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Injector Issues
I am at my wits end. I have a 95. It was bought at action and had some wiring issues wit the injectors. We got a painless harness to replace the OEM but now we are having issues with getting it to stay running. We have spark and injector pulse when starting but when it goes to run mode we lose injector pulse and it dies like you shut the key off. We have plenty of fuel pressure and have replaced the cap and rotor. Being in this industry for over 30 years you would think i could figure this one out but it has me stumped. We first thought it may have been the oil sending unit but that shuts down the fuel pump. Then we looked into the security system but we have a bypass and that to shuts down the fuel pump and starter. I am not to sure how this Opti spark works and where I am losing signal. I know i do have power on the injectors and that the pcm controls the ground so I am assuming that the pcm is shutting it down. My next guess would be the pcm but it starts and runs for about 2 seconds so don't think it is that. Any suggestions would be greatly appicaicted.
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Re: Injector Issues
There is no interlock between oil pressure and the fuel pump on your LT1. Stopped that at the 3rd Gens.
Is the “SECURITY” light on? When you turn the key to “RUN” the fuel pump should prime for 2 seconds, then shut down. Pressure should reach at least 40PSI, and if it bleeds down after shutoff, should drop very slowly. When you turn the key to “START” the fuel pump will not restart until 2 things happen: 1 - the PCM sees the low resolution pulse signal from the optical cam position sensor in the distributor. Needs that to time the spark and sequential injectors. 2 - the PCM receives the 50 Hz “fuel enable” signal from the theft deterrent module = TDM (part of the PASS-Key II or VATS system). The tach needle should jump up roughly 200 RPM when the starter is cranking the engine. That can confirm the cam position signal. There is also a diagnostic code set in the PCM if there is no fuel enable signal. If the starter is cranking the engine, the security system has successfully read the ignition key resistance (or your “bypass” is working - if it’s only the resistor in the wires from the key cylinder). The lack of fuel enable signal problem would lie in the TDM. When this happens the engine kicks over and runs for a few seconds on the residual fuel pressure in the rails. There is also a “bypass” for the 50 Hz signal, so I don't know which “bypass” you have. From Shoebox: Description and wiring of PASS-Key II system: 4th Gen LT1 F-Body Tech-PassKey/VATS http://shbox.com/1/pass_key.jpg Test to determine if the Opti cam position signal is reaching the ignition coil module (ICM) 4th Gen LT1 F-body Tech Articles |
Re: Injector Issues
Originally Posted by Injuneer
(Post 7015870)
There is no interlock between oil pressure and the fuel pump on your LT1. Stopped that at the 3rd Gens.
Is the “SECURITY” light on? When you turn the key to “RUN” the fuel pump should prime for 2 seconds, then shut down. Pressure should reach at least 40PSI, and if it bleeds down after shutoff, should drop very slowly. When you turn the key to “START” the fuel pump will not restart until 2 things happen: 1 - the PCM sees the low resolution pulse signal from the optical cam position sensor in the distributor. Needs that to time the spark and sequential injectors. 2 - the PCM receives the 50 Hz “fuel enable” signal from the theft deterrent module = TDM (part of the PASS-Key II or VATS system). The tach needle should jump up roughly 200 RPM when the starter is cranking the engine. That can confirm the cam position signal. There is also a diagnostic code set in the PCM if there is no fuel enable signal. If the starter is cranking the engine, the security system has successfully read the ignition key resistance (or your “bypass” is working - if it’s only the resistor in the wires from the key cylinder). The lack of fuel enable signal problem would lie in the TDM. When this happens the engine kicks over and runs for a few seconds on the residual fuel pressure in the rails. There is also a “bypass” for the 50 Hz signal, so I don't know which “bypass” you have. From Shoebox: Description and wiring of PASS-Key II system: 4th Gen LT1 F-Body Tech-PassKey/VATS http://shbox.com/1/pass_key.jpg Test to determine if the Opti cam position signal is reaching the ignition coil module (ICM) 4th Gen LT1 F-body Tech Articles |
Re: Injector Issues
The injectors will pulse in “RUN” briefly but the pump won’t start. Without the “fuel enable” signal, DTC 46 sets (does not turn on SES light). Quoted direct from the factory service manual, when DTC 46 sets, the engine will stall in 1.7-seconds. The cylinders that do fire are consuming the fuel sitting at 40-45 PSI in the rails and line from the tank. That fuel will run out very quickly as the pressure drops. Fuel is a non-compressible fluid. Only takes a few drops to reach the point where flow stops.
Trying to help while unable to see and hear the vehicle and how it behaves, all I can do is offer POSSIBLE solutions. I can’t say anything with absolute certainty. That's the best I can do. If you want to check if the PCM is getting the “fuel enable” signal, scan it for codes. Additionally, free download of 1995 factory service manual: https://www.mediafire.com/?40mfgeoe4ctti |
Re: Injector Issues
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Re: Injector Issues
Originally Posted by JamesWoods
(Post 7015888)
I also facing the same problem.
I see from your profile your country is "AE" = United Arab Emirates. Are there many 4th Gen Camaros in your country? ADMINISTRATOR |
Re: Injector Issues
Scan, scan, scan. There is nothing more important than this for diagnosis.
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