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need some serious help!

757 views 5 replies 6 participants last post by  brannonroushII 
#1 ·
alright to make things short i own a 2002 mustang gt SOHC it has 125k and has some slight mods like K&n cai, spec stage1 clutch, hurst sts, x pipe, flows 40.
It has been running like crap for the past year. I have replaced so many things but it still not running properly. I have installed a new clutch, fuel pump, fuel filter, intake manifold, mass air flow and tbs . I have always kept my oilchanges and routine maintenance on time.
My car struggles real bad taking off from a stop it stutters and feels like it is choking. if im going like 45 mph and put it in 5th gear and floor it there is no response the car just shakes.It feels like it is having a bad misfire. I took the car to ford and they told me it was the maf but i replaced it and the problem was still there. I took it to 2 different mechanics to get diagnostics one said the cats were bad but i dont got cats. the other one told me that the fuel injectors were leaking.
Im so lost, i have gotten to the point were i just want to give up but i dont have no other alternative its my daily driver and im a full time college student. anny help please thanks alot!!!!
 
#2 ·
Sounds like an ignition problem to me, more than likely COPS.
 
#3 ·
#4 ·
You may want to chech the AIC (air ideal controle valve). its mounnts to the front of your intake upper plenum, and acts like a choke. new run around 100 bucks.
 
#5 ·
If you are truly serious about solving this problem, IMO it will be necessary to re-think this.

Consider that many parts have already been changed and from the looks of it, no real results other than "knowing what it is not". So, since this has been an issue for so long without a solution, recommend taking a step back and asking some hard questions. Like for example, is the base engine OK?

Since the fuel pump and filter has been changed, we should assume it’s OK until the evidence says otherwise. Same for the MAF sensor itself, TPS, intake manifold, and clutch should be considered OK.

FWIIW, the IAC acts as an air by-pass device. It is not a restriction under normal driving. IMO, a bad IAC is not the source of this problem because the amount of air carried via the IAC is so small compared to the TB butterfly.

The dealer with access to powerful engine analyzers that can easily perform a proper ignition system test did not say there was an ignition problem. They said MAF. To me that says to focus on the things that can affect air fuel ratio. Further, if the ignition were breaking down to that level, this should at least give an occasional flashing check engine light (indicating misfires).

Have any changes been done to the way that the MAF is mounted inside the air tube? Has a larger diameter MAF housing been used? How is the MAF clocked? Is it possible the MAF has been installed backwards?

What are the results of a compression test? How much oil does the car burn? What does the exhaust look like (white, black, or gray)? What do the spark plugs look like (rich, lean, oil soaked, coolant, hot, cold)? How old are the front O2 sensors?

I am assuming that during all of this, there have been NO DTC codes.

Have you mentioned all of the modifications done?

What else has been done to rule out a vacuum leak, excessive EGR flow, stuck open EVAP purge valve, or PCV valve? Has the fuel pressure been checked or better yet, crossed checked to a known good gauge? Is the FP vacuum reference line connected and leak free?

FWIIW, the number one item listed in the Ford symptom charts is “excessive EGR flow”. Are the vacuum lines to/from the DPFE sensor connected and leak free? The exhaust gases are hard on these lines. In addition, because they are located so close to the firewall, it is difficult to perform a through visual inspection. Consider testing the EGR valve with a hand vacuum pump. When an external vacuum is applied, there should be an obvious change in engine performance.

Regarding a leaky fuel injector angle did you know that Ford has released a TSB regarding this? Since your car is out of warranty, the dealer will not help without charging. Consider using an injector cleaning and flow testing service such as injectorrx.com. Once cleaned and flow tested, the injectors are as good as new. Much cheaper than buying new. I have had great luck with their service.

Do you have access to an ODB2 scanner that can monitor operational data? It would sure help to know things like the Long term fuel trim (LTFT) at idle and under load. The value of MAF airflow would also be very valuable to know.

With the knowledge of the forum, this problem can be solved. However, it will take information and tests to narrow this down. Serious help is going to mean serious tests.

Good luck.
 
#6 ·
Sounds like coils, spark plugs, a fuel problem, or all of the above. I recommend idling the car and one-by-one, unplugging each individual coil plug and hearing if the engine boggs down and you hear a drop in RPMS. If you unplug one and hear no difference, then that coil, plug, or both is dead. I HIGHLY recommend doing this and if one of these things IS the problem, replace the coils and plugs (might as well at the same time) and see if that helps... I'd help you do all this if I could man... Let me know how it goes if you decide to do it! Good luck :bigthumbsup
 
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