Please someone help! Engine stumbling and bucking
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New User
Joined: Aug 2010
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I actually went with Accel cut your own to length. I was told that the factory wires were crap and they can cross contaminate if they are close to each other (especially cyl 7 and 8). I put them on before the shop changed the distributor and the van ran great with them on for 2 months. I'm pretty confident that they aren't the problem. And yes, the little metal heat Shields around all the plugs are still in place. I was actually thinking about changing the wire again though with some type of quality stock length kit. Any suggestions?
Lead Driver
Joined: Aug 2006
Posts: 5,670
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From: Sand Lake, MI
Unless you have a quality crimp tool to use to put the ends on you probably should avoid the cut your own type wire sets. A good solid crimp that will hold doesn't come easy and not at all with a made in china kinda tool!
Even with a quality crimp tool I won't by the wires you put the plug end on, I only buy the wires you trim and put the cap end on the wires.
Might want to inspect them all at that end, you or the someone at the shop might have pulled a wire end part way out or off while working on it without realizing it. Has taken a few miles to show symptoms/suffer from it.
Even with a quality crimp tool I won't by the wires you put the plug end on, I only buy the wires you trim and put the cap end on the wires.
Might want to inspect them all at that end, you or the someone at the shop might have pulled a wire end part way out or off while working on it without realizing it. Has taken a few miles to show symptoms/suffer from it.
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Ya, I'm leaning toward just replacing them again with something else. Any suggestions on a quality set that is not a cut to length? I'd like to just install them out of the box!
I'm a little hesitant replacing them with Autozone duralast ones. I'm afraid they could be worse than stock!
I'm a little hesitant replacing them with Autozone duralast ones. I'm afraid they could be worse than stock!
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Joined: Aug 2010
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I will not ague that the best thing to do is bring it back to the shop that did the work last. My only issues with that are 1 they charge $120 an hour labor because it's a large shuttle bus and 2 that it's our only work vehicle (been converted to a mobile pet grooming van) so we would be losing $200+ a day in revenue. Thank god it's still drivable, so I've been trying to work on it daily after my wife is done with her day and on the weekends. I'd really like to fix it myself if I can. The last time the shop had it, it was there for 4 days!
If anyone has any insight as to what I could have missed, please let me know. I'm very much open to suggestions! Just as a reference, below is a list of everything that has been checked or changed recently.
Please Please someone chime in!
Changed:
Fuel Filter
Plugs
Wires
Cap and rotor
Distributor
Coil
O2 Sensor
PCV Valve
All Injectors
Fuel pump in the tank is 4 months old and cat is about a year. Don't think either of those is the problem.
I pulled off the Idle Air Control valve and cleaned it. Also pulled vacuum on the EGR valve to insure the diaphragm wasn't bad and the valve wasn't stuck.
Also used a vacuum gauge to verify there isn't any vacuum leaks.
Checked base timing with spout disconnected (10 deg advanced which is correct for that year) and with spout connected to ensure the computer was controlling it properly.
Also, NO codes in the computer beside code 11 which means system pass.
If anyone has any insight as to what I could have missed, please let me know. I'm very much open to suggestions! Just as a reference, below is a list of everything that has been checked or changed recently.
Please Please someone chime in!
Changed:
Fuel Filter
Plugs
Wires
Cap and rotor
Distributor
Coil
O2 Sensor
PCV Valve
All Injectors
Fuel pump in the tank is 4 months old and cat is about a year. Don't think either of those is the problem.
I pulled off the Idle Air Control valve and cleaned it. Also pulled vacuum on the EGR valve to insure the diaphragm wasn't bad and the valve wasn't stuck.
Also used a vacuum gauge to verify there isn't any vacuum leaks.
Checked base timing with spout disconnected (10 deg advanced which is correct for that year) and with spout connected to ensure the computer was controlling it properly.
Also, NO codes in the computer beside code 11 which means system pass.
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New User
Joined: Aug 2010
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Hey Guys, I'm back again for help!
It's been almost 2 months now and the truck is still missing under load!
I finally gave up trying to figure it out myself and took it back to the repair shop that originally figured out the distributer was bad a while back.
