92 Cavalier No Spark

I'm not sure how to scan for cranking RPMs. Where is the Crank Sensor located?

I checked for codes last night, using the flashing service engine light method...All I saw was 12 which means no codes stored. (I did let it flash the 12 3+ times).

The Poping sound he heard concerns me...perhaps timeing belt?

I don't know if it has a belt or a chain. I would think if it had a chain, it would make noise when trying to turn over the motor.

How do I check to see if the belt went?

One thing the diagnostic book I have said is to check and see if the injectors are working. It talks about an injector test light, which I don't have.

If someone could outline the steps to diagnose this I'd be most grateful.

if you are sure about nospark such that time coil should be replaced or weak voltage test ohm value of secondary & primary coils the coil value for 1/4 & 2/3 cylenders {are couple acting } must be the same if not one of the coils is partially burnt & do this test for wires note : you must incorporate length of wires in your measures for ohm test note : ignition module can not be seperate from ECM I'm sure that is not ignition module

Yes it can...

I'm sure that it is.

Toyota MDT in MO

valve train is working by checking the compression. You could do a visual inspection by removing the valve cover or timing chain cover.

be wet with gasoline. If you can confirm that there is no spark and no fuel injection you probably have either a bad computer or bad crankshaft timing sensor.

Got nothing to do with it having no spark.

Thanks to all who responded so far..... latest update: I ignored advice to not change the crank sensor until I tested it....I broke if off in the motor, and had to remove the oil pan to replace it....I was warned that it may be hard to remove....

THe new crank sensor didn't solve my problem...

I have two new coils, a new crank sensor, and still no spark. I have compression, tested by sticking my finger in the plug hole. I found the section in an auto book about testing the ICM. I have battery voltage at the appropriate circut, as well as checking the resistance in the Crank Sensor circut. There is a millivolt test you can do on the circut, but didn't want my son turning over the motor while I was holding leads on the Crank Sensor. I also hooked my test light to one of the injectors and got flashing lights.

The ICM is a $130 part, so I'd really like to know if it's bad before I replace it....

Any other ideas ...before I pull out my checkbook ?

Thanks,

Neil Nels> > > snipped-for-privacy@gmail.com wrote:

If your injectors are really being operated by the ECM while cranking, then it must be getting a reference signal from the ICM (purple/white wire). Whether it's a good, clean signal or not would be up to a scope to determine.

I'm curious how you are determining that you have no spark. In general with GM DIS, if you have injector activity, then your coils should be receiving a control ground as well. On the 2.2 it's a bear to test the individual components and "wiring" between them while on the engine due to their location. But since you have done some parts shotgunning already, and assuming the newly replaced parts are good, it seems to reason that your ICM is bad given that the injectors are getting a signal. It's likely that the control transistor inside the ICM has failed and can't pass enough current to interupt the coil pack secondaries.

You could always grab one from a DIY junkyard for cheap or get a used one on ebay if money is tight. Without complete and proper diagnosis, your next step has to be an ICM. Luckily, it's a good bet.

Toyota MDT in MO

THanks to you all for responding. My experince with these sites, is usually after the first response, you get nothing.

I'm checking for spark by sticking a screw driver in the various plug ends and watching while someone turns over the motor. Crude, but it's worked for me in the past. I never did test the plug wires, because they arn't that old, and I doubt they'd all fail at the same time.

I should have started at the junk yard with this car, but the autoparts guy was positive it was a $40 coil. Then I found out there are two, and the shotgunning kind of snowballed from there.

This is true, I'm crawling under the car on the frozen minnesota tundra, because my garage holds another "car not running" project.

You should keep the companion cylinder's plug wire attached while testing the other wire for spark. Each coil fires two plugs. If you test one wire with the other disconnected, you are testing an open circuit. The coil potential can still find a path to ground, but not the way the system was intended to operate. Some people use two of those cheap adjustable spark testers, one in each wire, then they connect the alligator clamps together when testing DIS coil output.

He didn't even look at your car, and may not be a particularly sharp diagnostician, otherwise there's a good chance he would be working on cars for a living. Sure, it's a generalization, but it's based on real world observation. He probably suggested that because his store sells alot of coils. Your coil part number fits most GM 4 and 6 cylinders, and has a healthy failure rate, so they are going to sell the hell out of them. Many techs replace good coils when replacing a bad ICM in case the coils had caused the ICM's early demise.

