05 Mustang Gt Diagnosis Help....hard Fix!

Discussion in '2005 - 2009 Specific Tech' started by 805mustang, Jun 6, 2013.

  1. recently my car has been acting up, let me start by saying i have been a mechanic for 8 years and am good at diagnosing and repairing cars......but this is a different story as u will read......... I have been driving a 2005 mustang gt with 35000mi....accessories are CIA (says it does not require a tune) wheel spacers, full boy racer body kit w/ duck tail instead of the wing, modified mufflers (cut them open and hollowed them out).....was chipped until i was in a fender bender.....not bad, no airbags, no dammage to engine at all i drove away and car was fine for months.....i recently put chip back in to see if that was the problem but no difference. oh by the way it is a chip not a tune!!! best of all i took the manifold runners out and drilled the rivits that hold them to the shaft. there is one per cylinder and they are designed to stay closed until 2750 rpm then they go wide open. thats why the 05-09 mustangs would lag until u hit 2800-2900rpm then it really pulls. taking them out was the biggest power gain so far. more noticeable than the chip and cia!!!!!!! no engine light and passes Ca smog test no problem.....if you do this you will love the results! write me if u want to know how.
    ok, now for the issue at hand. my car has gradually been running rougher and rougher. idles fine and accelerates fine. drives good when its could and drives good warm! it will only occur one time a day at the same distance and the same driving conditions. same temperature same speed. no engine light and no other issues. i will be driving from home, about a quarter mile to the freeway on ramp and cruise at 70 mph, give or take a few,. i will make it about a 2.5 miles and it will buck and stumble. it will buck and stumble maybe 4 or 5 times within 1 mile and or about 1 minutes of driving then it goes away!.....I have a genisys evo 4.0 and can view live data, codes, mode six, component tests, pending, misfire data, sensor data and repair info and i cannot find anything too far out of value, nothing has tested bad and nothing has changed for the last year..........interest yet. the problem i just described happened 3 days in a row....all the exact same. now for the last 2 days i notice it runs rough at 1600 to 2500rpm and only in neutral but fine under load and fine on hard acceleration and idle. still no codes or info saying anything is wrong and sensors read good, all that seem important and that i can monitor.....and there are a lot!
    does anyone have any ideas, i dont even know where to start. checked throttle body; clean, checked oil, full and clean; added 8 gallons of shell premium to almost empty tank (was running 87); no difference. new air filter; same! disconnected battery for(i know, overkill) 7 hrs; no change. i do not see a problem but i can feel it! im going to break out the scope tomorrow does anyone know how to approch this? anyone have a similar problem? does anyone have a discription of tsb's? wiring diagrams? HELP!!!!!!!!
  2. The only possible cause that comes to mind is a dodgy OEM fuel pump. It can cavitate the fuel, which causes air bubbles and engine hesitation. However, the hesitation normally happens when the car is initially accelerated after a highway cruise. It has also been known to happen less frequently during a cruise or around town. The only solution is to replace the fuel pump.
  3. I've had the fuel pumps replaced not too long ago under warrantee, I have a bunch of Pics of live data if u care to take a look......maybe compair them to your car if u have a scan tool and a close to stock 05 - 09 mustang gt. it is acting like the computer needs an update. First I had current to all 4 o2 htr circuits then I didn't 4 two days and now I do again! I'm going to try and clean the maf because I have an aftermarket filter and it may be contaminated.....before I started my car this morn it was saying 84 degrees at air temp sensor which is in the maf but the ambient temp was 72. They should have been equal since the car was not in the sun nor was it started today. Also it's fine under load and happens within the first 3-5min of driving! Also I am getting very little readings on var cam timing sensor # 2 and large values on # 1. Not sure how to test those except to compair readings/values
  4. Unfortunately, my 05 GT has a tune, and I don't have a scan tool.
    Has the fuel filter been replaced recently?
  5. Not yet.....everything (fuel trim and rear o2s ) is saying its running rich! And i have a steady 40 psi of fuel pressure. but it couldnt hurt to put one in, i dont like throwing parts at cars im more of a fix it right the first time kinda tech! Last night after I did all that work I noticed the evap. Was reading between 30 and 150ingh also I'm only getting readings from one variable cam time sensor! Do u have any wiring diagrams? Any info will help! Also I see 2 cam sensors in each valve cover but I unplugged them at different times and I got a code for cam position sensor open circuit......is that the same sensor as the variable cam time sensor? And I see no map sensor anywhere so how am I getting engine vacuum readings......baro sensor?? What does this pic mean.....do I have a problem with var cam timing??

