Boxster with P1124 and P1126
Hey guys,
I have a 99 Boxster 2.5L which has has these two codes for a while. I've been reading a lot on these codes on this forum and other places and I have an idea of things I might want to try next but I wanted to brainstorm what would make the most sense with people here. Here are some details:
For next steps, here's what I'm thinking:
Do you have any additional diagnostic steps I could run? I have an OBDII reader that I can consult. I've read that air flow should be between 13-15 for example. Is that right? Any other values I should monitor? Thanks so much for your help! |
Quote:
My first guess is that you either have to much air for the amount of fuel going into the engine. Or not enough fuel for the amount of air going into the engine. So lets look for to much air first!! That would be caused by a vacuum leak. It could be the "AOS" Or lots of other things that cause vacuum leaks when faulty. Excessive unmetered air causes a lean fuel condition and can drive temps up. Very first thing I would do is a proper vacuum test of the intake system. If you have a vacuum leak then that gives you a starting point. If you don't have a vacuum leak then your AOS is probably ok as well. A vacuum gauge is a diagnostic tool that I think should be in every DIY,s tool box. They cost around $15-$20 and can give you a ton of diagnostic info on your engine . Vacuum reading should be 19-21 inches of vacuum with a steady needle at an idle. Second: Not enough fuel for the amount of air. You could have a faulty coolant temp. sensor. Use your OBDII scanner: to monitor your coolant temp. Start the car from cold.(make sure scanner shows the cold coolant temp) run engine till it reaches operating temp. see if scanner reading coincides with dash instrument temp gauge. If your OBDII scanner shows you live data: Then look at your "Short term fuel trims" if they are showing "high positive trim" that may be another indicator of a vacuum leak. Those are the first few things I would look at: You need to determine if the root problem is to much air for the amount of fuel. or not enough fuel for the amount of air. Then you will know which direction to go. The oil in the spark plug tubes is unrelated to the CEL codes To what air flow (air flow between 13-15) are you referring to???? Just trying to get on the same page with you. |
Blue62 thank you for sharing your diagnostic approach. I don’t have this problem but you intel will help understand how better to use the durametric tool. Thanks - Rick
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Quote:
Two things I think are very important when trying to diagnose a engine performance problem. (CEL or P codes). 1. Todays engine management systems (OBDII"s) number one priority is Catalytic Converter Performance. Power, fuel economy, what ever is secondary. So when ever I get an engine performance problem I try to figure out how it relates to Catalytic Converter Performance. 2. A vacuum test is usually the first test I do because: It is simple to do: the gauge is under $25.00. A vacuum leak is unmetered air. Meaning no sensor in the OBDII system is reading that excess air until after the combustion cycle. So a vacuum leak many times does not trigger any codes. It may show up as positive short term fuel trim but other things can cause that as well. If you don't have a vacuum leak you have just eliminated a ton of potential problems. The vacuum gauge can give you a ton of other information about engine performance and condition other than just a vacuum leak.;) |
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