My 1998 f150 4.6 has a strange shutter at about 38-40 mph @ about the time it is going to shift. Kind of a vibration like a clutch chatter from a leaky rear main(I have an automatic). It does not happen at higher rpms. I also have a rpm jump when I drive then let off the gas and then apply throttle. sort of like it's clutching. Any thoughts?

 

What gear is it in when it starts to shudder? 2-3? When you let off the gas (the tranny goes into engine braking mode), is the tranny trying to engine brake 3-2? More details would be neccessary, especially if it needs professional help.

Any add on items?
Shift linkage adjustment?
does the problem occur on:
upshift
downshift
coasting
rpm dependent,vehicle speed dependent, shift dependent, or gear dependent.

Whether anyone here can help or not, if you try and get every detail, you can better explain to a tranny expert.

I'll get out my manual for my 4r70w\AODE to help if I can...

 

My '97 f1`50 w/4.6L does that also. Very rough/hudder. Seems to be in either 3rd or OD whenever TC clutch engages. Mostly when accelerating very lightly. Sometimes the check engine light will come on, expecially if I'm pulling a trailer, but never stays on long enough to get the code pulled.

 

Change your trans. oil(including draining torque convertor) & filter. I'll bet that takes care of it.

 

I had the same shutter problem with my 98 4.6l automatic and found I had 3 bad plug wires that were causing spark loss when I tried to accelerate. I changed the plugs and the wires and my transmission works fine. No shutter from 3rd to OD at any speed. The engine could not produce enough torque because the wires were failing under load. Everything worked fine once up to speed. Only shifting from OD to 3rd while climbing hills or pulling a load caused the shutter.

Still working like new with 198,000+ miles.

Mark

 

I had a similar episode with my '97 v6 w/4r70w shudder in OD. The previous thread was on the money about the motor not having the torque available to engage the OD. The OBD 2 computer takes in so much info that affects the tranny shifting patterns... Incoming air temp, water temp, egr system etc. If you had the light come on, most likely a sensor around the motor is failing and coughed out a code. My DPFE sensor (the al' square box that reads Differential Pressure Flow through the egr tube). This sensor connects to the tube before and after a restricted passage yeilding a voltage change at the harness. This $124CAN part cut me down on power causing a code, and transmission shudder as you described. It could be so many things affecting power, that most times the tranny is not to blame. I also had shuddering when my plugs started fouling up a bit...The shuddering got worse until I changed the plugs/wires. Good as new for a Ford until the 1-2 accumulator o-ring went for a Florida monsoon break....

 

menmytruck,

Please take a look at my post from the v-6 forum (pasted below) and let me know if this is similar to what you experienced. Like you, I believe the problem lies somewhere in the engine or emission control systems.

Matt

All,

I have a 2001 V6 with 42K on it and I just recently noticed that the engine appears to shudder intermittently while I'm driving. The engine idles fine and the problem is most noticable while I'm at highway speeds: 65-70mph. The problem does come and go, and while it's happening if I back off the gas the shuddering will actually get worse. However, the problem usually goes away within a mile or two.

Any ideas as to what might be causing this? Seems like a emission control or other sensor issue to me, like maybe my O2 sensor is on its way out. Any input on this would be welcome! Also, if anyone knows how to read codes without a computer that would be great! I prefer to do my own maintenance and my manual has nothing on the topic.

Thanks,
Matt

 

First make sure the EGR is not seized, and indeed working...Attach a vacuum hose to the ege valve and while it is idling, suck on the hose-it should run very rough. Okay, now take a short piece of that vacuum hose and attach it to the egr valve again and stick in a gold tee in it to plug it. Now put another tee in the original hose that attached to the egr, and plug that one. Go out for your ride at 65-70mph. This will not allow exhaust gases to enter the intake at all, and if it still shudders, you've eliminated the EGR system. Keep in mind that your motor will run slightly hotter during this exercise, so don't do it more that a couple of hours IMHO.

Now if it does shudder, prepare to purchase the DPF sensor (approx 3.5"x2"x .5" aluminum block with two hoses leading into it, with an electrical connector). This cost me $124 Canadian at the Ford dealer ($1 US =~ $1.29 Canadian). Write down the part number off the part to give Ford in case of any ordering problems....The electrical connectors also went green (corroded) on my fathers 95 Explorer. You can disassemble the connector, and one by one clean each pronge to scrape and clean them (takes approx 5-10 minutes per pronge). Also the regulator that controls the egr may be at fault, so if the DFP sensor doesn't fix it, then, try that one. Good luck, and email me personally if you like (owen at iaw.com ) of coarse replacing the 'at' with '@' to prevent spam bots from scavenging email addresses from forum pages...

 

Thanks for the detailed input!

I won't have time to get too deep into troubleshooting the problem until next weekend, but I will let you know how it turns out based on your advice. The way the truck behaves, though, I definitely think we're on the right track when it comes to which system to suspect and T-shoot first.

Thanks again,
Matt

 

All,

Well, it might be too early to tell, but I think I might have found & fixed the issue that's been causing my shudder problem--thanks to the direction provided by you all & this forum!!!

In short, as advised, I went through the emission system part by part and reseated and, in some cases, cleaned the connectors on all the major sensors involved. I didn't really see any major corrosion on any of them, but since going through the system everything seems to be running smoothly. Again, I hope I'm not calling it good too early, as there may be a sensor on its way out, but all seems OK now.

Thanks again,
Matt