engine Cranks fast, but it does not
start and stay running. Why guessing sucks?
If your car is not cranking robustly, then go back here now (robustly?, is over 250 RPM)
BEGIN, "NO START" but cranks fast:
The cause of NO Starts, are the same, on all gasoline engines from 1900 to today. "Otto cycle gas/petrol engines"
Today, the CEL lamp must glow ore the ECU has lost 12vdc power. (IG-coil and "FI" fuses not blown)
Fails by BASICS: Bad engine (compression weak) Bad spark, bad fueling. (the classical 3 ways) The engine is and AIR PUMP, if it can't pump air?, it will not run.
Good compression is over 150 PSI, not 80, and cranking vacuum is near 5 inches HG, not zero with a clogged melted Cat converter (TWC) (HG is USA vacuum column in inches of Mercury "that gauge")
A good technician finds what is wrong, fast, using simple tests, using simple tools (gauges) The number 1 all time cause of no starts or bad running, is the infamous skipped tuneup . (skipped for 10 years, really)
The below Scotty tests can work, on the Suzuki 8 valve engine, the single injector is directly viewable with naked eyes, remove air horn/ pipe and look cranked, is it injecting? at all?
The Suzuki is also infamous for bad grounds, bad ECU Cap.'s 1989 to 1995) and bad power 12vdc distribution.
The Suzuki loves to strip out crank pulley main cog and keyways, see timing belt and ignored TSB warnings there.
In, most cases, if the engine compression is ok, you have combustion failures? it's only lost spark or bad fueling (too lean / rich) or EGR stuck open or the Cat is melted.
No compression on 1 or all cylinders, weak or no spark (timed wrong) or no fueling or too much fueling. (aka: starving or flooding) If the cam slipped time, the engine is now useless.
Then see SCOTTY do it ? "a VIDEO" & Scotty assumes engine is good and good compression.
Scotty's fuel test only proves the fuel pump is not dead "dry rail", and not weak. 30 PSI , NOT LESS ever. There are 3 numbers (pressure) ,keyon, running and wide open throttle seen here.
Do not starter crank over any DOHC "twin cam" engine failed , or risk, bent valves. for (interference engines) it's best to do hand cranked, cylinder leak down tests, shown on my compression page.
On all interference engines, we do this, to protect from further damage.
I use one mental trick, to fix engines, like this, I pretend it's 4 engines, not 1. (I-4) I check all 4, carefully first.
An engine with no fresh air can not run, clogged air filter, stuck closed ISC? to bypass ISC use 10% throttle while cranking, to mimic the failed ISC, with added air. Starts now?
Engine starts but stalls?
The Details of no starts:
We do the first things first deal: (my fast check list)
All USA cars, and 96+ means 1996 and newer cars, OBD2 EPA spec. cars. IMMO, means Immoblizer. EFI means electronic fuel injection and spark.
Have on hand a DMM volt meter, ($10 at Walmart or better)
This my order of testing, It saves time , most the time. (fate does win)
(the engine can't burn fuel ,with poor compression or weak/dead or timed wrong spark on all cylinders, not just one)
This is my general check list. Should work for most gas engines. Keep in mind, fuses that look bad are bad, and ones that look good can in fact be bad, (hair line cracks or hidden well)
Tools, DMM: Vacuum gauge, Compression gauge, timing light, and fuel pressure guage. ($100 in tools (gauges) At a total cost of one hour shop labor (dealers)
If it only fails to start hot, look here.
If you already know for sure, you lost SPARK?, Go HERE !
This failure can happen Cold or Hot engine or both. (coolant temperatures)
A very simple flow chart, for no starts.
The 3 reasons in the "proper order" are: (this is called checking BASICS in all ASE technician schools)
A macro view (see the details, later)
Top reasons: (statistics and experience) Nut shell list: (there are simple tests, to discover each)
Check for bad gas and blown fuses , first.
Not doing tuneup's, not ever doing the 60,000 mile, service point list. (spark parts, and filters) 100KM (kilometers)
Not replacing the cam timing belt per above list. It will slip and compression drops like a rock. "hopeless" case.
