Questions tagged [diagnostics]

Use this tag for generic questions related to tools, techniques and methodologies for diagnosing problems. Do not use this tag for case-specific problems, the "troubleshooting" tag is better suited for that.

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2
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0answers
56 views

Illusive evap code - Hard to find the issue

98 Honda Civic Ex. For a while now my car will throw a p1456 evap code but sometimes it doesn't and the system completes the test. I'll randomly hook up my obd2 scanner and it'll either have a ...
3
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1answer
23k views

What could be causing a grinding noise when car accelerates quickly?

My son is an hour away and we are trying to diagnose this problem on a 2001 Toyota Corolla. When the car is accelerated slowly and gradually everything is fine. However when the gas "pedal is to the ...
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0answers
35 views

98 Chevy Malibu 2.4 liter has fuel and fire but will not start

98 chevy malibu 2.4 liter .Has fuel to injectors and fire to the plugs but won't start?
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5answers
7k views

Suzuki sv650s will not start, no lights, no fuel pump, nothing

My sv650s will not start at all. I put the key in the ignition and turn it on and none of my accessory lights come on and the fuel pump doesn't engage. It's done this before and I fixed it originally ...
1
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1answer
160 views

Skoda Fabia 2005: what I need to know to buy a diagnostics machine?

I'd like to buy a diagnostics machine for my Skoda Fabia 2005. My issue is I'm absolutely newbie on this. I don't know which cable connection requires, if there's some standard, ... Will you provide ...
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0answers
4k views

Why does my gas engine sound like a diesel?

I have a 2011 Chevy Impala 3.9L police package car. I've had to issue with the engine running rough, stuttering, burning oil etc...but, when I am at idle, parked, or in traffic; I can hear a very ...
7
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3answers
9k views

Best practice to tell if an interference engine has bent valves?

I have a 2003 Mitsubishi Galant 2.4L SOHC engine with 251k miles on it. While I was driving it all of sudden the engine just died. I pulled off the road and then had it towed to a local mechanic. ...
3
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1answer
4k views

How To Diagnose 3rd Brake Light (Without Proper Equipment)

I have a 2012 Ford Focus (sedan version). The third brake light stopped working recently and I'm trying to determine if the problem is with the light itself or inside the vehicle, but a I have very ...
3
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4answers
2k views

Simple fool proof way to identify Bank1 and Bank2 side

Is there a simple and fool proof way to locate which "side" of the engine Bank1 or Bank2 is on, with reference to OBDII data? For example, you read ODBII live data and find that Bank2 Sensor2 (...
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0answers
266 views

Air conditioning hisses, but gauges show pressure, no cold air

So my 2010 VW Routan's (basically a Dodge Caravan) AC has gradually stopped working. I figured I had a small leak and it finally just didn't have enough juice to cool. I have a set of gauges that I'...
2
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1answer
14k views

2011 Jeep Compass No-Start

Car comes in with the complaint engine cranks doesn't start. Confirm the complaint and check for codes, P0688 - ASD Relay Control Sense stored in memory. After doing a quick fuse check I found that ...
3
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0answers
222 views

What does muddy transmission fluid indicate?

I'm in the process of pulling out the engine & transmission from my Lumina (progress here). The picture below shows the state of the transmission fluid. It has a slightly grainy texture to it. I ...
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1answer
40 views

When connecting diagnostic PC to OBD port - What is the most detailed output file?

When the garage connecting the "official" manufacturer software to the OBD port in the car - What is the most detailed file that can be retrieved, containing all the raw data information? Thanks,
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2answers
8k views

Is there a diagnostic that can be done on a used hybrid car's battery pack?

I'm looking at a used hybrid Lincoln MKZ with 70k miles. The manufacturer provides an 8-yr/100k mile warranty on the hybrid system, so I believe I should still be covered until 2019. I've read that ...
7
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1answer
151 views

Is an injector an injector?

In general terms at least - lately the engines I've been working on are diesels and I've never had to troubleshoot fuel injection problems on gasoline/petrol engines. So, I'm wondering, how many ...
5
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2answers
4k views

P0300, P0302, P0303 on 2003 Honda Civic 1.7

I'm in the process of helping someone with their 2003 Honda Civic, 1.7L engine, 161k miles on the clock. Pulling the codes from the vehicle I got three specific codes: P0300, P0302, P0303. The codes ...
3
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2answers
317 views

OBD reader returning “0 Codes” way too fast?

