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Unread 04-18-2014, 10:37 PM   #1
spiceminer
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HEMI studder, MSD issues. helppppppp

cleaned throttle body, replaced all 16 plugs, new egr, new air filter, changed oil 5w20.

hesitation at low rpm is pretty much gone, but hesitation at cruising speed is very bad mds keeps turning off and on off and on, its really annoying me need to figure out a way to get this thing running right. just bought it for the wife


Last edited by spiceminer; 04-19-2014 at 09:34 PM..
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Unread 04-18-2014, 11:25 PM   #2
CactusPillow
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Quote:
Originally Posted by spiceminer
cleaned throttle body, replaced all 16 plugs, new egr, new air filter, changed oil 5w20. hesitation at low rpm is pretty much gone, but hesitation at cruising speed is very bad msd keeps turning off and on off and on, its really annoying me need to figure out a way to get this thing running right. just bought it for the wife
What brand spark plugs did you use? Did you change out the wires too? Had similar issues when I bought mine with stuttering and the new champion copper plugs and Taylor Shorty wires helped a lot. Also check the pcv valve and map sensor. My PCV was very gummed up and barely functioning. The MDS can be annoying still and I plan on disabling mine this weekend with the use of the Flashpaq tuner. Not worth 2 mpg difference for the jeep to run like s**t in my opinion. Will let you know how it works out. Get yourself a catch can and your engine will thank you. Good luck.
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Unread 04-19-2014, 12:46 AM   #3
spiceminer
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champion Will try pcv tomorrow. 300+ bucks to turn off MDS is a *****
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Unread 04-19-2014, 03:18 PM   #4
spiceminer
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changed pcv still does it
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Unread 04-19-2014, 05:40 PM   #5
90grandoneer
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Definitely check the spark plug wire resistance, especially if it has more than about 75K on it and they look like they've never been changed. A new wire (~3 ft. long) should have a resistance of around 18000 ohms. Rule of thumb is no more than 10000 ohms per foot. If they exceed that, get the Taylor Shorties. Much better. Can you describe the hesitation at cruise.....speed(s) it occurs at, gear it is in, any drastic change in RPM? How many miles are on the Jeep? Have you serviced the transmission (fluid/filters) lately? First check the fluid level (trans. hot...after about 30 miles of driving) and the fluid condition. As far as the MDS goes, there are many things that cause it to work....or not work. One of the main things is engine load. Any excessive drivetrain drag, poor tune, transmission/transfer case issue(s), brake drag, tire condition/pressures, alignment, etc. will have an effect on how well the MDS works.

Since this vehicle is new to you I would recommend a full service of all drivetrain components, so you know exactly what has been done, and how it has been done. When I bought mine 4 1/2 years ago, it had been serviced by the stealer and had many (mostly small) problems. Once I fixed everything, I've only had an EGR Valve and and O2 Sensor fail.

CactusPillow, did you get the Advanced Trans. Tuning App. with your tuner? If not, IMO, you should. You can tune out all the crappy shift schedules and make it (trans.) and the MDS work 100 times better than stock. With my custom shift schedules and torque management settings, my modded 5.7 (see signature) works fantastic, and I wouldn't think of doing away with MDS. With nearly 100 hp. more than stock I still get 12-15 (usually 13-14) mpg in town, and a best of 24.4 (usually 22-23) mpg on the highway. In town my MDS "on" time is about 50% or better, and on the highway, it's usually 90+%.
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Unread 04-19-2014, 06:12 PM   #6
spiceminer
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Plug wires look like stockers, it has 150000 miles. Tranny acts fine haven't done anything with it yet. I'll check the fluid in a min. When the MDS comes on and off the rpms move about 150 rpm.

The hesitation is the worst at about 40mph and 60mph. When the rpms are 1100-1500

The transition fluid is full and smells/looks fine
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Unread 04-19-2014, 06:30 PM   #7
spiceminer
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I measured two wires and one was 10.6k and one was 13.5k
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Unread 04-20-2014, 11:02 AM   #8
90grandoneer
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MDS RPM drop is about right, as is the resistance in the wiring. You may want to check the rest of them, just for giggles, although I don't think that will cause your issue. I would still do the transmission fluid/filter change though, if for no other reason that you don't know if/when it was done.

