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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| G500 Terrible misfire, flashing CEL
Best snow car in the world. Made it right through the heart of the Blizzard early Saturday morning, Southern NJ, Delware, Maryland, and Virginia. I was really happy, but now the G is not so happy.
Was driving along the highway today, when the Check Engine Light (CEL) came on. Flashed twice, then solid on a few seconds, then flashed 23 times in sucession, then solid on, then about 15 seconds later I could feel a vibration and loss of power. I slowed down and realized it was a very bad misfire. Got off the higway, and I'd say it was running on about half the cylinders. It's a very consistent misfire, like half the plug wires are pulled. There is no smell of fuel in the exhaust, like it's flooded or an ignition problem. Everything else seems fine as far as intruments and the rest of the vehicle are concerned. Having just driven hundreds of miles through this huge snow storm, and a ton of salt spray, and a few hundred miles of deep snow, pushing snow, and lots of very rough bumpy road, I can't help but think there is a connection.
Any ideas?
Thanks
Garret
Edited by G4Garret 2/8/2010 9:27 PM
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: G500 Broke Terrible misfire, flashing CEL
A place to start would be Advance Auto Parts or somewhere that will give you a free readout of the DTC's. The CEL indicates that at least some of the fault codes are readable by a generic OBDII tester.
There' may be more proprietary fault codes, but the generic ones will give you a starting place. If you were closer to Atlanta, we could get someone here to connect up a SDS to read them all. |
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| RE: G500 Broke Terrible misfire, flashing CEL
Forgot to add OBDII DTC's from the carputer:
Stored DTC
P0305 Cylinder 5 Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0307 Cylinder 7 Misfire Detected
P0308 Cylinder 8 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected
Pending DTC Detected During Current or Last Driving Cycle
C1304 ASR/ETS/ESP hydraulic unit, left rear axle solenoid valve (hold) (A7/3y10), short/open circuit.
C0203 RF Wheel Speed Sensor Circuit High Input
I realize the last two are chassis codes, probably not related to the engine problem.
Edited by G4Garret 2/8/2010 9:21 PM
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| RE: G500 Broke Terrible misfire, flashing CEL
Oh, and now it starts and runs fine... Nothing jumping out as obviously wrong in the live data either. It is not idling quite as smoothly as it should be, but not bad at all.
Edited by G4Garret 2/8/2010 8:55 PM
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: G500 Broke Terrible misfire, flashing CEL
Richard just reported a similar event - he drove through some water in Mexico and cracked his cats. Then the engine started to misfire so badly that he hired a flatbed truck to haul him home. Once home the engine ran fine. He'll fill you in with the details, I guess.
Looks like the G500 does not like water/snow/bad weather. But is was developed in a on a bad weather continent. Hmmmmm |
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Indiana Drew
Expert
Date registered: Feb 2007
Location: Houston Tx
Vehicle(s): 2002 G500 LWB, 1980 280GE SWB (Sold), S500
Posts: 2223
| RE: G500 Broke Terrible misfire, flashing CEL
G4Garret - 2/8/2010 7:53 PM Oh, and now it starts and runs fine... Nothing jumping out as obviously wrong in the live data either. It is not idling quite as smoothly as it should be, but not bad at all. I gather you are referring to a 2000 truck? I had something happen like that and have been through all kinds of things with 2 shops (Dealer and Indy) trying to sort it out. Its been about 25,000 miles with a slightly off idle like you describe now. I was told everything from the wheel/tire combo was tripping the idle sensors to the timing chain jumped a tooth. Best they ever found was some funky plug wires, but the idle has never been the same. By comparison, we have a 2000 S500 and it idles as I recall the G did before ... Soon it will go in for another look and to have what the codes say ... Let us know what you find!
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W5YK
Extreme Veteran
Date registered: May 2006
Location: San Diego
Vehicle(s): 2002 G500, Unimog U2450,
Posts: 543
| RE: G500 Broke Terrible misfire, flashing CEL
Yes, I had the exact same thing happen to me this week in Baja. It was raining hard for a few days, and I got some misfires. The Check Engine light came on. Then I went through a stream and the catalytic converters cracked along the welds on both sides. I had very bad misfiring then, I think only one or two cylinders were firing. The check engine light was flashing, which means that fuel is getting to the catalytic convertor and you should stop before you damage the cats. I had to keep driving to get off the road, and after about a mile one of the cats blew apart completely. I got it welded back together at a roadside garage, but it still was misfiring. After I got it back to San Diego (long story) two days later, it decided to run perfectly without any further intervention. The Star system showed every misfire code in the book.
I suspect that the catalytic converters got blocked with water or mud, and the resulting backpressure caused the misfiring, which caused unburned fuel to get into the cats and blow them up. But I guess it's possible that the general wetness might have had an effect on the ignition system. My coil packs are mostly the originals, and some of the spark plugs are too.
To get from the middle of Baja back to the USA in a broken G500 is a bit of a challenge. Here's a photo of the first of three semis that I hitched rides on. Just getting onto it was a headscratcher.
