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Matt Johnson
04-11-2003, 01:42 PM
You wrote something to the effect that you questioned whether or not the "slow" idle at 500 rpm in "Drive" and at around 750 rpm in "Park" or "Neutral" and the corresponding lower voltage reading in your MM was normal....

My response was that I too had noticed the 500 rpm idle in "Drive" because I was used to smaller engines with idles speeds around 1000 rpm, but assumed the relatively slow idle for the MM was normal for and particular to this engine. Plus, the fact that the tach has the 500 rpm hash-marked led me to believe this lower idle was fine.

However, what has made my list to ask the service writer when I take my MM in for its first free oil change at 3000 miles, is it normal for the engine to rev up to 2000 rpm when I start the car (almost as if I were putting my foot on the accelerator when I turn the key, which I am not doing) before quickly settling down to a "cold" idle of 750 rpm while still in Park.

RF Overlord
04-11-2003, 03:45 PM
Originally posted by Matt Johnson
However, what has made my list to ask the service writer when I take my MM in for its first free oil change at 3000 miles, is it normal for the engine to rev up to 2000 rpm when I start the car (almost as if I were putting my foot on the accelerator when I turn the key, which I am not doing) before quickly settling down to a "cold" idle of 750 rpm while still in Park.

Matt: Mine does the same thing, although I haven't really paid attention to exactly how high it first revs...it does settle down quickly to about 750. I didn't think anything of it, as my T-bird did the same thing...sounds normal to me...

mtnh
04-11-2003, 04:50 PM
I am more than a little worried about a cold start rev like the MM's PCM does, and if it were resettable, I would have it toned way down. Revving the engine with no oil flow to speak of is just plain wrong. I know why they did it that way, though, to grab attention. Just listen to TripleTransAmMM's posts about remote starting the car as he approaches it to enjoy the roar to life. Sure, it sounds good, but cold starts are the most damaging time of an engine's life, so why would you piss it on a cold startup?

Mike

Matt Johnson
04-11-2003, 04:53 PM
Does Dennis's chip address this at all? Could it?

Blue Marauder
04-11-2003, 05:23 PM
OK. Let's try this again and hope it doesn't get lost.

Bought a Blue Pearl Marauder a few weeks ago. Both my wife and I love it. I picked the car, she picked the color and interior (light Flint).

Anyway, I have noticed that after the car warms up and the idle settles down, the idle speed in Park or Neutral is 750 rpm, but when shifted into drive, the idle speed drops to 500 rpm. I have never had a computer controlled, fuel injected car behave like this. No matter what the gear selection the idle has always remained rock solid at one speed (it seems most cars, at least all the Fords I have driven, idle at about 750 rpm these days). When the idle speed drops to 500 rpm in drive, the voltmeter also begins to drop from 13.5/14 volts to 12 volts and slightly below with any electrical load on (lights, auto climate control).

The dealer checked everything out and could find nothing that would indicate that there is something wrong with the idle. The computer seemed to be operating properly and the Idle Air Control valve was working properly. Ford couldn't provide them with any useful information.

As far as the voltage drop, they checked the charging system under max load and said it is putting out a solid 13.5 volts. They also said that the voltmeter was reading about 1 volt lower than the actual battery volatage. They swapped in two other voltmeters (one from another car on the lot, and a new, out of the box voltmeter) and said they both behaved the same way as mine. Theyalso cleaned all the ground connections which seems to have helped some. The voltmeter doesn't drop as far or as fast now even with the idle at 500 rpm.

They also compared my car to the other one they had on the lot (also blue) and said that both the idle and voltmeter on that car behaved the same as my car. They have reported the problem to Ford for further investigation and have left my ticket open in case things get worse in the future.

So, my question is, what is the idle speed of everyone else's car in Park/Neutral and in Drive? Also, how does your voltmeter behave at idle in Drive? I have seen a few references to low voltage but nothing similar to my complaint.

As far as the other comments about the engine speed jumping up to near 2000 rpm at startup, I consider that normal. The car goes into fast idle (around 1500 rpm) when cold then drops to normal idle speed as it warms up. Every car I have ever owned whether fuel injected or carbureted has behaved the same way.

Thanks. Sorry for the length of the post.

RF Overlord
04-11-2003, 05:39 PM
Originally posted by Blue Marauder
I have never had a computer controlled, fuel injected car behave like this. No matter what the gear selection the idle has always remained rock solid at one speed (it seems most cars, at least all the Fords I have driven, idle at about 750 rpm these days).

As far as the other comments about the engine speed jumping up to near 2000 rpm at startup, I consider that normal. The car goes into fast idle (around 1500 rpm) when cold then drops to normal idle speed as it warms up. Every car I have ever owned whether fuel injected or carbureted has behaved the same way.


