Choosing a battery with more cold cranking amps

I have heard that choosing a battery with more cold cranking amps than the original, will shorten the life of the battery. Is this so?

No! while the purchase of a stronger battery may cost more then needed for the given application, it has no problem for the rest of the car. The larger battery actually can give you more amperage and make the starter work easier.The battery requires less charging and after each start cycle it will also make the alternator last longer because the battery will recharge much faster.

Diagnostic Tech: '02 Olds Aurora

A 2002 Oldsmobile Aurora was in recently with two complaints. The headlights would dim intermittently and there was a Malfunction Indicator Light (MIL/Check Engine Light) on. The car had the 3.5 engine and all the luxury features you would expect in any top of the line automobile.

After spending some time trying to find a problem with the lights and having no luck, I decided to move on to the MIL complaint and come back to the lighting problem later. A lot of time can be spent checking a system but when the complaint can't be verified it can easily become time wasted. It's better to check for the cause of a problem while the problem is present.

I pulled a P0410 trouble code from the car's engine control module.

A P0410 will set when the engine computer has commanded the AIR pump on and the AIR valve solenoid open but does not see the O2 sensors go lean as they should when extra air is being pumped into the exhaust.

"An AIR pump?", you ask. Yes, an AIR pump. The modern version of the old belt driven smog pump is still alive if not well on many GM vehicles. The AIR pump no longer needs a belt. It is an electric motor and tucked away under the left front fender on the Aurora. The engine computer will provide a ground to the pump motor for testing or for normal system use. With a ground the motor should pump fresh air which is piped to a vacuum controlled valve at each exhaust manifold. With the vacuum control solenoid grounded by the ECM the vacuum will reach each valve and open them, allowing the fresh air to enter the exhaust and accelerate the catalyst operation. The fresh air entering the exhaust as it is commanded should lower the O2 sensor voltage to a lean condition. The lean condition should change the fuel trims. The engine computer does monitor the voltage on the command wire to the solenoid and will set a circuit electrical code if the voltage does not match the command. This means that when you see a code P0410 as a stand-alone code, you aren't likely to find an electrical problem.

One very common problem with the GM pumps is that the design of the air intake hose allows water to be drawn into the pump housing. This water will eventually cause the pump motor to be very hard to turn and even freeze up. GM Technical Service Bulletin 02-06-04-024G contains the related information. A replacement pump and an updated hose design to prevent the water contamination are available as a kit. The part number is 19515548. The original air intake hose filter is open to road splash from water while driving.

The new design is covered on the inner fender side and open to the engine compartment near the air filter housing. The install is fairly easy. The air filter housing and inner fender liner must be removed for access.
After finding the pump motor on this car to be water damaged and very difficult to turn I replaced it and the hose with the update kit.
While looking for the GM TSB and part number I had noticed something interesting. GM TSB 01-06-03-007A concerns headlamp and interior lights dimming in cold weather. The bulletin states that a revised alternator is available to fix complaints of headlamp dimming in cold weather and perhaps the blower speed slowing or changing pitch intermittently. The problem is due to intermittent low voltage. Engine vibration may cause the alternator to lose field continuity and the voltage regulator to reset. Now when the car owner dropped this Olds off he did say that the alternator had been replaced at another shop in an attempt to fix the light problem. I wasn't going to suggest yet another replacement. What really caught my eye is that the bulletin does go on to say that short term voltage drops with light flickers or fluctuation is a normal condition with high electrical demand AND that even after installing the revised alternator the car will exhibit short voltage dips and headlamp dimming DUE TO THE AIR PUMP CYCLING. Now just how much worse would this be if the air pump motor was water damaged and near frozen, causing much more current draw? It looked like the installation of the new air pump was going to help with the light dimming problem.

As important as it is to verify a complaint before starting a diagnostic job is verifying a repair after the work is performed. After clearing the trouble code a short test drive was in order. Everything appeared to work fine with no MIL on but a P0410 is a two trip code. In other words, if the air pump failed the monitor test during this test drive no code would be set and no MIL turned on. It would take a second ignition cycle and test drive to set a code. The air pump would need to fail the self test on two trips. To make things move along better and get the most of the test drive I usually take a scan tool along and record the ecm data.

A look at the scan tool data showed me that the air pump test had run and had FAILED during the drive. I would have liked to include the scan data capture in this article. You could clearly see the ecm activate the pump and solenoid three times and three times see no lean signal from the O2. It then gave up and logged a failure. Yes, I would have truly liked to include that but I did a software update on that scan tool earlier tonight not realizing it would clear the record memory.

