'03 3.9 surging

Gus_Mahn

Gus_Mahn

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My '03 3.9 LS has a new issue. It surges as I roll on the gas on the expressway to speed up. It's not always there and seems to happen between 2000 and 3000rpm. It happens only occasionally. It feels like more power, less power, more power, less power... Maybe once or twice a second. It's definately not a miss. It seems like a issue with variable valve timing, torque converter lock up, or intake runner valve control if this car has it. Any ideas?
 
I dunno man that really sounds like misfiring.

OP does the fan run at 100%??
 
Mine does/use to do it.. Like the trans shifting in the PCM was messed up.. It would go into 5th going 35 through town.. Shuttering (what I called it) was felt more around 50
 
Could also be a dirty MAF sensor. You can get a can of cleaner for about 9 bucks at most auto parts places. Or it could be a coil going but isn't bad enough to throw a code yet.
 
FASTLLS said:
OP:

Have you had Ford replace the coils? Are you under 100k?
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FWIW - Mine is but my dealer wouldn't even test until it threw a misfire code and would then only test (and replace) the one the code indicated. I tried to get them to at least test all the coils (I even told him that other members on here had gotten them all replaced,) but he said Ford scrutinzes their warranty claims very closely and his a** would be in a sling if they did more work than indicated by the code.
 
BlackBurb said:
FWIW - Mine is but my dealer wouldn't even test until it threw a misfire code and would then only test (and replace) the one the code indicated. I tried to get them to at least test all the coils (I even told him that other members on here had gotten them all replaced,) but he said Ford scrutinzes their warranty claims very closely and his a** would be in a sling if they did more work than indicated by the code.
Click to expand...

Take the letter with you to the dealer. Ford warranty does not require any misfire codes to be present. It requires at least one COP to fail a stress test.

If none fail, then you have to pay the standard diagnostic charge.
Maybe you need to try another dealer?
 
It has 150,000 miles. I'M 99% sure it's not a misfire. Lord knows I've been through that enough times! All the coils were changed at 100,000 miles and all the passenger side coils were changed again at 145,000 miles due to misfires and ETC Fail-safe mode. There's an exact rhythm to it. like it going from 60 horse power to 40 horse power once or twice a second. It's smooth and cyclic, not random like a typical miss. Light cruise, light acceleration, WOT it's fine. It only happens occasionally and only at moderate throttle opening between between 2000-3000 rpm.
 
Gus_Mahn said:
It has 150,000 miles. I'M 99% sure it's not a misfire. Lord knows I've been through that enough times! All the coils were changed at 100,000 miles and all the passenger side coils were changed again at 145,000 miles due to misfires and ETC Fail-safe mode. There's an exact rhythm to it. like it going from 60 horse power to 40 horse power once or twice a second. It's smooth and cyclic, not random like a typical miss. Light cruise, light acceleration, WOT it's fine. It only happens occasionally and only at moderate throttle opening between between 2000-3000 rpm.
Click to expand...

That's a new one on me then...
 
I have a code scanner. Don't think there are any codes, but I'll check. I'd say a shudder is a shaking or violent shaking, so I'd say no. There's no shake. The power just comes and goes in rhythmic motion. The next time I roll into the throttle it might be ok.
 
It's hard to explain.. It's not hard.. I would say a light shutter more like a 'chugg'.. For the scanner, see if you can do a KOEO (Key On Engine Off) self test (some scanners don't do that).. See if it will complete the test with no codes
 
Im approaching 100k miles and i have noticed something "similar"- I relate it to some slight driveline wear; the transition from powered forward motion to coast is not as seemless as it was when the car had 25k miles. Now, its nowhere as severe as a 200k mile farm truck but it feels similar. I dont think there is any definitive test, other than to observe a couple of conditions and try to duplicate/pinpoint the conditions during this event-

Engine temperature
Road speed
Road grade/incline
Throttle opening

I experience a VERY slight "surge" under light throttle, for example cresting a hill when the car will begin to coast with throttle pressure. (not that Im always driving with a light foot, but it is michigan...)

Just my thought, ive only owned rear drive vehicles and they all seem to do this at some point in their life.
 
Rich88LSC said:
I still say coils or dirty MAF sensor
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I agree ^
Especially if its a Gen I , mine didn't necessarily jerk but it stumbled slightly. I don't know what the difference would be between front and rear drive but I've had a car that noticeably jerked ! And There's no mistaking that. It would totally skip 3rd gear and slam into 4th. It was a front wheel drive automatic 4.

So ill leave this unaltered as a reminder of what can happen when you don't sign off before you leave. Sorry for the misguided info. Bro wanted to offer his insight on an eclipse that he owned. But didn't realize that the LS is a whole different beast than an eclipse and you weren't asking if you have an obvious catastrophic tranny failure.
 
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Rich88LSC said:
I still say coils or dirty MAF sensor
Click to expand...
I agree LOL I cleaned the maf and changed the spark plugs and boots. No more surge. Still running the same coils. I did it all at the same time, so no saying what it was for sure. The air meter makes the most sense to me. It definately was not a typical misfire.
 
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