3 second delay

White Lincoln

White Lincoln

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Birdcats Supporter
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Oct 2, 2023
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852
Location
New Mexico
Vehicle Details
1994 Mercury Cougar XR7, 3.8L, all stock
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Hey all and hope you are doing well.
Ever since I have had this car (almost 25 years) it has had a 3 second delay when you let off the gas while driving. When the car is in park and I hit the gas to rev the engine and let off, it drops to about 1000 rpm and then drops to normal idle after 3 seconds. As you may have guessed, everything I can think of has been replaced or swapped out over the years, but this issue has stayed with the car. The tranny, PCM, etc, etc... have all be changed out at some point and the only thing I can think of is maybe the speed sensor? I think it was the same one from the first tranny. Or maybe something to do with the cruise control? I thought that all went through the PCM. The 3 seconds has always been 3 seconds. Like the PCM is telling the engine to stay at 3 seconds then drops off. I did read a few articles, but nothing really like this. A few things came up, MAF sensor, dirty / clogged fuel filter, poor fuel economy, and a crappy designed throttle system. None of these apply.

Any thoughts on this? Weirdest dame thing.
 
Have you cleaned the throttle body? The back of the blade, the egr, all of it.

And clean the maf.It also has a lot to do with the response time of the throttle. A bug stuck to one screws it all up, lol. Mustangs I see either have no filter, or a huge k&n cone, both are really bad for the maf. That's where I saw the bug, lol.
 
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My 94 XR7 (3.8) did that too! I would let off the gas and it would take a few seconds to actually start to slow down. I could get around it by lightly tapping the throttle again after initially letting off, then it would immediately begin decelerating. I never did figure out if it was by design or some mechanical gremlin. Aside from that oddity (which I just wrote off as a programming oddity), I judged the car to be mechanically sound...
 
Honestly that sounds like the factory dashpot decay, it's there in V8 cars as well
 
Dang... gone for a few days and come back to a plethora of information! DAMN! I will look at all of these suggestions and give them a try. I am SOOO dang happy that I am not the only one out there that has had to deal with this.

And Supergordo, I will see I can get a video made of the sound of the engine waiting 3 seconds to drop to normal throttle.

THANK YOU!
 
Grog6 said:
Have you cleaned the throttle body? The back of the blade, the egr, all of it.

And clean the maf.It also has a lot to do with the response time of the throttle. A bug stuck to one screws it all up, lol. Mustangs I see either have no filter, or a huge k&n cone, both are really bad for the maf. That's where I saw the bug, lol.
Click to expand...
I need to replace the seal on the water pump tube back to the heater, which requires removing the intake. The last time I had the intake off, I was trying to figure out how from the throttle body back, was just black. I thought only air was flowing from there until the injectors. But then I remembered the return gas from the exhaust and valve covers. I have sprayed the crap out of it with SeaFoam before, but that did not do much for my throttle issue. Sounds like maybe I should try the ol' brush and gasoline method and scrub it out. The MAF was cleaned a few time recently with MAF cleaner and it is new, not the OEM (maybe a mistake).

I will update in a week or so when the parts come in for the water pump tube seal.

Thanks!
 
theterminator93 said:
My 94 XR7 (3.8) did that too! I would let off the gas and it would take a few seconds to actually start to slow down. I could get around it by lightly tapping the throttle again after initially letting off, then it would immediately begin decelerating. I never did figure out if it was by design or some mechanical gremlin. Aside from that oddity (which I just wrote off as a programming oddity), I judged the car to be mechanically sound...
Click to expand...
That is the first time I have ever heard someone mention the same issue even though I have asked dozens of people over the years. So, I thank you for relieving me of thinking I was just nuts or had the worse lemon of a car, ... ever.
 
