Wants to die when pressing gas

Larry85326

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I just changed my plugs and they looked OK. Put in Motorcraft plugs. Gas milage is not the greatest but runs fine . My new issue is it ideals rough and like it rocks side to side like a huge cam in it. When at a stop if I go to press gas pedal it wants to die out on me . If I feather the pedal it takes off and problem is gone until I stop again. This in a 2001 with a 3.9 with 159.000 miles. I been putting g money in to this car since April and was hoping that it would end soon bit its starting cost me again. Please help I love this cat and don't want to park it yet
 

JustALs

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sounds like its not getting enough gas...
I would start by removing the rear seat and under the rear passenger side seat is the fuel pump remove it and lift it out the tank and check if your strainer/aka/ in tank filter if its dirty or clogged,
mine was clogged and did the same and just ran it with the strainer removed..
Or it could be dirty fuel injectors
or the fuel filter and its located at the front driver side wheel under the shroud
it might be dirty or a weak pump but I would only suspect that the pump is weak only after you cleaned the injectors and checked the fuel filter
And strainer
I also had plugs that looked new but were fouled even when cleaned they were still causing a rought idle but only buy new ones after you checked everything I mentioned.

To clean the injectors I usually buy a can of carb cleaner and use a tire valve stem Cap and drill a hole on top the size of the can red straw
and put the straw in and tape it with electrical tape or super glue,

remove the fuel pump fuse and run the car till it stalls then find the fuel rail shrader valve and open it and untwist the guts and twist in your homemade piece with the straw on it and have someone start the car and rev it while your spraying carb cleaner directly in the fuel rail.

while your under the hood might aswell clean the mass air flow sensor with MAF cleaner but a dirty MAF usually just cause jerking while u press on the gas
Goodluck!
 
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Larry85326

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sounds like its not getting enough gas...
I would start by removing the rear seat and under the rear passenger side seat is the fuel pump remove it and lift it out the tank and check if your strainer/aka/ in tank filter if its dirty or clogged,
mine was clogged and did the same and just ran it with the strainer removed..
Or it could be dirty fuel injectors
or the fuel filter and its located at the front driver side wheel under the shroud
it might be dirty or a weak pump but I would only suspect that the pump is weak only after you cleaned the injectors and checked the fuel filter
And strainer
I also had plugs that looked new but were fouled even when cleaned they were still causing a rought idle but only buy new ones after you checked everything I mentioned.

To clean the injectors I usually buy a can of carb cleaner and use a tire valve stem Cap and drill a hole on top the size of the can red straw
and put the straw in and tape it with electrical tape or super glue,

remove the fuel pump fuse and run the car till it stalls then find the fuel rail shrader valve and open it and untwist the guts and twist in your homemade piece with the straw on it and have someone start the car and rev it while your spraying carb cleaner directly in the fuel rail.

while your under the hood might aswell clean the mass air flow sensor with MAF cleaner but a dirty MAF usually just cause jerking while u press on the gas
Goodluck!
Thank you JustAls
I think I forgot to say when I installed new Motorcraft plugs they said gap was like .040 or.045 . I was reading g here that they only need to be at. O10 is there any truth to this that just seems crazy to me
 

xford

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Most suggest a 1.0mm Gap and you should always double check prior to install. Did this start right after the plug change or later? If right after did you possibly damage a COP or associated wire? When I did plugs I did the COP's at the same time.

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JustALs

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I cant see how a plug gap could cause his problem but it might if its way off.. Most of plugs I bought for the llsv8 were pre gapped and I never even bothered to re-check the gaps.

Also if you mix up the cops wires you don't deserve to be under a hood..

The wires in length are right where the cop goes lol...
if you were to plug cyl 1cop wire on the cyl 2cop or the cyl 5 cop wire on cyl 6 wire you wouldn't be able to plug the cyl 4 or cyl 8 and they aren't long enough to go the other way unless it doesnt have the original cop's wires :'')

And even if you damaged 2 or 3 cop wiring harnesses the car would still run with but with way less power, I was driving my ls on only 1 bank for a month never had to feather the gas but it ran like shit

But if your problem started just after the spark plug change thats where you should look,
maybe you got bad plugs that some asshole dropped on the ground and damaged them if they're the precious metal electrode type plugs, but like I said ^ this wouldnt cause the issue that you have to feather the gas to get goin.. sounds like its not getting enough fuel *@ clogged filter or strainer, injectors or weak fuel pump. a clogged in tank strainer could act the same as a weak pump and could burnt down your pump fast
 
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Hated80

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I just changed my plugs and they looked OK. Put in Motorcraft plugs. Gas milage is not the greatest but runs fine . My new issue is it ideals rough and like it rocks side to side like a huge cam in it. When at a stop if I go to press gas pedal it wants to die out on me . If I feather the pedal it takes off and problem is gone until I stop again. This in a 2001 with a 3.9 with 159.000 miles. I been putting g money in to this car since April and was hoping that it would end soon bit its starting cost me again. Please help I love this cat and don't want to park it yet
I was having the same problem, i found that the dpfe sensor was bad.
 

JustALs

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Im not too sure about it being the DPFE sensor, both hoses on mine are broken off and the connector is disconnected.. Yeah broken off so I have a vaccum leak in addition

The only thing it gave me was a check engine light and the car runs fine.
This is clearly not the cause of the problem on his LS
 
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joegr

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Im not too sure about it being the DPFE sensor, both hoses on mine are broken off and the connector is disconnected.. Yeah broken off so I have a vaccum leak in addition

The only thing it gave me was a check engine light and the car runs fine.
This is clearly not the cause of the problem on his LS
Because you know that possible incorrect pressure readings are not causing the PCM to open his EGR valve too far when giving it the gas?
 