Blue: I find your first comment interesting as I have never driven ANY car that did NOT drop slightly in speed when put into drive, including my '94 Thunderbird SC, and all of my work trucks, a '95 E350 (way previous), a '95 GMC Sierra (previous) and an '01 GMC Safari (current). The only vehicle I've ever seen that didn't drop speed when in gear is my sister-in-law's '98 Jetta...and I thought that was mighty odd.

I am in full agreement with your second comment...

Blue Marauder
04-11-2003, 08:04 PM
Well, my Ford truck (5.4L engine) stays at 750 regardless of whether its in Park, Neutral, or drive, my wife's Mazda stayed at about 800 rpm, and the Taurus SE (V-6) that I had for a loaner while the dealer was trying to figure out the Marauder stayed at 750 rpm.

When you think about it, there really is no reason for the idle speed to change between Park or Drive. The Idle Air Control (IAC) valve controls the amount of air that the engine takes in at idle, and the computer mapping contols the amount of fuel used at idle. The most I have seen any of these cars I mentioned change idle speed is +/- 50 rpm when you first shift into/out of drive or the load on the engine otherwise changes. Once things stabilize, the idle returns to 750 rpm. You cannot manually adjust the idle like in the old days. The computer controls everything as far as engine management goes, and the computer can be programmed for any characteristic desired.

So, how does your Marauder behave at idle?

looking97233
04-11-2003, 08:26 PM
I think it may be programed that way. The Marauder is supposed to bring back the big Americian muscule car sedan thing. Remember those old cars with the carburators. Back before computers?

Blue Marauder
04-11-2003, 08:45 PM
Originally posted by looking97233
I think it may be programed that way. The Marauder is supposed to bring back the big Americian muscule car sedan thing. Remember those old cars with the carburators. Back before computers?

Yes, I do. Maybe better than you think.

But what does that have to do with the behavior of a modern, fuel injected, computer controlled, emissions regulated engine?

And you still didn't answer the question.

RCSignals
04-11-2003, 09:48 PM
I think in this case "they all do that" is the correct answer.
I also have a Crown Victoria, and while it doesn't have a tach, it noticeably reduces RPM putting it in Drive as well.

Murader03
04-12-2003, 06:18 AM
Okay! I just checked mine. 48 degrees and damp outside. Been setting allnight. 17200 miles with DR Chip and plugs. On initial startup, rpm surge to about 2000 with immediate drop back to about 1250 or so. Keep in mind my interpretation of the tach with respect to your eye.... 30 seconds after start rpm drops to 1000. At about 2 minutes time, it drops to about 900. After warmup, drops to about 750 or so. When placed in drive with foot on the brake, drops to about 600, or a needles width above the 500 hash mark. Slowpokes new handy dandy toy should be able to get this down to times and correct rpm figures.

How 'bout it Slowpoke?

TripleTransAm
04-12-2003, 09:33 AM
Originally posted by Matt Johnson
...I was used to smaller engines with idles speeds around 1000 rpm, but assumed the relatively slow idle for the MM was normal for and particular to this engine


First of all, you can never trust a factory dash-mounted tachometer.

Secondly, I think this behavior is normal. During startup, a really rich mixture is required due to cold cylinders. After the initial lighting of the cylinders, there is internal friction to overcome from the cold parts not yet at their tolerances. Hence the faster initial idle. Modern electronically-controlled engines handle this much better than the old carbed engines, since they can better tweak the mixture and maintain a better and slower cold idle... the old carbed V8s sometimes needed 2-3 minutes of 1800 RPM running before even *thinking* of running smoothly at an intermediate idle of 1200 RPM or so.

Eventually, the idle settles at the slower values, when the engine can maintain clean consistent combustion at slower engine speeds with less aggressive mixtures... ie. when the cylinders have warmed up a bit. If you take an old manual-choked carbed engine (like the 1.5l fours in my '84 and '85 Civics), it will buck and shake like a cheap whore if you release the choke too soon and try to accelerate from the slower idle when cold.

Considering that the warm EFI engine will run at 750 RPM in park, the added drag of the braked drivetrain on the engine via the torque converter causes the RPM drop we notice in Drive. Why don't they raise it back up to 750? Because then it would lurch every time you released the brake. And consume more fuel. And the IAC might not react fast enough, so you idle at 750 in park, then a quick drop to 500 in Drive, then a surge back up to 750 in Drive once the IAC corrects itself. Not very driveable, in my opinion.

What about the opposite? Why not idle in Park at 500? Same reason. Shift to Drive and the added drag makes the engine stall. The IAC won't open up fast enough to supply the engine with the goods once you shift into Drive from Park. Hence, the 750 in park and 500 in drive.

