95 Cavalier Z/24 Idle trouble

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Help! I recently replaced my water pump on my 95 Chevy Cavalier Z/24 now my car idles to fast and the check engine light is on.
I tried using a OBD scan tool but it won't work on my car. My Z/24 has a 16 pin ECM plug and I would like to use a jump wire to figure out the trouble.
The book says to connect at the 5/6 points BUT my Z/24 has connect points at 1,4,5,9,16. Does anyone know which numbers I connect my jumper wire to?
Thanks in advance

posted by  skuttle

Before going into this any deeper, read the underhood emmissions label and see if the words OBD2 show up anywhere on the sticker.

Some 1995 had the OBD1 computer and codes and the 16 pin connector while others used OBD2

posted by  tbaxleyjr

I did and I have the OBD I with the 16 pin. Any idea on which pins I use??
Thanks for the reply.

posted by  skuttle

check the attachment jumper a & b the service engine light will flash your code

posted by  osborste

Looking foward into the 16 pin connector with the long end on top, pin 5 is supposed to be ground and pin 6 is the diagnostic treminal

The a and b reference is for the 12 pin connector where b is the diagnostic connector and a is ground.

posted by  tbaxleyjr

I tried 5 and 6...no luck. I think this car is jinxed..

posted by  skuttle

i got a pic of both obd I and obd II
obd I you can definately ground teminal a & b left to right would be terminals 5 & 6 but you have a 16 pin which is obd II for this i don't recommend grounding anything as this system work differently you need to rent/buy an obdII scan tool
check the attachment

posted by  osborste

This is so bizzare. Under the hood it lists my car as OBD I but I have a 16 pin OBD II under the dash. I tried renting the Auto Xray OBD I/II but it didnt work on my car because none of the pins lined up. GM must have switched some things in mid-flight in 1995. And I thought replacing the water pump was going to be the tough job here. I start my car now and it races up to 3000 RPM's then goes to 1500 and idles like crap. I'm starting to hate this car....lol :banghead:

posted by  skuttle

can you tell me what size the engine is? i think its a 3.1L v6 but i just want to be sure i'm looking up the right stuff
for now go back over everthing in the area of the water pump check electrical connection and really check the vacuum hoses rubber and plastic make sure none are leaking popped off during the water pump replacement

posted by  osborste

No, I have a 2.3L Quad 4.

posted by  skuttle

if the fan is running constantly, you may have left the temp sensor unhooked...

posted by  dodger65

did you do anything to the timing chain?
did you unplug any sensors oxygen sensor for the exhaust pipe?
looked up the procedure its a little bit of a pain on that motor 2.3L and the 2.4L to change the water pump

posted by  osborste

Oh yesssssssssss...blech...the job was a pain in the a_ _! Had to remove the exhaust manifold to do the job.
There was no secret about the timing chain....the water pump simply unplugged from the sprocket with nothing to line up on re-assembly....I greased it well, new pump in....it was a text book job. Everything went back in fine.
THEN I STARTED MY CAR.......it tried racing to the moon on start up.....I am tempted to replace the TPS(throttle positioning sensor) but damn at $90.00 is that the first place to start when I cant read any codes that I know are waiting in my ECM.
I have almost 120,000 miles on this car, it could well be the PCM itself..... :banghead:

posted by  skuttle

If you cannot get the code reader to match up and are pulling the TPS, take it into like Autozone or similar and they should be able to bench test it for you befor you spend $90 on a new one you may not need.

posted by  srober32

Temp sensor is back on, did that on re-assembly

posted by  skuttle

THEN I STARTED MY CAR.......it tried racing to the moon on start up
check for vacuum leaks/hoses connections if you had to raise or lower engine during the water pump replacement may have pulled/broke some hose's off
check plug connetions at the iac valve (idle air control)this controls the idle if wide open would cause the engine to rev to high
is the linkage or throttle jammed partly opened?

