1990 Dodge Grand Caravan 3.3l V6 Stalling/rough idle

I have a 1990 Dodge Grand Caravan with about 130,000 Miles on it. It
has Chrysler's 3.3L V6 engine. Recently, I've had an issue with it
idling. What happens is that the idle will drop to about 300 RPM for a
second, then it will shoot up to about 1000 RPM, then it will fall to
the normal 600 RPM for about a second, and repeat. A few times it has
outright stalled.
Unfortunately, this is intermittant. It has only happened after the
engine has sat a few hours (though it's only happened 4 times or so, so
it may be concidence) or it may be related to a cooler engine temp.
When it's happened, hitting the gas to bring it up to about 3000 RPM,
then letting it fall back to idle seems to fix it - the car will
happily idle then. Anything above idle and the car runs fine. The
idle is a BIT rough, but keep in mind it is 15 years old. No violent
shaking or anything, but not perfectly smooth like a new car would be.
I've used my scan tool (Actron CP9150) and no faults are being logged.
The voltage on the TPS does change, but I haven't had the tool on it
while the fault is actually occuring (what idiot put the connector
under the hood! :-P )
This happened once about 2 months ago, and I asked around and was told
to clean the throttle body. So we took off the throttle body, cleaned
all the gunk out, put it back together and it didn't happen after that,
so I assumed it was fixed. Then this started happening this afternoon.
I also should note that we did change the timing chain a few days ago.
I doubt it is related, as this did occur once before back in december
(though the car wouldn't idle at all then, just started and died) but
figure I should mention that.
Any thoughts/suggestions/tests would be appreciated.

Thanks,
Eric Kotz

> wrote in message
oups.com...
> I have a 1990 Dodge Grand Caravan with about 130,000 Miles on it. It
> has Chrysler's 3.3L V6 engine. Recently, I've had an issue with it
> idling. What happens is that the idle will drop to about 300 RPM for a
> second, then it will shoot up to about 1000 RPM, then it will fall to
> the normal 600 RPM for about a second, and repeat. A few times it has
> outright stalled.
> Unfortunately, this is intermittant. It has only happened after the
> engine has sat a few hours (though it's only happened 4 times or so, so
> it may be concidence) or it may be related to a cooler engine temp.
> When it's happened, hitting the gas to bring it up to about 3000 RPM,
> then letting it fall back to idle seems to fix it - the car will
> happily idle then. Anything above idle and the car runs fine. The
> idle is a BIT rough, but keep in mind it is 15 years old. No violent
> shaking or anything, but not perfectly smooth like a new car would be.
> I've used my scan tool (Actron CP9150) and no faults are being logged.
> The voltage on the TPS does change, but I haven't had the tool on it
> while the fault is actually occuring (what idiot put the connector
> under the hood! :-P )
> This happened once about 2 months ago, and I asked around and was told
> to clean the throttle body. So we took off the throttle body, cleaned
> all the gunk out, put it back together and it didn't happen after that,
> so I assumed it was fixed. Then this started happening this afternoon.
> I also should note that we did change the timing chain a few days ago.
> I doubt it is related, as this did occur once before back in december
> (though the car wouldn't idle at all then, just started and died) but
> figure I should mention that.
> Any thoughts/suggestions/tests would be appreciated.
>
> Thanks,
> Eric Kotz
>

What step is the AIS motor on, 16 is a good number with the a/c off and a
clean throttle body.

> while the fault is actually occuring (what idiot put the connector
> under the hood! :-P )

What idiot made an after market scan tool with such a short wire after it
was designed for the DRB?

Was the Tamper proof plug removed on the Screw that adjusts the throttle
blade angle??
Glenn Beasley
Chrysler Tech

How do I read what step the AIS motor is on? I have a TPS voltage
reading (which is at .57v at idle) but I didn't see anything about the
AIS motor?
The scan tool has a 6 foot cable - hardly long enough to reach out the
front of the hood and back into the passenger compartment.

Unfortunately, yes, the tamper proof plug has been removed that
protects the throttle blade angle. How can I properly reset it?

> wrote in message
oups.com...
> How do I read what step the AIS motor is on? I have a TPS voltage
> reading (which is at .57v at idle) but I didn't see anything about the
> AIS motor?
> The scan tool has a 6 foot cable - hardly long enough to reach out the
> front of the hood and back into the passenger compartment.
>
> Unfortunately, yes, the tamper proof plug has been removed that
> protects the throttle blade angle. How can I properly reset it?
>

Have you thought about extending the cable? If it's a ribbon, it
should not be terribly difficult although you might want to ask
someone who fixes or does electronics. There are lots of different
connectors and cables, flat ribbons and what not, but you need
to order from electronics warehouses. Radio Shack has close to
nothing, unless you are very lucky, having driven all the little
stores out of business, as Walmart's is doing big-time, so you
can't find any electronics stores except Rat Shack now. Either
adding on to the cable is safest, or cutting the cable in two,
and adding your own connectors.

Almost never found any connector that was really proprietary.
But I can remember going through AMP catalog looking for
weird connectors, but found them and ordered them from
Newark or Digi-Key = DigiKey.com [used to be a really patient
company for newbies - find parts and so on].

If this goes well, maybe a small business set up here? Must be
lots of other people who want to extend their devices. Unless
and this is a big unless the device is not stable with more than
six feet of cable. This can happen but with very good cable,
usually low capacitance, they almost always can be extended.
I remember when printer cables had to be six feet, but now
I see them as long as 50 feet or 25 feet without amplifiers.

I barely know what an AIS motor is so can't help with the auto
part of your question.