Not changing spark wires 1 by 1 each, and mixing them up. oops, wrong firing order.
Setting the spark gap to .045" out of the box gaps are dead wrong. GAP them to Suzuki spec.
Using pure JUNK, no name China dizzy rotors, that illegally fit 3 ways, they are not factor OE spec. rotors, not at all. ($1 rotors are junk) BOSCH rotors FIT.
Not checking spark timing first, seeing it way off and knowing that the timing belt did slip (or OMG chain slip? on Suzuki J18/J20/J25/J27 engines).
Cam timing is first, then Distributor timing is 2nd, never ever the reverse. Do not attempt to correct a wrongly timed cam,by spinning the Dizzy base. Do the Sneak a peek test now.
Not checking spark at all 4 spark plugs. (if fail? check main ignition coil(s) directly , using the same test spark plug.)
If the spark is blue-white at coil, but weak yellow at cap and 4 wire endes, the rotor is timed wrong. (I always assume car is tuned up, new wires,etc)
Not checking if spark plug tips are wet or dry?, (soaking in raw fuel, is wet) Wet is flooding or lost spark, dry is no fuel pressure.
Not knowing the ECU brain, (puter) is programmed to cut all fuel ,if it even suspects, spark is bad or weak. (prevents T.V. style crash and burns)
Be adviced, about 1/2 the cars made only run the fuel pump cranking or running only, the exception is 91-98 Sidekicks they run pump for 3 seconds each key on, (G16 only)
The ECU also cuts fuel on the 3 bad signals (4 total, CMP dead or it misfiring, CKP dead or misfiring, TPS TP pin stuck above 3.5vdc.)
The 4th is spark bad. The PCM monitors spark at all times, and cuts fuel if it detects spark failure . Yes, it can think good spark is bad. (eg. tacho wired shorted)
After seeing dry spark plug tips, not doing the "runs on test fuel check" See Scotty do just that.
If the engine "only" runs good, on test fuel, see my page here.
Not cranking engine for 5 seconds, then checking ECU/PCM for DTC errors. it will report bad CKP/CMP sensors , for sure.
Do consult the ECU next, doing the Vulcan mind meld trick. (kinda?) SCAN THE ECU/PCM. ( flash codes or OBD2 scans)
Not reading the TSB that shows the new crank bolt (17mm deep socket) is set to 94Ft/lbs.
A bad engine signs, rarely, can be the CAT converter melted and the exhaust nearly 100% plugged up ! "mostly rare" This makes the engine no longer an air pump.
If engine can be made to start and run with 10% throttle the ISC is stuck closed, if it's much harder to start, the EGR is stuck open , if impossible to start?, that means you lost all fueling.
Using throttle foot action, is never needed on a working good EFI car, ever, only the ones that don't start. (and bad intake devices, or flooded)
If engine is flooding, try cranking with Wide Open Throttle (W.O.T), (oper.guide tells you this) and this cuts all fueling and it starts. It might start then flood again. (find flooding cause)
Truckers call this WOT, as Pedal to the Metal. Works on EFI and CARB cars , for secret unflood mode.
Keep in mind flooding can be dead spark (say the ignition coil secondary winding was open, the ECU can't see this and it floods) The ECU only monitors the primary side of spark.
On new cars 1996+ the ECU can report spark loss on the secondary side (P030x DTC's) but engine must run to do that, so is not part of this page.
The WOT tests might work , for a minute or so then the engine refloods.
Have at least: A DMM meter, Compression, fuel pressure and vacuum gauges. Just 4 tools, and you can diagnose and fix this car.
A full set of gauges are about $100 at harbor fright (pun) or about 1 hours shop labor here in the USA. So the tools are free.
Do the spark test, at all spark plugs. any or all can fail. If all fail ?,check spark directly at the coil , in 1996+ you must make and adaptor to find inside dizzy coil (ignition coil, Tesla)
You should have a test spark plug, do not use HEI spark testing devices. use a real spark plug. See a crude VIDEO.
