wierd stutter from stop
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wierd stutter from stop
i recently acquired a 96 ford f250 with the 351 in it but have noticed a stutter in accelaration from a dead stop or if i'm at a slow speed like in a parking lot without using much accelarator. i do have an exhaust leak that is going to be taken care of soon when i decide on a set of headers. i know this will help make my truck run better to fix the leak but i also notice that my battery voltage drops to around 9.5 volts at stop lights assuming my battery gauge is accurate and goes back up to the normal operating voltage when i start to accelarate again. it doesnt do it as bad when my truck is cold and trying to warm up with it idleing higher. my alternator seems to be charging decent putting out 13.6 volts which seems acceptable and battery was tested at almost 100 percent health. im new to fords so i'm a little lost.
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ill get the cap, rotor, and coil tomorrow. those are at least a few items that wont cost me to terribly much that should be changed anyways so i know i'm starting fresh since i don't know the last time the previous owner changed them. i need to get them done quickly or it will have my curiousity going wild about what it could be till i figure it out.
Posting Guru
Joined: Sep 2008
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From: Baltimore
I'd look into the fuel filter, and adding fuel treatment. Also, spray your butterfly valves and air intake ports. (They get really gunked up.)
Have ya hit the hi-way, yet? After doing all those I mentioned, take it on the hiway, and run her good for a spell. Be safe, and dont get a ticket or anything, but put your foot into it when traffic permits.
Have ya hit the hi-way, yet? After doing all those I mentioned, take it on the hiway, and run her good for a spell. Be safe, and dont get a ticket or anything, but put your foot into it when traffic permits.
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ya ive taken it on the highway. i only notice the stutter right when i start to leave from a dead stop or in a parking lot going very slow. ive tried fuel treatment and that didn't work. ill try the fuel filter and then make sure there is no gunk build up like you mentioned.
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Postmaster
Joined: Oct 2008
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From: Renton, WA
Sorry buddy you need an alternator!
You need to take care of the low voltage at idle, the low voltage is causing your ignition to be too weak and miss (stutter). At ANY time while your running your voltage should NEVER drop below 13V. It is dropping at idle because your alternator is starting to go. Alternators are actually three phase generators with a diode in each phase so it puts out DC. One or two of these can go and the other will still work. That is what's happening one or two are out and it doesn't have enough power to keep up at low speeds. But as soon as it has some RPM the one or two that are working can do the job and your voltage goes back up telling us the regulator is good.
A cheap fix is to just replace the diodes, they are usually the part that goes, test them first. If this is above your head, just get a new or rebuilt alternator and call it a day, that will take care of it.
You need to take care of the low voltage at idle, the low voltage is causing your ignition to be too weak and miss (stutter). At ANY time while your running your voltage should NEVER drop below 13V. It is dropping at idle because your alternator is starting to go. Alternators are actually three phase generators with a diode in each phase so it puts out DC. One or two of these can go and the other will still work. That is what's happening one or two are out and it doesn't have enough power to keep up at low speeds. But as soon as it has some RPM the one or two that are working can do the job and your voltage goes back up telling us the regulator is good.
A cheap fix is to just replace the diodes, they are usually the part that goes, test them first. If this is above your head, just get a new or rebuilt alternator and call it a day, that will take care of it.
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Sorry buddy you need an alternator!
You need to take care of the low voltage at idle, the low voltage is causing your ignition to be too weak and miss (stutter). At ANY time while your running your voltage should NEVER drop below 13V. It is dropping at idle because your alternator is starting to go. Alternators are actually three phase generators with a diode in each phase so it puts out DC. One or two of these can go and the other will still work. That is what's happening one or two are out and it doesn't have enough power to keep up at low speeds. But as soon as it has some RPM the one or two that are working can do the job and your voltage goes back up telling us the regulator is good.
A cheap fix is to just replace the diodes, they are usually the part that goes, test them first. If this is above your head, just get a new or rebuilt alternator and call it a day, that will take care of it.
You need to take care of the low voltage at idle, the low voltage is causing your ignition to be too weak and miss (stutter). At ANY time while your running your voltage should NEVER drop below 13V. It is dropping at idle because your alternator is starting to go. Alternators are actually three phase generators with a diode in each phase so it puts out DC. One or two of these can go and the other will still work. That is what's happening one or two are out and it doesn't have enough power to keep up at low speeds. But as soon as it has some RPM the one or two that are working can do the job and your voltage goes back up telling us the regulator is good.
A cheap fix is to just replace the diodes, they are usually the part that goes, test them first. If this is above your head, just get a new or rebuilt alternator and call it a day, that will take care of it.
Postmaster
Joined: Oct 2008
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From: Renton, WA
Sure but is your voltage low at idle? Test the voltage at your battery with the headlights and heater fan on high, at idle, and in gear if possable to get the lowest idle speed.
Postmaster
Joined: Oct 2008
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From: Renton, WA
The testers at auto parts stores just spin them fast and check for voltage, it will say yours is good, but won't say how good. They have no way to test for proper amperage at idle speeds. Running it on the truck as I described is a MUCH MUCH more accurate test.