TPITuned Port Injection discussion and questions. LB9 and L98 tech, porting, tuning, and bolt-on aftermarket products.
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I have a 92 350 TPI setup that is in a 96 Silverado, The system was working fine, but one day would not start, Found out the ignition module was bad (Tested at autozone). Long story short went through about 6 modules (all tested bad immedatly after cranking), along with a new distributor, coil, ECM (2 times), Checked injector, coil, and distributor resistance, all good. Wiring is good, triple checked, along with injector wiring, I can not figure out what the hell is going on, any help would be greatly appreciated
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Last edited by Brett427; 05-20-2008 at 06:52 PM.
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Ah, i hate to spend the extra money to just blow the AC delco unit, i guess i can try, I tryed a used GM one and it blew it also, so i dont see that can help
Did you check to see if any of the wires that plug into the module are shorted to either ground or power? Example b+ on the est wire could fry it. Also did you check them with the key "on" and "start"?
B killed at first power. (expensive parts being used as a fuse)
Solution : Double check all inputs and outputs.
C Ignition module is good. Tester is bad. Trouble somewhere else.
Solution : get all your modules tested at a different place.
The Factory Manual has long and boring, check this check that, type of flow charts. Some where some thing is very wrong. These units rarely go bad and usually just need replaced one time and problem gone for years.
The charts, diagrams, and alot of discussion about how to fix this is posted somewhere on this board. Search on "won't start", "no start", "no spark"
Typical trouble is unit tests good, no output. Trouble is found in the pickup coil, wiring, or spark coil. Heat related intermittents are difficult to find because the modules work fine cold when tested.
The good stuff can take more shorted outputs with out frying. People here have had better luck using the OEM GM AC DELCO ignition module.
If you are short on money and long on time. There are a lot of these modules at junkyards. The same unit is used in many different GM cars and trucks, 4-6-8 cylinder. Go to a pull your own part place and get a hand full to try. There should be some good ones in the bunch.
What is the best way to check inputs and outputs? Ive checked to ground and 12 for each of the 4 ECM feeds, and resistance, The harness is a good harness that i got from Mike on here, and it is run good also. I had modules checked at 2 different autozones and both came up bad, One module i blew was a used GM module, if the tester is correct. Ill try to focus on other no start probs, as i recall i am not getting any injector pulse while cranking, which i know is related to the Ignition Module,
Brett
Ignition module amplifies and directs, via relays, to spark coil under 400 rpm or when est wire disconnected, base timing only, no ecm involved for spark.
Over 400 rpm and with est wire connected, relays in the ignition module flip and sends the pickup coil pulse to the ecm which adds spark advance. Then back to the ignition module and on to spark coil. If no pulses to ecm no injectors pulses either.
Battery power is supplied to spark coil and ignition module applies a ground to fire the spark coil, when it is pulsed by the pickup coil. This is what the ignition points did (apply the ground), before electronics .
The pickup coil makes it's own power so any big (battery) power applied to these terminals, means instant death for the module. Shorted to ground, open, or crossed wires will not kill the ignition module at the pickup coil.
The output terminals are made to, short the battery volts and the current draw of a stock coil to ground, without any harm, and do this 24,000 times a minute (6000 rpm / 2 X 8 cylinders) for years.
Remember the heat sink grease, this is why it is needed, all that current/power starting and stopping makes a lot of heat.
It is obvious that you didn't even try or have the patience to search, but everything you need to know is right here on this board. Start looking for and reading about "no start" ect.... All the diagrams/schematics and the trouble shooting flow charts are here at TGO (buried in posts) and in the helms factory manuals.
Or you can just take it some where and change it all and pray it will cure it.
you have a bad engine ground or are using aftermarket modules,i have been burned by 10 of them in the last year,in my cars and on forklifts at work,i only run gm modules and have had no problems since.
You wouldnt have happened to put a 50,000V coil in the distributor when you changed it, would you? A few years back I bought one of those cheap 50,000V coils off of summit and it FRIED the ignition module.
I thought I had messed up reassembling the distributor but it turns out it was the coil. I swapped the stock coil and no change, but after I put the stock coil and a cheap Autozone ignition module in, it fired right up.
May not be applicable to your situation, but you never know...
