stalling, sputtering

StuckInMud94 · 08-05-2005, 06:35 PM

lately for about the past couple MONTHS my jeep has had this sputtering and stalling problem. its a 94 yj, 4.0. say im at a red light, idling. if i sit there for too long, when i put it in gear to go, the jeep will sputter and jerk and cut out when i hit the gas. if i turn the jeep off and back on, it seems to help. the harder i push the skinny pedal, the worse it is. i have no check engine light, and nobody can tell me what this problem is. i changed the plugs, wires, cap, rotor, and fuel filter. it has good pressure at the fuel rail, the gauge read about 30ish when i tested it. thats good right? any ideas?

TSEJEEPERS · 08-05-2005, 07:57 PM

This may sound like a stupid question but does your speedomiter work?

myztikrob · 08-06-2005, 12:08 AM

I am having a similar problem with my 88 I4 what does the speedometer have to do with it. mine hasnt worked since i bought it and it just started doin that a few days ago

Jeeper Kreeper · 08-06-2005, 10:36 AM

I have an 87 with 4.2 in it and it does it real bad. I have to triple pedal it a lights or it will stall. Its a real pain in the ***. Check over your vacume lines. I have a few bad ones and thats probley why mine runs like junk.

dcafaro · 08-06-2005, 11:57 AM

I'm not too familiar with the all the sensors functions on the 4.0 as I haven't had to do anything yet on mine. But it does sound like a sensor issue, TPS CPS(although this one is either works or it doesn't), MAP, also check your O2. Go to the auto parts place and have them scan for codes anyway. Some of the sensors may be failing but not to the limit that triggers the OBD system.

As for the 4.2, chances are if you've already done the tune up (completely) then check your pulse air system under your air cleaner cover make sure both holes have suction. If they do shoot some carb cleaner down the throat of the carb first cold then while at operating temperature and idling. If no luck there spend the 25.00 and the hour of your time and brake down the carb, clean it and rebuild it.

WCoon · 08-06-2005, 07:40 PM

Does it do it right away or only if you are idleing for a while? It definetly sounds like something is causing a plug to foul on one of the cylinders while its idleing. I had a 240SX that had similar symptoms. It turned out to be a fuel injector that was stuck open. It drove fine until you let it idle, then it started missing and flooded that cylinder/fouled the plug. It you let it sit for a while, it would start right up and run fine again until you let it idle. I ended up pulling the fuel rail out about two inches, pulling the ignition coil harness, and had a buddy crank the car. One fuel injector just pissed a constant stream of fuel. BTW, don't do it with a hot engine, fuel goes everywhere!

Also, on my YJ, if I go through water too fast, and my dist. gets wet, it will start missing. I pulled over after it happened once, and I had spark on all 6 cylinders at the plug boots. I changed my #5 plug since the plug wasn't firing, and it ran fine. Also, if I just nurse it home, and let it sit overnight, its fine the next day.

I think that your problem is a weak spark. I would change the ingition coil and the ignition coil wire if you haven't already. If your running any power mods, I would upgrade the coil to an aftermarket one.

StuckInMud94 · 08-06-2005, 08:57 PM

Quote:

Originally Posted by WCoon

Does it do it right away or only if you are idleing for a while? It definetly sounds like something is causing a plug to foul on one of the cylinders while its idleing. I had a 240SX that had similar symptoms. It turned out to be a fuel injector that was stuck open. It drove fine until you let it idle, then it started missing and flooded that cylinder/fouled the plug. It you let it sit for a while, it would start right up and run fine again until you let it idle. I ended up pulling the fuel rail out about two inches, pulling the ignition coil harness, and had a buddy crank the car. One fuel injector just pissed a constant stream of fuel. BTW, don't do it with a hot engine, fuel goes everywhere!

Also, on my YJ, if I go through water too fast, and my dist. gets wet, it will start missing. I pulled over after it happened once, and I had spark on all 6 cylinders at the plug boots. I changed my #5 plug since the plug wasn't firing, and it ran fine. Also, if I just nurse it home, and let it sit overnight, its fine the next day.

I think that your problem is a weak spark. I would change the ingition coil and the ignition coil wire if you haven't already. If your running any power mods, I would upgrade the coil to an aftermarket one.

ok how do i fix the injector stuck open problem? and how do i replace/check the coil? i SUCK at working on the engine, everything else i can do so please bear with me lol. thanks for all ur guys info, and yes, my speedo does work lol. this problem usually only happens when im idling for awhile.

