rough start continues......

[Landshark]

Originally Posted by alltrac

The only issues with the SVX 96-97 OBDII monitors are they reset after each cycle. It has no affect on the ecu ability to properly store the fault code. Landshark has a 97 SVX which is OBDII and if he is getting a CEL/MIL it will help point the way to the problem. It will surely make it easier for a tech to track down the problem with a subaru select monitor. You can either keep guessing and replacing parts that don't need to be replaced and tell yourself if it doesn't fix the problem it's good preventive maintence. Or bite the bullet and TITTD.

if TITTD = take it to the dealer, i've done that. "bad coil pack." yeah, right.

the reason i hesitate to take it back to the dealer, is that i'm only into this problem for $160 so far (coil pack/fuel injector). as you know, one trip to the dealer is usually several hundred dollars.

as i said numerous times, i get a CYLINDER #1 MISFIRE code at times (i own a code scanner.), so that's the direction its pointing me in. could a select monitor help? maybe. they'd probably have to keep the car for a week to replicate the conditions, because it only happens on cold start up. it would have to sit for 8 hours before they "take another stab at it." i really can't be without it that long.

[Beav]

If your scanner is already telling you that the misfire is #1 the Select monitor isn't going to tell you anything else about the misfire on that cylinder.

When you have a single cylinder misfire (or rather, not missing on all cylinders) you need to think in terms of ONE cylinder. MAF, T-body, etc. would affect all cylinders, not just one.

when i had a miss on cyl 4 my car would start and run with lack of power. then as the drive lengthend the car would run worse and worse till i think thrown in safe mode. it was a coil pack and bad plug. replaced those and fuel filter and air filter and car runs better than before. i also got a rough cold start im in ak and its still cold. it all started when i adjusted my idle. which at the level i put it i really like. the down side is the high rev start for 2 to 3 min. after that it all goes away and runs normal. with no problems.

[alltrac]

Originally Posted by Beav

If your scanner is already telling you that the misfire is #1 the Select monitor isn't going to tell you anything else about the misfire on that cylinder.

When you have a single cylinder misfire (or rather, not missing on all cylinders) you need to think in terms of ONE cylinder. MAF, T-body, etc. would affect all cylinders, not just one.

from endwrench

If you don't bother to use the misfire monitor, you're missing out on a good bet. This is one of out favorite features of OBD II because you can look at the misfire counts by cylinder, thus zeroing in on the problem wire, plug, etc. You can also clear the code, spray water or a special secondary ignition solution on the wires and cap, and see what you get. Typically, most cylinders will be okay, but one or two will show misfire counts. Pull the plug and test the wire. This is even better than using a traditional ignition oscilloscope, and it takes no set-up at all.

I think this one may help you more

We've observed that techs often don't take advantage of freeze-frame data. That is, the information recorded about operating conditions at the moment a DTC(diagnostic trouble code) is set, such things as vehicle speed, rpm, coolant temperature, and MAP value, long and short term fuel trim, etc. That's unfortunate because an abnormal number here can help point you in the right troubleshooting direction.

Doesn't the dealership have a guarantee? you bring them the car they tell you whats wrong and replace the part. If that doesn't fix it then they sold you something you didn't need.

[Beav]

You have to understand what you're reading. DTC P0301-30xx indicates misfires by way of acceleration/deceleration of crankshaft speed by way of the crank sensor. The code itself doesn't indicate the cause. Also marginal crank sensors/ECUs can indicate the wrong cylinder misfiring, I wish I had $5 for each time I found that to be true.

Freeze-frame data normally isn't very useful in single cylinder misfires as the information shown is system-wide. Typically engine temperature, MAF, RPM, O2, vehicle speed and transmission gear are displayed and are practically useless while diagnosing a single cylinder problem. Ditto with taking 'movies' of info from scanner displayed data. Scanners are too slow in displaying info, things are happening in milliseconds and the scanner displays in 1-6 second intervals. Graphing multimeters with high speed sampling rates are the ticket. The scanner can indicate where to start and the technician then devises a method of determining what needs to be checked and how.

Use this example of a problem I touched on elsewhwere: several plugged EGR ports will cause the cylinders with non-plugged ports to have excessive EGR flow, causing misifres due to low oxygen in those cylinders. The scanner may detect the cylinder misfire(s) but it won't tell you what the cause is. As far as it knows the EGR was commanded open and the EGR sensor detects flow. However it has no way of knowing some of the ports are plugged, as far as the ECU and scanner are concerned everything is peachy, other than the misfire. Ditto with a failing injector, coil, spark plug, burnt valve, etc.

Now some scanners will show voltage patterns of injectors, sensors, coil primaries, etc. through the OBDll port but that info isn't totally reliable. First, it is horribly slow (relatively.) Secondly, a scanner only displays what the ECU tells it to display. Marginal wiring, connectors or ECU can taint the info displayed. Any component shown bad at the scanner needs to be rechecked at the component in order to affirm/condemn the component or circuit.

You'll find that most good driveability techs use scanners mainly as code readers and little else. A good graphing multi-meter and a low-amp clamp are the tools they use most (along with experience and their gray-matter.)

SSCC = symptom, system, component, cause. That's the correct path to fix anything right the first time. Plus a good measure of "How can this bite me in the ass if I'm wrong?" Don't rely on one piece of equipment or hunch. Double check your diagnosis just as you would check your math.

[Landshark]

Originally Posted by Beav

If your scanner is already telling you that the misfire is #1 the Select monitor isn't going to tell you anything else about the misfire on that cylinder.

When you have a single cylinder misfire (or rather, not missing on all cylinders) you need to think in terms of ONE cylinder. MAF, T-body, etc. would affect all cylinders, not just one.

so if it isn't the plug, coil, or injector.....

there's always the possibility that one of these items was bad "off the shelf" when replaced, but that's kinda unlikely.

its temp related, too. car runs fine after a few minutes.

Beav, i could sweeten the deal with a Hooter's gift certificate for the right answer on the final fix.....

[Landshark]

snugging the bolts on the intake and injector stack didn't do the trick, but a good idea, though, Harvey.

[Beav]

Snugging the bolts is o.k., but what if the gasket is torn? Try spraying around each runner and injector with flammable carb cleaner. If the engine begins running rough/faster you'll have your answer.