4bangerjp.com

General Forums => The Mess Hall => Topic started by: Jeffy on November 29, 2014, 09:55:45 PM

Title: Stutter when launch
Post by: Jeffy on November 29, 2014, 09:55:45 PM
Basically what the topic is.  I get a stutter low in the idle when I'm starting from a stop sometimes.  I can't tell if it's a misfire or something else.  If I rev har, I can power through it and have no stutter.  No codes either.  On the highway, there's no stutter.  If I'm rolling, there's no stutter.  Cleaned the air box and filter.  Re-seated the elbow and made aure the box is sealed.  Swapped injectors a while back when I was getting the injector code.
Title: Re: Stutter when launch
Post by: h20pumper on November 30, 2014, 05:41:51 AM
when is the last time you did a top engine treatment? I have found on every vehicle over 30k that its really helps down low in the rpm.  I take bottle of transfluid because of the heavy detergents its basically engine cleaner. Put a small vacuum hose to your manifold and clamp.it off. Start up the vehicle, now pinch the hose. Your finger is now the throttling the amount of fluid. The engine is going to want to suck that bottle empty, finger tight. I will barely release in small increments until I get a slight stumble. I kept doing this for a few minutes until I get a little white smoke from the exhaust pipe.

I then pull the hose out of the bottle. and quickly shut it down. You have now soaked your head, valves, tops of piston in the transfluid. Wait 10-15 then restart, if possible get in it quickly and drive towards a secluded area. Your exhaust is going to be like a mosquito farmer. All that carbon burning off with the transfluid. first time I did this on my Ford exp sport trac the rpm was idleing up and down 800-1000. after it sat steady at 500.
Title: Re: Stutter when launch
Post by: sharpxmen on November 30, 2014, 07:56:55 AM
do you have a CEL?
my guess is TPS or O2 sensor but then again without a CEL is just a guess. Could be a few other things given that everything else is sound (I mean spark plugs, wires, rotor and cap and fuel filter if applicable): Fuel pressure, CPS, Cam sensor, loose injector wire/connector or even one of the temp sensors (coolant or intake air) - most of these would give a CEL though.
Title: Re: Stutter when launch
Post by: Jeffy on November 30, 2014, 11:36:05 AM
do you have a CEL?
my guess is TPS or O2 sensor but then again without a CEL is just a guess. Could be a few other things given that everything else is sound (I mean spark plugs, wires, rotor and cap and fuel filter if applicable): Fuel pressure, CPS, Cam sensor, loose injector wire/connector or even one of the temp sensors (coolant or intake air) - most of these would give a CEL though.
Like I said no codes.  And other then starting from a dead stop, it doesn't seem to stutter.  When I first drive it for the first time of the day, it doesn't stutter either.  Engine idles fine as well.

I'm wondering if it's maybe the clutch that's slipping a little when it warms up though the engine RPM's don't seem to rise.
Title: Re: Stutter when launch
Post by: chardrc on November 30, 2014, 06:44:25 PM
Could be the clutch. Me old s10 would have similar symptoms when I didn't drive it for a week or more. Had 180k on the clutch and a rear main leak so it was prone to sliping...
Title: Re: Stutter when launch
Post by: Jeffy on November 30, 2014, 06:54:24 PM
Could be the clutch. Me old s10 would have similar symptoms when I didn't drive it for a week or more. Had 180k on the clutch and a rear main leak so it was prone to sliping...
I need to pay more attention to the RPM and see if it rises.  If I slip it I can get through with a stutter.  The clutch is original with 87K miles.
Title: Re: Stutter when launch
Post by: sharpxmen on November 30, 2014, 09:13:55 PM
does it stutter when you're stopped and press the gas? clutch is more of a shake than a stutter, I've had it and it's pretty clear is not the engine.
Title: Re: Stutter when launch
Post by: Jeffy on November 30, 2014, 09:30:16 PM
I haven't pressed the throttle while stopped.  With trans in neutral I'm assuming.  I'm wondering if it's the CPS.  They throe off all kinda of weirdness when they go.

Might get some Autolite Copper plugs and a new PD ignition kit...
Title: Re: Stutter when launch
Post by: h20pumper on December 01, 2014, 03:31:06 PM
top engine treatment
Title: Re: Stutter when launch
Post by: sharpxmen on December 01, 2014, 07:34:31 PM
top engine treatment
won't do anything for this.
Title: Re: Stutter when launch
Post by: VA_YJ on December 02, 2014, 03:23:12 PM
Jeffy,

I had a similar issue that turned out to be spark plug related.  If I remember correctly, you are running a wider gap than stock, which provides a hotter, longer spark, but also accelerates electrode tip errosion.  The gaps open up (I verified this with feeler gauges) and the motor starts to stumble a bit under load.  I have gone back to a stock gap.