WCoon · 08-07-2005, 02:46 PM

Well, if one of your injectors is stuck open, your best bet is to just replace it. You can pick up a new one on the web for around $60.00, or go salvage yard hunting and get one for around $10.00. I ended up buying a complete rail with all the injectors for $45.00 at the salvage I went to. As for the coil, here's a pic:

I would probably do the coil first, since they aren't that exepnsive, and a lot easier to replace then a fuel injector. Another thing to check is your spark plug gap. You also might want to have your compression checked as well. You can do that yourself too, its just a $20.00 tool from O'Rielly's. Just take yout time and go though all the possibilities in the order that seems most logical. The good thing about doing all of your own work is that you will have that knowledge forever, and eventually you will be able to diagnose and fix almost any problem on any vehicle! Too bad you weren't here in Oklahoma City, I love trying to tackle these types of problems!

**madmax79** · 08-08-2005, 04:11 PM

I had the same problem in my '88 4.2, changed distro, plugs and wires. Still the same. Finally checked the timing, problem was solved. It hasn't stalled in traffic yet (knock wood).

boomhower · 08-08-2005, 05:04 PM

check your TPS, MAP, and o2 sensors like someone else said. i had a sputtering/almost stalling problem and it ended up being the Throttle Position Sensor. Are you getting a check engine light? I wasn't, but after pulling my dash apart and putting one in since someone had pulled it out, I found that I myself did. I did the 3 turn key thing and got a code telling me the TPS was bad. Do this and see what happens.

Start your jeep, let it run for a minute.
Turn it off.
Turn the key to the on position, then to the off position.
Turn the key to the on position, then to the off position.
Now turn the key to the on position, and wait about 10 seconds.
The check engine light should blink a certain amount of times, giving you a code as to whats wrong.

Do a search for YJ self diagnostics for the process and codes.

08-06-2005, 12:08 AM	#3
myztikrob Registered User Join Date: Jul 2005 Location: Taunton Mass Posts: 20 Profile Gallery Classifieds My Jeeps	speedometer I am having a similar problem with my 88 I4 what does the speedometer have to do with it. mine hasnt worked since i bought it and it just started doin that a few days ago __________________ [FONT=Times New Roman]Black andJ [COLOR=Red]Red[/COLOR] '88 YJ 2.5 5 speed 31s on 15" cragars custom flowmaster system mostly stock more to come cheap mod suggestions greatly appreciated[/FONT]

08-06-2005, 10:36 AM	#4
Jeeper Kreeper Registered User Join Date: Jul 2005 Location: Mason NH Posts: 2 Profile Gallery Classifieds My Jeeps	I have an 87 with 4.2 in it and it does it real bad. I have to triple pedal it a lights or it will stall. Its a real pain in the ***. Check over your vacume lines. I have a few bad ones and thats probley why mine runs like junk. __________________ Rides: 93 S-10 Blazer 2wd 4/4 drop 350 cid power plant 87 Jeep YJ 3 inch lift 31's busted tranny

08-08-2005, 05:04 PM	#10
boomhower Registered User Join Date: Feb 2005 Location: NJ Posts: 330 Profile Gallery Classifieds My Jeeps	check your TPS, MAP, and o2 sensors like someone else said. i had a sputtering/almost stalling problem and it ended up being the Throttle Position Sensor. Are you getting a check engine light? I wasn't, but after pulling my dash apart and putting one in since someone had pulled it out, I found that I myself did. I did the 3 turn key thing and got a code telling me the TPS was bad. Do this and see what happens. Start your jeep, let it run for a minute. Turn it off. Turn the key to the on position, then to the off position. Turn the key to the on position, then to the off position. Now turn the key to the on position, and wait about 10 seconds. The check engine light should blink a certain amount of times, giving you a code as to whats wrong. Do a search for YJ self diagnostics for the process and codes. __________________ --1991 JEEP YJ 2.5l-- (trail beater) RE 4". AA SYE. TW driveshaft. 33" TSL's. Snorkel. Olympic Rear Bumper. Warn XD9000i. Optima Yellow Top. Herculined Interior, Grill, and Rockers. TJ Flares. Cobra 19DX CB. Firestik antenna.

08-06-2005, 11:57 AM	#5
dcafaro Registered User Join Date: Dec 2003 Posts: 771 Profile Gallery Classifieds My Jeeps	I'm not too familiar with the all the sensors functions on the 4.0 as I haven't had to do anything yet on mine. But it does sound like a sensor issue, TPS CPS(although this one is either works or it doesn't), MAP, also check your O2. Go to the auto parts place and have them scan for codes anyway. Some of the sensors may be failing but not to the limit that triggers the OBD system. As for the 4.2, chances are if you've already done the tune up (completely) then check your pulse air system under your air cleaner cover make sure both holes have suction. If they do shoot some carb cleaner down the throat of the carb first cold then while at operating temperature and idling. If no luck there spend the 25.00 and the hour of your time and brake down the carb, clean it and rebuild it.