I've actually had the TB spring fail on a friends car, and it would do the same thing. I'd never check one if I hadn't seen it; but having rebuilt a set of imrcs, and a tb for the mark motor, I know the tb bearing can get rust and stick. I check all that crap by moving it w/engine off, and looking at play, and feeling for smoothness. The blade can hang on crap. The cable can hang. Lol, the TB blade can stuff into the hood, holding it wfo. :) The point is, look all that crap over, and make sure it's all ok before being sure on a diagnosis. A sticking iac is a sign of it failing suddenly. I drove my boss to the airport with a failed iac; it would not hold idle in any way. It's not good to start an engine, by dropping it into second, lol. It will start, tho. Neither the oil pump or trans pump are working, so that's as bad as it gets.
 
Any progress on this? I'm interested in the outcome.

Off topic, but isn't it kind of cool that your right foot is connected directly to the throttle body with a cable? That's where modern cars fall short in my opinion. I mean I understand there are countless benefits to electronic throttle control - but some feeling of connectedness is definitely lost.
 
That's one reason I stopped buying cars. All new cars can be remotel disabled, from what I saw in a presentation from a vendor. They made the chips.
 
Grog6 said:
All new cars can be remotel disabled
Click to expand...

The Fusion has an app that lets you remotely look up location, driving stats, vehicle info... when they shipped they used 3G modems and then when AT&T started yanking equipment they allowed some owners to get a 4G modem upgrade. Eventually the tech becomes obsolete and that remote connectivity is lost.

In short, if you're worried about the analytics (or whatever data) new cars may be sending to the manufacturers, yank the modem.
 
It doesn't require a modem, somehow; I asked for more details, and dude wouldn't answer. They knew if it got out, they would have problems. My nda didn't cover those technologies is what they said. I also got blown off asking about blu-ray chips, lol.
 
The modem in my Edge went out a few years ago but Sync still had connectivity. I'd assume it was either through the satnav or SiriusXM system.
 
Brandon, you said you have a fusion, right? if it has that type of dash, would you be willing to grab some data? iirc, there's only one bus, that goes everywhere, so it should be easy to get to.It's a small board that has microclips, and runs from a usb port, using a terminal program. I
t can copy bios chips, lol. $40. I bought one originally for work, but they're just so useful. I used this one to add the microcode for a socket 771 xeon to a socket 775 motherboard. It works, but some features weren't supported. Its a 5080, a 3.7Ghz processor. It runs cool at 4.7GHz with a decent cooler.
It still has pci slots, which I have cards for. We need ~10 minutes of data, both terminal program and datalog, and I can figure out what the commands are for what.
 
If nothing else maybe we can take a short drive before the eclipse or something. We can access the can bus at the obd2 port.
 
I admire those that can do it, but since the Fusion is the wife's car she'd kill me if I started messing with it while it's her primary DD...
 
The '94 is not OBDII compliant. Access port is on right side of engine (?). May be a bottom drawer of the toolbox really old scan tool thing.
 
Could the throttle cable be sticking? Easy enough to try and lube it up
 
1997ThunderbirdLXV6 said:
Any progress on this? I'm interested in the outcome.

Off topic, but isn't it kind of cool that your right foot is connected directly to the throttle body with a cable? That's where modern cars fall short in my opinion. I mean I understand there are countless benefits to electronic throttle control - but some feeling of connectedness is definitely lost.
Click to expand...
Hi 97 Tbird and gang,
Sorry for the belated follow up. It's been a rough month. So, the car has been running great and really does not do the 3 second thing. It is more like it is always at 1100 rpm and only drops down once everything has settled down. Along with the fuel rail and fuel pressure regulator, I also replaced the Air Charge Temperature Sensor, it's on cylinder 1 intake. The old one did not rattle inside like the new one. Should have replaced that years ago, thought it was fine. Anyway, now that I have the engine running really nice, I find that the tranny I got from RockAuto is a POS and was part of the problem all along. Rebuilt my arse. It hesitates at take off, which I thought was the engine, it acts like the bands are slipping during acceleration and does weird shifts, hard shift on second, up or down, on and on. All these things I thought were the engine are now down to the tranny. So, in a nut shell, installing the correct fuel rail, new fuel pressure regulator and changing out the Air Charge Temperature Sensor really made a difference. I really like driving the car again, except for what to do about the tranny now. If only life were simpler.

