03 Mach 1 issues plz help

mark23svt

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Hey guys I’m new to the Mach 1 world came from terminators and sn cobras. I recently purchased a 03 azure blue Mach 1 with 43k on the clock. The car has been sitting for over three years so paint is peeling but everything else seems real clean on the car. So to the point car has had an issue lately I can’t seem to fix. Car seems to have a slight misfire you feel it most when it’s under heavy load or you do a quick downshift to get up to speed it hesitates and stuffers then comes back. So things I’ve changed fuel filter, fuel pump, plugs (twice), oil, tps, IAC, air filter, alternator, battery, cleaned maff, check for air leaks, gas cap. Still car has a misfire and smells a lot like fuel, the spark plugs smelled like fuel as well. Check engine came on and gave me two codes p0135 and p0455. I’m just tired of not being able to find what is wrong I took it to a local mechanic he said prob internal cuz he couldn’t find anything . Next I’m going to clean 02 or replace them to see by some chance that works. Car has comp stage 2 cams, full exhaust, short shifter and steeda rai. Thanks guys any help would be great.
 

mark23svt

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No I bought a pair from a terminator but haven’t changed them. You think they can be the issue even? Would the check engine light not detect them? I will change them out this weekend also.
 

DSG2003Mach1

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COPs can definitely cause a misfire. The misfire has to happen X number of times within Y number of revolutions or it won't trip a CEL. Its highly recommended to stick with motorcraft. With no idea how old they might be I would just replace em all.
 

hotcobra03

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Cop was an issue on mine.

455 is a vacuum leak

Evap Purdue valve in passenger fender

Or like I had Main vacuum hose may be connected before throttle body vs after



In here
Chilton Library

On board diagnostics will have pin point tests for po135

Will also have Check list for you issue when no codes are showing

I find a new shop to go to
Saying internal problem says he is clueless

I would also do a compression test
And see how healthy motor is
 

mark23svt

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Ok will do the coils first then move onto checking the oxygen sensors then move on to the compression test. And def a better mechanic if I still can’t fix problem.
 

DSG2003Mach1

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Ok will do the coils first then move onto checking the oxygen sensors then move on to the compression test. And def a better mechanic if I still can’t fix problem.

depending on how long the plugs have been in Id be tempted to pull em again to see if any are fouled. While theyre out might as well do the compression test then put fresh coils in. It can't hurt to go ahead and know the health of the motor and you can get the tool through the loan a tool programs I do believe
 

hotcobra03

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Po 135 is right front o2 heater circuit fault

Being only one side gave a code it is most likely to be just a bad o2

Or if exhaust has been changed
Things like wires touching or to close
O2 extenders harness may have been added These wires can melt and short out

The heaters are on a fuse.
I would expect more heater codes of fuse was blown

Some time swapping o2 side to side the code will follow o2 and you get a different code po155 for leftside

Coils will just get weak. They don’t send a code until they are electronically bad
 

mark23svt

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Sorry guys been out, I tried changing the coils but my dumbass bought coils off of Facebook was suppose to be for a 03 cobra and didn’t fit. So just got a good deal on some Mach 1 (verified pic) with less then 30k. Right after coils will change left oxygen sensor. And yes car is tuned. Forgot to mention all this got bad after I seafomed the car. So I was thinking I didn’t completly get rid of seafoam and since it was sitting a lot of debris is what clogged the IAC and maybe dirtied the O2. I did re check plugs and they were all fine. Did smell like raw fuel.
 

hotcobra03

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Good news. On coils.

By the way.

What was a good deal.

I had gotten mine from ford.

Set of 8 shipped to door 215.

I noticed the numbers changed
From like
Dg 493 to dg 547 or something like that

Wonder if the others had issues
This should last longer than some see

I have to look back and see when I did mine Time/mileage
 

mark23svt

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I got mine used for 65 and they worked. Now need to change the O2 sensors see if they fix the idle issue
 

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