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2000 Malibu - Help with codes

 
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davescountry davescountry
New User | Posts: 15 | Joined: 12/09
Posted: 02/13/10
02:23 PM

Hello all.  I am working on a 2000 Chevy Malibu with the 3.1 engine. For background, about 2 months ago, I replaced the intake manifold gasket and the fuel pump.

I have notice a decrease in mileage and rough idle for a couple weeks.  A few days ago, my check engine light came on but hadn't had time to check it.

Today, I was driving it and it started running really, really bad.  The check engine light actually started blinking.  When I ran the codes, it came back with
P0300
P0205 (number 5 cylinder)
P0410

It appears from some quick research that P0410 deals with the air pump and is probably unrelated to the other two.  However, I am still not 100% sure what to do with that.


Logic tells me the other codes are related.  Does anyone have any advice or know of any particular problems with these cars or engines that tend to cause these?

I can just jump in and start messing around, but if anyone can give me some logical place to start, I'd sure appreciate it.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 02/13/10
06:41 PM

well

i googled OBD2 DTC

found this link

http://www.equus.com/support/obd2_definitions.php



P0300 Generic Random Misfire Detected

P0205 Generic Injector Circuit / Open - Cylinder 5

P0410 Generic Secondary Air Injection System


you need to go back and check the injectors .. make sure they are all plugged in..

check the air injection system...   if it has an upstream system like most do..  if it leaks uncommanded air into the exhaust manifolds upstream of the oxygen sensors.. it will mess with the fuel ratios...

i wonder if there are any vacuum leaks....   from the intake manifold..  lower... upper.. throttle body.... vacuum hoses...    

loose spark plug wires.. burned through boots...  terminals pulled off the ends of the spark plug wires.. deep inside the boots..   bad coil or coils...

take the upper back off .. examine the injector connectors.. i had one.. in the shop.. another tech was looking at it.. said the injectors were dead...    he replaced the non functional injectors.. and others started being intermittent ... he just had not latched them all the way down tight..


there are pages and pages of trouble shooting for each trouble code...

if you don't have a factory manual..  you will have to get a subscription to alldatadiy.com or eautorepair.net    

i would look it up right now.. but my book is out..  

davescountry davescountry
New User | Posts: 15 | Joined: 12/09
Posted: 02/24/10
02:10 PM

This car just keeps getting stranger.

Well, I had the codes above and decided to take it into a local shop.  He came back and said that I was now getting PO113 error code - Intake Air Temperature Circuit High Input, and that I was misfiring on cylinder 6 instead of 5.

He said the misfire was due to the intake manifold gasket causing a vacumn leak.  he supposedly tested that by spraying propane and carb cleaner around cyl 6 and could hear it draw down. According to him, every time he started it, it would run fine for about 20 seconds then he could see the code kick in.

I tried to replicate that at home, and couldn't see what he was talking about.  The car was actually running fine then, but he hadn't cleared the codes.  So, I drove it up to O reillys and cleared the codes. Sure enough, it did read with the PO113 and the other misfire codes I hd before including the misfire on 6.   The light came back on about 10 mins later, and this time the only code was the PO113.

I have messed around wih the wiring on the IAT since that is what is registering, but I haven't got very far.  I tested the two wires there, and am showing 5 volts on the tan wire when I go to ground with the car running, but when I try and loop back and put the negative on the black wire, it shows zero.  Based on some other form reading, I think that is the way to do it, and think when I test back on the black wire, it should read 5 also.  I might play with this some more and trim the wires up from the plug and see what happens.

I don't know whether this PO113 could cause the misfire or not.  I didn't feel great about the diagnosis from the shop so am hesitant to start tearing down to the manifold.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 02/24/10
02:48 PM

well it seems like you are intent on fixing this...

and thats a good thing...

you might want to print this chart...

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0900c152/80/06/7e/6a/large/0900c15280067e6a.gif

with the chart.. you can write down the sensor readings.. compare them to the list... so you know where you are at...

decent scan tools are not to much money also...

i actually have one of these and it does a lot of stuff..

http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=98614

i plugged it into a jag the other day... got misfire codes.. found the coil boots were dry.. used some silglide to lube them .. cleared the codes..  car runs great...


here is the complete intake manifold gasket set...
the upper and the lower set, one thing... my store shows it being out of stock... so it might be popular

http://contentinfo.autozone.com/znetcs/product-info/en/US/fpr/MS98003T/image/8/

vacuum leaks are usually the upper plenum gasket...  or the rubber isolators have allowed the upper plenum to come slightly loose...   so .. you might not have to change the entire gasket.. as on a 3.1... that also involves removing the valve covers and the rocker arms as i recall..

i will get back to you with more information...  if you need more.. print the chart... you will understand a lot more just by reading it..

a loose spark plug wire...  one with a boot cracked... installed without silglide or the spark plug boot lube can leak high voltage ... causing a misfire..    i have also found spark plug wire terminals pulled off inside the boot..  

davescountry davescountry
New User | Posts: 15 | Joined: 12/09
Posted: 02/24/10
05:49 PM

Yeah, I pretty much have to fix this.  We went from two incomes to one since my wife went back to school, and this is mycommuter car.  My commute is about 650 miles/week and my other car is a tahoe with 200K miles.  I can't afford the gas in that.

