1999 Ford Windstar

This Ford minivan with 139,478 miles was towed in as a no start/no crank issue. The shop owner suspected a theft issue and wanted confirmation. When I look at a possible theft issue there is one thing I always look at first. That is what does the theft indicator lamp/led do when the key is turned on. The majority of theft system will illuminate the theft indicator lamp for about 2-3 seconds then it should go out and stay out. But, before that I checked battery voltage first. This is an important step. Nothing worse than starting to track down an issue only to find out that the battery has low voltage and now you question everything you checked prior. Below is a shot of the dash and theft lamp.

 I flipped the key on and the theft light was flashing rapidly. Step one to confirming a theft issue. Next step is to confirm which type of Ford PATS (Passive Anti Theft System) you have. Ford has 5 different PATS systems that depending on year, make, and model all have their wrinkles. A good source of identification information is the PATS jobaid pdf available for free on the Ford website http://www.motorcraftservice.com/

On this minivan it is a type C PATS system. Type C system utilize the instrument cluster as the theft module. In this year, make, and model it also incorporates starter interrupt as well. From the diagram above you can see there isn't much to this system. The PATS transciever module also known as a "halo" has four wires, it gets a fused key on power and a ground. The other two wires send information from the key to the instrument cluster. From there the instrument cluster makes the call on whether it is the correct key and then sends a data buss message to the PCM to allow the car to start. So lets check some codes.

These are snapshots from my Ottotest. The first stop is the PCM. Here we have a P1260 engine disabled by PATS. Ok, we have a theft issue. But what? Think of the system. Let's scan the Instrument cluster.

Now we are getting someplace. I really do not like the description the Ottotest gives this code. I have the Ford description below.

The Ford definition is much clearer. It is saying that there was NO signal being recieved from the transciever. Do we have a bad transciever? Powers? Grounds? Communication? A little trick I do as well is flash out the PATS codes. On some systems leave the key on after about a minute of the rapid flashing. The theft light will go out and then flash a two digit flash code ten times. This will only flash the most recent code. I do this and get a code 13. A code 13 is equal to a B1600. Now, there is no known published information on this as far as two digit to scanned code conversion that I know of. Here, is what I have decoded.
Flash code 13-B1600
Flash code 14-B1602
Flash code 15-B1601
Flash code 16-U1147
So, what is my next step?
Let's have a look at the keys.

Look at how many keychain cards this owner has. There must have been twenty. These can interfere with key transmission. I stress can. The simple test here is to remove key from ring and retry. I really didn't have to though.

These keys are made by Texas Instruments and right where they put the transponder the key is damaged. In fact the transponder is missing. I look on the floor of the vehicle-no dice. I ask the shop owner to call the customer to see if they have another key. Customer informs us that this is the only key. Oh boy! At this point the customer is going to need a key erase and 2 new keys made and programmed. I can do the key erase and programming no problem. But, I don't have a key cutter and access to cost effective keys. I would have to buy the keys from Ford and it would be pricey. The shop owner has a very competent mobile locksmith that he uses and is far more cost effective. He swings by cuts two keys and programs the PATS and away we go. Now I have to be honest here. I knew what was wrong with this truck in about 30 seconds. But, I thought it would make for a decent case study.

2001 Ford Excursion

Here we have our vehicle with 108,904 miles on it. It has the 6.8 liter V-10 motor between the fenders. The complaint is that it originally came in with a MIL lamp on and misfire codes, three cylinder specific misfire codes. The shop replaced those specific coil on plug units and figured they had it fixed. A quick road test revealed it still had a misfire. Not as severe as before, but still an issue. With no misfire codes set the shop wanted to pinpoint the misfire. That is where I come in.....

There she is a big V-10. That is ten Coil On Plug Units to go wrong, ten spark plugs to go wrong, ten cylinders to have mechanical issues with. Get the idea. Well first thing I do is take it for a road test and make sure I put it through its paces. Idle, cruise, hard acceleration. This test drive serves two purposes. One it allows me to get a feel for the misfire and two I drive the car to make sure that the learned correction for misfire detection has been satisfied. On most Fords this is hard acceleration a couple of times making sure you get it up to 55mph. If you dont do this you may get false misfire cylinder results. After the road test I am pretty confident from feel that this is an ignition misfire. I check Mode 6 and sure enough cylinder #2 is showing some value where the other cylinders have nothing. I check fuel trims just to make sure my hunch about ignition is correct. An ignition misfire will not affect fuel trims as much as a fuel related item such as an injector. Sure enough my fuel trims are pretty tight. Out comes the low amp probe.