HEI is high energy ignition, we do not have HEI !, until about 1999.
1989-1998 (all are same) (open hood in USA look up "underhood "), see that white EPA sticker,yes, the timing and gap is stated there clearly)
Any fresh new regular J gap style plug set to gapped to. 0.028" inches 0.7mm, Never at 0.045 as see on , new, in box , or as it states on box. No maker of spark plugs ever pregaps any plugs for this Suzuki (none)
If your in car spark plugs are new, and not fouled, then you can use them , to test, but I never do this , unless away from my tools.
See normal spark plugs below , to check spark gapped correctly. You can uses Platinum , plain or irridium (tips)
Never use 2J ,3J or 4 J or for sure any surface fire plugs. or as some say, no gap plugs. Our system, is too weak for newer car HEI systems.
The best tool to test for spark is virgin gapped, stock spark plug , kept handy.
Normal, $2.00 each (dirt cheap) The upgrade to Platinum is ok, but on high mileage cars, the insulation fails first, so the Platinum buys you nothing IMO. Use stock.
Not this below 4J plugs, no surface fire plugs allowed, on this weakspark system. Same with Surface gap plugs , avoid them. (play mad science, after car runs perfect, then you know you broke it?)
The below is how to READ SPARK TIPS? Flooded spark tips , dripping or are wet with raw gasoline.
This is called reading plugs. (look for damage, oil , carbon fouling, soaking it raw fuel)
Usually fouled spark plugs, that are new, can be run to automatically clean them in the engine, after correcting the cause of the gross richness (say limphome mode)
Diagnosis: (all fuses good seen here )
(The 89/90 works quite different, the Dizzy (distributor) makes all spark by itself, in just those 2 years) (some like to fail heat soaked, or the gap inside is wrong)
If the 89/90 has bad spark, but has 12vdc power , IT'S A BAD DIZZY ! (or VR or ignitor device inside, that can be bought at huge costs..) I'd buy a rebuilt Dizzy."at Cardone?"
Starting in 1991 (USA) the ECU creates all spark. (using only the CMP, as a time base).
I can not understate, if it won't start, kill the fuel pump and reduce the 3 fail paths, to just 2, (bad motor , bad spark) for flooding,....wet spark plugs?
If the engine is good, then you know its bad spark, because it passes the TEST FUEL TEST (seen below).
1st Fast Checks: (besides robust cranking of starter and an engine, that passes a compression test.) Good motor so it's, bad spark or fueling)
The Check ENGINE lamp or SES ! (the flash codes. pre 1996)
1: The CEL works, comes on , key on. IT must glow or the ECU can be bad
If the 3 fuses, IG-coil, FI, and Dome are good, and the CEL lamp is not burned out, then look for a bad ECU. (CEL dead, never glows)
1989 to 1995: If 1996 and newer , jump to here.
2: The CEL flashes code 12 "good" or some other DTC codes (any code or sets of codes) when you command that, via the diagnostic jumper clip.
2a: if CEL stuck on?, and will not flash , move the USA Federal Mileage Nag switch ( a slide switch) over one time. (no found on any Calif. car)
You have code 12 flashing ! (or other codes, you can reset all stored DTC codes by pulling the DOME fuse for 2 minutes or more and putting it back)
Okay ,you have 12s flashing, now, key on.
Next, you crank the engine over.
Dead TACHO Signals:
3: If the Dash tachmemter twitches a tiny bit , cranking , this is a good sign of primary spark signals, some old cars the tacho is weak, or the car battery is weak, so will not twitch.
The only for sure way, to see this tacho signal (brown wire) is to check the ECU for CMP errors. 1991 and newer cars. (or a scope)
1989-95: What really counts, is this.....
4: Insert the diagnostic jumper into the DLC connector (a bent paper clip) and then crank for 5(is enough) to 10 seconds, does the CEL flash out 41 or 42?
Code 42 is a bad CMP and code 41 is bad spark. 41 means dead Tachmeter input. (or the ECU is not driving the Igniton coil or the ignitor is dead)
Code 42 means the CMP sensor is dead, (is the cam spinning at all?) No spark is even attempted by the ECU if the CMP is dead !