 (IMG_0396.jpg)
Attachments
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 IMG_0396.jpg (61KB - 3 downloads)
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W5YK
Extreme Veteran
Date registered: May 2006
Location: San Diego
Vehicle(s): 2002 G500, Unimog U2450,
Posts: 543
| RE: G500 Terrible misfire, flashing CEL
G4Garret - 2/8/2010 4:43 PM
There is no smell of fuel in the exhaust, like it's flooded or an ignition problem.
Garret - in theory, the engine computer is supposed to shut off the fuel to any cylinders that are misfiring above a certain threshold of misses to hits. That keeps unburned fuel out of the catalytic converters. So you probably wouldn't ever expect to smell much fuel at the exhaust, even though there might be an ignition problem.
Any cracks around your catalytic converters?. Mine both cracked right down the center of the welds to the pipes. I think that was the subject of a a recall on some MLs, but not the G500 as far as I know. |
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W5YK
Extreme Veteran
Date registered: May 2006
Location: San Diego
Vehicle(s): 2002 G500, Unimog U2450,
Posts: 543
| RE: G500 Broke Terrible misfire, flashing CEL
G4Garret - 2/8/2010 5:50 PM
P0305 Cylinder 5 Misfire Detected
P0306 Cylinder 6 Misfire Detected
P0307 Cylinder 7 Misfire Detected
P0308 Cylinder 8 Misfire Detected
P0300 Random/Multiple Cylinder Misfire Detected.
Those cylinders are all on the same side (driver's side) and share the same exhaust/cat pipes. Makes me wonder if there is/was a blockage in the muffler/cat system on that side. You can check it by removing the 02 sensor and screwing in a pressure gauge (you can buy gauges with the right thread for this exact task).
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: G500 Terrible misfire, flashing CEL
Richard,
my cats had opening welds like you describe some time ago - I attributed it to the bad roads in Mexico. Had them re-welded twice. They are holding up fine.
I always drive extremely slow when in water to keep the splashing down. Never had any mishaps.
Some pictures at the bottom of the following page (Baja can have quite some deep water) - just ignore the German captions:
http://baja101.com/las-puertas/weg.html |
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W5YK
Extreme Veteran
Date registered: May 2006
Location: San Diego
Vehicle(s): 2002 G500, Unimog U2450,
Posts: 543
| RE: G500 Terrible misfire, flashing CEL
After flooding and then blowing up my catalytic converters, and then driving miles on one cylinder with the CEL flashing away, I figured they would be toast. So I welded them up and went down for a smog test this morning and.... it passed by a mile!
Those things can take a beating. |
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4x4abc
Date registered: Apr 2006
Location: La Paz, Baja California, Mexico
Vehicle(s): 02 G500
| RE: G500 Terrible misfire, flashing CEL
beats a Toyota on which the gas runs away and the brakes don't take commands |
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ewalberg
Expert
Date registered: Apr 2006
Location: Past: San Francisco. Present: Germany
Vehicle(s): 2000 g500
Posts: 1887
| RE: G500 Terrible misfire, flashing CEL
W5yk, ,your statement that the computer will stop gas to cylinders that misfire would explain why when my car recently misfired, it kept on misfiring until i got home. (just a CL on... not blinking)... then i cleared the codes and started it back up and it hasn't missed a beat since.
Edited by ewalberg 2/9/2010 9:00 PM
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MarcO
Elite Veteran
Date registered: Apr 2006
Location: Irvington, NY
Vehicle(s): G 500 SWB, Volvo XC90 V8
Posts: 835
| Re: G500 Terrible misfire, flashing CEL
Yes, but Thai will swear that the Toyota problem is a conspiracy theory and that it is somehow safer .....
Take it away, Thai. 
Edited by MarcO 2/11/2010 3:05 PM
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ewalberg
Expert
Date registered: Apr 2006
Location: Past: San Francisco. Present: Germany
Vehicle(s): 2000 g500
Posts: 1887
| Re: G500 Terrible misfire, flashing CEL
VOlvo XC90 V8?!? No more cayenne? |
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MarcO
Elite Veteran
Date registered: Apr 2006
Location: Irvington, NY
Vehicle(s): G 500 SWB, Volvo XC90 V8
Posts: 835
| Re: G500 Terrible misfire, flashing CEL
Very observant. Though the prancing moose was probably a dead giveaway.
Had a little electrical problem with the Cayenne. Short story shorter.... it is gone. Volvo is a true appliance though suprisingly comfortable. Still have the SWB and it is better every day. |
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| RE: G500 Terrible misfire, flashing CEL
I just got to where I can look at the G again. Had to abandon it earlier this week.
I inspected the cats and exhaust, and I can't see any obvious problems, splits or damage from the outside. Although, I can't see on top of the cats well, but using a mirror and feeling with my fingers, I don't notice any cracks, just the seam. Also I don't hear any unusual leaking sounds. However, both mufflers are in relatively poor condition, and probably need replacement. No significant leaks, just rust damage and a little louder than when new. This has been going on for a year or so.
I have tried it on just one test drive since Monday, and here's what I found:
1. At initial start, no misfire. Seemed to run normally. No noticalbe loss of power or anything.
2. After about 5 minutes of driving, a misfire started again. No flashing CEL, just a steady light. This time on cylinder 5, according to the error code.
