Monday, May 23, 2011

Circle yer wagens!

We've all seen dummy spinners. But how about dummy wagon wheels for your early hot rod?

New for 1957!

There's no denying that the 1957 Ford Fairlane is a seriously cool car with the right set of wheels.

Saturday, May 21, 2011

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   

Sunday, May 15, 2011

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
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
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.

Friday, May 13, 2011

Ottotest Update

I have been trying to implement the Ottotest into my diagnostics as much as possible. It seems to have shortcomings every time I use it. I had a 2007 Chevrolet Trailblazer with a Service 4wd lamp on. The Ottotest didn't even recognize the four wheel drive module and I was forced to use the shops own Snap On Solus to retrieve codes for the four wheel drive system. How embarassing! Next up was a no start/no crank on a 2005 Jeep Grand Cherokee. The Ottotest did a great job on retrieving a PCM code of P0513 (Invalid Skim Key) and communicating with all the other modules save one. You guessed it no communication/no menu for the SKREEM (Security) Module. The one module I needed to communicate with, the scanner shut me out. I realize that immobilizer recoding is beyond aftermarket scanner abilities. But, let me in, so I can see if its on the data buss and maybe some parameters. I had to resort to tedious backprobing at the SKREEM Module to verify operation. More time wasted. The tablet is slow. So slow that sometimes if you get impatient with commands you will lock up the program forcing a hard reboot. More time wasted. The battery life is nowhere near advertised. I have been sending feedback to Blue Streak every week. I am starting to think this tool was not as advertised and it has cost me money rather than making it. Time will tell.  

Tuesday, May 3, 2011

Slow and Low! 1977 International Loadstar

We've all seen them at one time or another. A decked out big rig style commercial truck that's slammed to the ground and smoothed over with lots of chrome and wild paint. This is a take on one of those trucks. This '77 International Loadstar in it's stock form wasn't going to win any beauty contests back in the day. But by today's standards does have a nice sense of style compared to the cookie cutter looking commercial trucks today. Filled in seams, some minor reworking of some sheet metal and adding the cool suicide doors make for a unique look. Then add in the reworked frame, airbags, and the low pro tires and a new Ford diesel motor and you're starting to get a cool looking one of a kind truck. Rob from Ontario Canada had really built a wild ride! Just check out these stats below.

1977 International Loadstar 1600 – Complete Mods List

-Full frame custom built
-3X6 ¼” wall, fully sealed and used as air tank (25 gallons)
-3 link front with custom solid beam suspension
-front hubs and brakes from 1991E350
-3 link rear with Sterling 10.25 differential
-10,000lb transport truck bags at all 4 corners
-3/8” air valves, ½” hard line
-digital air gauge
-york engine driven compressor
-5th wheel hitch
-dual fuel tanks custom built
-7.3L Ford IDI diesel from 1991E350
-Ford E4OD transmission
-2001 Dodge intercooler
-2002Ford powerstroke turbo on custom manifolds
-massive transmission cooler
-turbo code injectors
-injection pump turned up and timing advanced
-5” exhaust to 5” slant cut stack
-3” intercooler piping powdercoated cream
-holley red electric fuel pump
-floor and firewall from scratch
-suicide doors with fabricated hinges
-shaved door handles
-welded and smooth front body seams
-pedestal mount cab lights
-LED front and rear lighting
-HID headlights
-chrome visors over all lights
-cargo basket
-painted Chrysler classic yellow
-smoothed and painted dash
-seat from 1993 Chevy truck recovered by owners wife
-autometer gauges for- speedometer, tachometer, boost, egt, trans temp, oil pressure, coolant temp, volts, fuel level
-alpine stereo in glovebox
-soundstream 5 channel amp
-RE Audio 6.5” speakers
- 2 12” RE Audio subs
-triple trumpet air horns
Wheels and tires
Front wheels- 22.5” semi wheels milled to 22”
Front tires- 255/35zr22 Falken FK452
Rear wheels- 24.5” semi wheels milled to 24”
Rear tires- 255/30zr24 Falken FK452
Custom adapters

Source: Hemmings.
Photo Credit: Steve Wharton

Remember the bookmobile?

I remember visiting a book mobile at least a couple times in my early childhood. Sort of like rolling libraries, they would be stocked with a collection of books that you could checkout and return just like in a library, only it would be in the parking lot of the local strip mall. Now-a-days you don't see a bookmobile too often, if ever. Recently, the Antique Automobile Club of America (AACA) Library and Research Center was donated a vintage bookmobile. The 1955 Chevrolet 3600 proudly served Anderson County, South Carolina. Dave Bowman (left) and Tom Gibson of Crossroads Restorations in nearby Anderson presented the bookmobile to the AACA at its recent regional meet in Charlotte. Looking very solid with it's nicely aged patina, the AACA is now accepting donations to fund a restoration.

This looks like a very cool restoration project. I can see this thing restored in its original livery with some AACA Library logos added for good measure criss-crossing the major car show circuit with a load of vintage auto books and magazines in tow to help promote the AACA and their museum in Hershey, PA and even their meets.

Source: Hemmings