I have had the restricted performance message with the check engine light twice in the last two weeks . The scanner showed a P0171 code, which is for too lean combustion in bank 1. The message goes out, and my performance does not seem to be restricted. I have cleared the code both times and drive ability does not seem to be impacted.

 

I checked previous posts and I will clean the MAF. My air conditioning was running both times that the message came up.

 

Add BG44K to a full tank of fuel and see what takes place.

Gus
www.jagrepair.com

 

Knock on wood. The MAF cleaning and gasoline additive that Gus recommended have worked so far. No messages or orange check engine light.

 

The plastic hoses get old and crack. It does not help the prices of these hoses are so much. When I did patch them I got no more codes. I refer to the hoses on the valve cover. They wrap around to the back of the engine. I forget if it is connected to the carborator. Since the patches worked, I went ahead and replaced them.

 

Code 171 showed up again while driving about 70 with the restricted performance message. However, there was no performance issues that I could detect. My OBDII reader does not do much detailed analysis. I have cleaned the MAF and used recommended fuel treatment, so maybe a new MAF is in order. I am finding a wide price range for the MAF between $50 and $200. Does anyone have a recommended source?

 

Check fuel trims to see if you have an air leak as if you do a MAF will do nothing.

Unless both sides trims are alike it's unlikely to be the MAF anyway.

Besides, a bad MAF usually underreads so you get RICH not lean codes.

Overall you so far have no reason to suspect the MAF (though with more data you might perhaps have).

 

I would think that an air leak would be constant and the fault code would come up right away. Mine does not have any pattern and might show up after 50 miles or 150 miles.

 

Add BG44k to your fuel and see what takes place.

Gus
www.jagrepair.com

 

Could be clogged injectors or else it's an air leak somewhere. If it happened while the engine was idling, it would likely be an air leak, if it happens at 70MPH it sounds more like lack of injector flow.

 

I would think that since you are only getting one lean code (for the one side), it probably is not cracks in the air tube or the MAF sensor or the fuel filter... it is probably more related to fuel on that side. I would do as Gus says and throw in a can of the cleaner he recommended for starters.

When I got lean codes it was for BOTH sides and then I saw that my air tube from the filter had cracked and once I fixed that I have been code free since (knock on wood)...

 

Bear in mind like many codes it needs TWO trips to be flagged so cannot flag immediately. That can make it seem a bit random as to when it flags.

 

EBay has been my favorite resource for parts and supplies.

 

If you can access the live data it will be easy to tell if it is dirty injectors (or some other fuel issue) or a vacuum leak. The trim will be a dead give away based on how it looks at startup and idle compared to WOT.

However, if the engine has not seen any major heat and none of the vacuum hoses look damaged then BG44k as Gus suggested would be the easiest and most likely fix. You can get little obdII scanners with live data for around $35 now days which is good for DIY, but if you dont have a way to look at the data just use BG44K and report back after 2 or 3 tanks of gas if you still have any issues.

Also, if you do not have a high idle on cold start that lingers a little you probably do not have a vacuum leak big enough to throw that code since I think it has to command 25% trim to throw that code.