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Discussion Starter · #1 ·
hello im new hearand have been searching through the forums for help for well over a week now with no luck. i was given an 01 sonata with a 2.5 liter v6, the car doesnt start.

the previous owner had a starter and a new crank sensor installed by the hyundai dealer,they also made sure the fuel pump was working, and they couldnt get it to run. they stated that it cranks over and then hits a hard spot like the timing is off,this was in january.

well here i am its now november. i pulled the front covers off. ibelieve the timing was wrong but cant be sure because when i pulled the harmonic balancer the crank gear came off with it. i set the timing put it back together and still nothing. i have fuel and spark, i have even tried spraying fuel directly into the intake but i just wont start. it turns over fine for about ten seconds then it will hit a hard spot and backfire through the intake. im wondering if it could be a plugged convertor,or if the valves may be bent or if may just be something else alltogether.

im about ready to just junk it but would hate to as the rest of the car is in imaculate condition, and my wife thinks it will make her a really cute car. any help or ideas on what to check next would be great.
 

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Well if the timing was off by belt, it certainly may have bent something. Easy enough to do a cylinder compression test by first removing all the plugs. Then continue on checking each cylinder. Then you can at least check and be definitive on mechanical end -since you know you have spark and fuel. Do you have use of a scanner with Live Data? That may be helpful also, but only AFTER checking compression first. BTW back firing through intake is usually a sign that spark is off and igniting at wrong time. Good luck... looking forward to your update
 

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Discussion Starter · #3 ·
i am getting a compression gauge dropped off in about an hour so i gotta get the upper intake off and check that. yes i have a scanner with live data but not sure what values i should be looking at and what a good or bad reading should be. i have been on the hyundai service website but they are pretty vague.
 

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well you won't need scanner til after compression testing -and if all checks out well there. Minimally would be good to know if it even connects to PCM, then to view things like RPM when cranking...this will show that Crank sensor is at least registering something and how accurate (if you see it jump around too much or not matching what you expect RPM to be, could be sign of a faulty sensor), ECT (too high could cause no-start), are just some of the examples. Also, have you tried checking for codes? Whether there are hard codes or not, it may show a pending code.

Try to keep battery charged while doing all the cranking and testing, as to keep any info or codes that may be stored while the testing process. If voltage goes too low or is disconnected, PCM will be reset or cleared. Maybe keep on a charger while doing (if possible)
 

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Discussion Starter · #5 ·
ok i just checked compression on front bank, cylineders 2,4,6 have 110-120 on all three, should i pull the upper intake to check the rear or assume they are decent enough to run. also if the crank is of by 180 degrees could it cause injection on the exhaust stroke.
yes i had a charger in place when i started working on it. codes present are uodoo-definitions not found and po 100- maf circuit malfunction. the undefined has been there,but the maf code is new.
 

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did you have the air intake hose off while testing? that would be the cause of the MAF code. Off 180* on crank pulley you mean? Then you would have caused internal damage probably. I would check intake cylinder side as well... just to confirm and be 100% certain of something. Compression is a big part of combustion... air, fuel, spark, and compression
 

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Discussion Starter · #8 ·
sorry i meant if the crank is off by 360. ie. do the injectors fire of the signal from the crank sensor or the cam sensor. if they fire of the crank then off by 360 would cause no start but also no damage. if the injectors open of a signal from the cam then it wouldnt matter
 

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well you stated you checked timing belt and redid it.... if all the marks lined up prior to install you should be right on the money. The crank pulley and harmonic balancer can only be installed one way because of the key. Don't over think yet. Do your basic testing.

When you did timing belt, did you rotate it by hand? How did it feel? Did the marks line back up after 2 rotations?

So far your checks of the exhaust side cylinders sounds good...which means valves are seating and camshaft is spinning and unbroken... still need to verify the intake side...broken camshaft or bent valves could cause similar backfiring issues along with no start
 

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Discussion Starter · #10 ·
ok just checked the rear bank, and again 110-120 on all 3. yes i spun it by hand and it felt pretty good. all marks line up after repeated spinning by hand and cranking with starter.
 

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Discussion Starter · #11 ·
well you won't need scanner til after compression testing -and if all checks out well there. Minimally would be good to know if it even connects to PCM, then to view things like RPM when cranking...this will show that Crank sensor is at least registering something and how accurate (if you see it jump around too much or not matching what you expect RPM to be, could be sign of a faulty sensor), ECT (too high could cause no-start), are just some of the examples. Also, have you tried checking for codes? Whether there are hard codes or not, it may show a pending code.

Try to keep battery charged while doing all the cranking and testing, as to keep any info or codes that may be stored while the testing process. If voltage goes too low or is disconnected, PCM will be reset or cleared. Maybe keep on a charger while doing (if possible)
so i have just gotten back to looking at this thing and i get about 180 rpm while cranking which seems a little low to me, but it sounds as though its cranking at about the right speed so is the reading accurate or off, what should it be.and what is ect. and could the previous crank sensor wires being shorted have screwed up the ecm,is there anyway to reset/reprogram it or might i need another and would one from a 2002 with a 2.7 be the same or not.
 
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