Previous Thread
Next Thread
Print Thread
97 Dakota 3.9 issue UPDATE #1830280
05/19/15 08:11 PM
05/19/15 08:11 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Truck worked fine going in to work this morning. I came out this afternoon, started it up (fired up easily as always), but was idling at 2000 rpms. It wouldn't "kick down". I had to get going to take my wife to the doctors, threw it into drive and it drove fine, though straining against the brakes a bit at stop signs and lights.

I did notice the trans not shifting like it should, but it did go through all the gears and lock-up, just far touchier.

I made it home, did the doctor thing, and just started it back up. Now it's idling at between 1200 and 1500 rpms, not steady.

The engine sounds fine, there are no dash lights on (and yes, they all work), the tune up is about 6 months old, and the only thing odd about the truck is the defective air control motor (or whatever it's called, on the TB) which makes the truck a hard start if it sits for days. If I run it daily (and in any temp) it shows no symptoms at all. It has 165000 miles on it, no work has been done beyond maintenance, bone stock, complete new exhaust with new cat.

Any idea what to look for?

Last edited by 79powerwagon; 05/26/15 10:14 PM.
Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1830303
05/19/15 08:45 PM
05/19/15 08:45 PM
Joined: Jan 2003
Posts: 31,874
Grand Prairie,Texas
stumpy Offline
I Win
stumpy  Offline
I Win

Joined: Jan 2003
Posts: 31,874
Grand Prairie,Texas
Fix the IAC (which is pretty cheap) and then let us know what's happening. It controls the idle speed. shruggy

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1830349
05/19/15 09:45 PM
05/19/15 09:45 PM
Joined: Apr 2010
Posts: 10,544
omotive Engineer.
Golden-Arm Offline
I Live Here
Golden-Arm  Offline
I Live Here

Joined: Apr 2010
Posts: 10,544
omotive Engineer.
put the key in your ignition and turn it to the "on" position three times. (insert key, on, off, on, off, on). leave it in the on position. the first trouble code will be displayed on your digital LED odometer. quickly cycle the key again (off, on) to display the next code, and just keep cycling the key to get the remainder of the codes. up


"When Tyranny Becomes Law, Rebellion Becomes Duty"

Re: 97 Dakota 3.9 issue [Re: Golden-Arm] #1830361
05/19/15 10:08 PM
05/19/15 10:08 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
That's cool! I never had to do that before! Thanks!

It's 12. I did it three times to be sure, and all that shows is 12.

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1830444
05/19/15 11:48 PM
05/19/15 11:48 PM
Joined: Mar 2003
Posts: 1,728
ST clair shores MI
M
moretoys Offline
top fuel
moretoys  Offline
top fuel
M

Joined: Mar 2003
Posts: 1,728
ST clair shores MI
A couple things come to mind. a vacuum leak, the iac (idle air control motor) is stuck, make sure the trans cable/linkage isn't froze. or since you have a shifting problem also, My money would be on the tps (throttle position sensor) If the tps is within it's spec it won't set a code. a scan tool to read the sensor would tell you right away. you could also read it with a digital volt /ohm meter, need a schematic to tell you what wires to read from. It works on a 5v reference. The sensor at idle should read a touch less than 1.0v and wide open is in the 4.5-5 v range. sometimes a temporary fix is disconnect the battery for a minute or so and let things relearn. a scan tool to read the sensors would pinpoint the problem in minutes.

Re: 97 Dakota 3.9 issue [Re: moretoys] #1830781
05/20/15 01:57 PM
05/20/15 01:57 PM
Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
70Cuda383 Offline
Too Many Posts
70Cuda383  Offline
Too Many Posts

Joined: Oct 2003
Posts: 21,345
Marysville, O-H-I-O
If you've been having a known problem with the iac solenoid/motor on the back side of the throttle body, then I'd start there.

Next time it's idling high, take the air hat off the top of the throttle body and put your thumb over the hole behind the 2 butterflies. If idle drops and you can stall it out, that rules out a vacuum leak elsewhere.


**Photobucket sucks**
Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1831051
05/20/15 08:24 PM
05/20/15 08:24 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Thanks for the ideas, guys! I'll have a look and see what I come up with! I'll report back!

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1831204
05/20/15 11:51 PM
05/20/15 11:51 PM
Joined: Apr 2010
Posts: 10,544
omotive Engineer.
Golden-Arm Offline
I Live Here
Golden-Arm  Offline
I Live Here

Joined: Apr 2010
Posts: 10,544
omotive Engineer.
12 is a "nothing" code. all it means is the battery was disconnected from the ecm, sometime within the last 50 off/on key cycles. try replacing the idle air motor, as suggested. some carb cleaner sprayed on the hoses, and around the tb with engine running, will reveal any leaks. as mentioned above, pull the air cleaner, and plug the rear hole with your finger. up


"When Tyranny Becomes Law, Rebellion Becomes Duty"

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1831488
05/21/15 03:06 PM
05/21/15 03:06 PM
Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
DaytonaTurbo Offline
Too Many Posts
DaytonaTurbo  Offline
Too Many Posts

Joined: Feb 2003
Posts: 21,318
Manitoba, Canada
Sometimes the IAC's still "work" internally, but are so gummed up with crud the plunger gets stuck.