What gear are you in when the hesitation occurs? You may want to see if it happens the same way in the next lower gear. A couple other things, if you are not aware......as far as the transmission goes, there is a torque converter clutch that locks up the converter under certain conditions. Sometimes the MDS and coverter clutch engage/disengage get "tangled up" with each other and will cause a slight hesitation or bump, more when in a low engine load condition and trying to accelerate. Also, I am sure you are aware, the Hemi throttle control is electronic (fly by wire) and does have a slight lag. Perhaps you need to reset the throttle. There is a so-called reset that I have found to be of limited value, but maybe it'll help you. BBK, the aftermarket throttle body manufacturer, says to do the following "Throttle Position/Gas Pedal Relearn" procedure when installing a new throttle body. It is suppose to work anytime there is excessive throttle lag though. They call it re-syncing the gas pedal and throttle body. Here's what they say to do:

1. Disconnect the battery for 5 minutes. Reconnect.
2. Use a code reader to clear any stored codes in the computer.
3. Turn the ignition key to the on position, but do not start the engine.
4. Slowly depress the gas pedal to the floor, then slowly release it. Do this three (3) times. Turn key off.
5. Now start the engine. The gas pedal is now in synch with the throttle body.

You may want to give this a try to see if it makes any difference. I didn't do this "relearn" with either BBK throttle body I installed on my two Hemi vehicles (90mm on my Hemi WK and 85mm on my Hemi LX) and didn't notice any throttle response difference from the stock units. I do have tuners on both vehicles (Superchips on WK and Diablosport on LX) though. Both tuners have, as part of their programming, throttle sensitivity/response features. Good luck, and let us know how it goes.
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Unread 04-20-2014, 11:47 AM   #9
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I got the acceleration hesitation out of it by doing the tune up and egr valve. But it just stumbles and hesitates trying to cruise with the MDS on. Mostly at 40mph and 60mph.

I'll do a trans service on it and maybe install a dehrale pan if they make one for it.
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Unread 04-20-2014, 09:40 PM   #10
spiceminer
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this MDS is junk. pretty disappointed by this motor. i had a 04 hemi without MDS it was a lot better. should stick to LSx powered vehicals
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Unread 04-21-2014, 03:51 PM   #11
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after running some fuel injector cleaner through it, wife reports the problem is not as bad anymore. says she got 23mpg on the freeway this morning
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Unread 05-16-2014, 12:01 AM   #12
spiceminer
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problem has been the same and bad, don't trust the wife to report how a engine is running.

cut the 1/2 & 2/1 o2 sensor wires runs like a top in open loop. gotta get the new ones in now.
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Unread 05-16-2014, 10:01 AM   #13
90grandoneer
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I'll bet at least some (and maybe all) of your hesitation problems are caused by the lousy transmission schedules. If you got a Superchips Tuner with the Advanced Transmission Tuning Application, I am sure you could eliminate most, if not all of your problems.
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Unread 05-16-2014, 12:13 PM   #14
spiceminer
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Quote:
Originally Posted by 90grandoneer View Post
I'll bet at least some (and maybe all) of your hesitation problems are caused by the lousy transmission schedules. If you got a Superchips Tuner with the Advanced Transmission Tuning Application, I am sure you could eliminate most, if not all of your problems.
i'm not talking hesitation like it hesitation when I step on the gas, i'm talking like shuddering, bucking, ****ty running motor type of bull****.

the only way I could see it being the transmission is if it was locking and unlocking randomly. but I can tell its just a ****ty running motor, it needs new o2 sensors put in
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Unread 05-20-2014, 05:59 PM   #15
spiceminer
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new o2 sensors, still runslike ****. only runs well with a CEL on hemi junk.

probably wouldn't use mds with cell on i'm guessing. runs so bad, jerky
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