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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115 views

Chevy 3.5 engine tick

I have a 08 Chevrolet Impala with a 3.5 with 70k miles. There is a tick that corresponds to engine speed. It's a pronounced tick but I highly doubt its piston slap or rod knock. It seemed like an ...
3
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1answer
88 views

Safe rounding of CCA during battery load testing

How do you determine the safe amp load of a battery tester? I am looking at testing a battery on a 2012 Mazda 3 sport which has a Mazda factory battery 75D23L (52). The service manual states in the ...
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0answers
188 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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248 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 ...
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0answers
70 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 ...
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0answers
69 views

Why is this RPM graph squarewave?

'07 Subaru Outback 3.0R 5 speed auto. I am logging using the excellent RomRaider and was kind of surprised that when graphed RPM looks like a square wave in most situations, don't know if it was ...
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0answers
221 views

2006 Mazda MX-5 P0126 + B1318

2006 MX-5 57k Miles USDM 2.0L 6-Speed P0126 and B1318 Set but no light on/Sporadic illumination. Coolant reservoir is full. https://www.obd-codes.com/p0126 That site references that there's a TSB ...
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53 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 ...
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0answers
2k 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 ...
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0answers
247 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'...
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24 views

Can I learn anything about a misfiring cylinder from the fact that the dialectric grease around the plug is discolored?

On the way to the in-laws yesterday my 2008 fusion started bucking. Code reader says I'm misfiring on cylinder 2. I popped off the coil boots thinking I'd swap them and see if the problem cylinder ...
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28 views

Drop down to zero during ride

Randomly during ride, the "D" from transmission indicator disappears for 2-3 seconds, during this time the car like switched to neutral (RPM raise without acceleration of the car). In the beginning ...
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12 views

Konnwei kw30 diagnostic equipment

Just got a konnwei kw830 diagnostic tool I plug it into my car which I know has a fault as I have checked on another system and that comes up with fault key 1 which means my car key has lost its ...
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1answer
91 views

How difficult is it to collect obd commands ?Will it be different for different brands?

OBD is something very interesting I found these days.Thanks to this repo https://github.com/pires/obd-java-api & wikipedia which provides the basic information of PIDs.But there is a lot of ...
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62 views

Check engine light won't stay off

I've attempted to get my check engine light fixed a couple times and at each repair facility they've scanned the code and told me it was a bad oxygen sensor. I had the oxygen sensor replaced at both ...
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2k views

Replaced transmission now car wont start

Had my transmission replaced drove car for three days now it won't start. Lights and radio work. No crank no start. Replaced battery, starter, and starter relay. PLEASE HELP HAVEN'T HAD MY CAR A YEAR ...
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237 views

How do I diagnose a blinking overdrive off light on a 2001 Ford F-150 with 4R70W transmission?

Today the "OFF" light on the transmission shifter starting blinking on my 2001 Ford F-150. It is the 4.6L with a 4R70W transmission. I pulled the codes but all I found was "Evap system inoperative" ...
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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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0answers
391 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 ...
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299 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 ...
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37 views

Can I read PID from other protocol?

My car (Renault Megane II) sharing PIDs through KWP protocol but also sharing other data (more advanced) through CAN. Some of data which I want to read is not available through KWP (PID). Is there a ...
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18 views

Misfire data log

I'm trying to understand what is the meaning of "Misfire" in this graphs, it always starts with value 0 and then can move up to 3. Is it a sensor? if yes what exactly it measure? if not, what is it? ...
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51 views

Nissan Qashqai “Test Mode”: What does the data mean?

I learned about a "test mode" for the display, which can be used for diagnostics, without an obd reader. I managed to get inside the test mode, but I am baffled by the data and am not sure what it ...
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2answers
61 views

What things cannot be tested(except by elimination) when trying to diagnose a sluggish engine?

As far as I'm aware there are certain things that cannot really be diagnosed if you have a sluggish engine and so you can only find them by elimination. As an example if you test a car due to ...
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1answer
213 views

Not receiving multi line response ELM 327

I am sending the following commands to my Hyundai i20 2012 model (OBDLink SX Bluetooth device): AT Z AT H1 AT L1 AT S1 AT AL AT SP6 AT SH 7D1 18 00 FF 00 The response I am getting is 7D9 10 0B 58 03 ...