JSchaefer97

iTrader: (2)

car - 97 formula ws6

My car cranks but will not start. We have been going through a list testing different things and the one result we cannot reproduce is a pulsing ground. What exactly will it look like, will the test light flicker? or kind of blink on and off? it says to test for pulsing ground at the non pink wire going to a fuel injector, while cranking the motor. I did this and do not see any light at all on the test light while testing the ground. It says if there is no "pulsing ground" then the optical sensor is bad. So not wanting to deal with that since I just replaced the opti last summer/fall, we continued testing things until we came to another "pulsing ground" check, this time testing the wire that goes to the coil from the ecm. Again, we were unable to get a pulsing ground, this along with the previous step of testing the cable to the ecm, it basically says to replace the coil and the ecm.

I also tested the signal voltages going to the plug at the opti and found that my male opti harness plug that plugs into the opti was cracked in two. So i just went ahead and got a new opti harness from EFI Connections and put it in, and the car started! for 2 or 3 seconds, and then died

Here is the article we are using: http://www.mainstreamtopics.com/foru...rt-diagnostic/

So my question is, what is a pulsing ground and is there a better way to check or it, or what other things do you guys recommend that I check?


Thanks in advance,
JS

djjab57

iTrader: (17)

Every time this has happen to me its either the ICM or the coil EVERY TIME

JSchaefer97

iTrader: (2)

I would much rather have it be either of those than the opti, fingers crossed.

Big Al

iTrader: (1)

To test for a pulsing ground you need to connect the other end of the test light to the positive side of the battery, not to ground.

Al

glassjaw1704

I will put $ on it being the ICM.

JSchaefer97

iTrader: (2)

Well I still can't produce a "pulsing ground" at the injectors or the coil, whether I'm doing something wrong or its just not working I don't know. The sheet says if there is no pulsing ground at the injectors than the opti is bad, but would the car have started and ran for a few seconds after I replaced the opti harness if that were the case? I'm gonna see if someone in my area has a spare 96-97 icm and coil I can throw on and try rather than throwing money at it. Any other ideas of are you guys pretty certain its the icm or coil?

JSchaefer97

iTrader: (2)

bump, retesting everything -_-

Big Al

iTrader: (1)

+

Slow down, put a known good test lamp right across the injector socket. Just unplug an injector and connect the lamp across it. Crank the engine and see if the lamp pulses.

Assuming your 97 ICM is close to what my 95 has, it's easy to check. The ICM gets pulses from the PCM. It then sends pulses to the coil. Here is a schematic: http://shbox.com/1/1996_ec_03_ign_system.jpg

Look at the dark green wire (D), if you put your test lamp from ground to this terminal the lamp should go on as soon as you turn on the key, and pulse when you crank it. If it does not go on with the key, unplug the connector from the ICM and see if the lamp lights. While it's off also check for power at pin A. (Key on)

Let me know what you get from these tests. You did check the Ignition fuse I hope.

Al

JSchaefer97

iTrader: (2)

After testing some more today, at one point we got spark all the way to the opti end of the coil wire, but not at the spark plugs. Then after testing a few other things tried again and could not get a spark at the coil wire again..

We can not get any pulsing ground at the injectors at all. We are getting correct voltages on all 4 of the wires that plug into the opti. this means the opti is not sending the signal correct?

Also,
Not getting any light at the dark green wire with the key turned on and no pulse when cranking, the light does not come on when when I unplug the connector from the ICM. And the pink on both to the ICM and the coil are getting power.

all fuses look fine.

Big Al

iTrader: (1)

You have "light" at the pink wire (A) but not at dark green (D) with the connector off? If that is true the coil is open. Hard to believe....

Do you have an Ohm meter? If yes, with the key off, read the resistance from A to D, connector off the ICM. What is it?

And, are you 100% sure your test light isn't flaky? If it is it will drive you nuts.

Al

JSchaefer97

iTrader: (2)

Yes, there is light at the pink but not at the dark green.

A little confused with which wires are A and D, with key off I got 0.00 between the pink at the coil and the pink at the ICM, and 0.00 between the green at the coil and the green at the ICM, but nothing registered when I mixed and matched pink and green.

Yes the test light is good.



I'm gonna have to agree with you on getting out of the LT1 business by the way

Big Al

iTrader: (1)

If what you posted is true it's the coil or a connection or wire between the coil and the ICM.

Do you get "light" at one of the two FI contacts, test light grounded, key on?

Al

Big Al

iTrader: (1)

I forgot, the ICM connector is clearly numbered. At least mine is. The wire numbers and colors are at the link I sent a few posts up.

Al

JSchaefer97

iTrader: (2)

we replaced the opti since i have a lifetime warranty on it so it was a free fix and because we got spark through the coil but not out the plug wires, and now it cranks and then struggles, and all the lights in the car (dash, overhead, etc) go out. -_-

Pulled the starter and it appears fine, its not cracked at least. i have previously shattered one starter with this engine during the winter seemingly out of nowhere. drove home one night, the next day it was in pieces.

Also my battery is a bit low at 8 volts so its on the charger.

any ideas?


will look into the coil if we still have spark issues

djjab57

iTrader: (17)

Man a coil is less than $20 at AZ I would have done that first. The old one may be giving you spark but not enough

JSchaefer97

iTrader: (2)

i know they are like $30 but the opti was free and its done and put back together now. But sparking isn't the biggest issue now since its struggling to even try to start. as in crank crank crank and then it like chugs (best word i can think of at the moment) like the starter isnt getting enough power or something else is wrong. so the battery is charging and I may get a free replacement starter since its a reman, which would be awesome if the starter is in fact bad.

JSchaefer97

iTrader: (2)

the starter also will also just click when i turn the key sometimes, and it does this 5 times or so before it turns over

1quick redz28

you should do a load test on the battery too.. if its clicking it does not have enough juice to start the car. how old is the battery... with a weak battery or poor charging system the computer could get a litttle crazy, i would check all connections with the battery and alternator.. if battery checks out test the voltage on the alternator when car is running..

also did you check fuel pressure? you could be having 2 different problems

JSchaefer97

iTrader: (2)

swapped on a good solenoid onto the starter, cranks good first time every time now

new opti on, we now have flashing ground everywhere your supposed to have it

new coil, we now have spark

it still struggles and actually fired out the throttle body about 4 inches when cranking. can these cars even be out of time?

going to try putting the maf and intake back on and see if that helps, maybe the computer is confused by lack of maf signals or something.

JSchaefer97

iTrader: (2)

we have fuel pressure and spark but it still will not start... it fired back out of the intake again while we were trying to start it. other than that it cranks all day but no luck.

Can an lt1 be out of time? the only thing i haven't tried is an icm, could a bad icm cause it to act out of time or spark in the wrong order?

Really out of ideas at this point and would really appreciate any help anyone can give.

thanks.