JustALs

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Because you know that possible incorrect pressure readings are not causing the PCM to open his EGR valve too far when giving it the gas?
You are right on that its possible, I was just thinking that my egr might be stuck so its probably why it hasn't affected the way my car runs.?

But it would throw a code so @Larry85326 have you got your LS on a scanner to check for codes ?
 

Larry85326

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I just picked up a Forscan but I can't install it on my laptop because a vindictive woman poured water on it. But as soon as I have a chance I wantbto check all codes again last was only 2 codes lean bank 1 and rich bank 2 and at one time EVAP had issues but that code has not showed up for some time
I did pull all plugs again and put new ones and gaped them at .040. Still having same problem maybe a intake leak? I did change all the vaccines last tube up when I put timing chains in and I do have a new DPFE installed along with a new EGR valve. When doing the plugs again. I made 100% sure wires were not crossed but every clip was broken I'm looking at putting zip straps to secure them in place I did replace 2 COP I know I should do all of them I'm looking at getting injectors next but that's a big chunk of change at the moment and even the clips on those are broke. I bought a used car and this is what I got go figure but it's a LS so my love took over now I have to nurse it back to health. I think right now life support is in t GG e forescan so until I figure out how to get it working and then dive in to it from there. I really do appreciate all the help and I will do what it takes and open to any suggestions you may offer. Please help. Thank you joegr,JustAls,Hated80, and xford. With out your help this car would be sitting else where but I still have it and want it even more.
 

JustALs

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I feel for you dude last time my ls was running like crap I was mad and it wasn't fun lol.. Dont forget to check the fuel filter and the fuel pump strainer to see if they are dirty.
Goodluck! And keep us updated!
 

Larry85326

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OK here is an update. Some asked for codes and I found them P0442 and P0402 one says EGR solenoid. Well I just replaced thata month ago
 

JustALs

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P0402 is EGR exessive flow and could potentially cause the issue your having if it lets too much.
Are you sure the EGR gasket is good? Did you connect the small vaccum hoses from the egr solenoid to the EGR correctly?
 

04_Sport_LS

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I think I forgot to say when I installed new Motorcraft plugs they said gap was like .040 or.045 . I was reading g here that they only need to be at. O10 is there any truth to this that just seems crazy to me

The plug gap is supposed to be .040... which is 40 thousandths of an inch... which is roughly equal to 1mm (not 0.10).

Your plug gap may be too small. Recheck them.

However... since the problem is at idle... I suspect the Idle Air control Valve (IAC) may be bad.
 

Larry85326

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I feel for you dude last time my ls was running like crap I was mad and it wasn't fun lol.. Dont forget to check the fuel filter and the fuel pump strainer to see if they are dirty.
Goodluck! And keep us updated!
 

Larry85326

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Well guy after a week of work k ing and coming home to do the car.
Again only 2 codes pop up. But these are not the same as last week (P0443,P0402) these are new P0420,P0430. I don't get it I didn't t anything as far as repair but I tried a dozen times see if it was a Flux but nope they keep popping upGrrrrrrrrrrr.
 

JustALs

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Start by using zip ties to hold the connectors on the coils. That way you eliminate that as a possible misfire issue.

How old are the coils... and what brand/make?
+9999 on the zipties,
I have about 8 holding my aftermarket cop's connector plugged in lol :')

But if this was the cause of his problem wouldnt he experience misfires and stumbling even after he took off? He said after he feathers the gas to take off then the car runs fine.

After my tensioner replacement I forgot to reconnect the whole passenger side cop's and I did not have to feather the gas to take off.
 

Larry85326

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Thank you gentlemen the zip ties as for brand of COPS, I'm going out on a lim here saying at least 6 are stock the 2 I know for sure are Motorcraft I just put them on.
I guess today is a day I go back and check and double check EVERYTHING I have done so if I did anything wrong I can correct it ( hope I didnt) but ...... thank you again. I'll be back in a few hours to update you on what I find or don't find.
 

Larry85326

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Well I double checked everything .... call me silly but was hoping to find anything I did or didn't do but everything is put together right so it looks like there is something else wrong. Now this costing me money. I guess I'm not mad not even upset I'm just a little perplexed about this it's like I'm just throwing money at it in hopes that I finely hit something I guess it's going to be 6 more Motorcraft COPS. I t early wish I could find some high pro fuel injectors but but I'm luck to fine even close to OEM injectors.
Well off to move some money around in some accounts and get a few more parts. Man and I thought my ex-wife cost me a ton of money
 

Larry85326

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Well I double checked everything .... call me silly but was hoping to find anything I did or didn't do but everything is put together right so it looks like there is something else wrong. Now this costing me money. I guess I'm not mad not even upset I'm just a little perplexed about this it's like I'm just throwing money at it in hopes that I finely hit something I guess it's going to be 6 more Motorcraft COPS. I t early wish I could find some high pro fuel injectors but but I'm luck to fine even close to OEM injectors.
Well off to move some money around in some accounts and get a few more parts. Man and I thought my ex-wife cost me a ton of money
 

04_Sport_LS

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I don't think the coils are the issue. The codes you are getting point more to the EGR system... and catyletic converters.

The recommendation of the zip ties... was meant to be a preventative measure.
 

JustALs

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Don't buy new injectors, if it runs good after you take off they are working and you can just clean them
 

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