Here I have my low amp probe around the #2 COP (Coil On Plug) unit power feed. Low amp probes are an excellent tool. They are unintrusive, fast, and concise. They can tell whether you have a shorted coil, poor connection, weak coil, etc. There is a learning curve here. you have to look at a lot of known good patterns before you can tell a bad one. I use the low amp probe frequently on COP units, fuel injectors, and fuel pumps. The uses for a low amp probe are endless.

Well there is the waveform from #2 COP unit. There are three distinct patterns. This Ford vehicle utilizes what is called Multi Strike technology at an idle and low speeds. It was an idea that was supposed to create a more stable and smoother idle and help out with emissions. When the vehicle is raced up passed approximately 1500 rpms we only have the one pattern. Lets dissect the pattern. 

This first ramp is the initial coil on plug activation. What we are looking for is a nice sloping consistent amp charge. It shouldn't go straight up. A straight up pattern is an indication of a shorted coil on plug unit. Things look good here so far.

The next two patterns are the multi strike patterns. These should have upward ramps. Reason being the coils resistance changes after the initial charge. This sloping pattern on the multi strike indicates an issue typically with the coil on plug unit. Here again this is where experience pays off. Scope patterns are usually a matter of interpretation. You have to see plenty of good patterns before you can differentiate bad. Lets put some values on the scope capture.

Here I added some cursors with amperage values. I normally see around 6.5 amps on Ford coil on plug units. So, this is a bit high. I have enough to say I probably have a bad coil on plug. Time to yank the coil on plug unit just to give it a visual.

There it is. No arc marks or discolorations. Nothing physically wrong with this coil on plug unit. I could do a primary and secondary resistance test. But, that is a static test where my low amp probe test is dynamic. One test that I didn't show was checking spark output with a registered 30kv open gap style tester. It failed miserably with inconsistent blueish spark. It should be a nice even white spark jumping across the tester. So lets get a COP unit in and retest.

Looks a lot better....Notice the vertical ramping on the multi strikes. What about my amperage. Lets add some cursors.

There we go. We have the normal 6.5 amps back again. A test drive confirms no more misfires and the performance is back. It feels like a V-10 again.

Some more words.....

Since I created this blog a couple of months ago I have recieved some great feedback from my peers. The main purpose of this blog is to promote my business and foster my love of writing. I have had over 1500 views of my blog. Mostly from here in the United States and Canada.  But, there have been some Germany, England, Mexico, and such. I wanted to say thank you to all for checking it out and reading. I have had some private e-mails as well from do it yourselfer's, techs, and shop owners as well. I would like to see more interaction between myself and the people that are reading my posts. Leave a comment or comments. Don't be shy. What would you like to see me discuss? Is there an issue that you would like to see how I approach it? Scantool questions? Anything? I hope to hear from you all. Thanks again.  

2000 Buick Lesabre Part 2

You remember our last case study. Well, I am called back to this shop because the vehicle left running well then a week later it has issues and a MIL lamp on. At this point do we have another issue? I arrive and start the car which seems to run pretty decent but the MIL is on for sure. I retrieve a code P0102 (Mass Air Flow Sensor Circuit Low). Hmmmm. Well, I do my checks and guess what? The culprit is a bad remanufactured Mass Air Flow Sensor. This car left a week ago with 137,052 miles on it and here it is with 137,182 with a bad MAF.