1996 + (USA) 1998 in CANADA the + means and newer cars.
On newer cars 1996+ there is no winking CEL codes or Diagnostic request jumper, on these newer cars,you must use a scan tool.
These are OBD2 ECU's and you will get, NO RPM while cranking, DTC P-355 /340 If those sensors are dead. 340s kill spark dead.
The ECU does react, to no spark feed back, by cutting all fuel. So it does monitor, it quitely at all times. (even cranking)
Some years of ECU will get engine start up for 1 second, then cut fuel for no spark detected. ( code 41 fails may do this)
Suzuki, only runs the fuel pump cranking and running only, the exception is 91-98 Sidekicks they run pump for 3 seconds each key on, "prime" (G16 only)
Some cars allow fueling for 2 seconds, the cuts the fuel if spark is bad (all Jeeps do that). The Suzuki;s cut fuel dirctly, by cutting injection and fuel pump power.
If all the above is good and no live DTCs presented, and spark is good, and timed right, then it must be fueling issues.
At this point, I must find out if I have no fueling , too little or too much fueling known as flooding.
If all 4 of my spark plug tips, when removed are dead dry, and no DTC codes, I then try Chads test fuel test see at below link (video)
You get about 3 seconds run time for each 3 second spray. Do not go hog wild here like Chad, this video proves, that humans can mimic a CARB.
Full PPE (You wear Goggles, Gloves, and not your head near the air induction ports of the engine, or air cleaner ports) Lean engine like to backfire , so be ready.
I never do this, until i know spark is good, and timed. A 5min test with any spark timing strobe light. (open hood look up , see EPA smog sticker with spark timing spec. in full view?)
To be safe us 3 second run tests, spray, run,spray , run and listen. Chad's way is extreme but lots of fun to do 1 time. (I've used alcohol , and propane too, as fuel.)
See Chads engine run on test fuel ? ( using any sprayed in gasoline or instart start in a spray can.)
His engine sounds funny, because the muffler is holed.
The engine should not sound odd, banking, clanking or rapping, pounding, thudding, clicking load or other odd noises. If yes, we fix that first.
See types of fuel here.
If it runs on test fuel , I then work on injections.
if it fails to run on test fuel now, I failed in my spark tests or engine good tests (compression or Cat clogged up)
My engine likes to flood and not start.
If the spark tips are soaking in fuel, I remove the left rear tail lamp (do not pull fuses) and pull the pink wire connector there, that KILLS the fuel pump.
Fuel pressure is zero now. (by your acts)
I then attempt to crank the motor dry from the previous flooding, if it starts and runs and goes dry now, good.
I then repeat with test fuel fuel now that the engine is dry. to see if it starts and runs dry each time. Listening for bad sounds inside the engine.
If it does start and go veeeerrrrrooooommmmmm die, that is a very good sign, and you do have a flooding problem, if restoring the pink wire cause flooding again.
If not?, then (bad spark or bad motor , back to square one, top of my page.)
Let's say the injectors are all dry, dry spark plug tips, at all times. (test fuel runs good)
DEAD FUELING IS discovered, the above fuel test passes:
Do the pump tests first.
16v , 40 psi cranking MPI spec.
8v, 30 PSI cranking, (about) TBI spec. both ball park.
Keep in mind, injectors do not like below 28 PSI, as a golden rule. (my Jeeps run at 58 PSI, so read the FSM spec.'s on your car.)
You release the key and the pressure holds for a minute, if not you have a leak. See the first 4 tests on the pump page. or jump to injector tests next.
Lets say the pump test shows low fuel pressure or zero. Do this.
Ok you suspect injection problems.
Keep in mind at all times injection issues,can be (low pressure, Dead Noid Test, open injector coil, clogged injector or leaking injector or the ECU has them shut down for up to 4 reasons. (bad:spark,CMP,CKP,or WOT cranking)
A scan tool will show the bad inputs. If no scan tools, or the CEL blink tests, and last, a DMM to test all sensors by hand.
