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Discussion Starter · #1 ·
Hi I have a 2003 zx5 focus 2.0 DOHC, my car has been running fine till last week i went to start it and i think i let off the key turn to early before the car could start and then when i went to crank it on again it came on rough idled back fired and died right away or it will idle real rough and eventually die out. I unplug the MAF sensor and it will idle rough and jump up and down RPM from 2-5k but wont cut out, if i try to plug in the MAF sensor it kills the engine. I replaced the MAF sensor still no luck same thing it starts, idles rough back fires and dies. I changed spark plugs, fuel filter, air filter, MAF, finally i took it to the mechanic he said he thinks the timing belt jumped. is the true and what would the symptoms of a jumped timing belt be. Please help i'm at my wits ends and don't want to spend to much money with xmas coming I really dont want to short change my kid on presents if i dont have too. if i give my car gas it sounds fine at high rpms but once i let of the gas it dies, the reason i changed the plugs were because the ones in the car were very black and had a strong gas ordor and seemed wet. I have gotten a small cloud of black smoke from the exhaust but i think thats just fuel being burnt off. can anyone help me or does anyone know what this might be.

the mechanic said he THINKS it a jumped belt my cel is on but because of my 4-2-1 race headers . what else could it be besides a jumped belt which doesn't make sense to me . he said the fuel pressure is fine so the pump is not bad and he tested two other MAF sensors and got the same response. my spark plugs are working and all spark plug wires work. to me this is very strange

back ground info
2003 ford focus zx5
68k miles engine changed last year with a rebuilt engine
4-2-1 headers no Cat
CAI
MSD ignition coil pack
10mm spark plug wires
new spark plugs


could it be an intake leak?? any ideas would help at this point.
thanks in advance

if you want email me at [email protected] with any suggestions being a single parent in these times I would like to save every penny I can.

thanks again.
 

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I have no reason to doubt the diagnosis. The symptoms you describe are what would occur if your timing belt somehow jumped ahead or back.

It's strange, but not unheard of, for this to happen on newer engines. One would hope whoever rebuilt that engine replaced the belt tensioner for your timing belt, but who knows....
 

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so replace the belt, its like $80 in parts. Took me a couple hours in the garage. Problem fixed.
 

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Discussion Starter · #5 ·
so the idea of a jumped belt is the MOST plausible cause? and is 400 bucks about right to replace the belt and tensioner pully? the mechanic said about 200 in labor and 200 in parts any idea if i should go for it or just take the time to do it myself and how long does it take?
 

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Discussion Starter · #6 ·
so replace the belt, its like $80 in parts. Took me a couple hours in the garage. Problem fixed.

did you have the same symptoms as mine?? cause if you did then that sounds really cost effective and thanks so much for the info.
 

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similar, but my belt also shredded about 15teeth off it, and retarded the timing like 15 degrees. it wouldn't even rev up above like2500rpms and sounded stupid loud, idled bad and everything. I would say that's most likely it.

only thing that caught my eye with yours is that you say it idles all over the place by itself, like it revs up and down without you doing anything? that almost sounds like a idle air control valve or idle sensor gone bad, but not sure what the focus has, its common on hondas to go out tho and because the car doesn't know where the idle is it jumps around.
 

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why dont you pop the valve cover off and the timing belt cover off and manually turn the engine by the crank bolt so that you can inspect the entire belt. It shouldn't just "jump", but if there are teeth missing on the belt you know the problem. That's what I did and when I got to a spot in the belt that was missing like 10-15 teeth, i immediately knew the problem.
 

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Discussion Starter · #9 ·
thanks for the info. so if it's missing teeth i just replace it right. should be simple pop it off and put the new one on right? or is it better for a mechanic to do it?
 

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essentially yeah, its pop off and replace, but you have to get it to TDC as well.
 

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Discussion Starter · #11 ·
TDC. great sounds time consuming from what I remember when i did my cam gears i had to set TDC no something i can do after 5pm. so does 400 bucks sound about right for a mechanic to do it for me with parts?
 

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yeah, most likely.
 

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Discussion Starter · #13 ·
ok update on my timing belt jump.... the mechanic said its not the timing belt he doesn't have a clue what it could be do anyone of you guys have an idea??
 

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Discussion Starter · #14 ·
Mechanic said fuel pressure is fine, spark plugs work, everything else seems normal, when he hooked it up to his cpu it said timing was off 5 degrees but that was my cam gears set at 5 degrees. so he is stumped as to what it could be........ any ideas why I could be having this problem???
 

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Does setting the cam gear timing back to stock cause any improvement?

What is the condition of the wiring harness going to the coil? I've had that break up on me because Ford put no slack into it, and it'd intermittently run rough when one of the wires would lose contact. If the engine idles differently when you move that wire around, there's your culprit.
 

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Discussion Starter · #16 ·
the cams were set back to zero and confirmed by mechanic when he ran it on his cpu. the wires to the coil pack are in good condition no frays or wear, the coil pack was upgraded to msd almost 2 years ago and no issues in that area. I'm stumped as to what could cause it. to me is sounds like the engine is fine mechanically once it goes up to 3000 rpm but as soon as i let off the gas to put it into drive it dies. the injectors are fine and it has the correct pressure for gas and oil so it's a mystery to me. any other ideas?? i'm thinking maybe a faulty sensor but what kind?
 

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Discussion Starter · #17 ·
the MAF sensor is fine and when it is unplugged it idles all over the place but plug it back in and the car dies... I have no clue what it could be. I thought for sure it was the MAF but the mechanic tried 3 different ones. he checked the timing belt and reset the time for the belt and cam gears and still no working car.....arhhhhhh anyone with an idea is welcomed to help me.
 

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maf wiring maybe? weird, maybe try another mechanic?
 

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Discussion Starter · #19 ·
good point, maybe I should try another mechanic but it just seems strange that he cant figure it out. he's done prior engine work on it and knows the car pretty well. the wiring on the MAF is a good idea to look at. I don't know if this has anything to do with it but about 2 weeks back my remote door locks would inadvertently stop working sometimes i could use the remote sometimes not. I changed the battery and same thing it works then it doesn't a day later it was working again. do you think they could be related?
 

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Check the maf connector. If there is a broken wire, it could give false air intake readings, making her run rich....giving black sooty plugs.

I say this because my friend has a similar up/down idle problem, and I KNOW the maf connector has a broken wire. When I connect the code reader, it gives P0113, which is something like air temp current high....so I'm thinking it might be the broken wire. Bought a new pigtail from the stealership today for it tho.
 
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