This the point where I get on my soapbox about the automotive industry. Here goes my rant. About 10 years ago the automotive industry changed from a quality driven business to a price point business. Today, it is all about getting the cheapest part possible. This saturation of cheap parts has driven the quality of automotive parts into the toilet. Manufacturers really don't care because even though they have a 30% defect or return rate, they are still making 150% profit. The general public is really ill informed about this. All they know is that they can go online and get that part for $45.00, why are you charging me $125.00. The big box stores reap the benefits of this by buying these cheap parts even cheaper due to volume and can offer these parts at ridiculously low prices. The real loser is the shop owner. He or she is put in a difficult situation. Should we try this cheap part to remain competitive. Possibly, tarnishing our image if this part comes back defective or worse yet doesn't even work out of the box. Not to mention the time and money lost on having to do the job over again. Or, do we offer a quality part that in some cases is double the cheap part price. Now he has to "justify" and educate the consumer on why it is more money. It is a slippery slope. If the customer pulls the car and the guy goes down the street and that shop installs the cheap part and it works, the first shop owner looks like a crook. This is a real issue in our industry. It used to be primarily starters and alternators. Now it is rampant. With auto parts just like anything else-you get what you pay for! The thud you just heard was me getting off my soapbox.
So what do I do here? It is not my fault this part failed right away. Do I charge the shop owner again to diagnose? He is one of my best customers. I take one on the cuff and inform the shop owner to only use a quality MAF sensor. We both live to fight another day. 

2000 Buick Lesabre

This fine example of GM engineering has 137,050 miles on it. It has the 3800 K motor in it and the complaint is simple. When it gets hot it stalls out and doesn't want to restart too well. Let the car cool down and away she goes. My mind is already thinking crankshaft sensor, ignition module, bad ground for the fuel pump, ignition switch heating up and going open. These vehicles have always had issues with those parts. I start the car and the vehicle cranks well, fires right up and runs well. I have other vehicles to look at so I close the hood to build heat and let it run. I hook up my scanner to check codes and there are none. I am really not that suprised. I leave the scanner hooked up and go off to check the other problem vehicles. I come back to our Lesabre about 20 minutes later and it has stalled. I try to restart and it starts and immediately dies. I restart and try to feather the gas and it stays running barely. I get the distinct odor of a vehicle that is overfueling. I have been down this road before. I get out and open the hood. I disconnect the vacuum hose from the fuel pressure regulator fully expecting it to be wet with raw fuel. This is a very common intermittent issue on these cars. In fact, when I was on the techline I used to tell the techs over the phone my trick to add a piece of clear airline tubing from the aquarium store between the vehicles existing vacuum harness and the fuel pressure regulator and look for liquid fuel.

Dry as a bone as you can see! I hook my fuel pressure gauge just to see where that is.

Nothing wrong here. Well within specs. Now, lets look at some scan data. When you have a gross mismanagement of fuel you want to look at the big four. No, not Metallica, Megadeath, Anthrax, and Slayer( I have my tickets for Yankee Stadium) but RPM, Coolant Temp, Engine Load, and Throttle Position. So, that is what I do. Everything seems to be in order until I look at my MAF (Mass Air Flow) pid on my scanner while cranking. See below.

Yikes! That is correct 170 g/s (grams per second) during a crank event. Remember, our general rule g/s should basically be the same as you liter displacement at an idle and 40 times your liter displacement at wide open throttle. So we should see approximately 4.0-5.0 g/s at an idle and about 152 g/s at full throttle. we have 170 g/s just cranking! Do we have a bad MAF? It does seem lately that every other car I look at needs one. I am not convinced yet. I need to check the wiring.

Well the first thing I do is check for the proper open circuit voltage from the PCM (Powertrain Control Module) to the the MAF. the PCM sends out a voltage of 5 volts that the MAF will bring down to ground and release creating a square wave. The speed of this action is the frequency. The PCM uses this frequency to determine engine load. This input along with others helps the PCM to map fuel, ignition timing, egr, etc.

Nothing wrong here. I shake the harness and look at my min/max voltages. They don't waver. The remaining two wires at the MAF supply power and ground. Whenever possible I like to scope powers and grounds using the battery negative terminal as my ground. So I set my scope up to capture mode. I reconnect the MAF to load the circuit and I backprobe. I crank the engine and record.

Channel 1 is the power feed and channel 2 is the ground. Nothing wrong here. The reason I scope is to look for noise on either circuit. Something that could be missed with a multimeter. I reset my scope parameters and caught this on a start and stall.

Lots of ugliness. I was able to capture the MAF failing after it cooled down some. Check out the screen shot below.

