89 Z24 starting probems

89 Z24 starting probems

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badsam56
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Mar 18, 2008, 4:09 PM

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89 Z24 starting probems	Can't Post

Year of vehicle 1989
Make of vehicle Chevrolet
Model of vehicle Cavalier
Engine size 2.8 V6
Mileage/Kilometers 145K

I have a Z24 that refuses to start. I have checked with a tester and it has no spark. It was internment problem that would only show up after driving a distance. I suspected heat soak and changed the coil packs and controller. I still get no spark, so I ran the line looking for any abrasions and found none. I then decided to try another computer and I still have the same problem. I'm not very familiar with the OBD-1 system and could use any suggestions on what to try next. Crazy

JIM N
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Mar 18, 2008, 4:20 PM

Post #2 of 8 (107 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

I assume by controller ,you mean the ignition control module that the coil packs mount to..correct?
I suspect the crankshaft position sensor and or wiring......
The module must receive a cranking signal from the sensor to fire the coils.
If you have access to a scan tool with data stream capabilities,check for cranking rpm.....

What line did you "run"?

badsam56
Novice

Mar 18, 2008, 4:28 PM

Post #3 of 8 (106 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

I ran the wiring from the control module to the computer and sensors. I unraveled the snake and checked for shorts, plus I ran a short tester in the line to look for resistance. All check OK.

Yes the controller is the module the Coil Packs mount to. I also ran a diagnostic on the crack sensor 1st thing, just didn't mention it. The crank sensor checks with an Ohm meter. There may be a better way to confirm it working and I'm willing to give it a shot.

JIM N
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Mar 18, 2008, 5:03 PM

Post #4 of 8 (105 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

Sensor should ohm out at between 900 -1200 ohms...

I assume there is no cranking rpm.....disconnect ignition module 2 pin connector,turn igntion on,connect a test light between harness terminals.<< if light is off>>,connect test light from harness terminal "B" to ground, light on= repair open in ground ckt 450.
<if light is on>>,= repair open in ignition feed circuit 439.

Now,back after checking 2 pin earlier,if light on- disconnect crank sensor 3 way connector from ignition module,with ohm meter in 2k ohms position,probe harness terminals A & C ( should read between 900 -1200 ohms-
If not ok...less than 900 ohm,sensor leads shorted together or a faulty crank sensor-if greater than 1200 - open sensor ckt faulty connection or faulty sensor.
If ok.set volt meter on 2 volt ac position,crank engine and observe voltage reading. reading should be greater than .1 volt (100mv)...is it?...if yes.replace the module- if no faulty connection or faulty sensor.

Hope that makes sense and helps you...let me know

badsam56
Novice

Mar 18, 2008, 5:22 PM

Post #5 of 8 (102 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

OK, by the way you're saying to check the crank sensor I should have a (900 to 1200 ohms) reading? I didn't have that as I check the system by spining the engine and watching the meter indicate #1 as I thought it did on these old systems. No wonder I'm confused. I get a 0 ohms reading without the engine spinning. Thanks, this will probably find the problem as I was thinking the crank sensor was fine. Learn something new every day. Smile

In Reply To

JIM N
Veteran / Moderator

Mar 18, 2008, 5:24 PM

Post #6 of 8 (101 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

Cool

Lets us know how you make out.

BTW..
Cool Avatar

Jim

badsam56
Novice

Mar 18, 2008, 5:51 PM

Post #7 of 8 (98 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

Thanks on the avatar. Also TY on the possible fix. I'm going to try it the 1st chance I get. In fact this car is taking on a new persona, from run around town car to a possible NHRA Stock class racer. In pure stock form it has gone 16.30 @ 95 mph. The record in the class is open and I have my tricks to up the ponies. BTW I'm not a GM mechanic and don't mind any advice. I am a MOPAR/ASE Certified mechanic/machinist or should I say was one before I retired. So I'm on a new learning curve with this baby. A Z24 convertible all black, but in need of a lot of TLC!

Thanks again Jim!!!! I'll post how I came out on it. Wink

badsam56
Novice

Mar 20, 2008, 5:27 PM

Post #8 of 8 (88 views)
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Re: 89 Z24 starting probems [In reply to]	Can't Post

I may have misdiagnosed this problem and thanks Jim for putting me back on track. The voltage to the coil module is OK, so that checks. The crank sensor is another story as it seems to be dead. I get no Ohms reading at all when checking it. I also have another question I'm thinking might be related. The tach will not register when real cold, but as the engine warms it would begin to work again. If the tach get a reading feed from the crank sensor this might confirm the problem as bing there and the if higher voltages forced the ignition to work yet not enough to signal, it just make diagnosing easier. What do you think?

Sam

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