As far as the clutch/flywheel/pressure plate possibility, does the stumble only happen when the clutch is starting to grab, or does it continue after you have fully engaged the clutch?
Title: Re: Stutter when launch
Post by: Jeffy on December 02, 2014, 03:33:17 PM
Jeffy,

I had a similar issue that turned out to be spark plug related.  If I remember correctly, you are running a wider gap than stock, which provides a hotter, longer spark, but also accelerates electrode tip errosion.  The gaps open up (I verified this with feeler gauges) and the motor starts to stumble a bit under load.  I have gone back to a stock gap.

As far as the clutch/flywheel/pressure plate possibility, does the stumble only happen when the clutch is starting to grab, or does it continue after you have fully engaged the clutch?
it's happening while the clutch is out all the and I'm on the throttle only.  I regapped by plugs a few months back but I probably should have just replaced them.  I'm running Autolite Platinum's.  I'm thinking about going with their copper line since Jeeps tend to like those better.  Just means I'll have to change them more often.
Title: Re: Stutter when launch
Post by: VA_YJ on December 03, 2014, 03:01:41 PM
I'm running the Champion copper plugs with good results.  You have to change them more often, but they are inexpensive.
Title: Re: Stutter when launch
Post by: Jeffy on December 03, 2014, 03:39:39 PM
Yeah, I when I wasn't running platinum's, I'd change the plugs more often.  Since coppers are $1.99 it's not an issue at all.  Platinum's are going to be a bit more.  I've always heard good things about copper plugs and crappy things about Platinum's or even Iridium's in Jeeps.  I started running the platinum's because they were given to me to test with the PD system.  I was thinking about going copper when I was running my old Jacobs system though.
Title: Re: Stutter when launch
Post by: Jeffy on December 03, 2014, 06:45:23 PM
Well, I ended up buying a new PD (red this time) kit as well as some Autolite Copper plugs.  Should be here in a week or so.  Hopefully this will fix the stutter.
Title: Re: Stutter when launch
Post by: h20pumper on December 04, 2014, 05:03:05 PM
won't do anything for this.

disagree
Title: Re: Stutter when launch
Post by: sharpxmen on December 04, 2014, 08:03:18 PM
disagree
well, still won't do anything  :lol:
Title: Re: Stutter when launch
Post by: Jeffy on December 06, 2014, 04:26:44 PM
Paid more attention to the RPM's.  THe RPM's stay low then jumps when the engine catches up and stops stuttering.  It's like losing cylinder then when the RPM's pick up it climbs to 1000 rpm and is okay after that.  No hesitation when reving the engine while in neutral.
Title: Re: Stutter when launch
Post by: Jeffy on December 13, 2014, 05:17:48 PM
So, here's the verdict.  It seems the spark plugs were bad.  Today it's gone and the Jeep pulls stronger as well.

I've got a PD Firewire set coming next week that I'll swap in and use my original as a backup.

Oh and with the heavy rain and winds we have had, I noticed the Jeep does still leak from somewhere.  I can't tell if it's the dash or the door.  Not really too worried about that though.  I just need to pony up and get a new door seal kit.
Title: Re: Stutter when launch
Post by: dwtaylorpdx on December 27, 2014, 01:41:50 AM
well, still won't do anything  :lol:

The only condition I've seen helped with the top end treatment (Oil, Seafoam, Mystery oil etc)
was an engine with carbon fouled rings, that had been parked. It had a lot of blow-by and using
the seafoam on it got the compression back and freed up the oil rings.  A buddy of mine that owns a wrecking yard
used Marvel oil in the cylinders and lets them soak for a day or two when he's prepping a motor to be sold that's been sitting.

You don't have to run the motor, just take the plugs out and and dump the Marvel in , about 1/4 cup each hole.
Let it sit with the plugs in for a week and then spin it with the plugs out to expel the oil. then fresh plugs, wires
and start er up. will smoke a field out till it gets warm. If you pull enough yard motors apart you find a lot with
the pistons corroded and the rings froze in them..

Title: Re: Stutter when launch
Post by: Jeffy on December 27, 2014, 12:15:07 PM
Carbon build up isn't usually a problem with my Jeep.  I typically rev upwards of 5000 RPM and do long road trips which keeps carbon buildup at a minimum.