This shot is at an idle. Notice we have great upstream O2 sensor activity, MAP kpa, and MAF value is at the expected 5.0 g/s. Then at about the 175 frame the MAF skyrockets and the MAP tanks, and O2 values peg. Let's get the cursor on that spike.

You are reading correct that is 307 g/s at an idle. To put it in perspective that would be a good value for a 7.7 liter motor at full throttle. The lesson here is never assume. Past experience and pattern failures are nice but you are better off looking at every vehicle as a brand new experience. Next.....

2002 BMW 325I

That is right a Bimmer. Now, I don't normally even touch these cars but I dabble from time to time. This is one of those times one of my good customers has this pretty clean BMW with 181,582 miles on it. Apparently, it had a Check Engine Lamp on and one of his techs pulled a P0171 (System Lean) code. When I get there the codes and more importantly the freeze frame data has been cleared. Since I don't normally diagnose these cars, all I can use is generic scantool data. So I focus in on our fuel trims and MAF (Mass Air Flow) sensor inputs. I know these have common issues with MAF sensors and Ventilation valves causing lean codes. I check fuel trims at an idle and they are pretty tight, raced up they start to drift into the positive side. I figure slam dunk I have a dirty MAF.

Looking at the MAF hot wire it is really clean and the customer has a factory BMW air filter. No cheapy air filter here. So, no slam dunk here. A road test is in order. I monitor short term fuel trim, rpm, and MAF g/s values. I am still thinking bad MAF here. The peak g/s easily achieves our liter displacement times 40 rule of thumb and short term fuel trims do not follow air flow. The one thing I do notice during the test drive is a distinct whistle on wide open throttle. Hmmm. Experience tells me when I hear a whistle it is usually caused by an intake restriction or some type of hole in the air tract. Since I already inspected the air box and it has a quality air filter installed. I head to the air ducting after the MAF sensor.

Bingo! Now I am a BMW expert. No way! A seasoned BMW tech would have probably found this in half the time. Here is another shot below.

The point here is some strategic testing even in generic mode and we can fix cars we are not exactly familiar with. I report my findings to the shop owner and advised him to change that much maligned ventilation valve with the updated one as maintenance considering the mileage on this car. I also advise him of Standard Motor Products new line called TechSmart that my good buddy Joe Donaggio manages. This new line is all previously dealer only, high failure, problem solving parts like these ventilation valves. It is a great alternative to going back to the dealer. I and others give Joe constant feedback from the technical "real" world and he does the leg work to make it happen. Check it out at http://www.techsmartparts.com/.   

2005 GMC Yukon Denali

This is a nice 2005 GMC Yukon with 156K miles on it, I am asked to look at on this nice and sunny morning. The customer complaint is that the Service Engine Soon lamp illuminates. I start the truck up and it runs quite well and the lamp is not on presently. I scan for current codes and get none. Scanning for history codes I get a P0171 (System lean bank 1), P0174 (System lean bank 2), and a P0101 (Mass Air Flow Performance). Now at this point most techs would say put a mass air flow sensor in it and send it on it's way. I need to be absolutely sure before I stick my neck out. So many factors could cause these codes from weak fuel pumps to glitchy connections at the mass air flow sensor to damaged air filters causing turbulence that would affect the mass air flow sensors calculations. So the first thing I do is a visual. You never know what you are going to find with your eyes.

Nothing amiss here. I check the air filter for fit and function as well as the air ducting. All seems to be in good working order. The mass air flow sensor is installed correctly as well. There are certain GM applications where the mass air flow can be installed incorrectly. There are arrows on the sensor indicating flow direction. I also look to see if there are any aftermarket air flow ducting, air filters, etc and make notes of it. It wouldn't be the first time I have seen the $450.00 chrome billet air flow tube that was supposed to give you 65 more horsepower causing issues such as this. Alright time to look at some scan data. These new generation GM V-8 motors have had their fair share of intake manifiold gasket issues. Looking at fuel trims at an idle and raced up show some pretty tight fuel control. Plus, looking at some freeze frame and failure records show me these codes set at mid range rpm's with the engine fully warmed up. Typical intake manifold gasket issues rear their heads more at low speeds and low engine temperatures.
Time to take a test drive. If you have been following my blog you know that I have been beating up my new scanner the Ottotest pretty bad. I decided to use it on this vehicle because of it's excellent graphing capabilities.