Generally I find I can fix most things if I know whats wrong.  This car seems to have one issue after the other, it its hard for me to know exactly whats wrong.  The diagnosis is the hard part.

I both question and don't question the manifold thing.  My first problem with that diagnosis is that I tried the same test the shop did, and didn't have anyting happen.  Second, when I took it in, it was reading misfire on 5, but the shop said it was misfire on 6. Their rationale for the difference was that their machine was more accurate.  When I went to clear the codes, it had both in there.   Assuming it did misfire on both 5 and 6, it seems odd to me that the intake gasket on both sides would go bad at exactly the same time and produce exactly the same result of misfiring.

On the other hand, I did actually replace those gaskets about 2 months ago due to some coolant leakage.  Although I am pretty confident, I know its not too hard to screw those up during install.

Supposedly the shop checked the wires and plugs and said they were fine.  Its probably worth another check.

So, I guess I am still scratching my head.  Maybe becuase I thought it was easier, I was hoping to fix the PO113 code on the air intake first.  The misfire codes aren't present right now.  I tend to like to isolate my variables whn troubleshooting if possible.  I don't know if the air intake code could cause a misfire, but it seems possible that if the air was running off that it could.

I haven't decided but I might try and take it to another shop, maybe the dealer, for a second opinion.  At least get the diagnosis and see if it adds up with the first shop.  I hate to spend more money I don't have, but the other side is that I don't seem to be doing well troubleshooting on my own and everyday I have this car down costs me money at the pump.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 02/24/10
09:10 PM

check your private messages... above.. to the left of the log out link... when logged in...


there are pages of charts on testing P0113

the air temp sensor in in the inlet ducting...

here is a picture of the location.. but you knew this.

http://repairguide.autozone.com/znetrgs/repair_guide_content/en_us/images/0996b43f/80/20/27/27/medium/0996b43f80202727.gif

new air charge temp sensors are 15 bucks...

http://contentinfo.autozone.com/znetcs/product-info/en/US/wl2/SU176/image/8/

here is the basic testing ... but you see .. you do need a scan tool to examine the test results..

http://www.obd-codes.com/p0113


text from link above

OBD-II Trouble Code Technical Description
Intake Air Temperature Circuit High Input

What does that mean?
The powertrain control module (PCM) monitors the temperature of the air entering the engine. The PCM supplies a 5 volt reference voltage to the Intake Air Temperature (IAT) sensor. The IAT is a thermistor that varies resistance based on temperature. As the temperature increases, resistance decreases. Low temperature results in a high signal voltage. When the PCM sees a signal voltage higher than 5 volts, it sets this P0113 check engine light code.


Potential Symptoms
There will likely be no symptoms other than illumination of the Malfunction Indicator Lamp (MIL - Check Engine Light / Service Engine Soon).

Causes
A code P0113 may mean that one or more of the following has happened:

Internally failed IAT sensor
Faulty connection at IAT sensor
Open in IAT ground circuit or signal circuit
Short to voltage in IAT signal circuit or reference circuit
IAT harness and/or wiring routed too close to high-voltage wiring (e.g. alternator, spark plug cables, etc.)
Faulty PCM (less likely but not impossible)


Possible Solutions
First, if you have access to a scan tool, is there an IAT reading? If the IAT reading is logical then the problem is likely intermittent. If the reading is less than -30 degrees, unplug the connector. Install a jumper wire between the harness connector signal and ground circuits. The IAT temperature reading on the scan tool should be maxed out at the high end. For example it should be 280 degrees Farenheit or higher. If it is, the wiring is okay, and it may have been the connection. If it isn't install the jumper wire between the IAT signal circuit and the chassis ground. If now the IAT reading on the scan tool is maxed out then check for an open in the IAT ground circuit. If you get no reading at all on the scan tool, it's likely that the sensor signal is open or the 5 volt reference is missing. Check using a DVOM (digital volt ohm meter) for a 5 volt reference. If it's there, then unplug the connector at the PCM and check for continuity on the IAT signal circuit between the PCM connector and the IAT connector.  

davescountry davescountry
New User | Posts: 15 | Joined: 12/09
Posted: 03/03/10
02:06 PM

I tried to send you an email direct but not sure you got it.

