NA engine quits, early diag tests? NA

Let'sgoflying!

Let'sgoflying!

Touchdown! Greaser!
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Dave Taylor
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Vehicle (to be specified once I find out) quits suddenly.
"Sounds funny" when cranked.
Some have pointed to timing belt failure as a possible cause.

Where would you start?
Pull plugs, inspect (including scope/compression chk)?
Valve cover removal?
 
First thing would be hearing the noise with the hood open to confirm what the "funny sound" is. The funny sound might just be a belt driven accessory going to hell and could be totally unrelated to the "quits suddenly".

The sound may tell me everything I need to know. If it doesn't..then...

Next thing would be pulling codes from the computer. The result of that plus the sound would dictate the next thing I'd be chasing.
 
First of all.... are we talking about an airplane or a car..??

Always do the easiest first..... gas..... spark, then go from there.
 
If it's a timing belt failure, and the valves are interference fit (most are on modern cars), that is a very bad thing and you tend to eat valves and pistons. But yes, as Jesse says, rule out the obvious things first that you can see, then dig deeper.
 
Actually, most modern cars have gone back to timing chains. It'd probably have to be in the 1975-2005 range to still use a timing belt.
 
Start with the basics: pull codes, check spark/clean MAF sensor and air filter/fuel. If all of those are good, move on to compression check, then timing. The noise may or may not be related. A bad/seized alternator/water pump/steering pump bearing might cause some funny noises when cranking, but I wouldn't think it would cause the engine to stop unless the belt were really tight which would probably shred the belt in short order anyway.
 
Does the engine turn over much faster than normal when trying to start it? If yes, it's a compression problem which is most likely the timing belt.

I did have a 1999 Nissan Maxima which did the identical thing and apparently had nothing wrong with it (even though it wouldn't start). The shop did a wet compression test (which it passed) and then it was fine. I was told it was a know failure on that car: computer hiccup caused it to dump gas in the cylinders washing the oil away. Without the oil the rings didn't do what they're supposed to and it couldn't spin fast enough to start (needed to spin really fast for enough compression). I'm not entirely sure I buy that, but it was fine ever after.

John
 
had an 87 chrysler la baron 2.5 litter 4 banger,
the map sensor would break down and kill the engine,
answer,, pull the electrical connection from the sensor,
engine ran just fine without it!
 
Pull codes. Then Google. Faster than screwing around with everything else. YouTube for demonstration vids if you're not certain how to do whatever needs done.
 
robert lomax said:
had an 87 chrysler la baron 2.5 litter 4 banger,
the map sensor would break down and kill the engine,
answer,, pull the electrical connection from the sensor,
engine ran just fine without it!
Click to expand...

MAP sensors are OBDI, MAF are OBDII. Most engines will act erratic if you unplug the MAF sensor.
 
Let'sgoflying! said:
slightly dismissive of their problem of a three-figure bank balance, and 4 figure expenses around the corner.
Click to expand...

Hard to help when the story is not clear.

SWAG. I am guessing you know of someone that has an older car that has stopped running for some unknown reason and you want some possible ideas on how to get it running again on the cheap?
 
Pull codes?

Not gonna tell you squat. You'll either get a whole lot of them or nothing. Or maybe a lean code that could mean 1000 things.

Start with a VISUAL. Broken vacuum lines. Loose spark plugs. Air or exhaust leaks. Broken or loose belts. Obvious cracks. Low oil or coolant. Check the oil for coolant and coolant for oil (4banger head gaskets seldom blow without mixing these). Put it in neutral or park, and crank the engine by hand through at least two revolutions, feeling for normal valvetrain resistance and listening for noises other than a slight whooshing sound as low-speed air blows past the rings. If it all looks good, then give it a leakdown test.

Most of the time, funny noises are bad idler or accessory bearings, or air/exhaust leaks. If the timing belt is broken, some of the cylinders will show very high leakdown. Most -- but not all -- engines are interference engines, so a broken belt is probably fatal for the engine.

Sudden quitting is usually an ignition problem, but those don't make funny noises while cranking. If the noise is isolated to an accessory, revisit the ignition system. A blown coil or cam pickup can cause instant stoppage. But, grab the analog voltmeter (no, NOT a DVM, unless it's an oscilloscope) and isolate where the ignition signal gets lost.
 
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Actually the codes can tell you very useful things, such as cam shaft sensor failure, crank sensor failure and many other things that can cause an engine not to run. If those are clear, then focus on spark, make sure you are getting them. Then fuel.
 