My Hondas have always slow-idled at around 900 RPM (my carbed Civics used to idle at 1000 or so, but I preferred setting it to 800-900... personal taste). My current '98 EFI Civic is also around 900-1000. These are smaller engines with correspondingly lighter engine internals, including the flywheel. At too slow an engine idle, I'm guessing not enough inertial energy is stored in the rotating assembly (incl. flywheel) to maintain smooth running. Hence the slightly higher engine speeds. If they don't drop much in RPM when in gear on the automatics, you can blame a much looser torque converter: behind those small torque 4s, they'll stall at 3000 or higher. Put the same converter behind the MM's 4.6l and it would stall at 5000, I'm betting!!!! Now THAT'S loose!

TripleTransAm
04-12-2003, 01:38 PM
Just to add my own data points...

I just got to work (after a slight detour ;) ) and noticed the following: based on the factory in-dash tach, warm idle in park is around 700-800, and popping it into Drive results in a gentle soft decrease in RPM to around 500-600 RPM. It's so loose you hardly feel it... a true indication of the higher stall converter. In comparison, my GTA delivers a solid THUNK when I drop the shifter into drive from its ~700-800 RPM warm idle... the idle in Drive is also approx. 550-575 RPM (as indicated by a SCAN tool plugged into the ECM... they were called ECMs back then).

Speaking of higher stall speeds, gunning it in the parking lot here at work resulted in a soft initial climb to around 2300-2400 RPM... At around 1000 miles on the clock, I'm thinking the engine will eventually loosen up some more and the improved torque delivery will push that stall speed up somewhat, since engine torque does affect stall speeds. Maybe I'll see 2600 RPM stall speeds someday? Lord knows it feels much zippier now than it did last week.

CRUZTAKER
04-12-2003, 01:43 PM
As I said before, not being a motorhead and all, I am thinking this is all good.

Blue Marauder
04-12-2003, 05:04 PM
Well, I'm not sure that I agree with some of the arguments as to WHY the idle drops from 750 in Park to 500-600 in Drive, but it sounds like it is common enough to be considered normal. Thanks to all who responded and actually checked.

By the way, I just installed the SS Inserts stainless steel "MARAUDER" name inserts in the rear bumper cover today. Looks terrific and really brightens up the rather plain rear end of the car. Even my wife likes it! Also polished and waxed the car and cleaned everything up. That blue pearl really sparkles!

TripleTransAm
04-12-2003, 05:35 PM
Originally posted by Blue Marauder
Well, I'm not sure that I agree with some of the arguments as to WHY the idle drops from 750 in Park to 500-600 in Drive, but it sounds like it is common enough to be considered normal.


Forgot to add one thing: Connecting to the diagnostic ALDL port on my GTA, you can actually see the ECM (PCM) order a 550-575 RPM idle once you put it in gear, and in Park it's commanding around 700-800 RPM. And I've seen this behavior with every other automatic including some 4 cyls with tight-for-a-4-cyl converters.

Once I get the s/w for ALDL connection to the MM's PCM, you can bet I'll be logging all this crap for further study.

TripleTransAm
04-12-2003, 05:40 PM
Originally posted by looking97233
Remember those old cars with the carburators. Back before computers?


Anyone remember the 426 Hemi? 2x4 Bbl carbs sitting on huge ports and humonguous heads.

The Hemi was a high-RPM screamer, and as cammed/valved/ported from the factory, was a little *soft* on the low end, soft being a relative term of course. As such, it was usually idling around 1200-1400 RPM. Putting it in Drive at that speed would result in a noticeable bark from the tires, along with the drop in RPM due to holding the brakes.

Those old cars may have sounded great but today's muscle does it so much better (fuel/emissions/performance/tuning/etc.)

SergntMac
04-14-2003, 08:54 AM
I'm a bit late with my .02C, so all I can add now, is that the behavior described by Blue, is 100 percent normal, and planned that way. I say this because it became an argument with my G/F, who thought I was just showing off. Once I added my Z-55 turbo mufflers, the argument was revived, until I started the car from the outside. Then she blamed the RPC, and we had to go to the dealer and let her hear it from the SM.

One thing I can add that may be helpful, is the question of oiling in a cold motor. When I'm starting cold, the motor turns over 10 or 12 times before it fires up. I think this is also part of the plan, to move the oil through the motor before it opens the spark. Restarting warm is like instant on, long cranks only happen when the car is cold. Any of you also notice this?

I too, have a Car Chip like Slowpoke's and I monitor my cold starts. Within 7 min., motor temps reach 186 degrees. Voltage averages 14.2, with drops to 13.6 while stopped, though my dash gauge reads like 11 something. I do see a flicker in my lights when stopped, and I can make it go away by feathering the gas, but after reading my data from the Car Chip, I'm sure I am not in a discharge state.

I've never driven any automatic transmission vehicle where putting it in gear did not load the motor and change the idle.

Like a lot of other stuff with this car, "that's the way it is," IMHO