Wednesday, March 30, 2011

A Quick Ottotest Update

Well, I haven't had a lot of time to play with my new tool. I started using it on my own 2001 Dodge Durango 4.7L. The first feature I tried was the DTC health check. This is where it searches all the modules and reports if there are any codes. Well it initiated and then the screen went to "error". I tried again and the same result. Another feature I tried was Mode 6 which I use quite a bit. The Ottotest started to populate Mode 6 and then stopped and said test was aborted. I tried again and same result. I was a little disappointed to say the least. Another item I noticed was there was no 4wd control module access on the scanner for my vehicle. I prompted the Ottotest to start communication with the ABS control module. I wanted to graph my wheel speed sensors. I am a big graph guy and the Ottotest has great graphing capabilities. Unfortunately, graphing on the Ottotest seems to be limited to the powertrain module only. I decided to update my Ottotest on line. The update went flawlessly and after the update I was able to get Mode 6 data on my vehicle. All the other issues remained. I left feedback on these issues on the bulletin board Ottotest provides. Let's hope they rectify these issues. I have faith that they will. I think I will start to incorporate the Ottotest in my testing now that I have a little time with it. I will keep you posted.   

2003 Chevrolet Impala

I always get the same comments from people when I tell them what I do. The conversation usually goes one of two ways. One is "Oh yeah I have this problem with my car.....what do you think?" When I explain that I only diagnose for the professional shop not the car owner the conversation either ends or the next line is "Well, don't these shops know what they are doing?" followed by "They just hook up the machine and it tells them what to change." This is the publics perception of how "easy" it is to diagnose cars today. When I tell people the shops I do work for in fact know what they are doing and it is not always that easy to diagnose today's cars it usually falls on deaf ears. Respect has never been part of the automotive repair business unfortunately. This case study is a prime example it is not always that easy as hook up scanner, retrieve code, change what it says on the scanner, and collect money.
So I get a call from Mr. D. He tells me he has an Impala with an evap code. He changed a part and it still has issues. Mr. D hates evap codes. So I get there and pull a P0446 code (Evap vent system performance). I look at two items when addressing trouble codes. One is description and code set criteria. Here is the description.

This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid Open and the EVAP canister vent solenoid Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid Closed and the EVAP canister vent solenoid Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets.
Now the code set.

  • The Fuel Tank Pressure sensor is less than -10 inches H2O.
  • The condition is present for as long as 30 seconds
 To put this in plain english. The evaporative system sees something other than 0" vacuum when it should be 0". How it sees this is the fuel tank pressure sensor. See below. Remember, click to enlarge pictures.

The normal voltage I see for a fuel tank pressure sensor on a GM vehicles at sea level is 1.49-1.52v with the gas cap off and during a leak test the voltage will rise to about 2.5 volts. This is the opposite of most manufacturers. So I am really interested in what our fuel tank pressure sensor voltage is on this vehicle.
That is right-0.22v on the scanner. This reading is saying this evap system is under pressure! So, my next step is to unscrew the gas cap and recheck. I do and the voltage stays the same. A new vent solenoid has already been installed by Mr. D.
At this point it is time to backup my scanner readings with DVOM (Digital Volt Ohm Meter). As much as I trust scan data whenever possible I like to see raw readings.

So I hook up my Dvom and.....
Dvom agrees with scanner. My next thought is what if the sensor signal wire is partially shorted to ground causing the low voltage. That is easy enough to check. We will jumper the 5vref to the sensor signal and see if the voltage at the scanner changes. Lets first see if we have a good 5vref.
No problem there. Lets jumper.

Now lets recheck our fuel tank pressure pid on our scanner.

A little fuzzy but it is 5.00 volts. So now we know we don't have a wiring issue. What could we have? Given the fact that the voltage didn't change when the gas cap was removed my next suspicion is the actual fuel tank pressure sensor itself. GM is kind enough to give us an access panel. So off it went.
Lets look inside. A bit grungy in there, but no chafing issues which can happen.

At this point I am pretty confident a new fuel tank pressure sensor will solve this issue. So a new fuel tank pressure sensor is popped in.