posted by  osborste

in 1995, GM used the 16 pin connector with an OBD1 type system on some cars. If grounding 5 and 6 don't work with an OBD 1 car, the dealer or another qualified shop may need to help.

posted by  tbaxleyjr

Hmmmmmmmmmmm... I think I may have found the trouble(I hope)....I started disconnecting sensors and starting the car to see what happened...
The check engine light stayed on every time EXCEPT when I disconnected the up-stream exhaust manifold sensor. Then the light went off. I ordered a new sensor tonight and will pick up from Checker auto tomorrow...hopefully the 23.00 I just spent will fix this problem, if not YES it is shop time, I am out of ideas and patience.............lol :banghead:
And yes you are correct, I have a OBD I with a 16 pin,just my luck huh??

posted by  skuttle

when taking off the exhaust manifold did you pinch any wires when you put it back on, if the o2 was still hooked up and you let it hang or drop you may have damaged the wires, but that still wouldn't explain why it races to 3000rpm, i would be checking vacuum leaks or disconnected sensors

posted by  BanffAutoSpa_ap

I've looked everywhere..I cant see anything disconnected or broken....I did replace the o2 sensor but that didnt help a thing.....all I can figure now is the TPS or ICS or the PCM itself.......I start my car and it races to a high idle the to 1500 and idles very rough,not really drivable like this.

posted by  skuttle

you didnt remove anything for the intake manifold or throttle body when you did the water pump? did you
the tps if adjustable and was put back on incorrectly would do this
or the iac valve if not preset before installing the computer would have incorrect reading(counts)on the lenght of the piston on it. the pcm thats ify if the car ran well before the water pump replacement. then i dont think the computer would go like that unless the battery connections were reversed on install the setback to proper pos and neg that would pop a few things electrical

posted by  osborste

if it's running that bad at idle, it really sounds like a vacuum leak. maybe pull on some hoses lightly with it running and see if it changes or the hose breaks. it could be that something got bumped or pulled and it cracked, but didn't break. idk if it's been mentioned yet, but autozone will read your codes for free, whether it's obd I or II...

posted by  dodger65

Nope, never touched the intake manifold just the exhaust...didnt reverse the connections and I've tested the TPS with my multimeter and it checks out fine.

posted by  skuttle

I will go through all my hoses one more time but I just dont see any leaks but the hoses are getting old and a bit worn. I wish I had an Autozone close by, this car is in really no shape to be driven at this point.

posted by  skuttle

Could it be something really simple like the rad being low? I know we had a problem with a car in the tech shop today (idling too fast) and it turned out it was really low on anti freeze/water (open the cap and see nothing) and so after that was topped up it ran fine. Just an idea, you've probly already checked that anyways. Good luck with the problem.

posted by  car_crazy89

Well..............the mystery is over!!!!!!!!!!!!!!! and go figure this one :banghead:

I took my car into a repair shop not far from here and they solved the trouble for 398.00 OUCH!!!!!!!!!!!! :ohcrap:

It took them all day to do it but here goes...
They ran a scan, to many codes...
They then did a full diagnostic, that returned nothing.
They thought it was the timing chain so they checked that, Nope.
They disconnected my cruise control...BINGO!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!! :thumbs:
The cruise cable under the hood was broken somehow (probably when I let my 21 year old son work on a stubborn bolt for me) and it was causing the engine to race....The cruise was NOT on inside the car itself on the column.
They said they will be talking about this one for awhile because it is the weirdest thing they've seen....of course it has to be my car..... :laughing:
Oh well, 120,000 miles on this thing.....time to sell and get my Mercury Mariner. Thanks to all who put in there :2cents: worth trying to help me...I never would have guessed the cruise control as the source of the problem.

posted by  skuttle

Yeah, was gonna suggest that, yup, uh-huh. lol. Glad you got it fixed :thumbs: , sorry it cost you so much. :ohcrap:

posted by  srober32

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