Fun!

Toyota MDT in MO

Good to know about the companion wire. I did not realize that, but I did test em one at a time. I decided to find a cheap spark plug tester(s) after I read your last post. And this eveing I will test the plug wires. The way they wrap around the motor, it's not inconceiveable that they would all melt and short out, but i saw no visible signs of that.

I knew better than to trust the kids at the auto parts store...But is was 5:00 Sunday evening, My son needed the car on Monday, and I was running out of options....Now a week later, I'm getting used to getting a ride everywhere.

I have just enough mechanical skills to get in way over my head!...and why is it that "the houshold mechanic" loses his ride, when someone elses car breaks down? :-)

Well, I'm back to square one. Still no spark, tested by pulling one wire at a time, sticking a screwdriver in it and laying it across the motor.

To recap: No engine codes, New Crank Sensor, Used coil/ICM pack. I have compression (tested with my finger in the plug hole). The plugs are wet with gas (I did dry them before trying to start the car). I hooked a test light to one of the Fuel injector leads and it flashed. The junk yard told me they test the ICM/coil packs before putting them on the shelf. I do have battery voltage to the ICM.

I havn't tested plug wires for resistance yet.

Twice now between swapping parts, it fired a couple of times, and then nothing.

Can I hook my test light between the plug and wire as a better test (perhaps for weak spark)? or is too much current generated.? I did do the spark test at night, so I'm pretty sure I have nothing.

Would the Brain Box/Computer cause this sort of problem?

Perhaps a broken wire somewhere?

Two bad wires, one on each pack, *could* cause limited spark at all four plugs.

I wouldn't. Get a spark tester w/ adjustable gap and pigtail wire at the local parts store. They're cheap.

Low current in a coil secondary collapse, but vey high voltage for a few milliseconds per spark event (assuming there are any). A standard test light is designed to work on about 12volts and draw about .25 amps.

Probably right.

As far as I know, no. It reads RPM info (which we can assume is available if your injectors are getting pulsed) and then sends back modified timing information (EST) to the ICM. The ICM has the capability of firing the coils without ECM input, but in a non-feedback, base timing kind of way. If the ECM detected EST issues, it should set a code 42 (I think it's 42 or 43 anyway).

Yes. Check the ground wire specifically at the ICM. I think it is Black/White, but I'm w/out info at the moment. There are two main power wires to the ICM: B+ (Pink) and ground (Black/White) -- guessing at the colors here. Use a DVOM set to volts, and backprobe the Pink with the positive lead and the B/W with negative. Check for full battery voltage with key on, then have someone crank the engine and see what you have. It should not deviate more than about .4 volts from battery voltage.

If you want to isolate one wire (I suggest ground) do this: positive probe on the B/W wire, neg probe on battery ground terminal. Look for a reading of < .3 volts while cranking car. You may want to get some piercing leads.

I wouldn't worry too much about wire insulation integrity on a 1992 Cadaver. It's only time before it's going to be too expensive to keep running from a moneywise perspective anyway.

Don't forget that if a wire tests good while backprobing or piercing, it doesn't mean that the connector female to male contact is sufficient. You can usually eyeball the connectors and tell if theyre OK, though. Green corrosion = bad. Loose female (tee hee) terminal also = bad.

Toyota MDT in MO

Finally got back to my little project.

I tested the Plug wires, and found one that was suspect... I replaced em all.

Battery voltage was 12+ volts at the connection to the ICM. I didn't want to lay under the car and test the voltage while it was being turned over....

I did find (I think) a connector by the injectors that had the same black and pink wire that is hooked to the ICM. I noticed the voltage drop to 8 volts while cranking. I tested one injector again (with the used ICM installed) it flashed my test light.

Does the volatge drop mean I have a bad ground when turrning it over? Or is that normal? Perhaps the ground to the ICM is broken while turning the ignition.

I guess I may have to crawl under the car and do the test at the actual ICM connection (black and pink wire).

When you (Comboverfish) talked about isolating ground, did you mean running a ground wire from the battery to the black wire? I'm having a bit of trouble figureing out which wire in the harness (black & pink) actually runs to the ICM

At least the weather here in Minnesota has been warm!