A NOID is a $1 test light bulb, you can buy one or make one, it's purpose is to see if the ECU is sending Injection signals
It takes 3 things to Inject, NOID signals, over 28 PSI pump pressure, and a not clogged injector. (the fuel filter can't be clogged , the 10 micron screens in the injectors clogged and the fuel pump needs 12vdc to run)
INJECTION failures seen here , all tests.
Do not fall in to the dark side and ever think to hot wire any TBI 8V fuel injector. please ! The 8V injector will draw 12amps and burn up. FAST. Burned to a crisp , toasted.
See NOID tests here. (this checks , if the injector is FIRING)
Follow the full injector tests, seen here for TBI Injection (on 16v it is more complex and is covered on the same page)
There are up to 8 or more injector tests on a 16v. including leak down , and balance testing. All covered in the FSM and the above injector page.
The Fuel pump regulator FPreg can be leaking (or stuck open) , or stuck closed (flooding) or have a cracked diaphragm ! The pump pressure leak down test finds this.
Buy this time any injection issues are seen and known, and finding which is bad is covered above.
The ECT sensor, if stuck cold (say at 8000 ohms) will cause horrid flooding at all times.
A Dead MAF, will cause limphome mode, lost power and rich running and horrid MPG.
Before condeming the injector (s) check ECU inputs and fuel pressure with due care.
It only takes 1 cheap $20 fuel pressure gauge to do the 3 major fuel pressure test, Pump pressure cranking and running, leakdown test and blance test (16v)
TEST FUEL ! all the ways
There are 3 or more types, ( #1 propane #2 the Can below, #3 Gasoline "Molotov cocktail" )
(Using raw gasoline, in an open container is nuts do to back fire risk !!!, 2 ways, fire and breathing benzene)
However many shops have a spray bottle, that uses gasoline.
Propane is not a liquid when dispensed, and can not spray you with fuel or burning fuel. So is the safest way.
Some shops use the carb cleaner in spray can. (used for many things, )
WD40 don't work now, they took out the propane, inside may years ago. (read the MSDS , it's all there)
Instant start fuel (CRC makes it with top end lube)
( I use the comes with,,, straw (see it on side of can?)
I insert the straw, in the the first intake manifold nipple, I can find.
I use 3 second max bursts. (3 repeats max. no starts) Watch Scotty !
Do not spray in 50cc or more at 1 time, or the piston will hydralock and you bend the rods. Don't go nuts with the juice.
Practice, on you lawn mower or good running car, with fuel pump killed., to learn this. Or ASK SCOTTY ? "VIDEO"
If say, the fuel pump is dead, the test fuel runs for 3 seconds and dies, and the engine sounds perfect. (no loud banging,etc)
Now you feel good, that engine is ok, spark ok, so what happened to my fueling???? (out comes the fuel pressure gauge)
If say, it now starts the car, then most likely the engine was flooded.
See Chad run a VW with an 100% empty gas tank. (the human CARB, I've done this 100s of time, countless) DO were PPE, (goggles)
Do not stand over any induction portal of any kind doing this, arms length or better a remote start button.
For sure face not at throttle body opening, or at the air cleaner box, ever.
Think BACK FIRE, and you will be safe. (picture it in your mind) this is not hard at all.
BTW (buy the way) 2: WD-40 took out the propane propellant in year 2000, so it will not work here, sorry old schoolers.
Australian, 3second bursts, very funny name. I use CRC engine safe starting fluid.
or Propane test fuel: (any)
Propane for 5 -10 second bursts , , ( Propane is far safer in a back fire situation, but a weaker fuel . )
Please be safe,
Practice on a good motor first. THAT IS ALWAYS THE BEST ADVICE ! PRACTICE !
The below is a professional tool, you can make one in 1minute flat with any regular store bought propane torch, just remove the nozzle end , add hose..... and insert it just like SCOTTY did above.
Do not use MAP or MAPP gas.