Thanks all!
 
White Lincoln said:
" I find that the tranny I got from RockAuto is a POS and was part of the problem all along. Rebuilt my arse. "
Click to expand...
I started thinking about what was new and old when I replaced the transmission. I do not believe the torque convertor was replaced and the more I read about a bad torque convertor, I have to wonder it that was my problem prior to replacing the transmission. Hence, there is nothing (at least yet) with the transmission, but the issue is the original torque convertor. I also mentioned the speed sensor was never replaced. I will be contacting the mechanic that replaced the tranny and ask if he recalls the torque convertor was replaced or not.
 
That delay to idle, is normal. Reduces emissions, prevents idle surge. With the A/C commanded, which includes defrost mode, the idle is slightly higher, and often hangs longer. If you are coasting with your foot off the gas, it should have a bit of idle air bypass. All normal.
 
You need to find a local guy to build a transmission. For a 94, it's more of a pain in the ass, as it needs those internal solenoids for the eec, so you need to buy the right parts to use to rebuild it. You want to start with a 2002 trans from a gran marquis or crown vic NON police. It will be the same length as yours. You want a 2002 for the parts. If you have a 3.8, you have a different case; a 2002 v6 mustang will work as a core to start with. You want a tc from a 2004 mustang gt, and a small pattern flexplate from summit. Also find a dorman pan, with the drain plug. I buy trans parts from these guys:

Trans Parts Online AOD 4R70 Transmission Parts

www.transpartsonline.com

Or these guys:
transmissioncenter.net

Performance Automotive Transmission Center

Performance Automotive Transmission Center. High Performance Transmissions, Torque Converters and Parts. Browse our Shop or call 888-877-1008
transmissioncenter.net transmissioncenter.net
You will want a new connector, tcc solenoid, epc, and shift solenoids. They must be the low impedance ones for a 94 eec.
Here's a thread on rebuilding them:

How to: - 4R70W Transmission Rebuild Diary

Foreward to this Diary: I have only been building transmissions now for about 4 years or so. I do not claim to be a pro, expert or genius about this topic. Yet, I have been wrenching for 30 years now and at one time did work for FORD. (Seems like another life). I have built engines, component...
www.explorerforum.com www.explorerforum.com
 
I know it sounds stupid but just a thought. could it be the throttle body is going back to the right position and not hanging up? have someone sit in the car with it running while you are under the hood have them rev it up and let off and watch where the throttle cable attaches to the TB and see if its doing what it should. I'm wondering if the cable or the butterfly in the tb are hanging up
 
Hi Guys, thought I would follow up on this thread since I seemed to have "forgotten" about it. Old age I guess. :p

So, I did some digging on dash pot and how it is set to control the engine speed when the throttle is closed (letting off the gas). In all cercumstances, the engine should just slowly drop to idle, not hang for 3 seconds at whatever RPM you let off the gas and then drop to idle. And the reason I have an issue and think something is wrong is because the Town Car, though OBDII does not do this. I let off the cable and the engine will slowly come to a stop if I do not keep "giving it the onions", which is how an engine should react. Even my 88 Mark VII and my 89 Continental (3.8l) would not hang when you let off the throttle. I have also had two mustangs that had the 4 banger in them, neither did this.

Back to the dashpot and the PCM. Something is telling the PCM to hesitate and I think, at least to my understanding, is the air intake is not consistant, is not correct or is broke. Now, testing the throttle cable is a good start and working backwards with the throttle body and IAC then the MAF to see where the incorrect information is coming into the PCM to hesitate on adjusting the idle drop when the gas is let off.

Lots to consider and when I have the intake / fuel rail off, I can look more into this issue. I keep wondering why my TB is black at the intake - pre fuel. So, maybe the TB is to blame, but we will see. I see a junk yard run coming up.... PS: I recall I have had this issue since the the 2000's.

Is this an excellent collection of Fords or what? I miss my Mark...sometimes. But something had to go.

IMG_0902.JPG
 
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