Now to recheck scan data. Remember, what we should be at.....

It is real fuzzy but it says 1.49v. I run an evap service bay test on my scanner and everything passes. At this point I guess you are wondering. Why didn't it set a fuel tank pressure sensor code? Good question here is why. Look at the code set criteria for P0452 (fuel tank pressure low).
  • The FTP sensor voltage is less than 0.1 volt .
  • All conditions are present for more than 5 seconds .
  Were we meeting the code set criteria? Nope. Almost. This is a great example of how important code set criteria is. Most techs love to look at the tree. I like to look at the code set criteria. Remember, the scanner doesn't tell you what part to change, proper diagnosis is still needed. 

Monday, March 21, 2011

2004 Saturn Vue 3.5L

I was called to one of my favorite shops recently. The shop owner I will call Mr. D is a larger than life type of guy. It is the type of shop you stop in for morning coffee and you don't leave until the afternoon or later after he has bought you lunch. I am also eternally grateful to this shop owner for employing me "piecemeal" when I was in between jobs. His shop has some really good people that come there for service as well.
Anyway back to the task at hand. The complaint is that the car would run then stall and have issues restarting. After talking to Mr. D he tells me that he had it running in the shop and it ran rough for a second and then stalled after a period of time. Trying to restart the vehicle it would start and stall immediately. "Like a theft issue Johnny". After letting it sit it would restart and then the whole cycle would repeat itself.
Doing a quick visual it is apparent that this vehicle took a hit in the left front and was "repaired". I will leave repaired in quotations. I hope the body shop saved this guy his deductible at least.
I start the vehicle and it runs well with a MIL lamp on. So lets pull some codes. I pull a P0300 (Random Misfire), P0301(Cyl. 1 misfire), P0302 (Cyl. 2 misfire), P0303 (Cyl. 3 misfire), P0304 (Cyl. 4 misfire), P0305 (Cyl. 5 misfire), and a you guessed it P0306 (Cyl. 6 misfire). Geez, what is going on here. All sorts of thoughts run through my head with these codes and the complaint. Do I have a fuel pump pressure problem, possibly a power issue to the COP (Coil on plug) units, or something else affecting all the cylinders with 122k anything is possible. So, I hook up the scanner and set it up to read map kpa, rpm, and short term fuel trims on both banks. Now I wait and observe the scan data and how the engine is running. Map kpa is smooth amd fuel trims are well within reason. As myself and Mr. D are leaning over the car commenting on the "fantastic" body work, I say to Mr. D that I bet this thing stalls when the cooling fans come on. No sooner than I say that the cooling fans come on and the car runs rough and stalls. Trying to restart nets me the start and stall issue. So, I disconnect the cooling fans because I already know where I am going and the car starts and stays running. Lets examine the wire schematic for the cooling fans below. By the way double click on the image to get it to be full size.
G101 is the ground for the cooling fans. More importantly it is part of splice pack SP101. Splice packs are where a manufacturer will share wiring paths from one area. In this case Saturn will use this splice pack to give many other components ground from this one ground connection. Now want to take a guess where this SP101 is located? You guessed it right behind the left front headlamp assembly. Right where the vehicle got hit and right where the "body work" was done. At this point we remove the left front headlamp assembly which wasn't too hard considering how it was "installed".
Above is the picture of SP101 installed on the left front frame rail. I removed the harness going to SP101. It is in the next picture. Sorry for the blurry pictures, but you get the idea. As my good buddy Joey Bag of Donuts would say "What part of a bad ground don't you understand?"
Lots of green mold, one bent terminal, and signs of water damage here. But we still need to get the part that is attached to the frame out and clean. Between Mr. D and myself we get it out.

There is enough filler, undercoating, and goop on this framerail that I do not want to use this as a ground. I would need to spend some serious time grinding to get it clean enough to where I would feel comfortable about using this as the ground for SP101.

A little time with a terminal brush, straighten out the bent pin, and some wd-40 with some shop air I feel confident that we can save SP101. While we are at it, look at the schematic for SP101/G101 below and you can see how many items are grounded here.

