Too Lean Chk Engine Light???

[Chairboy]

Instead of paying $50 a shot to get the code read, go to a well equipped parts store like Autozone, more and more they have an OBD-II reader that they'll use to get the code for you for free.

Pre OBD-II, it was a good bet that your O2 sensor was busted when the check engine light came on on a B series Mazda truck.

[Hawklore]

Originally posted by Chairboy
Instead of paying $50 a shot to get the code read, go to a well equipped parts store like Autozone, more and more they have an OBD-II reader that they'll use to get the code for you for free.

Pre OBD-II, it was a good bet that your O2 sensor was busted when the check engine light came on on a B series Mazda truck.

Autozone is where I go to get my chck engine light read..

Ever since I found out they do it for free, and their prices are AMAZING..

[Captain Virgil Hilts]

That's an OBDII system. The light will not go off until you have a mechanic use a scanner to reset the ECM. Autozone and Advance do not reset the ECM, as they are not supposed to. Most of their scan tools are not capable.
Only a real shop can reset it. Unhooking the battery will not clear the codes on an OBDII system. That information is not necessarily for you Hawklore, just general information in light of someone suggesting you disconnect the battery.

I hate anything Ford computerized, their system just plain sucks. The newer is not so bad as the older stuff, but it still sucks.

Check to see if the backfire caused it to blow a gasket or seal anywhere in the exhaust. If it did, it can pick up fresh air in the exhaust and read lean.
Check the fuel filter to see if it is clogged. You can also look at the general state of tune, plugs, wires, cap, rotor, filter etc. I doubt you can move the timing. Tap on the mass air flow sensor, if applicable, and look for wiring problems with the sensor connectors. If you find none of the above (and really look, test, and try, if this is an intermittent problem you'll have to work at it) then have them hook a scan tool to it and see if the O2 sensor is switching like it should. if it is not, replace it. With a genuine OEM sensor and not some cheap crap from Autozone or Advance. Only genuine OEM tune up parts or sensors should be used on late model vehicles, there's too much crap floating around in the aftermarket pretending to be good parts.

By the way, the only reason to step on the gas when trying to start a vehicle with electronic fuel injection is the extremely rare case of possible flooding, which is next to impossible to do with EFI. All stepping on the gas does is SHUT OFF the fuel.

If they put an IAC motor on it, and did not properly reset the base idle,  the idle air counts, and the minimum air rate, it will not start good, and it will not maintain an idle speed. It may die, stall, rev up at idle, surge, or just generally act stupid.

[Maverick]

You might check the O2 sensor.

[rpm]

Originally posted by Captain Virgil Hilts
That's an OBDII system. The light will not go off until you have a mechanic use a scanner to reset the ECM.

BZZZZT!! False. You can reset a Ford computer simply by using a jumper wire. You can also read the codes using the same jumper wire. It should tell you how in your Haynes manual.

On a Dodge system you can read the codes just by turning the ignition on 3 times in 5 seconds. You can reset the system by starting driving a few feet and killing the engine 3 times.

On a GM system you simply drive the vehicle into a nearby ditch, exit the vehicle and go buy a Ford or Dodge.

[Captain Virgil Hilts]

Originally posted by rpm
BZZZZT!! False. You can reset a Ford computer simply by using a jumper wire. You can also read the codes using the same jumper wire. It should tell you how in your Haynes manual.

On a Dodge system you can read the codes just by turning the ignition on 3 times in 5 seconds. You can reset the system by starting driving a few feet and killing the engine 3 times.

On a GM system you simply drive the vehicle into a nearby ditch, exit the vehicle and go buy a Ford or Dodge.

For OBDII (around 1995 model year and later), by federal law, the codes cannot be reset unless the ECM is reset with a scan tool. This was a prime part of the OBDII requirement, because in many areas emissions testing on OBDII equipped vehicles is done by merely scanning for codes. The OBDII system is designed to prevent the owner, or a shade tree mechanic, from clearing the codes, or dumping the stored data, on order to make it easy for the emissions tester to determine if the vehicle had been modified, or was operating with a system fault.

