bad misfire, Actron CP9125 not reading codes

[leo8888]

Hello,

My wife has a 2003 4 cyl vue that just started missing very badly the other night and would not go over 2000 rpm in neutral. Last year the coil pack and ignition control were replaced but she says the symptoms before having those replaced were more of a general loss of power. I tried to take it out for a road test and the service engine light was flashing and I couldn't even get it up to 10mph so I parked it right away. I wanted to find out what codes there were so I bought the Actron OBDII Pocketscan from Autozone but it shows 0 codes found even though her service engine light has been on for a while. I read other posts from people who said that Autozone could not read any codes with their scanners. The package says "OBD II 1996 and newer". It will show the I/M Monitors but no codes. I'm pretty sure given the way it is running and the amount of time the service engine light has been on their must be some codes stored. Any suggestions? Could this be an incompatible code scanner or could it actually run this bad and have the service engine light on for a long time with no codes stored?

Thanks for any opinions or suggestions.

[fdryer]

Remember (1)one important fact; if the SES light flashes, your catalytic converter can become damaged in a very short amount of time/miles driven. Just having the SES light turn on and stay on is OK as it indicates some kind of fault that can be assessed in a more leisurely pace. Not the flashing SES light. The worst that could have occurred with the flashing SES indicator and continued driving is possible catcon damage along with it breaking up inside to clog the exhaust system choking off exhaust flow. If this is the case, the damage is done and a replacement catcon will be necessary. At best, the catcon wasn't damaged as the SES light reset from the engine computer.

Normally, any SES light that remains on allows any reader/scanner to retrieve the error codes. If yours cannot read them (it should) try Autozone or any other place that will read codes for free. Autozone uses readers that by sheer demand from customers, must be able to read all the generic codes. Generic codes are the universal diagnostic trouble codes (DTC's) every vehicle manufacturer agreed to use for compatibility to reduce confusion and creating exclusivity. There are manufacturer specific codes, termed wrench codes, that are specialized for each manufacturer that does require better reader/scanners. Autozone or any other place isn't required to scan for these codes. They're providing a free service to encourage business.

If your Vue can idle, you may be able to remove the front O2 sensor (before the catcon) to allow another exhaust outlet for a quick test. If you're able to remove the sensor the exhaust will be LOUD but if there's renewed power to rev past 2k rpm (don't redline it as there's a rev limiter built-in to prevent over revving) you may have found a clogged catcon. If you're not able to try this, then a good muffler shop can test for a clogged cat. Call around.

[Gerry Proctor]

Cheap code reader probably can't interpret KWP2000. OBDII is a very broad standard that describes what is monitored and what codes are specified in OBDII (like a P0301 will always be a cylinder 1 misfire no matter what car the scanner is reading). There are a number of data protocols used to present the information. If your scanner can't understand the protocol language, then it won't display anything. This is one of those "you get what you pay for" deals.

[leo8888]

Thanks for the replies and suggestions. :cool:

I also tried the Actron scanner I just bought on my 98 sw2 and it found a transmission code, which surprised me because it runs so good, anyway the scanner was able to pull codes from my 98 but not from the 2003 which should have several stored by now. I did take the wifes 2003 Vue to Autozone on more than one occasion when the light was on (when it was still running ok and I could still drive it) and they couldn't pull any codes either. They even thought it was strange since they were using a much better scanner than the one I bought. I spoke with the manager this time before buying mine and he showed me all the models they carry and which one they used. They were all Actrons and the main difference as you go up in price is whether they can show real time data or store readings, other than that they were all supposed to be able to read any OBDII codes. Is it possible that there could be a fault in the computer stopping it from storing or displaying codes?

I was thinking of picking up an ignition module from the local dealer and giving it a shot since I can't drive it anywhere to get diagnosed in it's current condition and I read other posts from people who have had theirs go bad more than once. I hate just changing parts but I also don't want to fork out the money to have it towed to a mechanic since I don't know any that I would trust. I am also going to check the CAT's back pressure per fdryers suggestion.

Thanks!
Dan

[ssicarman]

Sounds very much like the ignition module. If you do replace it make sure to replace the spark plugs at the same time.

[leo8888]

Replaced ICM and running fine again. Thanks! I forgot to pick up plugs but am going back out to get them today.

Thanks again everyone! :D:D:D