88 Z24 no spark, please help!!!!!!!!!

I have an 88 Z24, 2.8L MPFI. It was running fine, then one day, I went out to start it, and it wouldn't start. We figured out it had no spark. First, I replaced the crank sensor. This fixed the problem for about 2 days. Then, driving down the road, it started to spit and sputter, then died. I haven't been able to start it since. It again has no spark. I removed the ignition module and coils, and replaced them all. The coils were cracked, but the old module tested fine (I replaced it anyway, was told they sometimes come and go when they're bad). After replacing all 3 coil packs and module, and a new crank sensor, I still have no spark. I tested for signal from the crank sensor to the module (mechanic friend told me which plug to test), and it is receiving signal. It is not reading any codes. My mechanic friend is stumped, adn so am I. Does anyone have any ideas?

There is also a Camshaft position sensor. Might want to have that looked into. Also See if you Mechanic friend has access to All Data. If so have him/her look up the flow chart for cranks wont start, that will help you along the way. You might even have a Sick ECM

When you say no codes out of the computer.... does that mean you got absoulutly nothing? just cerious, you should always get 1 code, a code 12, usually if you dont get any codes at all, with the situation you have, Just like C_sepiroth said.... you may have a bad ecu.

yeah, i am getting a code 12, and my mechanic friend is looking into All data, i think thats what he called it. Thank you very much!! i'll check into the camshaft sensor. anyone know where thats located?

What about the ignition switch? does anyone think that would do that? it cranks over fine........

I am having this same problem with my 97 2.4l. I have replaced the same exact items you have and I still get no spark. I would be very interested in knowing what fixes it! I have a hard time believing it is an ECM as I can get it to report codes by unplugging various sensors. The cam sensor is something I haven't check beyond unplugging it and getting no code reported.

I didn't try unplugging sensors to test the ECM, thats a good idea. I did figure out that I tested the wrong plug when I tried to test for signal from the crank sensor. Where would I find the cam sensor? I have a haynes manual, but I can't find anything about the cam sensor in there. I haven't gotten any codes at all since this happened, have you? When I tried to test the right plug last night, my battery was too dead to get a good signal, so I've had the charger on it all night. I did discover that there was a ground wire that comes out of the crank sensor plug, but doesn't go all the way to the crank sensor, and it wasn't grounded out. I tried grounding it, and didn't get any improvement, but like I said my battery was dead, so I'm not sure. Someone said something to me about a crank trigger? I've never heard of such a thing. Also, someone else said the ignition switch. And this sounds kinda crazy, but I thought since my coil packs were cracked, maybe it got water in there and shorted out, and maybe fried my plug wires? Is that possible? And would it take out ALL of them? I'm grabbing at straws here, I have no idea where to turn now.

I didn't try unplugging sensors to test the ECM, thats a good idea. I did figure out that I tested the wrong plug when I tried to test for signal from the crank sensor. Where would I find the cam sensor? I have a haynes manual, but I can't find anything about the cam sensor in there. I haven't gotten any codes at all since this happened, have you? When I tried to test the right plug last night, my battery was too dead to get a good signal, so I've had the charger on it all night. I did discover that there was a ground wire that comes out of the crank sensor plug, but doesn't go all the way to the crank sensor, and it wasn't grounded out. I tried grounding it, and didn't get any improvement, but like I said my battery was dead, so I'm not sure. Someone said something to me about a crank trigger? I've never heard of such a thing. Also, someone else said the ignition switch. And this sounds kinda crazy, but I thought since my coil packs were cracked, maybe it got water in there and shorted out, and maybe fried my plug wires? Is that possible? And would it take out ALL of them? I'm grabbing at straws here, I have no idea where to turn now.

Sounds like you have a 6 cylinder (3 coil packs). I have a 4, so I only had to replace 2. The camshaft sensor is bolted directly to one of the camshaft covers or at least I assume it is as my haynes manual doesn't cover it either. But since it is the only sensor other than the oil pressure sensor (which WAS covered in my haynes manual) anywhere close to either of the cams, I feel reasonably sure it is it. For me, it is directly above my intake and is a 3 conductor plug which is larger than the crankshaft sensor's plug I replaced this past weekend.

To answer your question, no codes other than the ones I created on purpose to make sure the ECU was reporting. I have never hear of a crank trigger... Are they talking about a signal generated by the crankshaft sensor?

You were asking about key lock cylinder in an earlier post. I'm not sure you would need to worry about that. The reason someone would have brought it up (and the reason I have researched it) is that GM started making their cars harder to steal. I don't remember exactly, but I think in '86 they started installing something called passkey theft deterent in their higher end models, like corvette. It is a key with a resister built into it. When the key is inserted into the lock, the resistance is read and the computer can then verify if the actual GM key was in the ignition. If the key you use has a black dot on it, then you have a passkey system. You should also have a security light in your dash panel. If the key has lost some of it's resistance, the reading will no longer be valid. The ECU will shut off the fuel, starter and one or two other items rendering the car unstartable (nice, if someone attempts to smash your steering column to steal your car). The only thing you can do to correct this is to replace with key with a new one of proper resistance. So the question for this is, do you have a security light and is it on? I have a '97 so I have theft deterent, but mine is slightly different than yours would be on an '88.

Yes, it is a 6. I just talked to my mechanic friend, and he said he doesn't think it has a cam sensor, so that rules that out. He also said unplugging other sensors might not be a sure bet the computer's working, but I don't think that would be whats wrong with yours, but I dunno. He said to check for signal from the ignition switch, in mine its a pink or red wire going into one of the plugs on the ignition module. also, check for signal to the injectors, run a testlight across both wires on one of the injectors whire cranking over. And of course, check for signal from the crank sensor. Should be about 5 volts, pulsing, while the car is cranking over. Oh, and no, no security light. In fact, its not the original ignition tumbler, it has been replaced. I got the car from my cousin, and before I got it, I helped replace that for her. If I get any more info, I'll let ya know. Btw, where are you from?

Well, I tested for signal from the crank sensor last night, and there wasn't any. So I pulled it out, and it had a big crack in it, just above the plug. And I just replaced it a week ago!!!!! I'm going to replace it tonight, and hopefully that fixes it. I got a code when I unplugged the map sensor, so my computer is at least working that much, but if the new crank sensor doesn't fix it, then its prolly the computer anyway. Oh, and the mechanic said there is no crank "trigger", the person was prolly talking about the sensor. My best advice to you would be to check for signal from the crank sensor, the ignition switch, and the injectors. Yours being a 97, it's different that mine, so I would see if you can get some advice from a mechanic. Let me know what you find out, and I'll let you know tomorrow if the crank sensor fixes it.

ok, replaced the new crank sensor and she started right up. thanks for all your help!!! now my oil pan gasket is leaking, but i think i can take care of that. i may be asking for more help in a couple days though, lol!!!!!!!!