Sputtering on acceleration

[XJeeper87]

My jeep SOMETIMES sputters on acceleration and almost died a few times. The question is could this be the spark plugs? I just got new but have not installed them yet because of the rain. And if not what else could cause this problem.

BTW it is a 87 4.0L it has a MSD ignition box and a MSD coil other than that everything is stock

 

[SCupstateXJ]

I'm betting on EGR valve. I had the same probelm with my 89. Especially after it got up to operating temp. Does it do it when it's warm?

 

[XJeeper87]

It does it no matter what. plus when it is idling if u hit the throttle it stalls out then picks up

 

[XJeeper87]

And to add to it i can smell gas at exaust pipe every time i walk near it after it has run

 

[Shorty]

MAP sensor is supposed to tell the ECU the amount of intake vacuum. Your fuel map is adjusted by the ECU according to engine demand (vacuum level) and will not respond to heavy acceleration or quick throttle changes without a good vacuum signal to the MAP sensor. Make sure the vacuum line to the MAP is attached solidly to the side of the throttle body and has not broken anywhere between the two.

The result of no/ little vacuum to the MAP sensor is a signal to the ECU that it needs to add fuel to accommodate the excess air entering the intake and reducing vacuum.

 

[XJeeper87]

ok where is the MAP sensor???

 

[Shorty]

basically centered on the firewall above the valve cover. It should have a flat bracket that it's mounted to.
three wire plug connected to it and one vacuum line that runs forward along the fuel rail and terminates at the throttle body.

 

[xcm]

the vacuum hose going to the MAP can become plugged very easy, blow thru it.


when you replace the plugs, make sure the old ones look consistant.
you could be running on 5/6, check the fuel injectors to make sure theyre all working,it is an 87

 

[XJeeper87]

I unplugged 1 injector at a time and it caused the jeep to run rough at idle

 

[XJeeper87]

Will a busted EGR valve cause a major enough vacuum leak to cause this??? . If not what will?

 

[xcm]

have you replaced the fuel filter? what about in the tank? maybe your fuel sock is clogged, or semi clogged.

ive seen some solid black fuel socks....

 

[XJeeper87]

Whats a fuel sock???? and is fuel filter external??? is there a way to clean it temporaraly? to see if it does need replaced??? i dont have the $ right now and need to find out what is wrong so when i do get da $ to fix it

 

[ehall]

you can eliminate EGR by disconnecting the vacuum hose between solenoid and diaphragm (plug it with a golf tee or machine screw or something). with the diaphragm disconnected from the solenoid it won't engage

 

[xcm]

the fuel sock is in the fuel tank, its basically the first fuel filter, before the fuel goes thru the in-tank pump.... its a pain in the ass to check, gotta pretty much drop the tank...
wait for when your on 1/8 of a tank or less!

the fuel FILTER is external, its on the inside of the driverside 'unibody rail', theyre about $6. maybe take it off and blow thru it to check for clogs.

heres a picture of a fuel sock, im too lazy to rehost it, so im not gonna hot link it.
http://www.pirate4x4.com/forum/attachment.php?attachmentid=208175&stc=1&d=1128096226
ive seen them as black as tar....

 

[Shorty]

I unplugged 1 injector at a time and it caused the jeep to run rough at idle

have you eliminated the MAP sensor through testing or are you just looking for other suggestions?

Will a busted EGR valve cause a major enough vacuum leak to cause this??? . If not what will?

although the symptoms of a faulty EGR valve could cause the stumbling, it's highly unlikely that you would smell raw fuel at the tailpipe from it's failure.

 

[XJeeper87]

WTF charged my battery and it runs like a champ??????? HTF does that work??

 

[ehall]

lol bad connection to coil probably

replace batterry terminals

 

[XJeeper87]

um i was reachign under the hood while jeep was running and touched the coil and got a shock that cant be good any ideas why it would be shorting like that??? it is a aftermarket MSD coil not made for the jeep cus MSD dont make one for my cherokee

 

[XJeeper87]

any1 know why???

 

[selarep]

Your coil will shock you not matter what. I replaced mine and my old one was in good shape but it really shocked me. I upgraded and put a complete accel kit in.