Bucking under load when warm

OrangeMustangGt · Jul 28, 2007

My last resort is to see if anyone on here has the same issue. For the last month this has been getting progressively worse. when my car is hot, and i give it gas it bucks real badly.

I have cleaned my new MAF, and run codes. All i got was a 02 sensor rich on left side, so i replaced it....no help.

Anyone have ANY ideas?

BlackVert · Jul 28, 2007

i had a very similar symptom. it was worn out spark plug wires, one was loose and got flakier as the engine warmed up

mine was more like a miss with hesitation, i wouldn't have described it as bucking though

blksn955.o · Jul 28, 2007

Dont you have a tweecer/SCT?

I know you took off your ter-bo's but what else are you running now cam and such?

I had a bucking issue from when I first installed my non-ported gt40's, TFS1 cam, and ported lower gt intake. I added 24's but ran a C&L as I didnt have a tweecer yet. Had a bucking at around 1,700-2,500 rpm or so IIRC.

Went with the tweecer and stock maf along with a cobra base file and 0 issues. I now run a 98gt maf and had a VERY VERY VERY slight bucking at like 2,000-2,200 in like 4th on the hwy. I didnt even really notice it and thankfully I did notice it when I ran a datalog...I actually thought it was the wind since it was windy out. EA suggested a VERY VERY VERY small change in the MAF transfer in that exact area...now its gone too.

Methodical · Jul 28, 2007

blksn955.o said:
Dont you have a tweecer/SCT?

I know you took off your ter-bo's but what else are you running now cam and such?

I had a bucking issue from when I first installed my non-ported gt40's, TFS1 cam, and ported lower gt intake. I added 24's but ran a C&L as I didnt have a tweecer yet. Had a bucking at around 1,700-2,500 rpm or so IIRC.

Went with the tweecer and stock maf along with a cobra base file and 0 issues. I now run a 98gt maf and had a VERY VERY VERY slight bucking at like 2,000-2,200 in like 4th on the hwy. I didnt even really notice it and thankfully I did notice it when I ran a datalog...I actually thought it was the wind since it was windy out. EA suggested a VERY VERY VERY small change in the MAF transfer in that exact area...now its gone too.

Did EA suggest you to richen or lean the MAF curve? I had a similar issue but realized I had not done any DLs after having the lower intake ported and EA had me richen up many areas on MAF.

mustang1994bob · Jul 28, 2007

Its almost definatly plug wires!! I had the same problem chased it and chased it, the bad part was I had just done some rearend work and so I almost paid someone to "fix" the problem in the rearend. Remember always start with the simple stuff, to check them just go out to the car in the middle of the night with all the lights out, and just start it up and look under the hood you can spot the leaks right away, also look for spots that the spark might like to jump to, like the engine lift eye, then when you replace them make sure to avoid those kind of things and use wire looms

Fopar · Jul 28, 2007

plugs here too, 1 was cracked 2 were loose...

OrangeMustangGt · Jul 29, 2007

Thanks guys, I will look at my plugs/wires.

Its not a tuning issue, although I still have some light mods the car was running flawlessly for a while after i removed the PITA turbos. I like how it drove like a stocker....untill now.

You have a good point.....Even at WOT it still has the bucking issue...and I thought i heard a bit of detonation, which it never had....possibly wires cross firing. I just put these Ford Racing Blue plug wires on a few months ago....so if there dead Im gonna be pissed. They LOOK to be in great shape, and I put High temp boots around the plug ends at the heads.....

blksn955.o · Jul 29, 2007

Methodical said:
Did EA suggest you to richen or lean the MAF curve? I had a similar issue but realized I had not done any DLs after having the lower intake ported and EA had me richen up many areas on MAF.

Honestly, I get confused on that part...all the criss cross of numbers meaning opposite things...I made a note on Tweecer on my laptop to keep it straight but that is in the backseat.

My K's were like .93-.87 in the erea of the transfer that was suggested be changed, I moved the graph ever so slightly to the right on the transfer...

zenboy99 · Jul 29, 2007

One thing to check.... ACT versus ECT, our stock EEC will richen the mixture up when the ACT gets above 120. I had driveability issues in the heat that were fixed by changing this value in my Tweecer.

mustang1994bob · Jul 30, 2007

turbo?? im in the mood for a PITA, do you still have the set up??

iwashmycar · Jul 31, 2007

i had an issue like that a while back...got the Sensor and Relay package from 50resto...i actuall think the 02s fixed it because it cleared right up after theie install...

http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071K302 1&comp=LRS

gcomfx.com · Jul 31, 2007

iwashmycar said:
i had an issue like that a while back...got the Sensor and Relay package from 50resto...i actuall think the 02s fixed it because it cleared right up after theie install...

http://www.latemodelrestoration.com/iwwida.pvx?;item?item_no=M12071K302 1&comp=LRS

Dang... that's a pretty good deal. Usually O2s are about $50 shipped. It's almost like getting all the other sensors free.

OrangeMustangGt · Aug 1, 2007

I still have the turbo setup. Really All I need to do is to install V-bands instead of the clamps i was using. I may put it back on someday

OrangeMustangGt · Aug 2, 2007

I FIXED THE PROBLEM!!!

today the drive to work was sooo nice.

It was a plug wire shorting to my headers, I reversed the wire so the short 90 deg end is at the head....it clears the long tube opposed to the 45 deg on my fms plug wires that were melted and sparking. It dident do it cold, so i drove the car untill hot at night, and opened the hood with it running and misted the engine with water.....then I saw the arcing.

BlueOvalStangGT · Aug 2, 2007

Good deal on fixing it, now sell me your front bumper

BlackVert · Aug 3, 2007

plug wires ... it took me almost 6 months and lots of money in unnecessarily replaced parts to find mine. man was i stupid about it. oh well, live and learn.

i'm glad you're good to go! :SNSign:

Bucking under load when warm

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