PaulS said:
Actually the codes can tell you very useful things, such as cam shaft sensor failure, crank sensor failure and many other things that can cause an engine not to run. If those are clear, then focus on spark, make sure you are getting them. Then fuel.
Click to expand...
No, no code can tell you these things by itself.

What a cam sensor code says is that the computer did not detect a correct cam sensor response for conditions. That might be due to a bad cam sensor, or several other items such as poor sensor grounding, or maybe just because the cam wasn't actually turning. Codes are a first step, not a diagnosis. And they are not the most appropriate first step.

Blind code reading is much more likely to result in a nonrunning vehicle AND a much lighter wallet than it is a successful repair. Most no-starts are not related to the electronic control system, except perhaps for poor power and ground distribution. PCMs are pretty good at limping along even with 10 P-codes.

And you're not going to get CURRENT codes if you can't start the vehicle. A year old pending P0171 is totally useless.
 
If you're thinking timing belt, should be easy enough to pull lower cover on timing belt side of motor and either visually see a broken belt or a pile of dust and/or teeth that used to be on the timing belt...in absence of one of those, I'd move on from timing belt.

My wife's TDI Jetta randomly made a section of timing belt into dust and bits. That resulted in my first (and hopefully last) removal of a TDI cam to allow for lifter inspection. Dodged a bullet and appear to have avoided the physics problem that occurs when a valve and a piston try to occupy the same point in space at the same point in time.
 
MAKG1 said:
No, no code can tell you these things by itself.

What a cam sensor code says is that the computer did not detect a correct cam sensor response for conditions. That might be due to a bad cam sensor, or several other items such as poor sensor grounding, or maybe just because the cam wasn't actually turning. Codes are a first step, not a diagnosis. And they are not the most appropriate first step.

Blind code reading is much more likely to result in a nonrunning vehicle AND a much lighter wallet than it is a successful repair. Most no-starts are not related to the electronic control system, except perhaps for poor power and ground distribution. PCMs are pretty good at limping along even with 10 P-codes.

And you're not going to get CURRENT codes if you can't start the vehicle. A year old pending P0171 is totally useless.
Click to expand...

You are splitting hairs, with out the codes you are shooting blind, if you get a cam sensor code it gives you a place to start, and most times, not all but most, the clue to the answer. The codes, if there, are great to have and definitely tell you more than "squat".
 
PaulS said:
You are splitting hairs, with out the codes you are shooting blind, if you get a cam sensor code it gives you a place to start, and most times, not all but most, the clue to the answer. The codes, if there, are great to have and definitely tell you more than "squat".
Click to expand...

Splitting hairs, eh?

Which is worse, no information or a code that sends you in the wrong direction?

Check basics BEFORE going after codes, or you will get a wrong answer. Rather expensively, too. It's not a minor point.

If you actually diagnose the car, you are not shooting blind. A human is a whole lot smarter than an OBD-II diagnostic.
 
MAKG1 said:
Splitting hairs, eh?

Which is worse, no information or a code that sends you in the wrong direction?

Check basics BEFORE going after codes, or you will get a wrong answer. Rather expensively, too. It's not a minor point.

If you actually diagnose the car, you are not shooting blind. A human is a whole lot smarter than an OBD-II diagnostic.
Click to expand...

Nah, get the code first. Having a problem, go for the codes, if you don't own an OBD reader go somewhere like Autozone where they let you borrow one. Last 2 or 3 problems I've had with cars I've gotten the code, identified the problem, bought the part and been underway in less than an hour or two. The human comes in in the interpretation of the code. Some are easy, some are hard. Trying to diagnose before you check the codes is kind of dumb in my opinion, unless you charge by the hour.

Oh, one of those problems was my son's car, misfired on acceleration then the MIL illuminated. He was 150 miles away. He called me, I had him do the key dance, came up as a mass flow sensor code. I told him to look for loose wires, then a mouse nest. If those are good, then call me back. He found a nest, cleaned it out, good to go. Code lead him right to the problem.
 
PaulS said:
Nah, get the code first. Having a problem, go for the codes, if you don't own an OBD reader go somewhere like Autozone where they let you borrow one. Last 2 or 3 problems I've had with cars I've gotten the code, identified the problem, bought the part and been underway in less than an hour or two. The human comes in in the interpretation of the code. Some are easy, some are hard. Trying to diagnose before you check the codes is kind of dumb in my opinion, unless you charge by the hour.

Oh, one of those problems was my son's car, misfired on acceleration then the MIL illuminated. He was 150 miles away. He called me, I had him do the key dance, came up as a mass flow sensor code. I told him to look for loose wires, then a mouse nest. If those are good, then call me back. He found a nest, cleaned it out, good to go. Code lead him right to the problem.
Click to expand...