They had the truck for 3 days trying to figure out what was wrong and I just picked it up today. After 3 days of troubleshooting, they can't seem to figure it out either.
I'm so irritated with this truck! It feels like a fuel related issue, but according to my fuel pressure gauge and the shops, the fuel pressure is perfect! Could this be a PCM issue? Is it possible the PCM is not changing the injector pulse for load. Map sensor is sending a clean signal so I could only assume the PCM is messed up!
Please someone chime in here! Take a look through this post and you will see all that's been changed and checked. I'm loosing my mind over here! Any help is greatly appreciated!
Thanks!
It's been almost 2 months now and the truck is still missing under load!
I finally gave up trying to figure it out myself and took it back to the repair shop that originally figured out the distributer was bad a while back.
They had the truck for 3 days trying to figure out what was wrong and I just picked it up today. After 3 days of troubleshooting, they can't seem to figure it out either.
I'm so irritated with this truck! It feels like a fuel related issue, but according to my fuel pressure gauge and the shops, the fuel pressure is perfect! Could this be a PCM issue? Is it possible the PCM is not changing the injector pulse for load. Map sensor is sending a clean signal so I could only assume the PCM is messed up!
Please someone chime in here! Take a look through this post and you will see all that's been changed and checked. I'm loosing my mind over here! Any help is greatly appreciated!
Thanks!
Thread Starter
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New User
Joined: Aug 2010
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Thanks for the suggestion, I'll see if I can do it! I know I can get to 5 out of 8 cylinders. 3 cylinders are very hard to get to on these dumb vans.
If anyone else has some suggestions, please let me know!
Thanks!
If anyone else has some suggestions, please let me know!
Thanks!
New User
Joined: Jan 2011
Posts: 7
Likes: 0
That was exactly my problem. While replacing the heater fan my FAT HAND had worked a vacuum line lose. After taking a break and another look under the hood I spied the loose tube. All's well. Really explained why it ran fine BEFORE I lifted the hood and replaced the fan.
Swammie
Swammie
Don't forget vacuum leaks! Bucking and stumbling are classic symptoms of a vac leak.
There's several different methods for checking for them. What I've done in the past is unhooked every vac line from it's apparatus [such as the EGR or vac canister], plugged them, and then, with the engine running, hook them back up one by one. If a particular component is bad, the engine will start the bucking and stumbling. Granted, your problem is under acceleration so this may not work, but you might get lucky.
Also check the TPS. You may not have an error code for it but that doesn't mean it's not bad.
There's several different methods for checking for them. What I've done in the past is unhooked every vac line from it's apparatus [such as the EGR or vac canister], plugged them, and then, with the engine running, hook them back up one by one. If a particular component is bad, the engine will start the bucking and stumbling. Granted, your problem is under acceleration so this may not work, but you might get lucky.
Also check the TPS. You may not have an error code for it but that doesn't mean it's not bad.
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New User
Joined: Apr 2008
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Any more input from these old threads concerning this problem. It's been awhile since the last post so I'm hopeful that someone will come back and share some updates.
My 94 F350 7.5L idles fine but falls on it a$$ when I press on the accelerator.
Thanks Guys!
My 94 F350 7.5L idles fine but falls on it a$$ when I press on the accelerator.
Thanks Guys!
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
Flat spots/ poor throttle response are most ofter related to combustion chamber carbon build up & poor fuel atomization due to injector fowling. Relatively easy fix & cheap date to restore. I'd post more on that, but gotta make a store run. Back later.
Senior User
Joined: Feb 2003
Posts: 247
Likes: 0
From: Greenville, NC
I ran through this nightmare with my truck, too. Ended up being a bad ignition module. Problem went away for about 50 miles when I replaced it with a non-Motorcraft one, then resurfaced; but ever since I used a Motorcraft module I haven't hand any stumbling problems.
Der Postmeister
Joined: Sep 2006
Posts: 6,859
Likes: 560
From: Long Beach, Calimexiforia
I ran through this nightmare with my truck, too. Ended up being a bad ignition module. Problem went away for about 50 miles when I replaced it with a non-Motorcraft one, then resurfaced; but ever since I used a Motorcraft module I haven't hand any stumbling problems.
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