1999 SL500 Codes P0300, P0303 and P0305
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Star Diagnostic System (SDS).
While CarSoft from Belgium is cheaper, it may not work with the RST (Roadster Soft Top) controller.
And there are always Chinese clones.
I wonder what, aside from the injectors and the other items tested so far, are cylinder specific and have to perform differently at various RPM's?
In any case it would be interesting to see a graph of short and long term fuel trim.
In any case it would be interesting to see a graph of short and long term fuel trim.
There are so many inexpensive (and expensive) scanners out there. I would think any of them that can stream live data should give you similar options, as far as what engine data can be read. I wouldn’t spend too much money on this kind of tool. I doesn’t matter how fancy these third party scanners are, they will always have their limitations as compared to Star system. You might as well put that money towards the real thing.
I use Autel AL519 (to supplement my SDS setup), it’s actually pretty decent scanner with live data stream.
Amazon.com: Autel AutoLink AL519 OBD2 Scanner Enhanced Mode 6 Car Diagnostic Tool Check Engine Code Reader CAN Scan Tool, Advanced Ver. of AL319 : Automotive
Thanks for the information all. I'm researching scanners to see what my options are. Photodude, is the Autel you noted above capable of performing the tests on the trouble shooting guide you provided on the first page of the thread?
Fuel filter has been replaced. Fuel pressure (at the rail) is 56 psi at idle and doesn't drop below 55 during a snap throttle test.
Fuel filter has been replaced. Fuel pressure (at the rail) is 56 psi at idle and doesn't drop below 55 during a snap throttle test.
I see you've looked at ignition and replaced the consumable items in that area, and now you're looking around at fuel delivery items. But I wonder about the fuel pump itself since the car doesnt seem to like high demand situations. If its the original 20 something year old pump, lets not overlook the real possiblility that it just isnt capable of reaching its max effort anymore. I know you're not gonna just out of the blue jump in there and replace the pump for no obvious reason, but im just saying lets not just assume it can do everything it used to. I had a similar issue in my mustang when I'd take it to the track. Daily driving, punching it around town all was good, but at the track at the very top of the revs it would just kind of lay down, no codes or anything (probably because it was an OBD1 car) but once I tried to find the issue on a dyno with live data being looked at, right around 4800 it would detonate just a bit. Put a fresh filter in, no change. Car had a higher flow pump in it, but it had a good number of miles on it. So I got mad, bit the bullet, crawled under there and put a new pump in, same flow rating, but brand new.... problem was gone.
Also one more thing, Im not sure if your car has cam sensors like my 97 has, but those are something that could bring up a misfire code too as well and would just be good maintenance to replace (maybe 50 bucks) at this age/ mileage. Crank and cam sensors were some of the first things I went for when I got my 94k mile SL even though they werent giving a problem. I also have a MAF sensor I bought too, but nothing has prompted me to change it yet.
Also one more thing, Im not sure if your car has cam sensors like my 97 has, but those are something that could bring up a misfire code too as well and would just be good maintenance to replace (maybe 50 bucks) at this age/ mileage. Crank and cam sensors were some of the first things I went for when I got my 94k mile SL even though they werent giving a problem. I also have a MAF sensor I bought too, but nothing has prompted me to change it yet.
Yes, alll things that could be the culprit. The snap throttle fuel pressure test doesn't show volume issues very well, and yes, cam sensor could do something like this. Crank sensor was replaced last week.
I did bring it up to high rpm range with little load (left transmission in low gear and just brought the revs up with light throttle) and it set the codes.
This is why I'd like to find a scanner that will help with live data rather than put parts in it hoping for a fix. I'm all over replacing parts that are known to go bad prior to them actually going bad, but would like to know what is actually going on here.
I did bring it up to high rpm range with little load (left transmission in low gear and just brought the revs up with light throttle) and it set the codes.
This is why I'd like to find a scanner that will help with live data rather than put parts in it hoping for a fix. I'm all over replacing parts that are known to go bad prior to them actually going bad, but would like to know what is actually going on here.
That sounds like timing rather than a fuel cut out issue. Im interested to see how this works out.
Yes, you’ll have enough there to do the basics. Air Mass, Fuel Trims, Manifold pressure and much more…
Not very difficult but, impractical and unnecessary. On M113 to remove injector, all 8 need to come out, by lifting entire fuel rail. On re-assembly, even when re-installing old injectors, you need set of new o-rings for all of them.
Fuel injectors can be tested via actuations, while on the car. If one or more is determined to be problematic, you may as well replace all 8 of them.
Because this is what it is, a clone software and clone hardware, there is aways an element of uncertainty when buying these systems. I couldn’t even recommend the system I bought 3-4 years ago, which is bullet proof and was priced very reasonably… because this is a moving target. Vendors come and go, products evolve to a different packages.
Do your own research, what people are buying these days and what works. There is a section on this forum dedicated to diagnostic tools.
Diagnostic Tools
Discussion forum for all Mercedes-Benz diagnostic equipment. Moderator - rudeney
www.benzworld.org
I believe it's been established that there are two specific cylinders that learn to mis-fire after hard acceleration. I think the P0300 simply refers to the pair because no other cylinder-specific codes are presented.
The problem is to find out how those two specific cylinders learn to misbehave and then self-repair at a re-start. I still lean towards fuel injectors but so many other folks point to broader-linked items It will be great to find the actual answer to this problem and I wish the OP the best in getting this resolve.
Air compression system??
2000 SL500 Designo Edition, 1992 500SL, 1991 300SL, 1977 450SL, 1999 E320 4matic Wagon
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After reading all this, my friend had a problem with his 1998 600SL. Another friend came over and scan the car and came up with a problem on the left front 02 sensor was providing a signal to computer but no signal output, he check and came up with a PCM problem on the left bank. The car ran rough especially when warm and being driven the car ran like it was running on 6,7 or 8 cylinders.
We had someone else come over and placed his Matco Tool scanner and show a misfire on cylinder 2 and 7. We had a new set of spark plugs around, so the mechanic suggested why not changed the plugs first and see what happens. We did and no more misfires. The car is running perfectly and it's been 6 days now and no more misfires. He also cleared all codes and rescanned and no faulty codes came up. To this day, I can't believe that "spark plugs" made the difference, but it did, amazing..
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We had someone else come over and placed his Matco Tool scanner and show a misfire on cylinder 2 and 7. We had a new set of spark plugs around, so the mechanic suggested why not changed the plugs first and see what happens. We did and no more misfires. The car is running perfectly and it's been 6 days now and no more misfires. He also cleared all codes and rescanned and no faulty codes came up. To this day, I can't believe that "spark plugs" made the difference, but it did, amazing..
Star Diagnostic fuel injector test is a definite must try
I don't know what Star Diagnostic does in testing Fuel Injectors but injectors have had my vote since the coil and spark plug changes failed.
Best of luck on this one!
The injectors get turned on and off one by one. No misfire induction means obvious bad injector. I remember Photodude running that test on my 500 last year
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