Voyager problem

I could use a bit of diagnostic help please. I have a Plymouth
Voyager Van, 1993 4 cyl 2.5L, 145000 miles, 3 speed automatic.

On a recent trip of 750 interstate miles, at about 500 miles I noticed
what I thought was an intermittent light miss with an occasionally
more significant one. I tried, but could find nothing causing this
although I left the possibility of water in the gas as a possibility
or some electrical thing I couldn't detect.

I turned around on the next day as the condition didn't clear up and
strangely, after about 250 miles the problem disappeared and I had
not one incident in the next 500 miles.

After a couple of days of normal driving at home I again felt the
miss, but now it felt more like a mechanical problem. I even thought I
was making some progress when I found that I could make it do the
bigger "miss" by trying to accelerate faster than my normal driving
habits. It's more of a jar then would be caused by a miss IMO.

I've just taken an inspection of the CV joints, the boots are intact
but I could detect a bit of up and down play at the inner joint but
I have no reference as to what is "normal/acceptable". It also seems
to me that to do this correctly the weight should be on the wheels
though my reference does not indicate one way or the other.

What is the correct way to check and what's normal for CV joints?

Am I on the right track or should I be looking somewhere else?

Thanks for any help.

 

Forget the CV joints, if the boot is intact then the joint is fine.

Is the Check Engine Light on? If there is emissions inspection in
your state does the vehicle pass? (many states have state-run
inspection programs where you can get a free test-only, that
would tell you if the engine is misfiring since the emissions would
be too high) Have you done a physical inspection of all vacuum
lines on the engine to make sure everything is plugged in?
Have you tried pulling codes from the computer with the
on-off-on-off-on ignition key sequence?

Ted

 

Thanks for responding Ted. I'll drop the U-Joint quest.

No check engine light on. On pre-'95 cars there is only gas cap
check here. Had a valve job done at 143000, bad back precluded
me doing it. Chap screwed the job at least somewhat as 2 valve-stem
seals were not seated (I didn't have to worry about anyone following
me too closely) and I wrestled 4 days to replace them.

I broke and replaced the vacuum line from heated air inlet temperature
sensor to the heated air inlet diaphragm before the trip. I don't detect any
vacuum leaks by listening and all lines are connected.

Earlier today, I found the gearbox lock up solenoid connector only
held in place by the rubber boot ... it fell off the connector when I
reached for it. From the amount of oil and stuff inside the transmission
side connecter it has not been connected in some time. I cleaned it as
best I could and re-connected it. A test drive indicated no change
in the condition. Didn't use VOM on it as I had no idea of values and
didn't want feedback into computer to be a new problem.

Hmmm, is it possible that I reversed the vacuum lines at the heated air inlet
temperature sensor and that's causing my problem?

I've neglected the codes as I was told that once stored they're there
until the special dealer tool erases them ... is that correct? I'll
try to read them tomorrow.

Thanks again for being willing to help.

Jack

 

I have a pre-95 Voyager and there are 30 odd codes at least.
Sometimes the check light does not come on long enough to see the
problem,
but it's often stored for so many engine starts before it gets
erased automatically. On my 1994 Voyager, around 20 or 30 starts
and the code goes away until the problem comes back again. I have
an intermittent problem with a failing oxygen sensor, code 21.
And when the thermostat was failing, I can't recall if I ever
saw an engine light. I should have but I just don't remember now.

Older VOM's use a bit of current but newer DVM's use very little
little.
Your point is interesting about feedback. I guess it's possible.
Would need to know the specs of a DVM or digital volt meter and the
specs regarding your signals to the computer and if you could introduce
voltage or amperage which would confuse the computer.

I think not with new DVM's which have, if I can recall, the resistance
is way up, like 10 megaohms which should blunt anything going back.
But VOM's had very little comparison, like 50,000 ohms. In fact, a
VOM could polarize electrodes I used when taking resistance readings
because of the relatively large amount of voltage/current the meter
was using.

 

It sounds to me like a fuel issue. Question: what's your EGR like?
Could it be stuck open? Are you loosing coolant? Can you put a
vacuum guage on the manifold and take a look at the vacuum at
idle?

Is getting it on an emissions test bench even an option in your state?
If you have a fuel problem that should show up as bad emissions.

Ted

 

: It sounds to me like a fuel issue. Question: what's your EGR like?
: Could it be stuck open? Are you loosing coolant? Can you put a
: vacuum guage on the manifold and take a look at the vacuum at
: idle?

: Is getting it on an emissions test bench even an option in your state?
: If you have a fuel problem that should show up as bad emissions.

: Ted

Ted:

I'm still with you, trying to get items you suggested checked out before
reporting back. Yesterday (Monday) I had a lot on my plate and didn't get
much done other then re-establishing a base line on the blink codes. I had
checked them 3 years ago when I bought the car used. I asked the dealer
to check them out and he said he did .... only problem is I hadn't re-
checked since.

4 (actually 2 of value) are the same as there originally. I have 12, 22,
24, 37 & 55. My reference (Haynes) indicates 12 is a throw-away as is 55.
Originally I had 22 & 24 (coolant sensor voltage too high/low & throttle
position sensor voltage too high/low). 37 is new (part throttle un-lock
circuit (open or shorted). I've been through about 20 on/off cycles on
ignition hoping that when I get to about 50 I at least see the 37
disappear now that it's connected.