You can see why this caused the stalling issues. This ground is used for the fuel pump relay. When the fans came on they "sucked" the ground from the fuel pump relay. The vehicle basically ran out of gas. This was evident looking back at my scanner readings the short tem fuel trims elevated drastically right before the stall. So now we are left with where are we going to ground SP101 and get this vehicle back on the road. So we decide to go right from battery negative to the splice pack itself with a nice 10 gauge wire. Considering the rest of the vehicle is suspect for ground potential after the "body work" we feel this is best.

Now, by no means is this a "correct" repair. But, all things considered this was the best path. I cleared the codes and ran the vehicle through a couple of cooling fan cycles. No problems.

Sunday, March 13, 2011

2004 Ford F-150 5.4 Liter

Upon arriving at one of my shops I am given a 2004 Ford F-150 5.4 liter 3 valve motor. The customer complaint is that it runs rough and the check engine light is on. The vehicle has 117k miles on it and I am told it has always been well maintained. In fact it just had a recent tune up. Sure enough it runs rough and has a MIL lamp on. I also notice a decent rapping noise coming from the passenger side valve cover. I am told by the shop owner that this vehicle has had that noise "forever". Now, noise complaints on the 5.4 liter triton motors are not uncommon. This noise however is excessive.
Well first thing I do is pull codes. I have a P0300(Misfire detected) and a P0012(Variable Cam timing over retarded Bank 1). I also notice that the miss is more of a low speed misfire. It gets slightly better above idle. A quick test drive later and I feel that this truck has other issues besides a miss. It also has a lack of power as well.
Whenever I can I utilize Mode 6 data. Mode 6 simply put is the code before it becomes a code. I use it a lot on Fords with misfires and to confirm Evap code fixes. It is quick and concise. So I check out the misfire TID's(Test ID). It tells me that cylinder #1 is missing like crazy. Ok I have something to go on. Remember on most Fords cylinder #1 is on the passenger side. Remember, our noise? Furthermore, looking at #1 cylinder there is a new Coil On Plug unit and a new pigtail for the coil. Hmmm. As much as I trust Mode 6- I like to confirm. So I disconnect the COP connector and really no change in rpm, pulling #2 COP connector results in a decent rpm drop. Well I found my cylinder. My mind is still fixated on that rapping noise coming from under that valve cover. Another item I check when dealing with misfires is fuel trim-both short and long term. This vehicle has good fuel trim on both banks. That tells me we don't have a vacuum leak or a fuel issue causing the misfire. Next, out comes the low amp probe on the COP unit, nothing wrong there other than a short duration of operation which clues me in to what to do next.. My next step here is to check the actual spark plug itself. If you ever had the pleasure of doing spark plugs in a 5.4 Triton motor you know there is some praying to various deities when doing this job. First off these spark plugs require a special 9/16 spark plug socket to remove properly. Then you have the issue with the lower portion of the spark plug breaking off and staying in the cylinder head. luckily, various tool manufacturers have tool kits to make this job go easier. I felt better knowing that someone recently changed the plugs. I removed the #1 spark plug and.....
Yup, this plug is missing some pieces. Now, where did those pieces go? Could this be my noise? I crank and start the engine with the #1 plug out and hear something fly out.
This is a new plug with a dap of anti seize compound on it. Compare it to the one I took out. So I send this plug home and start the motor. The noise is still there but the miss is gone. I clear codes and road test. The truck has no more miss but still has power issues and a MIL lamp on. Code P0012 comes back. Time to break out the scope and look at some signals.

The Cam sensors give the PCM information on the cam position as well as variable valve timing. I prefer to backprobe at the PCM whenever possible. Thankfully the PCM is accessible. So we break out the wiring diagram and PCM connector views and backprobe Cam sensor bank 1 and bank 2.

Channel 1 is bank 1 and channel 2 is bank 2 respectively. I see an issue with bank 1 already. The amplitiude of the signal is in question for sure. Here is another shot.

