Just wondering if any of you Ford Techs out there have seen a 2003 Gt that surges under light accel between 1000-1750 rpms? No after-market mods.

Thanks,

Mike

 

yep. seen it.

if you provide more info about your car we'll be able to tell you if our situation was relevant to yours.

 

Sure. No mods at all on a 2003 mustang GT Convt with 36000 miles. I've replaced the air and fuel filters so far.

 

have you pulled any codes? I'm betting you have a dirty sensor in the intake path or your IAC is nasty dirty.

Part throttle surging can be a handful of things. Timing advanced too far, stuttering IAC, slight vacuum leak, clogged injector are among the most common. First thing I'd have to do if it were in front of me is to pull the codes. Many Autozone type places will pull your codes for free.

LIsten for a vacuum leak. Sounds like a whistle that changes pitch with engine RPM. Check the IAC for dirt buildup. Report back and we'll take it from there.

 

No codes found stored. No leaks found.

 

perhaps it's time for a set of plugs.. I've seen plugs cause nasty stuff at really specific RPM's but mostly when you stab the gas. Just cruising... nope.

 

Hey bud (r3dn3ck) not trying to jack your thread but i do have a simular problem on deceleration and accel on my 01Roush. (my car does a have Vortech S/C) i had the tune fix most of it, mine was surging bad!!!! Its alot better now but i can still feel a little surging every know and then from 2-3k? My car was burning pig rich before the tune. Already changed the plugs put a new MAF so i guess i dont have to clean it. Any suggestions?

 

too much timing? just a guess. Try backing off 1 degree in that rpm range. If that doesn't work, get the to a dyno and make them drive it.

 

You thinkin plugs huh? Even after only 38k? Any recomendations?

 

autolite 104's. It shouldn't be the plugs but you'll want to examine the existing units closely and check to see if the electrode is worn away. THe stockers are platinum tipped with a nice fine head on them so it doesn't take much damage/wear to make them basically useless.

Mine were causing a similar problem on mine, granted at 65K miles but still every time I'd stick my foot in it or hit a certain range it'd stutter like a *****. Replaced the plugs and cleared the adaptive data (disconnect battery for 10 mins) from the ECU and bingo... like a new car.

You'll have to replace the autolite copper core plugs every 12-15K miles but they're a helluva lot cheaper than platinum tipped and they always work. Gap em to 40-45 IIRC.

 

I had mine on a loadbearing dyno not to long ago, tuner tried just about everything the only problem the tuner was noticing was the car going lean at 5k and up car was making power but goin lean up top he said i might need a bigger fuel pump or possibly my stock catback was a restriction?? any chance my IAC can cause that surging? it did it today on decel on my way to work, seems to do it more noticeably if i get on it and quickly get of it. Other then that it idles great even with the A/C on.

 

yeah.. if it's sticky there's a distinct possiblity that it needs cleaning or replaced.

stock catback... yeah. I could see fuel problems with the nitrous on but just trolling down the street.. that's usually tuning. If he tinkered with your IAC duty cycle settings then that could be a place to look. I've had to adjust it so the car wouldn't just flat die when I hit the clutch and the brake together. There are other settings but that one's easy to find and test a change on.

He needs to make it drivable before the tune is done right.

 

I'll have to check that out (IAC) sometime this week? I have nitrous on the car but didnt tune for it cause of the Fuel pump, so running just on the blower and basically the car just surges slightly, ironically took it for a long ride over the weekend and drove great surged slightly when i deceled of the Highway?