I'm not losing any coolant. When the guy did the valve job he apparently
somehow broke the heater control valve. I had no heat after I got the car
back. I replaced the valve with another and it apparently is now working.
I have the impression that it now takes longer for the engine to reach
"normal" but I'm guessing that may be an indication that my thermostat
needs replacing.

I dug through my stuff today and found my manifold vacuum gauge. Hopefully,
I'll get it hooked up tomorrow and look at those numbers.

I couldn't find my vacuum testing pump, called around and stores are
asking $50 ... trying to borrow one ... apparently I need it to check
EGR. Is it possible that oil pulled in from valve stems re-cycled through
EGR and caused it to fail?

Might be another day or two 'til I get the skinny on the EGR.

Thanks again.

Jack

 

Anything is possible but I think it's unlikely. EGR's usually fail because
they
get crudded up with exhaust gas carbon. That usually plugs them and you
don't
have a noticeable problem except your NoX goes sky high and you don't pass
emissions. But it could be possible that it sticks open. Since the EGR
bleeds off
manifold vacuum (a lot of it) if it opens at the wrong time you will get
stumbling
and such.

Did you replace the TPS? That is an easy part to check with a voltohmmeter.
It's also an easy part to check with a scan tool. And you did say that if
you
accellerate faster than normal you get a bigger miss - that seems to concur
with
your codes that there might be a problem with that sensor.

Ted

 

:>
:> I dug through my stuff today and found my manifold vacuum gauge.
: Hopefully,
:> I'll get it hooked up tomorrow and look at those numbers.
:>
:> I couldn't find my vacuum testing pump, called around and stores are
:> asking $50 ... trying to borrow one ... apparently I need it to check
:> EGR. Is it possible that oil pulled in from valve stems re-cycled through
:> EGR and caused it to fail?
:>

: Anything is possible but I think it's unlikely. EGR's usually fail because
: they
: get crudded up with exhaust gas carbon. That usually plugs them and you
: don't
: have a noticeable problem except your NoX goes sky high and you don't pass
: emissions. But it could be possible that it sticks open. Since the EGR
: bleeds off
: manifold vacuum (a lot of it) if it opens at the wrong time you will get
: stumbling
: and such.

: Did you replace the TPS? That is an easy part to check with a voltohmmeter.
: It's also an easy part to check with a scan tool. And you did say that if
: you
: accellerate faster than normal you get a bigger miss - that seems to concur
: with
: your codes that there might be a problem with that sensor.

: Ted

Well I replaced the rotor and cap with no improvemment. Checked manifold
vacuum and it's 19" and less then a needle width of fluctuation. I
used VOM to the throttle position switch and resistance changed smoothly
between 0.9 (closed) and 3.75 (open). If I have an EGR valve, I've
yet to find it. I found the elbow on the vacuum connection to the
hwaded air/canister purge nipple on the throttle body to be not
seated fully and thought I had found the problem but that didn't
help either. I checked the timing and it seems to be 11 degrees
(specs call for 12, but I left it alone for now), I disconnected the
temperature sensor as required before checking.

Strangely, the condition is now worse, so something I did has
changed the conditions. If I now try to accelerate on a steep
grade, I get the "hard" miss and then the engine continues to
miss/stumble even after I crest a grade and am moving down
hill. Then, if I stop, the engine stalls (there are no warning lights
before the stop); when I re-key, the engine starts easily and runs
smooth.

Jack

 

Well, the other thing that might fit that symptom is if the timing belt
jumped a tooth or two. Is the belt original?

Ted

 

: Well, the other thing that might fit that symptom is if the timing belt
: jumped a tooth or two. Is the belt original?

I insisted the timing belt be replaced before I bought the car and,
when replacing the afore-mentioned valve stem seals, I took the
time to examine the timing belt and it looked fine. I didn't verify
the cam timing or the belt tension then, however.

I've got to take a closer look at the MAP sensor voltages. It's a
tough one for me to do alone, might have to collar a friend to help out.
A book I have indicates that MAP should be about 4.7V off, 3.75 at 5 in-Hg
and 1.2V at 20in-Hg .... Does that sound right? Was the 19in-Hg a
"normal" value for the manifold vacuum reading?

Jack

 

: : Well, the other thing that might fit that symptom is if the timing belt
: : jumped a tooth or two. Is the belt original?

: I insisted the timing belt be replaced before I bought the car and,
: when replacing the afore-mentioned valve stem seals, I took the
: time to examine the timing belt and it looked fine. I didn't verify
: the cam timing or the belt tension then, however.

: I've got to take a closer look at the MAP sensor voltages. It's a
: tough one for me to do alone, might have to collar a friend to help out.
: A book I have indicates that MAP should be about 4.7V off, 3.75 at 5 in-Hg
: and 1.2V at 20in-Hg .... Does that sound right? Was the 19in-Hg a
: "normal" value for the manifold vacuum reading?

: Jack

Following up on my last post:

I finally found a thin enough probe and got a good connection
to the MAP sensor. I got 1.2V @ 20in, 2.0V @ 15in, 2.9V @ 10in,
3.8V @ 5in and 4.6V @ 0in. There was smooth transition of the
reading.

Also positioned on TDC and rough checked that timing belt was
OK by peeking through the cover hole ... dead square in the middle.

Any chance it could be Hall pickup assembly? Any easy way to check it?

Jack