Something is messing with the cam sensor signal on Bank 1. Before we go further we need to see if the actual VCT(Variable Cam Timing) system is working. I normally like to do a dynamic check where I ground the actuators on each bank raced up and look for rpm change.

Both banks show rpm change. So I now know we have the ability and we don't have totally clogged oil passages. I advised the shop owner a tear down is in order. I suspect something with the bank 1 cam sprocket or what Ford calls the phaser. All I know it is not going to be cheap. I advise the shop about oiling issues and to really look for sludge. Any sludge and I would recommend motor replacement versus repair.
Shop owner tears it down and the timing chain has substantial slack, the passenger side chain guide is completely broken and pieces are everywhere. Remember our noise. Above is a shot of a cam sprocket/phaser. But, there is absolutely no sludging. Customer decides to fix the truck. I tell the shop to save me the passenger side phaser. Below is a shot of the passenger phaser reluctor ring compared to the drivers side.
It has two bent reluctor tabs. Now, I know why we had that cam sensor pattern. How did they bend? My guess is the the timing chain guide that has been flopping around got wedged and bent them. Below is a shot of the phaser taken apart.
Here is one of the actuator and oiling metering block.

Like I was told this truck was extremely well taken care of. I was asked to retake scope shots to confirm repair after the timing chain, phasers, guides, etc was done. Below is the updated scope shot.
As you can see with my cursor set the amplitude is almost identical. Driving the truck afterwards the noise is gone and the truck has good power.  

The Ottotest is here!

After some wait I have recieved my new scantool. The Ottotest by Blue Streak electronics. I have been using the Blue Streak BDM scanner and have been quite happy. I actually got a chance to test drive this scanner last May and was really not impressed. Since then Blue Streak has done a ton of updating and I have been monitoring the updates. I feel confident that this tool by far will be the best "bang for the buck" scanner. The shortfalls of this scanner is it's European specific coverage. Since I really don't delve into European diagnostics that much, save the ocassional Volkswagen this fits my needs perfectly. The upsides are many. One being that this is also a J-2534 tool which will allow me to flash vehicles.
The scanner consists of a VCI that plugs into the data link and a tablet PC. You can connect the two via usb or wifi wireless. It is updated via the internet along with online feedback from user to engineers to make the tool better. I always like to test new equipment on my own vehicles and get comfortable with them before using them out in the field. I really don't want to learn the tool thoroughly when it is on someone else's dime. Some of the highlights with this unit is it's ability to configure GM Body Control Modules. No other tool other than the GM Tech2 will do this.  Another nice feature is DTC health check. This is where it will scan all the modules in a vehicle and report if there any codes and also clear all in one step. I am sure there will be a steep learning curve here. It is a Windows based operating system that uses a touch stylus so I am not totally clueless. I had a little problem setting up the wifi and customer service was very helpful and got me going.
In the coming weeks I hope to show some the highlights of this tool. 

Saturday, March 5, 2011

1989 Toyota Camry

This comes from one of my best customers I will call him Mr. H. Customer complaint is battery goes dead after a couple of days. A new battery and a new alternator has already been installed. So lets do some testing.
A quick check of the charging system tells me no issues here.
Lets check for a drain properly with an ammeter in series with one of the battery cables.
Here we have a 121 milliamp drain. After letting it time out for 20 minutes it stayed the same. Time to put our thinking caps on. I am fairly famaliar with these vehicles. I worked on enough of them throughout the years. Experience has taught me that this type of drain is in memory circuits. Likely suspects are the factory clock and the radio. Over time these circuits draw more than when they were brand new. So we pull the Cig fuse in the interior fuse panel that powers the cigarette lighter and the clock.

Now we are getting somewhere. Rule of thumb on drains is 50 milliamps or less. We are at 40 milliamps here. Acceptable, but a car this age it should be lower. So I pull the radio memory fuse and.........

17 milliamps. That is more like it. I advise Mr. H about what I found. We agree leave the cig fuse out and keep the radio fuse in. This way they can still enjoy their tunes.
A little knowledge goes a long way with these problems. Having dealt with these cars over the years you kind of get a feel for them......