Normally, when I read my '07 Hyundai Sonata, the reader takes about 10 seconds and then returns "0 Codes" (or whatever). However, I just was checking out a 2010 Sonata. I hit Read and it popped up "0 ...
5
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2answers
5k views

Why does Honda Civic 05 overheat when water reservoir gets full?

My father in law's Honda Civic overheats when the water reservoir is full or to the top. He is wondering what could be the problem if the radiator needs water when the reservoir is full. The ...
2
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0answers
599 views

Check engine light is on but no codes provided when checking with reader [closed]

I have a 2004 Chevy Trailblazer. My check engine light is on, but I'm getting no codes when checking with reader only blank screen. How could this happen?
7
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4answers
176 views

Basic Automotive Maintenance Repair - Compiling a Toolset

I am looking into getting more serious about doing my own automotive repair and maintenance, and am working toward gathering the appropriate tools. However, I am admittedly can be a bit of an ...
1
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1answer
493 views

Help !!! 2007 Honda Accord 2.2 diesel not starting intermittently

my Honda Accord has developed an issue where by sometimes it fails to start when the key is turned, it will turn over but not start, the green key light stays Stays flashing on the dash, does this ...
3
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0answers
282 views

SilLabs OBDscan can't connect to Alfa 147: latency too high!

I have an OBD Scan tools built around the Silicon Labs CP210x chipset, but I can't get it to connect to my car at all. When I connect the scan tool to my laptop USB port I have a driver installed and ...
9
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6answers
4k views

Can I confirm clutch slippage by shifting without disengaging the clutch (while stopped)?

This question got me thinking about a possible test that anyone driving a manual transmission could perform to diagnose severe clutch plate slippage: Engage handbrake, make sure there is nothing in ...
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0answers
318 views

Difference between black and blue eml327 diagnostic tool

I've recently bought an Alfa Romeo 147 1.6TS 2001 105hp(77kw), and the previous owner had an instrument, or gauge, or mileage table replaced along with electrical window and mirror button table on ...
3
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1answer
58 views

Best way to access fuel efficiency data during operation?

I'm looking for ways to track real-time fuel efficiency data while driving, using an app on my phone. Will a Bluetooth OBD adapter generally allow me to do this?
5
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3answers
15k views

Used Car Condition - Is a Compression Test a good proxy of engine health? (and what's a leak down test?)

I'm looking to buy a used car and aside from the advice here (which is mostly functional) I want to know if the oil has been changed "enough" to prevent gunk build up that could starve parts from ...
2
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2answers
808 views

Car starts when it wants

I have a 2008 Toyota Corolla and I am having problems with it starting, it seems to only start "when it wants to". I have taken it to 2 Toyota dealers who can't find the problem with it. I have ...
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2answers
1k views

What data are OBD-II scanners capable of logging?

I've been reading that certain scanners are capable of logging data that can be recorded while driving. What sort of data are most popular to be recorded? Can someone comment with examples of data ...
5
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1answer
5k views

Subaru clunking and whining - differential?

I have a 2002 Subaru Outback with a 5 speed manual and 160k miles on it. The previous owner claims to have replaced the front differential, because it was locked up. Now, I have been hearing whining ...
3
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3answers
1k views

Diagnosing an engine oil leak

I have a 2001 Honda Prelude SH w/ 190k miles and a slow oil leak (~ 0.5-1 qt/week depending on how much I drive it) that I believe ultimately comes out the lower timing belt cover. I also need a new ...
6
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4answers
37k views

Technique to test an alternator - fact or fiction?

A friend explained that the following is a simple way to test an alternator to see if it is working: Turn on the vehicle. While it is running, carefully remove one of the 12V battery leads. See if ...
17
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2answers
3k views

Is there a rule of thumb for estimating volumetric efficiency?

Here's a situation I encounter quite often During diagnosis, I want to determine if the mass air flow sensor(s) [MAF(s)] is/are healthy. I hook up an OBDII reader to a vehicle that I'm trying to ...
10
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1answer
994 views

Are resistance/capacitance based brake fluid testers reliable?