    Attached Files:

  6. I replaced fuel filter and changed oil! I need a wiring diagram.......multiple sensor values are not right and I'm wondering if they share a common ground or are tied in together! Does anyone have one??? Oil temp, intake air temp, cylinder head temp are all too high!
  7. I had a cam position sensor fault code, bank #1, an engine check light, and slight hesitation at 2K rpm. Replaced the sensor, same problem. My son found that the alternator diode emits emi when it wears out and causes the cam position sensor to malfunction. I replaced the alternator and it's all fixed. It's a long shot since your car has only 35k miles, but worth checking. Good luck.
  8. Hey Jason do you have a close to stock mustang gt? Could I compare my live data readings to yours, if you have a scantool that is? I know why the hesitation occurs but it will buck maybe 4 or 5 times when the car goes from cold to hot, I.e. when the thermostat opens up! I am having slightly high readings on oil temp sensor when the car is cold but seems to be fine when the car is warm too! Don't know if that is an issue either. Does your oil temp read higher than your air temp, ect and cylinder head temp before you start the car for the first time after sitting overnight? Thanks -mike
  9. That looks like your answer right there, the cam sensor. Are you still looking for a service manual/wiring diagram. PM me, I might be able to help.
  10. If you changed the cmcv plates by taking the flaps(manifold runners) out, then you need a tune for this. You essentially made delete plates which require a tune.
  11. Why do you need a tune? If you keep the linkage hooked up the car does not know the plates were removed and will adjust fuel trim accordingly! The only reason I see you needing a tune would be if you installed delete plates which do not have any linkage to hook up, no linkage equals engine light. If there's something I'm missing please enlighten me.
  12. Hmmm...after extended highway speeds with cruise control, thecar will very rarely hesitate slightly the first time I accelerate from a stop. Sound about right? It isn't a big enough issue for me to replace the pump, I just always wondered.
  13. If you notice the hesitation at exactly the same rpm (2800rpm plus or minus 100rpm) and you own a 05-07 gt this is most likely due to your imcr (intake manifold control runners) if you notice it at any other rpm w/ ac off I would guess its probably tiny air bubbles developing around the pumps. I'll put up the tab in a moment!
  14. Here's the tsb

    Attached Files:

  15. Have you datalogged while getting this to reoccur?

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  16. Yes I have, if your referring to the hesitation issue I use a genisys 4.0 to record data! Imcr's open up at 2800rpm at every condition from part throttle to WOT and in any gear. If your mustang is a stock 05-07 gt it is very noticeable. Not sure about the automatics, i have a 5speed. See for yourself and tell me if you notice, steadily accelerate under part to 3/4 throttle, even WOT if you wish and you will notice at 2800rpm a slight hesitation will occure right before a noticeable increase in power! This was driving me nuts so I did some research and came to the conclusion it was due to the intake manifold control runners, took the intake off, pulled the runner assembly and drilled out the rivets, hooked the linkage back up and reinstalled the intake! Bye bye hesitation!
  17. This seems to be the best explanation:
    Originally Posted by Preston951 View attachment 123364
    TacoBill's tech thread to the rescue, once again!!!! View attachment 123365

    Mod: Charge Motion Control Valve Deletes (aka CMCV Deletes or just Delete plates.)
    Tune: ALWAYS, Car will go into limp mode without one.
    Why: The intake manifold of the S197 has a second set of butterflies in them, placed just before the intake valve. The goal of these plates is to increase the velocity of the air as it moves into the combustion chamber. Increasing the velocity of the air as it enters (also called port velocity) helps the engine build torque and maintain fuel efficiency. In Theory, as the engine speed increases, these butterflies are supposed to open (between 1500 and 3000 RPMS based on engine load) and allow the air into the cylinder without restriction. In function however, these plates do still end up providing some small restriction to the intake. As their name implies, the CMCV Deletes remove these butterflies completely. When you remove these plates however, you must tell the computer that they are no longer on the car. The computer has entire strategies of timing, cam phasing and fueling that it applies based on these plates being closed. If there are no plates to close, but it thinks that there are, I think you can see where the problem comes in here.
  18. Your theory is very plausible except for a few issues.....my plates have been deleted for 7 years and never goes into limp mode. Also I believe that the cars PCM will be able to adapt to the changes in airflow at low rpm, when the valves are closed. I was under the impression that the tune simply would keep the CEL off and that the PCM adapts accordingly. When I get a tune I will monitor the pids before and after the tune on my gennisys
  19. Not my theory, but that of the author. Looks like being a mechanic and putting a lot research into this you were able to circumvent the need for a tune. You have the equipment and knowledge to figure all this out - more power to you. I already had a tuner when I installed my deletes and Brenspeed adjusted the tune I already had and it ran great for 5 years with the charge motion motor removed. I removed the deletes when I installed my Saleen VI s/c this year. If someone already has a tuner and their tune can be updated without cost and it works great that should be ok as not everyone goes through the research you have. But, if you can help others avoid a costly tuner and tune, I'm sure people will definitely be interested in that.

    Oh, BTW shortly after I purchased this Mustang in 2006 and after a long cruise, it would often buck and stutter on acceleration. I'm not saying this was your problem, but Ford replaced my fuel pump under warranty and that problem was eliminated.

    Just recently I started to get a P0340 code, so I've got a New PA Performance alternator coming. Car runs fine just throws a code.
    #20 lenko, Oct 14, 2013
    Last edited: Oct 14, 2013