Lean Windstar

I have a 1999 Windstar. Two years ago we had the engine light go on. I don't know what the code was at the time but the mechanic said it was the uptake O2 sensors. Had them replaced, light stayed off for about 3 weeks took the car back in to havethe code read, again I don't know what the code was, read that it was the other o2 sensors. The mechanic really didn't think that was the problem cleared the codes again and said if the light came on again than he will replace the other 2 sensors. Well, the light stayed off for a long time. Came on again a while back. Had no money to have anything fixed so just left it be. The car runs just fine, it doesn't run rough when hot or cold. It is a little gutless sometimes feels like I am running on air instead of gas. For example when I push the gas sometimes I don't get the response from the engine I should. Doesn't happen all the time but does happen. Also, started getting a little engine ping. I am using a higher octane gas now so the ping is virtually gone but as soon as I put unleaded in it pings.
I finally have money to put into the car and want to get it fixed. I had a coupon for a free code check on the car. The reader said Lean Bank 1, Lean Bank 2. I can't find the paper with the exact code but the mechanic seemed to think 02's again!? With all that I have described what may be the problem? I want to be prepared with the right questions and look for the right repair. Thanks!

Read this thread and do a search on P0171/P0174 here and on other sites. There is a specific TSB that covers this issue on your year and it is definitely not O2 sensors. Ask your mechanic if he can get a printout of the TSB number listed in this thread, parts should be around $100 or less. If not ask a dealer for a copy and you might ask if they are covering some of the repair costs, some have gotten them to cover labor but many others have gotten nothing out of Ford for this problem.

http://www.automotiveforums.com/vbulletin/showthread.php?t=165812&highlight=P0171

Read this thread and do a search on P0171/P0174 here and on other sites. There is a specific TSB that covers this issue on your year and it is definitely not O2 sensors. Ask your mechanic if he can get a printout of the TSB number listed in this thread, parts should be around $100 or less. If not ask a dealer for a copy and you might ask if they are covering some of the repair costs, some have gotten them to cover labor but many others have gotten nothing out of Ford for this problem.

http://www.automotiveforums.com/vbulletin/showthread.php?t=165812&highlight=P0171

Thank you for the link. Just read the entire thread. Makes me wonder if I needed the o2 sensors I had put in 2 years ago. I wont be taking the car to the dealer but have talk to the mechanic on the phone and he said he doubted seriously that it was the o2 sensors. That is why I posted... I had one mechanic that said it was the 02 after reading the codes and one mechanic who said it probably isn't who hasn't even seen the car. I will take the car to the later mechanic. I will go in armed with everything I read here. Do you think a non dealer machanic will do the work for less than the ford dealer?

Depends, the dealer is seeing quite a few of these and can probably do them fairly quickly and might even eat some of the labor. But then again their hourly rate is normally higher. A independent mechanic might be able to do it as quick with a lower rate, make sure to show the TSB which outlines the specific work when you get a quote. I'd try the dealer first and get a copy of the TSB and ask for Ford to help on the repair since this is a common problem, then take the TSB to the local mechanic for a quote. Just remember that you'll need to order the parts from Ford no matter who does the work.

I have a 1999 Windstar. Two years ago we had the engine light go on. I don't know what the code was at the time but the mechanic said it was the uptake O2 sensors. Had them replaced, light stayed off for about 3 weeks took the car back in to havethe code read, again I don't know what the code was, read that it was the other o2 sensors. The mechanic really didn't think that was the problem cleared the codes again and said if the light came on again than he will replace the other 2 sensors. Well, the light stayed off for a long time. Came on again a while back. Had no money to have anything fixed so just left it be. The car runs just fine, it doesn't run rough when hot or cold. It is a little gutless sometimes feels like I am running on air instead of gas. For example when I push the gas sometimes I don't get the response from the engine I should. Doesn't happen all the time but does happen. Also, started getting a little engine ping. I am using a higher octane gas now so the ping is virtually gone but as soon as I put unleaded in it pings.
I finally have money to put into the car and want to get it fixed. I had a coupon for a free code check on the car. The reader said Lean Bank 1, Lean Bank 2. I can't find the paper with the exact code but the mechanic seemed to think 02's again!? With all that I have described what may be the problem? I want to be prepared with the right questions and look for the right repair. Thanks!

Took the above mentioned car to the shop. It was the MAF sensor. Had is cleaned out and the fuel injectors serviced and all is good.
FWIW here is something I found on MAF symptoms and codes:

MASS AIR FLOW (MAF) DISCUSSION

MAF sensors can get contaminated from a variety of sources: dirt, oil, silicon, spider webs, potting compound from the sensor itself, etc. When a MAF sensor gets contaminated, it skews the transfer function such that the sensor over-estimates air flow at idle (causes the fuel system to go rich) and under-estimates air flow at high air flows (causes fuel system to go lean). This means Long Term Fuel Trims will learn lean (negative) corrections at idle and learn rich (positive) corrections at higher air flows.

If vehicle is driven at Wide Open Throttle (WOT) or high loads, the fuel system normally goes open loop rich to provide maximum power. If the MAF sensor is contaminated, the fuel system will actually be lean because of under-estimated air flow. During open loop fuel operation, the vehicle applies Long Term Fuel Trim corrections that have been learned during closed loop operation. These corrections are often lean corrections learned at lower air flows. This combination of under-estimated air flow and lean fuel trim corrections can result in spark knock/detonation and lack of power concerns at WOT and high loads.

One of the indicators for diagnosing this condition is barometric pressure. Barometric pressure (BARO) is inferred by the Powertrain Control Module (PCM) software at part throttle and WOT (there is no actual BARO sensor on MAF-equipped vehicles, except for the 3.8L Supercharged engine). At high air flows, a contaminated MAF sensor will under-estimate air flow coming into the engine, hence the PCM infers that the vehicle is operating at a higher altitude. The BARO reading is stored in Keep Alive Memory (KAM) after it is updated. Other indicators are Long Term Fuel Trim and MAF voltage at idle.


NOTE: THE FOLLOWING PROCEDURE MAY ALSO BE USED TO DIAGNOSE VEHICLES THAT DO NOT HAVE FUEL SYSTEM/HO2S SENSOR DTCs.


Symptoms

* Lack of Power
* Spark Knock/Detonation
* Buck/Jerk
* Hesitation/Surge on Acceleration
* Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0171, P0172, P0174, P0175 may be stored in memory

me too, and more. engine light on. went to a shop they wanted replace my alternator. for $400 they quoted i decided to just let it fail and ignore light. 6mo laterwent for emission test. banks 1 and 2
lean. fail ok whatever so much for repair shops diagnosis. make appt to fix lean banks 1 and 2. drive to iowa,must see willie nbelson corn maze, car wont start at perkins by iowa city. forget appt. tow van to ford shop, $130 cab ride back to moline. week later pick up car in rental ($300) in iowa city. shop replaced intake gasket, sp plug wires ($600). drive back to davenport. go to borders. get ready to leave car wont start. hoppn' mad. need ford ceo immediately. ford shop tows van back to iowa city. wait till monday bad fuel pump.($600) double whammy. drive home, ok. this morning, flashing engine light!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! wtf!!!!!! does it ever end :banghead: