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View Full Version : Hesitation at 4-5,000 rpm...



89VERT
02-24-2005, 09:48 PM
I have read posts regarding the sensation of the trans slipping when under 3/4 or Wot .

I have never experienced this until tonight . I was coming home from work , when I stepped on it at about 60mph .It revved to about 5,000 , then started slipping and it felt that it was struggling to get fuel. I've tried this at different speeds and with O/D off and it 's happening about 3/4 of the time . My car has the 1725 Superchips tuning and prior to that I had the Pcm re-flashed by the dealer . Until tonight my MM has run really strong and exhibited absolutely no sign of hesitation when accelerating .I always use 92 or 93 octane and my car now has about 20,000 miles on it .

I've removed the 1725 tuning , as it's going into the dealer in the morning, but this has me confused . Could it possibly be a fuel management / timing / knock sensor related issue ? And why would I experience for the first time now ?

Does anybody have any experience with this ?

MENINBLK
02-24-2005, 09:49 PM
With 20,000 miles on your Marauder, I would say its time to change your fuel filter...

Another question...
Since you are in Canada, isn't it 20,000 Kilometers ?
That would equal about 12,000 miles...

89VERT
02-24-2005, 10:00 PM
I have not changed the fuel filter yet , as I thought that 30,000 was the correct interval .

My car actually has about 35,000 km , which is about 20,000 miles

MENINBLK
02-24-2005, 10:16 PM
I have not changed the fuel filter yet , as I thought that 30,000 was the correct interval .

My car actually has about 35,000 km , which is about 20,000 miles

35,000 KM is closer to 22,000 miles.
I NEVER wait for Ford's recommended interval on ANYTHING.

If you are at 35,000 KM, change your Fuel Filter, and on my recommendation,
add a bottle of Gumout "Regane Complete" Fuel System Cleaner to your next fillup.
Its in a clear bottle and the liquid inside looks like Gold Tequila. :)
Its the ONLY Fuel System Cleaner I use and I swear by it.
I've been using it over 20 years,and on every vehicle I've used it on,
I've felt a difference in the perfomance, after 2 tankfuls of gas, after you apply it.
It is Gumout Stock # 7727, UPC code 0-71948-07727-0

If the problem still exists, then take it back to the dealer and let them check it out.
At least they'll know that there is a fresh fuel filter in the system.

89VERT
02-24-2005, 11:53 PM
Thanks for the 411 , I appreciate it!

I just got in the door from driving my MM with the stock tuning .I also filled up with a fresh tank of 92 octane. It pulls perfectly. Absolutely no hesitation at all .
I 've been thinking that if the previous problem was fuel related , would it have not created a condition that the OBD could sense and indicate a check engine light ?
I wonder if the Superchips tuning created the condition , or was it just as simple as some bad fuel ?

warren
02-25-2005, 12:01 AM
I have read posts regarding the sensation of the trans slipping when under 3/4 or Wot .

I have never experienced this until tonight . I was coming home from work , when I stepped on it at about 60mph .It revved to about 5,000 , then started slipping and it felt that it was struggling to get fuel. I've tried this at different speeds and with O/D off and it 's happening about 3/4 of the time . My car has the 1725 Superchips tuning and prior to that I had the Pcm re-flashed by the dealer . Until tonight my MM has run really strong and exhibited absolutely no sign of hesitation when accelerating .I always use 92 or 93 octane and my car now has about 20,000 miles on it .

Does anybody have any experience with this ?

89VERT,
I had the same problem. Drove me nuts. Thought it was major problem.
Talked to Dennis R and Denso Factory people - suggested ck plugs.
Using IT20's with real old Diablo chip, new 410 and 180stat from Dennis. It was the plugs. Gap grew too much. Replace or regap & bingo all go and no problem.
I change my plugs, fuel filter and air filter ( tap it clean every 2 months ) once per year to be on safe side.

Good Luck,
WarrenB

89VERT
02-25-2005, 12:05 AM
Thanks for the info Warren .
I just got back from San Francisco / Santa Rosa on Monday .
I trust that your rain is all gone ?

89VERT
02-25-2005, 05:17 PM
I called Superchips this morning and the rep said that occasionally the Ford computer goes into "learn mode" . He said if I re-load my tuning it should be okay again .

Does this make any sense ?

89VERT
02-28-2005, 07:47 PM
Anybody...?

CRUZTAKER
02-28-2005, 08:36 PM
When you mashed on it at 60...were you in OD?

At 19,000 US MILES, I pulled my trans to find my OD clutch bands fried. This happens as a result of hammering the car in OD, rather than turning off the OD beforehand.

I have since learned my lesson.

89VERT
02-28-2005, 09:48 PM
I usually have O/D off when I'm getting ready to play, but the hesitation was there either way .It almost felt as though it as hitting the rev limiter. I 've checked with several of my friends that are mechanics and they all agree that if it was a fuel or transimission issue,it would have triggered a Check Engine " light.

But of course, since I've loaded the stock tuning back in , it runs perfect!

What gives ?

DEFYANT
02-28-2005, 11:00 PM
Could he be referring to the WOT bog????

MENINBLK
03-03-2005, 12:03 AM
Thanks for the 411 , I appreciate it!

I just got in the door from driving my MM with the stock tuning .I also filled up with a fresh tank of 92 octane. It pulls perfectly. Absolutely no hesitation at all .
I 've been thinking that if the previous problem was fuel related , would it have not created a condition that the OBD could sense and indicate a check engine light ?
I wonder if the Superchips tuning created the condition , or was it just as simple as some bad fuel ?

A lit MIL (Malfunction Indicator Lamp) or a Check Engine light, as you guys so eloquently call it,
ONLY lights under certain conditions, and those conditions are very specific.

First, it can light if several emission testing processes fail.
It can also light if a single or several emission related sensors/senders are out of a normal measured range or calibration.
It can also FLASH if it detects a TIMING related issue such as a bad spark plug, injector, crank, or cam sensor.

One circuit that is not measured as accurately as it should is the Fuel Pressure and its regulator.
The only thing in the circuit that is measured is Fuel Pump VOLTAGE.
If the fuel pump is overworked, as in starved for fuel by a clogged fuel pump strainer, and the voltage goes too high, it will set a light.
If the fuel pump is overburdened by higher than normal pressure, such as when the fuel filter is clogged, the voltage will drops, it will set a light.
It will NOT set a light for anything else that is fuel related, prior to combustion.

Because you flashed your PCM back to the Stock Calibration, it would have reset the PCM
and any conditions that existed that may have caused your situation to occur would have also been reset.
If I were you, since you now know that ELECTRONICALLY your Marauder is safe,
I would flash back the Custom Calibration, and allow the PCM to relearn to idle,
and then drive it around again until the situation returns.
When it DOES return, you will need to capture a data stream from the PCM while you
re-create the situation, so that it can be viewed, and troubleshooted for your particular Marauder.

After you catch the data stream, simply reset the PCM, no need to re-flash it again, and then see if the problem goes away again.

By this time you should be able to determine if it is software related or not.

MENINBLK
03-03-2005, 12:39 AM
I 've checked with several of my friends that are mechanics and they all agree that if it was a fuel or transimission issue,it would have triggered a Check Engine " light.

[/Flame Suit ON]

89VERT,

Check back with these friends, and ask them to refresh themselves on a OBD and OBD-II course.
The MIL only lights if it is linked to the Electronic Emissions Computer.
If it is a MECHANICAL failure, they would never find it if they relied on a "Check Engine Light"...

I know that they will tell you, and I know the choice words they will have for me,
but I've got just as much experience working on OBD and OBD-II vehicles as they have,
and I've worked in a dealership, and had to read it, eat it, and test for it while I was there.
I even held a NYS Emissions Inspector License for the dealership.

I had to face the Service Manager of my Ford Dealership to show him the problems
I had with a 98 Contour's CD4E Transaxle and how it was dying because of HEAT.
He INSISTED that it would show a MIL if that was the problem.
It wasn't until I had a Technician and the Shop Supervisor verify my troubleshooting,
and my temperature readings, before I would even get any consideration that the transaxle had any problems at all.

My simple question to him was, "When do you decide to go back to the basics,
start from scratch, and ditch all of the technology you've gotten so focused on ?"
The Service Manager I worked with in my Buick Dealership had ALWAYS stressed that
the obvious is not alwasy what it seems, and if your basics are not verified first,
you'll never be able to troubleshoot anything properly and with any certainty.

We coincidentally rated #1 in Customer Satisfaction consistently, year after year, for all GM dealerships in Westchester County.
You only get that rating by,
1 - Customer Feedback
2 - Service Repair Issues cured on the FIRST visit.

[/Flame Suit OFF]

89VERT
03-03-2005, 12:02 PM
Thanks for all your input MENINBLK. You sure seem to be well versed in OBD technology!

But the plot somewhat thickens ...

My car started hesitating badly at 4,000 Rpm with the stock tuning .It pulls hard to 4,000 , then it shudders a second or two and spins up to the shift point.
It did it repeatedly over a 30 minute drive .
But when I stopped to get fuel , it was gone .
Is the computer having some issues ?And if they dealer messes with the computer flash , will my Superchips tuning still work . The Superchips rep said it might cause some problems , but I'm not sure how .
It really feels as though it's hitting the rev limiter or the T/C is coming on .

It's going back to dealer in a day or so ...

Still perplexed !

MENINBLK
03-03-2005, 08:10 PM
My car started hesitating badly at 4,000 Rpm with the stock tuning .It pulls hard to 4,000 , then it shudders a second or two and spins up to the shift point.

Okay...

Does this happen in EVERY GEAR ?
e.g.
Start from dead stop. RPM -> 4,000, ->, shift
2ng gear, RPM -> 4,000, shudder, shift
3rd gear, RPM -> 4,000, shudder, shift
OD gear, RPM -> 4,000, shudder, rev limiter

If this is it, then it could be the converter lockup that you are feeling.

89VERT
03-04-2005, 03:52 PM
Of course it's not doing it right now , so I can't drive it as you suggested .

But if it was the torque converter locking up , what would be causing this to happen ?

MENINBLK
03-04-2005, 04:58 PM
Of course it's not doing it right now , so I can't drive it as you suggested .

But if it was the torque converter locking up , what would be causing this to happen ?

Our Torque Converters are supposed to lock at high speeds.
This is because the Torque Converter has a clutch system inside that is controlled by hydraulic pressure.
When the stator and the housing are both spinning at the same rpm,
the PCM commands lockup, and hydraulic pressure is applied to the clutch.

In some cases, it doesn't always work this way, and you get shudder for a variety of reasons.
One of the most talked about reasons here is that the Overdrive in our transmissions tends to burn out if you beat on it a lot.
Meaning, you jump on the gas to accelerate while traveling at highway speeds.
You will notice a delay in the shift from OD to 3, and your RPMs will flare for a second.
This is a characteristic of our transmissions, and as much as everyone here has tried to correct it,
it can be cut down dramatically, but it can't be corrected completely.

The second most talked about problem is the Torque Converter itself.
Some owners have had them replaced under warranty and the shudder goes away.
But to keep things normal, you'll need to hit the OD OFF button BEFORE wiggiling your right toes...

Most of us here have made it a habit to drive with the OD OFF until we are over 60 mph,
in order to save the OD in our transmissions.

I for one, practice this as well.

When you get the chance, drive your car again with the stock programming
and see where sn ahow you can re-create your shudder.
You may have to get your dealer's transmission tech to ride with you, and re-create it for him.
He will know EXACTLY what the problem is once he feels it and understands how it is re-created.

DEFYANT
03-05-2005, 09:16 AM
Most of us here have made it a habit to drive with the OD OFF until we are over 60 mph,
in order to save the OD in our transmissions.

When I had my PCM flashed, I had the computer set so that OD doesnt come on until 50 MPH. Throttle response is right on with no dreded downshifts. :D

89VERT
03-05-2005, 07:55 PM
I picked up my MM from the dealer last night and they were unable to duplicate the problem I have been experiencing . It's a well run shop , as the owner is a hot rodder and the ulimate Ford guy .

I've been doing some more research on this situation and it really seems that my problem is not similar to the others I have read about .
My car just doesn't just shift poorly under WOT , it really feels like it's bouncing off the rev limiter or the T/C is coming on.
Rather than feeling like it's shifting poorly , it really seems like it's loosing power for a second or two , as you can feel the engine struggling .

Still confused .. !

Anybody else have an opinion .. ?

Marauderjack
03-06-2005, 05:02 AM
I have the SCT program that holds the TC out until 60 MPH (like Lidio's) and it still feels like the TC stays locked when flooring it above 65 MPH!! :mad2: If I back off the throttle slightly....IT REVS MUCH BETTER!!?? :confused: Maybe the TC unlocking then?? :confused:

David at SCT was working on a program that unlocks the TC any time the throttle is depressed slightly but he has not responded to my emails inquiring about this?? :( This would have taken care of all the low speed "tip in" knocking that was so annoying earlier on!! :bows:

If any of you SCT "Tuners" are aware of a program that unlocks the TC at any speed with light to moderate accelerator depressing....PLEASE LET US KNOW!! :bows:

I'm sure it can be done but not sure that anyone that can do it understands what is happening?? :confused:

My $0.02...

Marauderjack :cool:

MENINBLK
03-06-2005, 09:45 PM
I picked up my MM from the dealer last night and they were unable to duplicate the problem I have been experiencing . It's a well run shop , as the owner is a hot rodder and the ulimate Ford guy .

I've been doing some more research on this situation and it really seems that my problem is not similar to the others I have read about .
My car just doesn't just shift poorly under WOT , it really feels like it's bouncing off the rev limiter or the T/C is coming on.
Rather than feeling like it's shifting poorly , it really seems like it's loosing power for a second or two , as you can feel the engine struggling .

Still confused .. !

Anybody else have an opinion .. ?

Here is an idea, and I've found that my Marauder likes this better.
When you are accelerating, don't just nail it to WOT,
accelerate by tipping it in quickly, hold the accelerator at about 50% - 60%,
and then edge it slowly out to WOT.
I've tried this and found that the engine likes to be fed gradually,
instead of dumped all at once.
It also makes for a quicker acceleration and a firmer SOTP feeling.

89VERT
03-08-2005, 07:36 PM
Problem solved , I hope !

I just got back from taking the tech from the dealership along with me to diagnose the problem .

He plugged his computer in the OBD port and discovered in about a minute , that my MM only had 10lbs of fuel pressure .

They've ordered a new fuel pump and it'll be installed on Friday .

Thanks again to everyone who helped me through this !

Allan

hrtn_monky
03-08-2005, 09:13 PM
Not sure if you are describing the same kind of feeling I had, but. Have you tried flushing/changing transmission fluid? I had a stuttering problem under acceleration load, usually between 3rd and 4th gear and 4th to OD. Transfluid was burned. Flushed and changed no more problem. It happened mid to late 20k Miles, 35K miles now - so far no issue. I also know of someone else with a similar issue.

John

89VERT
03-10-2005, 02:31 AM
I have been thinking about this fuel pressure problem and I was wondering why the pump still operates at only 10 lbs of pressure .
When the fuel pump went in my SHO ( twice !) it stopped the car right now .

Does the MM have a fuel pressure regulator ?
And if it does , is it part of the fuel pump ?

Haggis
03-10-2005, 04:33 AM
I have been thinking about this fuel pressure problem and I was wondering why the pump still operates at only 10 lbs of pressure .
When the fuel pump went in my SHO ( twice !) it stopped the car right now .

Does the MM have a fuel pressure regulator ?
And if it does , is it part of the fuel pump ?

Ouch!!! That is a little lean, better have your pistons check with a bore scope for scorching, just in case.

My car is S/C and I was having a fuel pressure problem, but mine was dropping to around 30psi at WOT. I change the fuel pump and will add a boost-a-pump in a couple of weeks.

MENINBLK
03-10-2005, 03:50 PM
Does the MM have a fuel pressure regulator ?
And if it does , is it part of the fuel pump ?

The Fuel Pressure Regulator is on the Fuel Rail and it is Vacuum Regulated.
The Fuel Pump itself has a check valve to keep the fuel from flowing back into the tank.

Low fuel pressure can be a defective pump, or a leaky check valve.
Both of which are replaced when replacing the pump.

wchain
03-11-2005, 08:48 AM
Here is an idea, and I've found that my Marauder likes this better.
When you are accelerating, don't just nail it to WOT,
accelerate by tipping it in quickly, hold the accelerator at about 50% - 60%,
and then edge it slowly out to WOT.
I've tried this and found that the engine likes to be fed gradually,
instead of dumped all at once.
It also makes for a quicker acceleration and a firmer SOTP feeling.


Wow,thats exactly how I drive mine!

89VERT
03-11-2005, 11:24 PM
Picked up my MM earlier this evening, after the replacement fuel pump was installed.... and on the drive home ...
back in horse power heaven !!