GDI diagnostics question

Phillip Diagnostician Anchorage, Alaska Posted   Latest  
Discussion
Driveability
2014 Hyundai Santa Fe Sport 2.0T 2.0L (A) 6-spd (A6LF2)

So as the years go by I am starting to see more and more GDI vehicles come in to the shop. I have been getting stumped on a couple things when it comes to diagnosing say fuel related problems. So before I ask the questions I personally own said vehicle in the description so we can use that as a test subject if need be. So my first question is testing he injectors. I noticed some aftermarket scan tools don't have a injector test while others do. eg ford has one for their GDI engines as Mazda does not on say a 2010. Would I still do the injector test for these high pressure injectors using a injector pulse tester and then just use say, the scan data for the fuel rail pressure as my gauge? If not what are some of the procedures you all would use to test the injectors if you were concerned about a flow problem? The last question is how the hell do you tell if the camshaft lobe for the high pressure pump or if the high pressure pump itself is at fault(assuming that tank pump is good, the current and voltage measurements have tested good) Cause I would not be able to tell the difference between a good cam lobe and bad one. The only way I know how to test to see if the lobe is good is replace the pump and see if the pressure comes back if not then I would go after a lobe. I would like to develop at test so I am not throwing a part at something cause I really don't like doing that.

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Brandon Diagnostician
Reading , Pennsylvania
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Regarding the question cam lobe vs pump... A visual inspection would have to be conducted Prior to condemning pump. One would physically have to inspect the camshaft prior to putting a pump in

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Eric Mechanic
Chapel Hill, North Carolina
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The only bad lobes I've run into were on VWs. It was obvious, the lobe was ugly and the bucket that rides on it was badly damaged.

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Albin Diagnostician
Leavenworth, Washington
Albin Default
 

Good questions. So my first question is testing he injectors. I noticed some aftermarket scan tools don't have a injector test while others do. In all the driveability work I have ever done, I have never used an injector flow test. I have always used fuel trim data with FRTD to get my information. A restricted injector will rear its ugly head pretty quick while doing the test drive. On…

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Michael Owner/Technician
Cartersville, Georgia
Michael Default
 

Hi Phillip, I would suggest that you find some Bosch information on GDI. If you can understand the theory behind it you should be able to figure out fuel related problems on any direct injected car. The theory is the same but each manufacturer puts their own twist on it. I would suggest that you find something from John Thorton as he is the one that taught me.

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Felix Diagnostician
Miami, Florida
Felix Default
 

hi Pillip, try to get the ATG manual of direct injection and air induction systems diagnostics, is for import, but is very good

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Ray Diagnostician
North York, Ontario
Ray Default
 

This capture is from a 2015 Hyundai Sonata 2.4 with an intermittent idle misfire. The shop had replaced the COPs and the spark plugs. CH A is a 2 wire distributor pick up coil on the intermittent misfiring COP4. I use the 2 wire distributor pick up coils on COPs because sometimes the regular COP "Wands" don't work on some COPs. The cylinder 4 GDI injector is intermittently dripping fuel. I…

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Wow Ray that is a sick capture. Pardon my ignorance, how exactly are you picking up the secondary?? Those are amazing secondary captures.

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Ray Diagnostician
North York, Ontario
Ray Default
   

The problem with the regular COP "Wands" from Snap On or Pico or AES, is that sometimes you can't get a decent signal, on some COPs because some of them have the windings near the plug boot reduces the actual signal voltage. Another issue with using only one COP Wand on one COP is that you need at least 2 COP Wands to compare the spark times of the suspect COP with a good COP's spark time. If…

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Christopher Technician
San Antonio, Texas
Christopher Default
 

This is probably a silly question, but what about putting a regular KV probe on a short extension between the COP and the plug to grab a secondary pattern? I've never really had the need to do it, but every now and then I see my old LED spark tester in the bottom of my box and think "I wonder if that would work?".

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Ray Diagnostician
North York, Ontario
Ray Default
   

Removing the COPs and connecting the Coil-On-plug HT extension Lead set will give you the secondary patterns, but on some vehicles, the secondary burn voltage is very poor and is useless to diagnose injector issues. For the "Cassette" style ignition system, you have to use the Coil-On-Plug Extension Leads. On the GM 5.3 coils with the single coil wire, you can get the secondary on the plug…

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Phillip Diagnostician
Anchorage, Alaska
Phillip Default
 

this is a good capture. As soon as i get some tie I would like to ask you some questions if you don't mind.

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Randy Curriculum Developer
Raleigh, North Carolina
Randy Default
 

To your injector flow testing question, you cannot use a traditional pulse tester for a couple of reasons. One, GDI systems use high voltage to actuate the injectors. Second, the engine has to be running or cranking to build HP fuel. That only leaves us the specialized tests in the scan tool software. For example early GMs crank the engine automatically through the test and later ones performed…

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Phillip Diagnostician
Anchorage, Alaska
Phillip Default
 

I'm sorry and I don't intend to be rude, but time to remove an injector, ship it out, get it tested and put it back in. Just to potentially tell them their is nothing wrong with it is to much money for a hope and dream. To me this is unacceptable. It be more cost effective to rule out all other problems and make that the last possible failure.

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Stuart Owner/Technician
Prestonpans, United Kingdom
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Ideally the injectors can only properly be tested on a flow bench such as the ASNU . This allows you a visual check on the spray pattern and will show any leakage issues. Through experience in testing I’ve noted that BMW piezo units when cleaned can make previously good units leak at the seats. The cleaning process removes crud etc that may be sealing the the valve seat thus causing an issue on…

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Michael Owner/Technician
Cartersville, Georgia
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Hi Stuart, I too have done many BMW piezo injectors. I think there is a certain amount of “educated guess” when replacing them. I can’t think of one time I actually proved one bad but through disproving everything else I’ve replaced them and it fixed the car.

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Stuart Owner/Technician
Prestonpans, United Kingdom
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Part of the problem is often the insulation shorting so I use a megger tester to test the insulation as well. When leak testing I use blue paper roll, any dampness showing at all and it’s a bin job.

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