The above is part of a graph I did on the road test. Remember, click on the pics to enlarge. I graphed mass air flow sensor grams per second, short term fuel trims for both banks, and power enrichment mode. I took actual photos of these screen shots for two reasons. One, I wanted to show you the multi colored graph which is very cool. The second is that when you save the graph on Ottotest to export, it is a xps file that is black and white. Something I hope they fix. Saving it on the Ottotest retains the color, you can also scroll after the fact, as well as play with the cursors. The above screen shot is meant to show you the relationship betwen air flow and short term fuel trim. The actual numbers on the right reflect cursor 1, which isn't even on any event in this field so diregard for right now. Here is another screenshot below.

Do you notice something yet? Short term fuel trims follow air flow. When air flow increases fuel trims increase. It may be hard to see due to the graph scaling. In the above screenshot the cursor is on this screen and on frame 792, so the numbers on the right are correct. Let's zoom in and recheck something the Ottotest does really well.

Now it becomes more apparent. remember this is a normal test drive. Whenever, you have fuel trims following air flow you have an air measuring error. Remember, that an air measuring error is conditional on proper air ducting, filtration, etc. Now what? Do we call a bad mass air flow sensor? Not yet. I always like to do a couple of wide open throttle runs at speed and record some parameters to calculate volumetric efficiency. So changing my parameters to graph. I go with engine rpm, mass air flow sensor g/s, intake air temperature, and power enrichment.

Here is a screen shot of a wot (wide open throttle event). Remember, the cursor is all the way at an idle event see the rpm and low g/s. I wanted to illustrate a full from idle to wot event. I always get asked what is a good g/s reading at an idle? At wot? Well, there are no hardfast rules but g/s at an idle should equal your liter displacement on anything over 2.5 liters. Wot readings should be your liter dispacement times 40 as a general rule. This 6.0 liter had a value of 7-8 g/s at an idle. Lets look at some more data.

To figure out VE (Volumetric Efficiency) you need these parameters and use your highest g/s reading. Here I snuck up on it with my cursor. Given our rule of thumb is this reading low or correct for this vehicle? Looks a bit low since we should be seeing close to 240 g/s at wide open throttle. But, lets let the VE calculator be the judge. You can find VE calculator downloads all over-some free-some not. Let's do some calculations.

Engine Size (Cid)-366.15
Engine Rpm-5048
G/S-178
Intake Air Temp (F)-96.8
Volumetric Efficiency-61.667%

A good VE for a naturally aspirated engine is 80% or better. Any type of forced induction should net you 100% or better. We are well below our 80% goal at 61.667%. Let's see what happens when we add our theoretical proper g/s value.

Engine Size (Cid)-366.15
Engine Rpm-5048
G/S-240
Intake Air Temp (F)-96.8
Volumetric Efficiency-83.146%

So, there may be some truth in that value. I always take a couple of wot runs and check a bunch of them. Here is another.

I will zoom in....

Behold, the power of graphing! On the road test the vehicle definitely didn't have the power a 6.0 liter should have and detonated quite badly. I graphed the o2 sensors on wot runs as well just to make sure I wasn't also running out of fuel. They were definitely showing enrichment. Now, I could have gone further and done a low amp probe on the fuel pump circuit as well as fuel pressure and volume tests. But, given the data I had with the customers complaint I was sure we had a bad mass air flow sensor. The detonation is coming from an improper timing schedule due to the under reporting mass air flow sensor. Typically, this is how a mass air flow sensor will fail. It will report correctly at an idle and under report as airflow increases. This is not always the case though. You can have any combination for failure. Oh, by the way I do not agree with cleaning mass air flow sensors to fix them. Cleaning to verify you are going in the right direction-yes. The reason for my thinking is simple. Once you clean that customers mass air flow sensor and it takes care of his problem they are going to think a MAF cleaning is going to fix any issue from check engine lamp to rear brake noise. I report my findings to the shop owner and move on to the next vehicle.