AircraftTech

Ok the other night I was passing someone and in 4th at about 4 thousand rpms the car kind of stuttered in and out, it was windy out so I thougt nothing of it. Last night I was on the highway at about 3AM so I thought I would check it again. I was going about 105 or faster in 4th gear and was slowly winding that gear out when the crasy stuttering / hesitation got really bad! I backed off the gas and the check engine light came on, and off about 5 times and then went out. The car only does it at high speed and works great and has all its power from a start all the way to 100-110, then the problem returns. I'm stumped, ony one have any ideas?

pittperson

Add another person to the list.

I've been trying to pin point this problem for about 5 months now. I have the C&L with the 93 octane diablo tune. This only happens to me if I have been holding a constant speeds for > 30min. When I downshift to 4th and get on it, the car completely chokes. This is not a problem durning normal daily driving. I am heading out to Pittsburgh (which is when I experience the problem the most) for Thanksgiving and will reinstall my stock airbox and tune before I leave to see if that cures the problem.

There are a couple other people on the board that have experienced the same problem but no one knows what the deal is. I've been sending PMs back and forth to Boltzman who seems to be having the same problem in his auto tranny when he tries to pass someone.

AircraftTech

thanks, looks like a C&L software problem. I wonder if there is a better tune out there???

300HPGT

I have a manual and when Im just crusing along and I go to down shift and punch it it falls flat on its face and then slams you in the seat. I have also had it do that while just normal driving. Its as if the throttle completely closes. It almost sounds like a computer error. but we all have the C&L with the Diablo Sport tuner. I think its time to switch over to SCT. Im really sceptical about my diablo now. I however havent noticed any shakes besides that I need to have my tires re balanced.

Rebel73

woah, now you guys are making me nervous. I have the same setup. I can't say I've noticed the same problem, but then again I haven't been over 100mph much. Guess I need to test it out now!

KWMJ-KTP

I'm not sure that this is being caused by the CAI or tuner, since I've not installed either on my car, and it does just as you describe.

This has happened to me 3 times in the past few weeks with the automatic, and strangely in the exact same place all 3 times under the same conditions.

On my way to work, I drive about 32 miles on the interstate maintaining a speed of 70 to 80 MPH. My off-ramp goes up hill and has a traffic light up at the top. When coming up the ramp it turns to the right just a bit, where I coast down to probably 45-55 MPH, and then there is about a 45 degree turn to the left still going uphill. Once I come around that 45 degree left turn, I can see the if the signal which is probably 100 yards ahead is red or green. If it's green, and there is no traffic in front of me, I will punch the gas to make sure I make the light, and that's when it happens.

It downshifts, you feel it push you back for just a hair of a second and then it falls flat and sounds as though the engine has died, and then it comes back promptly throughing you back into the seat. It lasts maybe half a second. After this, I can punch it again on the main road and it acts perfectly fine.

It sure sounds like the same issue you guys have described, but the only mods I hve completed are the Underdrive Pullies and the Flowmasters. I was actually thinking that maybe it would go away after I put on the C&L and the SCT Tuner in a couple weeks, but maybe not.

pittperson

Although this sucks, it's making me feel a bit better that there are actually more people out there with this problem. Hopefully more people will see this an we can figure out what the problem is.

I can get around the problem if I downshift to 4th and slowly ease into the throttle as opposed to just mashing it to the floor.

WB2005GT

This happened to me one time after maintaining about 80 mph for 45 minutes. I have the C&L but my tune is an SCT.

pittperson

So it has happened with autos, manuals, stock air boxs, C&Ls, predators, and SCTs.... sounds like a factory problem that Ford needs to look into to me.

bamaburnum

Even if it is a factory problem, it may be hard to get a dealer to test at those speeds. If it doesn't show up on the computer, they would have a hard time finding out what is wrong. My dealer won't test drive much over the speed limit. The techs don't want to risk getting a ticket and losing their job.

pittperson

True. Add to the the fact that it doesnt seem to happen unless you hold a constant 70+ mph for about 30min.

300HPGT

they need to put the cars on a dyno that will simulate these conditions. To bad dealerships didnt have that option. I feel that it would be more benificial to the customer too and you dont have to worry about them testing your car like the valet guys on "Ferris Buler". But yeah i thinks its the factory computer that is the issue and there is a bug in the Fly By Wire section.

clockworks

This has happened to me once a long time ago. I was on the highway and downshifted to third and it felt like the engine completely died for a half second, sending my head towards the steering wheel, then it kicked in slammed me back in the seat.

I can't remember what mods I had then, but I want to say I was completely stock.

Also, I think I had just got on the freeway...i.e. I hadn't been holding a constant speed for a while.

I may be wrong about what I remember, it was a while ago and only happened once.

lodom

Isn't there a way to datalog the activity in the computer while simulating the driving conditions this happens under? This would help pinpoint the problem, since it can be duplicated.

If not, I'd take the car into the dealer and explain the situation to them. If it takes a 20+ mile ride with a tech, I'd be willing to do it. Maybe the dealer's tech can help if he knows what he's looking for. He may not immediately know what is causing the problem, but at least he does have Ford's engineers to assist if necessary.

pittperson

Good idea. Anyone know what I should datalog for this situation? I'm heading to PA for thanksgiving and would like to give this a shot.

SaleenPowr

Wow! This happened to me also on my way to Orlando 2 weeks ago. Cruising at 75mph, threw it into 4th to pass a slower car and it did the exact same thing you guys are saying. Stutters and feels like the motor is just dying. The at the last second, it kicks back in. All I have is the SCT and have it set on 93 torque tune.

clintoris

Here's a curveball for you.. I have a 2000 Expedition that will do something similar. When I'm braking kinda hard coming up to a light, and then get right to the gas when the light turns green, it will fall flat on it's hiney for a second, then get itself together and go. ??? similar problem ???

oh.. need I say, the Expedition is bone stock.

srichard

My car is stock except for a bassani X-Pipe with comp cats and I've experienced this issue several times on the highway. I don't think it is your Diablo tune. A lot of people are having this issue regardless of mods.

pittperson

Agreed. I do not think it is a tune issue either. Now we just need to either 1) pinpoint the issue ourselves or 2) Make it known to ford that is seems to be a common problem.

Like I said before, I am making a road trip for thanksgiving so if someone can tell me what parameters I need to datalog to diagnose this problem I'll do it.

W2bStanger

I havn't nopticed this yet, but could it be the variable valve timing? Doesn't it switch between low RPMs (~75 in 5th) and then high RPMs (~75 in 4th)? Might have something to do with it. I'm looking to get a C&L so any info on this messing with the car would be useful.