When I got out of the general repair business in around 2000, after about 18 years of part time and full time employment as a line mechanic, there was still no way to reset the codes in an OBDII system without a scan tool that was capable of a reset. It was also still against the law, under a $50K fine penalty, to clear a code without repairing the fault. If you cleared the code on a vehicle and then allowed it to be tested for emissions without repairing the fault, they could literally padlock the building and fine you a minimum of $50K. That's also the reason Autozone and Advance will not clear codes, and their scan tools are generally not capable of doing it. They don't want a store shut down because some neophyte "partsman" clears the codes and joe dipstick slips his car through emissions, or at least tries to.

On older, OBDI systems, you could clear it by disconnecting the battery. Or if it was the stupid Ford system, you got one shot to read the codes, after that it dumped them, so yes, on a Ford OBDI system, a jumper wire would display and clear the codes, whether you wanted them cleared or not. Also, the Ford system did not give live data. The Chrysler did to some degree. The Ford required a "breakout box" be installed at the firewall connector, and you read data with a DVOM in the form of voltages and resistance readings. You then had to correlate that into actual data. The GM system could be read with a jumper key, and would flash the codes until you pulled the key out. The codes were cleared by pulling the ECM fuses. They gave full live data as well, the scan tool would display every function. The exception was Cadillac. The Cadillac system displayed the codes and live data through the climate control display. If you pressed and hold the "off" and "warmer" buttons, it went into diagnostic mode, and gave both codes and live data.

The piss poor design of Ford's system was a major factor in the OBDII requirements, as was the desire to prevent the OEM's from keeping the systems and data proprietary so they could hinder the aftermarket shops from gathering all the information necessary to fix problems. All data and codes are now somewhat standardized, at least for actual emissions issues. And all systems must use the same connector to link to the ECM, and must have live data available on that link.

[Chairboy]

Ford used the EEKIV before they switched to OBD-II, is that what you're talking about?

Anyhow, I have an OBD-II interface to my computer that can read and reset.  I used it to expose a fraudulent emissions joint.  I think I wrote about it here two years ago or so.

[Captain Virgil Hilts]

Originally posted by Chairboy
Ford used the EEKIV before they switched to OBD-II, is that what you're talking about?

Anyhow, I have an OBD-II interface to my computer that can read and reset.  I used it to expose a fraudulent emissions joint.  I think I wrote about it here two years ago or so.

Well, there were several Ford systems, though most were very similar. The EEC series started with EECI and made it through to EECIV. Although I do think EEK is a more appropriate term.

Of course, an OBDII interface for a lap top or a desk top could also clear codes, depending on the software. I was speaking of "scan tools" as that is what most people see. There are of course the big "Sun" machines with scan tool style capability, the "tuner modules" that take the place of "chips", the tuner software that goes in either a lap top or desk top system, as well as the scan tools. With the OBDII stuff, a dealer can use a scan tool to download the entire ECM program, dump it into a desk top terminal, and then upload a new program, and download it to the ECM. Most independent shops don't have access to the stuff to do that.

We had a problem a few years ago with some of the employees at emissions test centers scamming people. I had a customer bring me a 1/2 ton pick up that failed. It did actually fail, and needed a carburetor overhaul, a major tune up, and an oil change. It left the shop clean and legal, then proceeded to fail the test. Three times. I checked it, calibrated my 4 gas infrared twice, and took it through myself. It failed again, but was clean at the shop. I had noticed the girl who did the test putting her hand on the bumper when she put the probe in the tail pipe. I looked at the bumper, and underneath it, on the bottom edge, was a row of 3/4" diameter brightly colored stickers.

