[kenamyford]

I have a 1999 ZX2 DOHC automatic. It has been idling very rough. It sputters and stalls when I slow to a stop then runs ok when I get it rolling :? . The check engine light is on so I had AutoZone pull the code and it was P0171 "System to lean". I thought that fuel delivery would be a good place to start so I replaced the fuel filter first. Nothing changed. I was getting ready to have the fuel pump done but I found that the car still had good acceleration after it would get going so I abandoned the fuel delivery track.

I just checked the throttle body and it looked clean. I have some cleaner but have not seen a reason to use it. I have read the forums here and now I am thinking I should look at the MAP sensor. These are expensive and I do not know how to test or evaluate the sensor. I was also thinking of other things like the idle air control valve and PVC valve.

Doe anyone have any thoughts on this?

 

[RobinUKR]

Most likely the mass air flow sensor. 200 dollar part so I wouldnt buy a replacement unless you have it checked first, or you could get one at a junk yard or pull-a-part yard for a few bucks and try that.

Be careful if you decide to clean it (it can be done but it is VERY sensitive.)

Does the car bog down when you floor it at start off?

 

[kenamyford]

RobinYKR Thanks for your reply. To answer your question, the car does bog down at start off. I was waiting to reply to you after I did some other things. I did so.

I replaced the PCV valve and checked the hoses that reconnect it to the system. No luck

I then replaced the MAF sensor with a rebuilt one. No luck either.

I am ready to give up and pay for a "diagnostic" service handled by a repair shop.

I still think it is a vacuum leak.

Does anyone have access to a diagram with the major points in the vacuum hose system?

Thanks for your help!

 

[kenamyford]

RobinYKR et al.
The car is now operating! I took it in for a diagnostic and it was a leak in the vacuum system. It was the elbow located to the rear of the engine. My mechanic told me that it was visible from underneath the engine. I actually had the car up on jacks when I replaced the fuel filter at the beginning. I could not obtain the vacuum hose diagram that I requested in my previous message so I did not put the car back up to look for leaks.

So I am out for the cost of an MAF sensor, a fuel filter and a PCV valve. I hope I have better luck next time I return to this site. This Escort is actually my wife's car and I am learning about it more and more.

I will continue to consult this site for people having problems and when I have problems with the Escort.

 

[troyhq]

maybe you have already checked them but the elbows to the pcv valve are prone to melting do to i don't know what but they just turn into goo. i have replaced 3 of them both the front and back one (a real pain to find first time). way back and under the intake manifold. The last time i just bought harder rubber elbows that fit the pcv tube. they are holding up way better one boot only lasted 1 month when i bought oem i was pissed.