Make real sure the cylinder has only Propane inside, nothing else, and surely with no added oxidizers,
Avoid oxy-MAPP (only pre 2008 tanks had the dangerous oxidizers.) avoid all with MAP or MAPP on can.
I use only Walmart, green camping stove propane, known to be very safe .
Converting any old cheap Propane torch tool is easy, take off the nozzle and add a hose. for $1.
"OTC" branded: model 7148 , pro grade tool. $80-$100
Then screw on the tank to the valve, seen above.
end test fuel ways:
The Test fuel fails , oops? (compression tested long ago and is good) 8v = 150 + PSI 16V = 170PSI+ (min) Timing a dead engine is useless.
80 PSI is the hallmark of a slipped timing belt.
None of this is for the uninitiated or those whom, have never seen a Dizzy based engine. ever........but... here goes. (the best way is in a school , hands on !)
You timed it wrong, this is covered on my timing page, every way but Sundays, but here is my nice, crib sheets on Ignition timing.
My timing audit drawing is below, I connect my strobe light to the #1 spark wire. My buddy cranks at the KEY, and I point the strobe to the scale, and bingo,
I get consistent flashing at 0 or near, more than 8 degrees advanced is too much, set it to zero now, and later when the motor runs perfect,set it to SPEC. !
The timing freeze jumper will stop the bouncing , this bouncing is how the ECU fine tunes IDLE speed, (advance is faser RPM)
I repeat this 3 more times. I clamp my inductive pickup to wire #3, and me mate, cranks and the strobe lands ,where?, not at 0 degrees, but 180 degrees below.
Bingo wire 3 is wired right, if not?, correct that now. (the wires are crossed at plugs or dizzy cap.
I repeat to were 4, and it fires at 0
I finish this Audit at #2 wire, and the strobe lands at 180. We have a go !
If any thing acts odd, or non consistant flashing the Ignition is HOSED. (Kaput !) Let say you bought a $1 no-name CHINA POS rotor, and it fits on 3 ways?, (unlike real rotors)? bingo.
The spark plugs must be gapped near 0.028" (28 thou) never at 0.045, ! 0.7mm (metric)
Never trust the autostore or the spark plug maker to get this correct, only the FSM is correct ,every time.
The rotor must be pointing to #1 spark wire. at TDC #1 firing. if not FAIL.
If the china cloned (P.O.S.) rotor is not indexed right, as my timing page shows, FAIL ! (Real BOSCH or Suzuki parts , never do this!) Sad, I must even say it.
If you timed the dizzy first, then time the cam (belt), you FAIL ! (the dizzy is last ! to time, CAM is first)
Strickly G16 engines below, no others.
At crank pulley V mark to 0 scale mark, the rotor (not indexed wrong) must point to the red cap button seen below, the valve lash is loose on #1.
If not, you timed it WRONG.
Kill the fuel pump ( on 96+ cars, the fuel pump is a pain to reach (behind glove box) but 1996-1998 Sidekicks.
On early sidekicks the relay has a green socket below the ECU.
The relays like to drift about (age) above, so find the large pink wire and that is the fuel pump relay for sure.
Remove left rear tail light lens, see huge connector with that large Pink wire, Pink is the fuel pump, seperate this connector, and pump is now dead. (helps solve flooding issues)
Parting shots? A the least:
If the timing belt slips, that means the cam is now late, called a retarded cam , and compression falls like a rock! The Crank wants to out strip the cam. (move faster and further)
The end of the now late cam shaft turns, a Dizzy or CMP sensor and spark RETARDs.
Retarded cam and spark only makes wasted heat and not weak combustion and pressures.
This, waste heats the coolant and exits the exhuast unused. (some old cars, with weak (clogged) radiator, now overheat, or burn and melt the CAT element.
Late Induction mode. Blue #1 below, causes poor cylinder filling "incomplete", and less air (and fuel) to compress.
and p2 compression cycle , starts late causing even less to compress less again.
The combustion happens P3 below and the exhaust valve opens late .
This can cause exhaust gases to not purge completely and poison the next fuel/air charge ( EGR like action)
Most engines in this state show about 1/2 the normal spec. compression, 80PSI not 170.