> wrote in message
oups.com...
> How do I read what step the AIS motor is on? I have a TPS voltage
> reading (which is at .57v at idle) but I didn't see anything about the
> AIS motor?
> The scan tool has a 6 foot cable - hardly long enough to reach out the
> front of the hood and back into the passenger compartment.
>
> Unfortunately, yes, the tamper proof plug has been removed that
> protects the throttle blade angle. How can I properly reset it?
>
I have never used that generic scan tool and don't know what it is capable
of doing, But I would assume if you can read voltages on it you should be
able to read sensor values. And It should show what step it is on. If the
throttle body was dirty and someone adjusted the Throttle blade angle/TPS
sensor..... That may be your problem.. I normally put the system into a
minimum air flow test and adjust the idle/sensor that way. Once again, not
sure if your scanner is capable of doing that....Turn the screw out about a
half turn to see if that stops it

OK, I looked through the scan tool again and found that the AIS
position is generally about 65-70
A couple new developments today. The engine seems to do it more when
it is cold/not do it when it is warm. While it was doing it today, I
had the oppertunity to hook my scan tool up and nothing looked terribly
out of the ordinary, but it's hard to tell. While it was happening,
the O2 sensor was reading rich.
It also no longer seems to be an idle problem, as when I held my foot
on the gas it was still having the issue, up to about 1500RPM. Past
that it seemed fine. Also, one time I hit the gas and it seemed like
the engine speed did not increase. Additionally, I heard 2 clunk
noises coming from the engine at one point. Perhaps it was just
backfiring, but it did sound like it came from the engine, not the
exhaust.
I plan on disconnecting the EGR valve today and seeing what happens,
but any more insight is appreciated.

> wrote in message
oups.com...
> OK, I looked through the scan tool again and found that the AIS
> position is generally about 65-70
> A couple new developments today. The engine seems to do it more when
> it is cold/not do it when it is warm. While it was doing it today, I
> had the oppertunity to hook my scan tool up and nothing looked terribly
> out of the ordinary, but it's hard to tell. While it was happening,
> the O2 sensor was reading rich.
> It also no longer seems to be an idle problem, as when I held my foot
> on the gas it was still having the issue, up to about 1500RPM. Past
> that it seemed fine. Also, one time I hit the gas and it seemed like
> the engine speed did not increase. Additionally, I heard 2 clunk
> noises coming from the engine at one point. Perhaps it was just
> backfiring, but it did sound like it came from the engine, not the
> exhaust.
> I plan on disconnecting the EGR valve today and seeing what happens,
> but any more insight is appreciated.
>
65 to 70 steps? thats too high, you need to get the the throttle blade set
back and make sure the blade and bore is clean.Typically the out of adjusted
TPS will cause problems when cold and could also cause a hestitation and
other problems

Can you give me any advice on re-setting it properly? My scan tool
doesn't seem to have a minimum airflow test - are there any other
things that test can be called?
Failing that, is there another way I could set this screw properly?
The blade and bore should be clean - about 2 months ago I took them off
and used a toothbrush and about 1/2 a can of carb/choke cleaner to
clean them and they were virtualy spotless. The van has only been
driven about 1000 miles since then, so they should be clean.

> wrote in message
oups.com...
> Can you give me any advice on re-setting it properly? My scan tool
> doesn't seem to have a minimum airflow test - are there any other
> things that test can be called?
> Failing that, is there another way I could set this screw properly?
> The blade and bore should be clean - about 2 months ago I took them off
> and used a toothbrush and about 1/2 a can of carb/choke cleaner to
> clean them and they were virtualy spotless. The van has only been
> driven about 1000 miles since then, so they should be clean.

Back off the screw about a half turn, restart and see if that changes, if
not back off some more and recheck, see if that makes a difference, Our
scanner allows us to perform these tests by programed tests in the scanner.
keep in mind that you may have other problems and it isnt related to the
adjustment. Do you have a sensor value for adaptive fuel memory on your
scanner?
>

> wrote in message
oups.com...
> Can you give me any advice on re-setting it properly? My scan tool
> doesn't seem to have a minimum airflow test - are there any other
> things that test can be called?
> Failing that, is there another way I could set this screw properly?
> The blade and bore should be clean - about 2 months ago I took them off
> and used a toothbrush and about 1/2 a can of carb/choke cleaner to
> clean them and they were virtualy spotless. The van has only been
> driven about 1000 miles since then, so they should be clean.
>
REPAIR PROCEDU
This bulletin involves checking the throttle body calibration for settings
that effect operation at idle.

1.. Remove the air cleaner.
2.. Remove the vacuum line from the PCV valve and install the 0.185 inch
orifice tool, No. 6714 into the vacuum line.
3.. Disconnect the 3/16" canister purge hose at the front of the throttle
body and cap the nipple.
4.. Install the Scan Tool (DRB II) and start the engine. Warm the engine
to operating temperature.
5.. Using the Scan Tool (DRB II), scroll through the menus as follows:
select - System, select - Engine, select - Fuel and Ignition, select -
Actuator Tests, select - Engine RPM, select - Minimum Air Flow. The Scan
Tool will count down to stabilize the idle rpm, and display the minimum air
flow idle rpm. The Idle RPM should be between 500 and 900 RPM. If the idle
is outside these specifications, replace the throttle body.
6.. Remove the Scan Tool.
7.. Remove the orifice tool and install the vacuum line on the PCV valve.
8.. Install the idle purge hose on the throttle body
9.. Install the air cleaner.
The reason why it says replace the throttle body is because legally we cant
remove the plug to adjust the angle, but when someone does tamper with it,
here is a guidline to the proper setting to get it back, However this test
is no good to you because your scanner sounds like it is just a read out box