I own several code SCANNERS -- not the useless readers -- and visuals find mouse nests faster.

They also find nonexistent sensors. Go find a cam sensor for 2000 Saturn. I dare you. They DO set cam sensor codes, rather frequently.
 
MAKG1 said:
I own several code SCANNERS -- not the useless readers -- and visuals find mouse nests faster.

They also find nonexistent sensors. Go find a cam sensor for 2000 Saturn. I dare you. They DO set cam sensor codes, rather frequently.
Click to expand...

Scanner, mine scans too. Myriad of issues can cause misfires, bad wires, bad gas, fuel issue, electrical issue. You be my guest and search all that stuff first. I'll take two minutes, plug in my reader, check for a code and if its there go right to the problem.
 
I have a 250k mile Audi that we keep around as a spare/dog/snow car. Had a run down battery and we were expecting snow, so I put the charger on overnight. Next day, wife drives it and reports check engine light, hard to start, bad idle, and keeps stalling. Scanned codes (Rosstech, the only way to go for VW/Audi... http://www.ross-tech.com/ ) and got a code for bad MAF sensor. Turns out I had set the battery charger down right on the MAF electrical connector, and it was very slightly unplugged....
 
It is so easy to pull codes why wouldn't you. When I attack a problem I want all the available information and it literally takes a couple minutes. No issue with doing a quick visual inspection.

Since lean codes codes were mentioned as an example, they can at least get you started in the right direction sure it can be a lot of things and if your dumb enough to shoot the parts cannon at it you can spend a lot of money. Recently had a lean code on my 2002 Silverado, also had pegged out fuel trims. Didn't take long to figure out it was the intake manifold gasket that is a common issue on the 5.3l vortec.

If you suspect the timing belt pull the cover and check because again as mentioned if it is an interference engine and if the belt is broke the engine is likely toast anyway so don't bother throwing parts at it until you know that.

Not sure what engine it has but here is the list for KIA.
Kia

• 1.5L DOHC Interference
• 1.6L DOHC Interference
• 1.6L SOHC Non-Interference
• 1.8L DOHC Interference
• 2.0L DOHC Interference
• 2.0L SOHC Non-Interference
• 2.4L DOHC Interference
• 2.5L DOHC Interference
• 2.7L DOHC Interference
• 3.5L DOHC Interference
 
PaulS said:
Nah, get the code first. Having a problem, go for the codes, if you don't own an OBD reader go somewhere like Autozone where they let you borrow one. Last 2 or 3 problems I've had with cars I've gotten the code, identified the problem, bought the part and been underway in less than an hour or two. The human comes in in the interpretation of the code. Some are easy, some are hard. Trying to diagnose before you check the codes is kind of dumb in my opinion, unless you charge by the hour.

Oh, one of those problems was my son's car, misfired on acceleration then the MIL illuminated. He was 150 miles away. He called me, I had him do the key dance, came up as a mass flow sensor code. I told him to look for loose wires, then a mouse nest. If those are good, then call me back. He found a nest, cleaned it out, good to go. Code lead him right to the problem.
Click to expand...
What's a key dance?
 
Where did you ref that? I only see two models for 2002, a sedan and the LS sedan - both with a 1.8L engine
Thanks
DFH65 said:
• 1.5L DOHC Interference
• 1.6L DOHC Interference
• 1.6L SOHC Non-Interference
• 1.8L DOHC Interference
• 2.0L DOHC Interference
• 2.0L SOHC Non-Interference
• 2.4L DOHC Interference
• 2.5L DOHC Interference
• 2.7L DOHC Interference
• 3.5L DOHC Interference
Click to expand...
 
paflyer said:
What's a key dance?
Click to expand...

With some cars you can turn the ignition on and off a number of times (usually 3 or 5 times) without starting the car and code will display on the dash or the MIL will flash the code out.
 
Pulling codes is simple and can be helpful at least as general practice. On OBDII models, it will generally be able to tell you the cylinder(s) that are misfiring, which can shorten the time to diagnose things. However, there are also instances where it throws a code to a sensor that isn't related to the real issue because it diagnoses the symptom instead of the problem.


Sent from my iPhone using Tapatalk
 
PaulS said:
With some cars you can turn the ignition on and off a number of times (usually 3 or 5 times) without starting the car and code will display on the dash or the MIL will flash the code out.
Click to expand...
Or initiate SELF DESTRUCT.
 
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