WOT popping - help!
Thread Starter
Melting Slicks
Joined: Nov 2008
Posts: 2,938
Likes: 65
From: Rochester Hills MI
WOT popping - help!
since the weather warmed up, ive had some slight popping out of the exhaust at wot around the upper rpm range (5500+). i had a custom street tune in the early spring. Ive done some research, and this is a common problem when running lean. I would think the ECU should be able to adjust for the temperature change from spring to summer though. ive come up with some possible causes, and was looking for some opinions. the car has brand new ac delco irridium spark plugs and gm performance red wires. i also use koolsox on the wires.
my thoughts on possible causes:
-needs retuned?
-bad coil pack (will check tonight)
-fuel pump not keeping up (can i even check this without a wideband?)
-excessive carbon buildup (i use techron about once a month. should i try seafoam?)
the car has 127k miles. mods are listed in my profile. rev limiter is set to 6500. can anybody think of any additional causes or things i may want to try? is it bad on the engine to keep running like this?
Thanks,
Dan
my thoughts on possible causes:
-needs retuned?
-bad coil pack (will check tonight)
-fuel pump not keeping up (can i even check this without a wideband?)
-excessive carbon buildup (i use techron about once a month. should i try seafoam?)
the car has 127k miles. mods are listed in my profile. rev limiter is set to 6500. can anybody think of any additional causes or things i may want to try? is it bad on the engine to keep running like this?
Thanks,
Dan
Instructor
Joined: May 2010
Posts: 237
Likes: 0
From: Albuquerque NM
yes the computer should adjust for this but is only capable of adjusting so much hence the need to do custom tuning.
1st try seafoaming before doing anything else you have high milage and a tune cant compete with carbon build up.
2nd get a fuel pressure gauge and drive around "spiritedly" if the pressure drops more than about 5-8psi you might to upgrade the fuel pump.
So far you are on the right track
1st try seafoaming before doing anything else you have high milage and a tune cant compete with carbon build up.
2nd get a fuel pressure gauge and drive around "spiritedly" if the pressure drops more than about 5-8psi you might to upgrade the fuel pump.
So far you are on the right track
Le Mans Master
Joined: Aug 2005
Posts: 5,375
Likes: 328
From: CA.
St. Jude Donor '13-'14-'15
1st of all---HOT weather will make it run richer not leaner---Cold air is denser---has more oxygen--therefore cold air needs more fuel to keep the same AFR
Hot air is LESS dense (thinner) needs LESS fuel to keep the same AFR
The commanded AFR for WOT in the Tune remains the same regardless of weather--Say it's set at 12.5 ------ In the winter it may be leaner or just perfect and in the summer it's rich--Tha's why tuners always allow for weather changes while tuning WOT AFR's and will error on the side of rich --a tad--
The ECM corrects the AFR via it's fuel trims but only during P/T opeation and NOT at WOT
My guess is plugs and wires--- mostly the wires---Aftermarket wires tend to be thicker and harder to get them onto the coil---make sure you hear them "snap" when putting them on---air gets trapped in the plug boot and won't escape when installing so the air pressure will sometimes pop the coil end off--- try using some dielectric grease and i will stick like a thin wire tie (zip tie) into the coil boot when installing them--this allows a path for the air to escape--snap them on and then pull the tie out---
Hot air is LESS dense (thinner) needs LESS fuel to keep the same AFR
The commanded AFR for WOT in the Tune remains the same regardless of weather--Say it's set at 12.5 ------ In the winter it may be leaner or just perfect and in the summer it's rich--Tha's why tuners always allow for weather changes while tuning WOT AFR's and will error on the side of rich --a tad--
The ECM corrects the AFR via it's fuel trims but only during P/T opeation and NOT at WOT
My guess is plugs and wires--- mostly the wires---Aftermarket wires tend to be thicker and harder to get them onto the coil---make sure you hear them "snap" when putting them on---air gets trapped in the plug boot and won't escape when installing so the air pressure will sometimes pop the coil end off--- try using some dielectric grease and i will stick like a thin wire tie (zip tie) into the coil boot when installing them--this allows a path for the air to escape--snap them on and then pull the tie out---
Thread Starter
Melting Slicks
Joined: Nov 2008
Posts: 2,938
Likes: 65
From: Rochester Hills MI
1st of all---HOT weather will make it run richer not leaner---Cold air is denser---has more oxygen--therefore cold air needs more fuel to keep the same AFR
Hot air is LESS dense (thinner) needs LESS fuel to keep the same AFR
The commanded AFR for WOT in the Tune remains the same regardless of weather--Say it's set at 12.5 ------ In the winter it may be leaner or just perfect and in the summer it's rich--Tha's why tuners always allow for weather changes while tuning WOT AFR's and will error on the side of rich --a tad--
The ECM corrects the AFR via it's fuel trims but only during P/T opeation and NOT at WOT
My guess is plugs and wires--- mostly the wires---Aftermarket wires tend to be thicker and harder to get them onto the coil---make sure you hear them "snap" when putting them on---air gets trapped in the plug boot and won't escape when installing so the air pressure will sometimes pop the coil end off--- try using some dielectric grease and i will stick like a thin wire tie (zip tie) into the coil boot when installing them--this allows a path for the air to escape--snap them on and then pull the tie out---
Hot air is LESS dense (thinner) needs LESS fuel to keep the same AFR
The commanded AFR for WOT in the Tune remains the same regardless of weather--Say it's set at 12.5 ------ In the winter it may be leaner or just perfect and in the summer it's rich--Tha's why tuners always allow for weather changes while tuning WOT AFR's and will error on the side of rich --a tad--
The ECM corrects the AFR via it's fuel trims but only during P/T opeation and NOT at WOT
My guess is plugs and wires--- mostly the wires---Aftermarket wires tend to be thicker and harder to get them onto the coil---make sure you hear them "snap" when putting them on---air gets trapped in the plug boot and won't escape when installing so the air pressure will sometimes pop the coil end off--- try using some dielectric grease and i will stick like a thin wire tie (zip tie) into the coil boot when installing them--this allows a path for the air to escape--snap them on and then pull the tie out---
