01-04-2017, 06:28 PM
First off all, Thanx again for your help. I am am still not all the way done with resolving my (really goddang frustrating!!!) misfire issues, but is a bit better.
It was six degrees with a windchill of minus twelve this morning when I left for work. The Saturn started right up and idled at 1400 rpm. No blinking Service Engine light. Let it sit for a bit and left, and it started running rough with the light flashing. Would go 60mph in 4th gear until the slightest hill, then I had to downshift and go up to 3500 rpm to climb the hill. Got to the first of many stoplights and idle went down to almost stalling. (Temp gauge is 1/3rd of it's travel.)
I went to the local O'Reilley's and their code reader just shows 0300 multiple random misfires. I have NGK spark plugs in it, as well as the items that were replaced after reading various posts here and asking a mechanic. No other codes show up.
Still wondering how this could have shown up so abruptly after the vehicle ran so good.
If anyone can help, I would really appreciate it! Otherwise I will have to take it in and blow a lotta bux that I can't afford!
It was six degrees with a windchill of minus twelve this morning when I left for work. The Saturn started right up and idled at 1400 rpm. No blinking Service Engine light. Let it sit for a bit and left, and it started running rough with the light flashing. Would go 60mph in 4th gear until the slightest hill, then I had to downshift and go up to 3500 rpm to climb the hill. Got to the first of many stoplights and idle went down to almost stalling. (Temp gauge is 1/3rd of it's travel.)
I went to the local O'Reilley's and their code reader just shows 0300 multiple random misfires. I have NGK spark plugs in it, as well as the items that were replaced after reading various posts here and asking a mechanic. No other codes show up.
Still wondering how this could have shown up so abruptly after the vehicle ran so good.
If anyone can help, I would really appreciate it! Otherwise I will have to take it in and blow a lotta bux that I can't afford!