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1831693
05/21/15 08:33 PM
05/21/15 08:33 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Yeah, I've got one on order. When it comes in, I'll install it and report back. smile

Re: 97 Dakota 3.9 issue [Re: 79powerwagon] #1831858
05/21/15 11:52 PM
05/21/15 11:52 PM
Joined: Aug 2009
Posts: 456
corpus christi tex
C
Cheatham Offline
mopar
Cheatham  Offline
mopar
C

Joined: Aug 2009
Posts: 456
corpus christi tex
i just bought a 97 today and am having the same issue with the idle at 12-1400rpm, no codes but ill remove and look at the iac then go from there, glad i found this post

Re: 97 Dakota 3.9 issue [Re: DaytonaTurbo] #1831888
05/22/15 12:23 AM
05/22/15 12:23 AM
Joined: Jan 2003
Posts: 15,487
Between Houston & Galveston TX
Satilite73 Offline
I Live Here
Satilite73  Offline
I Live Here

Joined: Jan 2003
Posts: 15,487
Between Houston & Galveston TX
Originally Posted By DaytonaTurbo
Sometimes the IAC's still "work" internally, but are so gummed up with crud the plunger gets stuck.


And if the IAC is gummed up, the throttle body itself is probably long overdue for a good cleaning.

On my '93, I didn't have the idle extremes you are but, the idle was never consistent. I pulled the TB, pulled all the electrical parts off it, and gave it multiple hits of oven cleaner to clean it out (it was cheap).

Idle is nice and steady now.

twocents


John

Imagine a '73 Satellite Wagon picture here. 😁
Re: 97 Dakota 3.9 issue [Re: Satilite73] #1832146
05/22/15 01:33 PM
05/22/15 01:33 PM
Joined: Jan 2003
Posts: 16,373
D
dogdays Offline
I Live Here
dogdays  Offline
I Live Here
D

Joined: Jan 2003
Posts: 16,373
Yes, for a dry manifold they sure do gunk up. My Taurus SHO engine has 12 runners and it took something like four cans of carb cleaner and some rubbing to get the gunk out. Throttle body was also gunked up.

I seem to remember a thread a few years ago about aftermarket Idle Air Control valves not lasting a long time.

On the original IAC valve, first you check it for having continuity, then if it does, get after the working parts with carb or fuel injection cleaner.

Really there's nothing to go wrong with an IAC valve, except having an open circuit in the solenoid coil, and the need for cleaning every blue moon.

R.

Re: 97 Dakota 3.9 issue UPDATE [Re: 79powerwagon] #1834827
05/26/15 08:57 PM
05/26/15 08:57 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Part arrived today, so I installed it. No troubles with install, and the TB was surprisingly clean. I shot out the opening for the IAC anyway, for good measure.

Truck started right up (which is a good beginning since it hasn't been run since this problem started), and idled at 3000rpms. The instructions said that it would do that, and to drive it up to temp, then drive it 40mph or faster for five minutes for the computer to reset.

I drove it quite a bit, and it is still running at 3000 rpms. If the rain stops, I'll disconnect the battery overnight and try it again (unless you all have another trick that is more affective?)

Re: 97 Dakota 3.9 issue UPDATE [Re: 79powerwagon] #1835520
05/27/15 08:38 PM
05/27/15 08:38 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Turned on the headlights for a good 5 minutes after leaving the battery disconnected all night, just to clear ANY residual voltage. Hooked it back up, and gave it a start.

She started hard, but then caught and idled as normal! I took it for a long drive (so teh computer can start to relearn me) and all was perfect!

I'll drive her to work in the morning, see if there remains any hard start condition, then attack that problem (if it exists).

Thanks all! up I LOVE this old truck!!!

Re: 97 Dakota 3.9 issue UPDATE [Re: 79powerwagon] #1838001
05/31/15 02:22 PM
05/31/15 02:22 PM
Joined: Jan 2003
Posts: 27,728
places
7
79powerwagon Offline OP
Too Many Posts
79powerwagon  Offline OP
Too Many Posts
7

Joined: Jan 2003
Posts: 27,728
places
Still a hard (or slow) start condition when cold. Before all of this, If the truck was unused for more than two days, it would be like this. It would have no issue when used daily. Now, it has the issue on any cold start, including daily.

What might be a place to look for this? Engine temp sensor? Ambient air temp sensor? Coolant temp sensor?







Powered by UBB.threads™ PHP Forum Software 7.7.1