Back in the shop, I used the command function of the scan tool to command the air pump on and verified the ecm could provide ground and the pump was fully functional. If the pump was working as commanded then the shut-off valves were the next place to check. Vacuum from the intake manifold is piped to the vacuum solenoid. When the ecm grounds the solenoid it opens, allowing manifold vacuum to reach the shut-off valves. The vacuum should then open the valves allowing the fresh air from the pump to reach the exhaust system. If the solenoid has an electrical problem the ecm should detect that and set a related solenoid circuit code. There was no circuit code so I used a simple vacuum gauge to verify 18" of vacuum to the solenoid. With the engine running and the vacuum gauge at one shut-off valve port I grounded the solenoid and got only 5" vacuum. I blocked the other shut-off valve port and tried it again. This time I had 18" of vacuum. The rear-most (right side) shut-off valve was bad and losing vacuum. With the vacuum loss, neither shut-off valve could open so no air from the pump was reaching the exhaust.

I actually do have scan data on the test drive done after replacing the shut-off valve. It was saved to the pc after being captured on a different scan tool so escaped the fate of the first data capture.

You can see the O2 sensor go lean when the pump is on verifying the system is operational.

I love my job!

Kenneth Hayes

aka Deranger

The modern day Jeep Wrangler- Was it created by the Willys-Overland company?

I have heard that the modern day Jeep Wrangler was created by the Willys-Overland company for the army in WWII. Is this so?

No! Karl K. Probst designed the original vehicle and in 1941, the Bantam Car Company of Butler, PA, developed the Bantam Reconnaissance Car in response to a U.S. Army request for an all-purpose military vehicle. This vehicle became the prototype of the Jeep, later manufactured by Willys and Ford, and is the direct ancestor of the four-wheel drive vehicles of today. It easily met every requirement called for by the army, however Bantam didn’t get the army contract and sereptiously the design was passed onto Willys who called it the General Purpose Vehicle, shortened to GP which became known as Jeep. The contract changed to AMC which was bought by Chrysler in 1987 and the headlight design was changed from round to square and then called the Wranger. The original 2.5 liter engine is still around, but the 258 straight six carbureted engine has been replaced by a fuel injected engine in 1991.

Using the recirculate setting on your air conditioner

I have heard that using the recirculate setting on your air conditioner is unsafe and can result in depleted oxygen in the cabin. Is this so?

No! Almost all vehicles heating and A/C systems provide for some freshair to be channeled into the passenger cabin at all times, regardless of whether the controls are set to recirculate or fresh. This is done for several reasons.

1. To keep the cabin under slight pressure so that exhaust fumes don't get sucked inside.

2. To keep the air in the cabin fresh at all times.

3. To help purge stale or obnoxious odors from the cabin.

4. to prevent someone from suffocating inside the car in the event they are trapped inside.

Diagnostic Tech: '92 Ford Tempo EECIV

We're going to need to set the Wayback Machine for 1992. Ford was using Electronic Engine Control System IV, or EECIV. By today's standards EECIV lacks sophistication but in its day it certainly performed its tasks very dependably.
On the plate today is a 1992 Ford Tempo w/2.3 engine and automatic transmission. The complaint is an intermittent Service Engine Soon light on and a high idle speed at that time. This system does store trouble codes in memory but should only turn the SES light while a code setting condition is present. In this case it just seemed to me that a test drive to verify the complaint was in order.
Initially the car ran fine. No light came on and even though I was driving in stop and go traffic there were no idle speed problems. I decided to return to the shop and just run the EECIV self-tests. When I pulled into the driveway the SES light came on. The idle speed was fine until I stopped and put the car's shifter into park position. The idle speed went to around 2000 rpm and stayed there for about three seconds before slowing back to normal. I had just verified the complaint. Time for the EECIV checks.
The car's test connector is at the left shock tower, near the battery. Technically there are two connectors. One is a single wire called the self-test input connector.
I'm going to mention that there are alternatives to retrieving codes. You don't have to use a scan tool. That being said, you will find the scan tool method more reliable with less chance of misreading a code number or accidentally clearing memory codes.
It is important to understand EECIV self-tests before using them to find a problem. Ford has the car's computer run specific tests and report back areas that failed the tests. The failures are reported as trouble codes. Running the tests improperly can give you misleading results.
A quick warmup cycle for the engine and I'll get started.
After connecting the scan tool to the test connector and entering the car data I want to start with "Quick Tests" and the Key On Engine Off tests. If a sensor fails the KOEO test then it should be repaired. You'll need a "Pass" or a no fault found condition in the KOEO self-test before any KOER (Key On Engine Running) tests can be reliably done.
The KOEO running test results are called "On Demand" codes. In this case I get a Pass code 111 which means no problems were found. After the On Demand codes are displayed the Keep Alive continuous memory codes will be displayed. The Keep Alive, or continuous codes are codes from the car's computer memory. Codes that have set in the past. This car has a 332 in memory. A 332 indicates insufficient EGR flow. I don't think a problem with the exhaust gas recirculation system it going to be related to the high idle or even the SES on at that time. An EGR not flowing should not cause the idle speed to be higher and since the EGR is not supposed to be flowing at idle anyway I don't think it would turn the light on at that time. I'm going to move on to the KOER tests because that test should be done before getting too involved with Continuous codes. The KOER test will reveal any sensor failures that happen during the test.
The KOER test codes indicate a 332 again. This time I know the EGR failed a test in real time and currently has a problem. Again though, I don't think it is related to the idle speed problem. Two more codes do indicate a problem with idle speed control, a 412 and 411. These codes indicate the car's computer not being able to control the idle speed. These codes do not store to memory so without running KOER tests we would not see them. If you think that was a lot of trouble to find that something is wrong with the idle speed you have a point. What was learned though is that the several sensors that contribute to the computer choosing an appropriate idle speed do pass self-tests. That means I should start by concentrating my efforts in testing the computer's ability to control the idle speed. In other words, I've learned that the inputs to the computer are likely to be fine but there is a problem with the idle control output circuit.
It's a good idea, I think, at this point to check the base idle and minimum air adjustment. Before any throttle adjustments are made I want to be sure I have a clean throttle plate. I'll remove the air intake hose, the MAF and the air cleaner cover as a unit. The throttle plate actually doesn't look too bad. It's pretty clean on the air cleaner side. The air filter looks good and the air cleaner housing was properly fastened.

