Topic: Stutter when launch

[Jeffy]

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.

[h20pumper]

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.

[sharpxmen]

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.

[Jeffy]

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.

[chardrc]

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...

[Jeffy]

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.

[sharpxmen]

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.

[Jeffy]

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...

[h20pumper]

top engine treatment

[sharpxmen]

top engine treatment

won't do anything for this.

[VA_YJ]

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?

[Jeffy]

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.

[VA_YJ]

I'm running the Champion copper plugs with good results.  You have to change them more often, but they are inexpensive.

[Jeffy]

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.

[Jeffy]

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.