3. As soon as it misfired, the computer went into open-loop mode. At this point it would show no live O2 or mixture data. I'm guessing this is normal in Open-Loop mode?
4. If I stop and restart, it always clears up the misfire, for a while.
5. I cleared the OBD-II codes, and only one code reappeared, which was the cylinder 5 misfire.
I'm wondering if there is a chance this could be something as simple as a failure to replace spark plugs or wires or bad coil or something? I really can't imagine that, but then I'm thinking what is happening is that once the computer detects the misfire, it is shutting down the misfiring cylinder. Then when I restart, it is allowing it to run again, until it detects the misfire and shuts it down again. The truck has about 85K miles on the original plugs/wires and most everything else except the Mass Airflow sensor.
In thinking back, I now remember a couple additional that happened prior to this Monday:
1. During my mad dash through the blizzard, there was a point when I was stuck in a 4' snow bank and let the truck idle for about 30 minutes. During this time, I notice a slight roughness which I was pretty sure was a misfire, but it cleared right up when I started driving. FWIW, I wasn't really "stuck", but blocked in by a Hi-Lift which was having trouble, with large scary spinning (non diff-locked) wheels which I didnt' want to get close to. It was stuck becuase a chain reaction of idiots in thier pick-up trucks caused it to swerve off the road. (The trip was about 1600 miles, but only about 200 of it was through the snow storm.)
2. The same slight misfire also happened while I was sitting idling for about 3 hours on interstate 95 during a massive truck/tourbus clog. No check engine light though.
3. About two weeks ago, I got the fast flashing Check Engine Light, but it only blinked a few times, then went out with the next restart. At the time I had never seen it blink before, so I thought maybe it was just my eyes flashing.
4. Monday, the day the bad misfires started, when I first started the truck on the ill-fated drive home from work, I did immediately notice the engine did not feel as responsive as usual, in the sense that I had to press the throttle slightly farther than usual. Otherwise it seemed ok, until the misfires started anyway.
5. During the blizzard trip, I put fuel from a lot or different sources in the truck. And probably there is some water in there too, as I imagine that some small amounts of snow got in the tank. With all the ethanol in our modern day fuel, I would think this would soak it right up and not be any problem.
Next course of action:
1. Look at coils, plugs, wires etc.
2. Get the correct fitting and then the exhaust pressure at the O2 sensor ports.
3. Put a scope on the injectors and confirm that it is the engine shutting the cylinders down
4. Drive the Unimog next time the snow is this deep
And...
I have an appointment to have the diagnostics read at the dealer in the morning. I'm assuming that they will be able to read much more data with the SDS than I can with the OBDII. Is this a correct assumption, or am I getting ready to waste some money?
Thanks everyone for the help. I'll post update as soon as I know something more.
Garret
Edited by G4Garret 2/12/2010 4:56 AM
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G4Garret
Veteran
Date registered: Apr 2006
Location: Oak Ridge - Knoxville - Windrock Tennessee
Vehicle(s): 2000 G500, U1100, SLK350, LR 101, WC-63 6x6
Posts: 243
| RE: G500 Terrible misfire, flashing CEL
Richard,
Interesting that you had the same misfire symptoms as I did. Where were the seams and cracks on your cats? Is it the seam running lengthwise on the top? I'm wondering if yours are the same as mine? Mine is a late MY 2000.
What puzzles me the most about this is that there are no other codes set in the computer. Nothing but misfire codes. I would think a bad cat or leaking exahust would set some kind of mixture or O2 sensor code or something. Also, something I forgot to mention: on my test drive yesterday, as soon as the #5 cylinder started to misfire, the computer went into open-loop mode. Also, I did not get the blinking Check engine light, just a steady light.
Glad you (and the G) made it home ok.
Garret
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Indiana Drew
Expert
Date registered: Feb 2007
Location: Houston Tx
Vehicle(s): 2002 G500 LWB, 1980 280GE SWB (Sold), S500
Posts: 2223
| RE: G500 Terrible misfire, flashing CEL
A mistake the a young tech made while trying to diagnose mine was not thoroughly checking the wires and coil packs. When he laid out the wires flat and straight, the tested fine, but when the problem persisted an experienced tech twisted the wires around as he tested them and found the faulty wires ...
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DUTCH
Administrator Doppelgänger
Date registered: Apr 2006
Location: US, GA, Atlanta
Vehicle(s): 2015 Audi Q7 3.0 TDI,2018 Sprinter
Posts: 9963
| RE: G500 Terrible misfire, flashing CEL
G4Garret - 2/12/2010 3:57 AM
I have an appointment to have the diagnostics read at the dealer in the morning. I'm assuming that they will be able to read much more data with the SDS than I can with the OBDII. Is this a correct assumption, or am I getting ready to waste some money?
Thanks everyone for the help. I'll post update as soon as I know something more.
Garret
You are correct. The SDS can read the proprietary fault codes that are not on the OBDII list. It's too bad you're not closer to Atlanta. You could get them read for free here. |
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