No Spark at the PLugs, WHY???

[Dog House]

My 89 started running poorly two weeks ago, I had to ease into the throttle to get it to go. If you put too much peddle to it it would not go it just coughed and sputtered and wanted to die. Went out the other day started right up and died when I put it in gear. Let it set a while and it would start then die. Now it does nothing when you turn the key. There is no spark at the plugs and no pulse to the injectors. I checked with a test light and have power on the pink wire coming out of the distributor with the ignition on and power on the white wire while cranking. I replaced the coil, cap, & rotor and also had the module checked which was good and still no spark. What would cause no spark?

 

[boomdriver]

My 89 started running poorly two weeks ago, I had to ease into the throttle to get it to go. If you put too much peddle to it it would not go it just coughed and sputtered and wanted to die. Went out the other day started right up and died when I put it in gear. Let it set a while and it would start then die. Now it does nothing when you turn the key. There is no spark at the plugs and no pulse to the injectors. I checked with a test light and have power on the pink wire coming out of the distributor with the ignition on and power on the white wire while cranking. I replaced the coil, cap, & rotor and also had the module checked which was good and still no spark. What would cause no spark?

sounds like low voltage to me. Knock-off chinese ignition modules will also do this. Everything inside the distributer cap needs to be Delco.Also check the fusable links/ grounds...all of them.

 

[Dog House]

They only grounds I have been able to find are about five wires grounded by a bolt on the tranny/bell housing. I can’t even find a ground strap from the engine to frame. Where are the fusible links located?

 

[WRECKER88]

Shorted Injector

I had the same problem with my 1989 and it turned out to be 1 shorted fuel injector. To check them disconnect them and they should be around 16 ohms each. My number 7 injector was shorted (3.4 ohms) and it kept the engine from starting. I got new injectors from FIC and now my cor runs like it did 21 years ago.

High Performance New Fuel Injectors - Delphi - new Delphi 22lb Flow MAtched TPI fuel injector set for L98 - Fuel Injector Connection

 

[Dog House]

When you discovered you had a bad injector did you also have NO spark at the plugs?

 

[WRECKER88]

It started as stalling but would restart. Then it would not start until it cooled down and it would not start at all. If you have a shorted injector the computer will not let it start. After i found the shorted injector if i diconnected it the engine would start and run.

 

[vetteoz]

When you discovered you had a bad injector did you also have NO spark at the plugs?

ECM shutting down injector bank because of bad injector(s) does not affect spark.
If ign module is bad then you will get no ref signal to the ECM and get no spark and no injector pulse

 

[vetteoz]

. If you have a shorted injector the computer will not let it start.

It is not a matter of the ECM not letting it start.
The ECM only shuts down the bank with the bad injector ( unless you have bad injectors in both banks)
Other side continues to pulse and engine will still get spark.
I have started my engine with a whole injector bank disconnected ( accidentally left inj plugs off ).Ran like crap but still fired up

 

[LLC5]

My 89 started running poorly two weeks ago, I had to ease into the throttle to get it to go. If you put too much peddle to it it would not go it just coughed and sputtered and wanted to die. Went out the other day started right up and died when I put it in gear. Let it set a while and it would start then die. Now it does nothing when you turn the key. There is no spark at the plugs and no pulse to the injectors. I checked with a test light and have power on the pink wire coming out of the distributor with the ignition on and power on the white wire while cranking. I replaced the coil, cap, & rotor and also had the module checked which was good and still no spark. What would cause no spark?

No spark to the plugs and no injector pulse, at the same time, could easily be a primary circuit problem in your ignition. It sounds like the only components that you have not replaced are the ignition module and the distributor pick up coil. Check the pick up coil carefully with the problem active, wiggle the wires into the coil as you check it for any changes on your ohm meter. Accurate diagnosis is key to any repair, because when replacing parts you could be just making more problems for yourself (bad/cheap parts, harness pin fit, etc). Make sure that you have battery voltage (with a voltmeter, not just a test light) at the distributer with the problem active, as it could be a wiring harness or ignition switch problem also.

 

[Dog House]

Is the 4 Terminal EST connector the one behind the distributor that goes to the ECM?

 

[John Robinson]

Tps

Possibly the TPS(Throttle Position Sensor) is bad.. If you have an FSM look up the TPS. I don't now on the L98 engine but on my lt1 it controls the input of several sensors used by the ECM to run the engine. I discovered that the whole system is very sensitive to having good grounds. In my case I had broken wires in the connector plugs for the TPS and a bad ground connection in the wiring harness were the grounds from several different sensors were bundled together. I also used electrical contact cleaner to clean the connections on the ECM from corrosion. Follow through by cleaning all the grounds to the chassis (I believe you can find there location by doing a search here GMJunkie has posted them several times.)

 

[Dog House]

Tested the pick-up coil today with an ohm meter and while cranking the engine the needle stayed in one position it did not fluctuate up or down. Don’t remember the number but it was low.

 

[Highway Man]

coil wire resistance

No spark to the plugs and no injector pulse, at the same time, could easily be a primary circuit problem in your ignition. It sounds like the only components that you have not replaced are the ignition module and the distributor pick up coil. Check the pick up coil carefully with the problem active, wiggle the wires into the coil as you check it for any changes on your ohm meter. Accurate diagnosis is key to any repair, because when replacing parts you could be just making more problems for yourself (bad/cheap parts, harness pin fit, etc). Make sure that you have battery voltage (with a voltmeter, not just a test light) at the distributer with the problem active, as it could be a wiring harness or ignition switch problem also.

Could you tell me how much resistance a coil wire should have on a 92 vette lt1? Also if I have a bad coil I should probably look at the possibility of a damaged coil and ignition module? If you could answer this I would really appreciate it! Thanks

 

[John Robinson]

Hope this will help you out

 

[Dog House]

It must have been the pick-up coil. Being I am putting on a Holley Stealth Ram on soon I put the small cap distributor and remote coil in that I had purchased and it started right up.

 

[Schrade]

Sounds great. Closed loop idle smooth too?

That's the real test... hnoes

 

[Dog House]

Yep, now I can proceed with the Holley Stealth Ram and Header mods