I would like to test my brake fluid to see whether it needs replacing rather than spend the time and money on it unnecessarily. I've seen inexpensive brake fluid testers on the market which work on ...
1
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1answer
521 views

2010 Chevy Cobalt will not turn over

I have a 2010 Chevy Cobalt. I drove the car shut the engine off, when I went to restart the car it did nothing. All of my dash lights worked and my radio would play, but the car wouldn't turn over. ...
4
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1answer
75 views

Coil On Plug, Testing The Primary Coil

Are there any alternatives for scoping the primary coil on a COP system other than using a low amp probe? I'm guessing backprobing doesn't work since the ignition control module is built into the coil ...
10
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1answer
371 views

More In Cylinder Pressure Testing Questions

So I was looking at a 06 Pontiac G6 2.4l with a complaint of low power on hills. Had been at another shop to have the transmission checked and they referred the customer to us. Road test confirms car ...
11
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3answers
2k views

In Cylinder Pressure Testing With a Pressure Transducer and a Oscilliscope

Recently I've been looking into buying a higher PSI pressure transducer to do in cylinder pressure testing. I've encountered vehicles which would of benefited from this approach and wish I had thought ...
10
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3answers
56k views

How to diagnose the cause of no power reaching the spark plugs when power reaches everything else, after checking fuses?

I've been trying to get my long-suffering Toyota RAV4 first generation (1998) to start after numerous different problems, the latest of which I've narrowed to the spark plugs not firing seemingly due ...
8
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1answer
7k views

How to check if spark plugs are firing? Coil-on plugs

While trying to diagnose a tricky car not starting problem I was asked to check if the spark plugs were firing at all. I've found plenty of resources on inspecting the condition of spark plugs after ...
1
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1answer
65 views

Why does a diagnostic tool that can erase messages cost so much more?

My check engine light was on, so I went to an O'Reiley's to buy a diagnostic tool. Basically, they had two versions of the same brand: one that just checked the engine codes and gave you the ...
5
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1answer
3k views

Does Fiat need dedicated FiCom OBD hardware and software for diagnostics?

I got an ELM 327 with Bluetooth from my brother in law. We have tested it in his Chevrolet Aveo with several apps and it works like a charm. When I tried it on my Fiat Panda 2012, the apps couldn't ...
14
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10answers
106k views

How can I detect vacuum leaks without access to a smoke machine?

In the course of helping my friend sort out a lean condition with his Mercedes GLK280 we have to pinpoint the source of a vacuum leak in the intake plumbing. The interwebz tend to recommend having ...
3
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0answers
80 views

1987 GMC Sierra - Can't connect to OBD diagnostic connector

I own a 1987 GMC Sierra and it has an ECU, I took it to a workshop to see if I've any issues, when they tried to connect a diagnostic reader to the connector (underneath the steering wheel) they ...
9
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2answers
256 views

Firing a Coil on Plug

I was wondering if there is a simple way of firing a coil on plug outside of the car. The coil in question is just a two wire coil on plug and I don't know if its possible to just hook up a 12V ...
7
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1answer
302 views

Can I use a digital multimeter in resistance mode on a “no-load” circuit?

While this question is probably more at home on EE.SE, the implications can be quite profound when troubleshooting automotive problems. If I want to test for continuity on a 12 V circuit with next to ...
5
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4answers
7k views

How to Test an Ignition Coil with a Multimeter

I have a 98 Mazda 626 GF and I'd like to test the ignition coils with a multimeter to see if any of them are starting to fail. The car has ECU controlled timing / ignition and there are two coils, ...
6
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1answer
5k views

What is a smoke test and what kind of tools do I need to do it?

I've seen 'the smoke test' referenced several times in answers to OP's. I would like to ask; What is a smoke test? What kind of tool(s) do I need to do a smoke test? What is the proper procedure to ...
9
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2answers
967 views

Why are the spark plugs from the same 2 cylinders corroding faster than the others?

On my engine ('99, 360 v8 Magnum), I replaced the spark plugs less than 15k miles ago, because of misfires in cylinders 2 and 8. Those two plugs were badly corroded. Today I had to replace them again, ...
10
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1answer
155 views

Is firing order sufficient to tell if a crankshaft is cross-plane or flat-plane?

If I know the order in which the cylinders on a V-engine fire, can I know for sure whether the engine has a cross-plane or flat-plane crankshaft?
3
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2answers
5k views

OBDII ELM 327 Bluetooth adapter - is it reliable? [closed]

I got myself such a bluetooth adapter for my car, because the display on the radio stopped working, and I wanted to see if it will show up any errors. There are even apps for Android that work with ...