I took the 5 printouts from my 4 gas, dated and time stamped, and their printouts, and went back to the station. She did the same thing. Put a sticker on the bottom of the bumper, slipped the probe in, and failed the truck. I got out, grabbed her by  the arm, took her in the office, and showed her boss all the papers, and took him out to the truck and showed him the stickers. I made him give me all the test fees back, and kept the stickers and the printouts. I told him to either fire her on the spot, or I'd have the TV news crew on the scene in 5 minutes (I worked on the investigative reporter's truck). He fired her, and when I got back to the shop I called the Dept. of Health, reported them to the guy who ran the emission dept., and he went down and cleaned house.

[rpm]

The one I was familiar with was a 96 Explorer. Haynes manual gave you all the info to read and reset. All it took was a jumper or test light. I'm not sure which system it had.

[culero]

rpm you info is correct but way out of date. Savage has it right for current stuff.

culero

[Captain Virgil Hilts]

Originally posted by culero
rpm you info is correct but way out of date. Savage has it right for current stuff.

culero

Hell, I'm way out of date as well. I've been out since 2000 for the most part. And I don't miss it at all. The closest I get is when I work on one of my own street cars (daily drivers) and even then I have to get a buddy at a dealership to bring home a scan tool. I've had some guys asking about the late model EFI cars in Stock, I can build the engines and transmissions, but I'm not up enough on the tuners. I'm not even sure I want to fool with lap top racing. I like the old school 69 Camaro and 69 Corvette I'm fooling with in A/SA more than I ever liked fooling with the late model stuff. I'm hoping we end up with a SS/CA 69 Camaro before long.

[bj229r]

I've had a series of Chevy Vans last few years at work--- turning on key (not engine) then hitting gas pedal like 12 times resets 'service' light--although the intent of that light may not be same as 'check engine'--the Chevy actually TELLS you when to change the oil via that light

[crowMAW]

Originally posted by Captain Virgil Hilts
If they put an IAC motor on it, and did not properly reset the base idle,  the idle air counts, and the minimum air rate, it will not start good, and it will not maintain an idle speed. It may die, stall, rev up at idle, surge, or just generally act stupid.

Hawk, I agree with Capt Virgil..it may still be the IAC.  If is was not installed correctly, it may still cause problems.  

It may also be your throttle body.  Make sure the butterfly valve is not sticking.  At that milage it may need a good cleaning.  A product called Seafoam does wonders. (If you are still in Mandarin...the Advance Auto Parts at Loretto & San Jose has it).  You can clean the TB and if you put it in a spray bottle and mist it into the intake with the car is running, it will give the car a good top end cleaning.

Capt Virgil...many have discovered hacks to reset the CEL even on OBDII cars.  My Honda is easily cleared by pulling the fuse to the ECU.  Mazda Rotories have a complex proceedure involving pressing the brake pedal several times with the key in the on position...others have a sequence of key turns and odo button presses.  Folks find these backdoors and post them on the internet.  You might check a forum dedicated to the car you have to see if someone has discovered a procedure to clear a CEL on your car.

[Hawklore]

Originally posted by crowMAW
Hawk, I agree with Capt Virgil..it may still be the IAC.  If is was not installed correctly, it may still cause problems.  

It may also be your throttle body.  Make sure the butterfly valve is not sticking.  At that milage it may need a good cleaning.  A product called Seafoam does wonders. (If you are still in Mandarin...the Advance Auto Parts at Loretto & San Jose has it).  You can clean the TB and if you put it in a spray bottle and mist it into the intake with the car is running, it will give the car a good top end cleaning.

Capt Virgil...many have discovered hacks to reset the CEL even on OBDII cars.  My Honda is easily cleared by pulling the fuse to the ECU.  Mazda Rotories have a complex proceedure involving pressing the brake pedal several times with the key in the on position...others have a sequence of key turns and odo button presses.  Folks find these backdoors and post them on the internet.  You might check a forum dedicated to the car you have to see if someone has discovered a procedure to clear a CEL on your car.

MMkay..

I'm gonna run by Advanced again, with my Haynes manual that I forgot I had when they ran the last Chck Eng. Light, and compare their notes to it.

If it comes up with IAC or anything, lets just say Car Max is going to catch hell..

Let me restate,

Buying Experience was great...