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Have spark but No injector pulse

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Happys_TSI

5+ Year Contributor
34
4
Nov 29, 2017
Oregon, Ohio
I have a 1990 Eagle Talon Tsi having issues with injectors. I have fuel pressure at the rail, fp works, I have spark. Checked injectors 3-4 ohms at each. Used a noid light to test each injector clip, no dice. So I went in and tested the pins directly at the ecu by probing The injector output pins 51,52,60, and 61. With ignition on Pin 51 was the only one that was showing functional voltage 11.53v. The other 3 pins were at a solid 0.09v so basically my question is, is my ecu dead? Also getting a code 41 after trying to start it. Injector code I believe. Also when attempting to start the car the tac needle jumps to 3 grand every time it cranks.
 
Last edited:
The injectors need to be unplugged when you check pulse at the ecu, also your looking for a ground pulse not a positive voltage pulse.
 
The injectors need to be unplugged when you check pulse at the ecu, also your looking for a ground pulse not a positive voltage pulse.

I thought that the ecu should be putting out 12v at the pins with the ignition on that’s what everyone on here has said. Is that correct?
 
The injectors need to be unplugged when you check pulse at the ecu, also your looking for a ground pulse not a positive voltage pulse.

I’m sorry I suck at understanding wiring it makes my head hurt. So those wires I was testing for 12v are actually the ground wires for the injectors?
 
injectors will have battery voltage (+) to them, the injectors fire when the ecu provides a path to ground. Its like that on everything i have ever messed with

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Check all grounds in general? Or for injectors? Would any other loose ground cause just my injectors not to fire?
Should check all under the hood and the dash since your tachometer moves weird when cranking as you mentioned above. Also check if the power transistor is connected well. Especially if it doesn't have the clip to hold.
 
The 12v supplied to the injectors is not supplied by the ecu, only the ground is...check each injector for 12v positive with the key to the run position (with the injectors unplugged) and then connect one end of your test light (noid light) to the positive and probe the other end at the ecu were the injectors get their signal (four different pins) and crank the engine over while looking for the test light to light up and pulse. Have you noticed the tach moving during cranking?
 
The 12v supplied to the injectors is not supplied by the ecu, only the ground is...check each injector for 12v positive with the key to the run position (with the injectors unplugged) and then connect one end of your test light (noid light) to the positive and probe the other end at the ecu were the injectors get their signal (four different pins) and crank the engine over while looking for the test light to light up and pulse. Have you noticed the tach moving during cranking?

Yes it jumps to 3 grand when cranking
 
CAS???
 
You could have a bad cord going to your cas, but during cranking you would likely still get a batch fired injector signal.
 
You could have a bad cord going to your cas, but during cranking you would likely still get a batch fired injector signal.
Well the other day I cranked it after testing for spark and it sounded like it wanted to start. I assumed my injectors had leaked a bit of fuel. But since then nothin just dry cranking.
 
At this point you need to find out for sure whats going on, start with a compression test, then check for spark on all four and then a noid light test on each injector pigtail.
 
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At this point you need to find out for sure whats going on, start with a compression test, then check for spark on all four and then a noid light test on each injector pigtail.

Compression is 150 across the board. I have spark on all 4. Noid light test unsuccessful. I have yet to test injector plugs with multimeter I’ve been busy. But I’ll do that this weekend and get back to you.
 
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