When I open the throttle fully and look past the plate I can see major carbon buildup. I can even see why the EGR flow is low. The EGR passages are just behind the throttle body and fully plugged with carbon. The best thing to do here is remove the throttle body, remove the EGR valve and do some cleaning.

While we are in the neighborhood, this is a good time to remove the Idle Air Control (or Air Bypass Valve) and clean that passage as well. The engine computer uses this valve to control the amount of air that bypasses the throttle plate. The amount of air allowed controls the engine idle speed.

Once everything is clean and reinstalled it is a good idea to clean the MAF sensor or at least see if it needs cleaning. Two tamper proof screws hold the MAF to the MAF housing. A torx T20H will fit the screw heads. Carefully remove the MAF from the housing. With a magnifying glass and a good light you can look for dirt on the two tiny wires at the bottom of the sensor. If you see dirt, carefully clean it. These days there are spray MAF cleaners on the market. That wasn't always the case so I still use the same Berryman Spray Carb Cleaner that I always did. For stubborn spots I use a Q-tip as well.

This particular MAF looked pretty clean so after reinstalling it I let the engine warm up again. I know that I now have a clean throttle, a clean MAF, a clean IAC and a clean EGR passage but what I don't know is if I've fixed any of the complaints. It's time to run the KOER test again.

After getting the same results with the KOER self-test as before all this work, I decided to see just what was happening at the Idle Air Control as far as the computer control was concerned. The voltage at the IAC signal wire should roughly match the position being commanded by the computer. A command to open the valve 34% would have 3.4 volts. As a load is placed on the engine the command would increase, so a voltmeter could be used to check the command to see if the computer is trying to slow the idle speed during the high idle problem. Another method would be to disconnect the IAC wire connector from the valve and see if the engine slows. You see, the valve is spring loaded to return to minimum air position without a voltage command to the contrary. In fact, it is by disconnecting the IAC and adjusting the throttle position stop screw that minimum idle air is adjusted. All I have to do is wait for the high idle problem to appear. After a few minutes of running time the engine idle speed begins to race. When I disconnect the Idle Air Control the rpms do not change. The IAC valve is bad. I suspect a vacuum leak within the valve is the problem.

After replacing the IAC valve I now have no more racing idle and no more idle control related fault codes. One thing very good about the EECIV testing method is that I can rerun the test after a repair to verify the problem is fixed. The idle problem is fixed! BUT the EGR problem remains. I still have a 332 fault code in the KOER test.

During the KOER self-test the ECM will open the EGR vacuum regulator solenoid very briefly. This allows manifold vacuum to pass through the solenoid to the EGR valve. The vacuum should open the EGR valve. The pressure in the exhaust tube that runs to the EGR valve is measured by the PFE sensor. If the ECM has commanded the EGR solenoid to open yet does not see the PFE sensor voltage indicate a pressure change the ECM will assume the EGR is not working and will set the 332 fault code.

For testing purposes I like to use a length of vacuum hose and bypass the solenoid, feeding the vacuum directly to the EGR valve with the engine running at idle. If the engine nearly stalls then the valve is passing plenty of exhaust flow.



I started to do that here but noticed that the hose that feeds pressure from the EGR exhaust tube to the PFE sensor was broken. With a broken hose the PFE sensor would not be able to monitor the exhaust tube pressure change and would indeed set the 332 code. A replacement hose and another KOER test and this time the repairs were done! A complete system pass. No more light, no more high idle, no more codes!

Blotching seen on side windows

I have heard that the blotching seen on some side window glass under certain light conditions is normal and isn’t caused by flawed glass. Is this so?


No! This phenomenon is commonly found in tinted and tempered window glass which is used in side windows and the blotching is caused by a heat treating process which varies from batch to batch and the tint appears blotchy when the light reflects off of it at certain angles. It seems to be more prominent in some cars then in others.