Well, I decided the best move for me was to take this to the dealership
locally for some more diagnostic.  I figured the price of the diagnostic
was probably less than whatever trial and error I would put in.  I think I
might have been wrong.

First, they told me the PO113 IAT error was caused due to a broken wire,
so I went ahead and authorized them to fix that.  I had actually started
to peel back the wire cover and tape with the same idea in mind, but
didn't see any break.  Not to say I maybe didn't go far enough though.

As for the misfire, they told me that my number 5 injector was out.  At
first, they didn't even seem to pay much attention to the misfire problem.
Their computer told them that the cylinders ( 5 and 6) had only misfired
something like 1500 times apiece and typically when there was a problem,
the misfire count was over 20,000.  After going back over it, that was
when they told me that the number 5 injector was going out.

Since I was encouraging them to double check after intially dismissing the
misfire, I also told them that someone else (another shop) had said there
was a vacumn leak on the mainfold.  When they called me back about the
injector, they said there was also a leak on or near number 6 on the upper
plenum.  Granted, this makes a little more sense to me than the previous
guy who said it was on the lower manifold.  But maybe I just want it to be
the upper since that is so much easier to fix.  They were really convinced
it was the upper but said they had to try real hard when spraying around
there to get it to pick up the leak.

When I picked it up, oddly it was misfiring again for about a minute then
smoothed out.  This is only the second time I have actually had the
misfire and blinking SES light when driving.  The light went back off
after about one minute, basically until the car warmed up a bit.  I have
noticed the past few months that the idle has been rough.

However, after aout 10 mins of driving, the SES light came on again,
solid.  This leads me to believe that the PO113 IAT error wasn't actually
corrected by whatever wire they fixed. I have checked and cleared that
code about 4 times the past two weeks, and each time it takes almost the
exact same amount of time to come on.  I haven't gone back and checked it,
but I bet it gives me that same PO113 IAT code.

So, I am leaning towards taking their word on the injector issue, but a
bit hesitant just becuase of the cost.  I am about at the limit of my
diagnostic ability and don't have the tools to do anything super in depth.
I am just a basic, home garage mechanic.

Thanks for all the advice you have given me.  I am really torn on this
car.  When it runs, it runs nice, but it has been giving me a lot of
problems.  I think I might have mentioned that I have this car for a
commuter.  Between 2 and 3 times a week, I drive about 300 miles round
trip for work. So, I put 600 to 900 miles on it per week, and the trip is
mostly country driving.  It makes me a little nervous to think about
breaking down in the middle of nowhere.  

waynep7122 waynep7122
Addict | Posts: 4561 | Joined: 08/09
Posted: 03/03/10
07:06 PM

i still think that you should check the injector connectors..

push them down with the tip of a long screwdriver.. see if the engine idle changes...

the connector bodys don't latch when they are broken.. or when the wire retainer falls off.. or does not get put back on...  

davescountry davescountry
New User | Posts: 15 | Joined: 12/09
Posted: 03/09/10
06:26 PM

well, I'm not sure what I accomplished this weekend.  I got some new plenum gaskets and decided to see what that might do.

My check engine light had been on (solid - so assuming it was the PO113 code)for a couple days, and went off right before taking down the plenum.

When I finished, it ran great, no lights for a couple days.  I put about 250 miles on it, and the Check engine came back on - solid.

The next day, today, it was running real rough, especially at idle and low RPM.  Once you get the RPMs up, it smoothes out.  A couple times, the check engine light went flashing, which I think indicates the misfire.

Just for troubleshooting, I ran it in the drive and checked random vacumn lines.  I sprayed carb cleaner all around the plenum and the various vacumn lines just to see if there were any leaks.  I couldn't detect any. There was one line, very small hard plastic that runs from the front of the engine to the back (thats the best I can describe it - although I actually have a picture somewhere) - it was pretty loose.  When I actually disconnected it, it did not seem to matter.  There was no difference between connected and disconnected.

I also tried to press on the Number 5 injector a few times, and didn't see a difference.

I can't imagine the code will be anything new, but will go check tomorrow.  I will be interested to see if the misfire code is for Cyl 6 or 5 or both.  When they showed up before, according to the dealer, the number 6 misfire was due to the plenum gasket, so if it shows up again, I won't know what to think.

I haven't done the full diagnostics on the PO113, since I hoped it was fixed.  I don't know if I have access to a reader that gives that detail. I couldn't see the product link above, but might see if I can just find that part.  For $15 it might just be an easier way to remove a variable.  

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