The net results are a huge power lose. Not 1/2 but like 3/4 loss.
Once the belt slips it wants to slip more, and as it does, then engine can hardly pump air , let alone, compress a fuel and air charge correctly.
The ECU/PCM brain has at least 4 very great weaknesses.
Some engines, like Honda's which all have interference engines. (so called NOT free running) or all Suzuki J18 or J20 engines, and others. The Suzuki J engines are chain drive cam but seems folks let them slip too.... amazing fact.
Wits end: all the above checks out.
You do a TDC check on the damper pulley and you found the rubber ring (vulcanized) has slipped, the PULLEY LIES the TDC marks are BOGUS. Big time suck that, and is caused by, too tight accessory belts.
You then find to your horror, the dizzy bottom gear was pulled by someone, (no matchmarks) and put put back on 180 degrees out.
13 teeth. 27.7° dizzy degree's each tooth and 2 times that for the crank making the timing 55 degree's off kilter. (that slot is not that wide)
If my Geometry is still right (me older than dirt) you can not bisect a 13degree gear, and be symmetrical. (so the gear must be put back as found, or corrected if wrong) Never pull gears and not lay down matchmarks first.
Add to that, triple dang horror, 3, all 2 above wrong and China rotor on wrong 2 ways.. Triple dang hell mode. or DOOMED !
I won't add cam timed wrong, here, as that be hopeless....or crank or cam keys stripped out;.
So what happens is the dizzy base slot, can never be in range again. I saw one guy filing this slot. I feel your pain, I do....
Pure Physics : The EFI controls and the engine air pump.
The ECU does all it can to start the engine,and more important to sustain it.
At the moment if start , it works even harder to get the fuel mix perfect for engine temperature and air temperatures. It excels at this....!!!
It can not for the following physics reasons.
An engine with no compression is just an Army Flame thrower.
The whole point?, is to burn all the fuel and leave no oxygen left. (pure physics) and make max torque.
"The peak cylinder pressure (PCP) occurs between 10 and 20 degrees ATDC" on most engines and the combustion process is complete by 20 to 25 degrees ATDC..
The peak temperature within the combustion gasses, will reach somewhere around 5000 degrees Fahrenheit and pressures may be anywhere from 300 to 2500 psi depending on the engine. (and compression ratio)
Spark is advanced, to make the above happen at any RPM. (under load (hills) , less advance is needed, because pressures are much higher, and the flame front is much faster) ( the ECU has magic tables for this)
AF/R is best between 10 to 1 (rich) and 20 to 1 (lean) air/fuel ratios. (by weight, not volume)
Most gasolines will burn fastest at fuel ratios in the 12.5 to 13.5 to 1 range. (for max power)
In pure physic terms, the engine will not sustain running, if any of these factors are way out of bounds, compression, spark timing, or AF/R.
An engine is started at about 5 Degree's before top dead center spark timing "5° BTDC."
If the spark, is too early, the pressure peak happens too soon, and the piston is too high, the rod angle is no steep. In fact, if too soon, the engine wants to run backwards.
To see this , take of the engine head off, put #1 at TDC and push with your finger, it don't want to move, does it?, now back up the crank 10 degree's now pusth the piston top, see it go backwards?
This is what happens on the fly , and is a huge waste of power, giving you no torque to sustain running, In fact it's torture to any starter motor, this backfiring.
If spark is late, the pressure is low and the fuel burns like BBQ pit, wasted heat slams the water jackets and wasted burning still fuel )many a weak radiator fails now, and overheats., the remaining waste,exits the exhaust ports.
Timing is everything here. Compression , spark timing, and fueling.
The #1 cause of melted cat is driving with the CEL glowing or limphome and even worse flogged up a hill or with a heavy load.
On 1996 and newer cars the CEL flashes if the ECU even THINKS the cat is ready to burn up.
Ver 1, early 2008
rev 22, major redux (in March) and 3-27-2013 , some edits, 3-8-2014 added parts to make it more useful for other cars.