WindyCityZnut Posted July 15, 2010 Share Posted July 15, 2010 For starters, I am just starting to learn MS, as I have only owned this car for about 5 months. Here is the set-up of the car as I know it: Stock L28 turbo short block P90 head Delta cam Schnieder springs, light port work. BHJ damper 550 RC injectors PT61 T4 turbo( GT35R compressor wheel, P trim .58 hot side) 35mm WG Running Megsquirt 'n Spark extra, MS1 I believe I had a very reputable shop dyno tune the car a couple of months ago. It seemed to run strong when I got it back. Then I got side-tracked when the head gasket blew. Got that fixed and was working on getting the car running again. As soon as I put power into the system, the injectors open, without even cranking the engine. I took it back to the shop for some help in trouble shooting. We verified that the tune is still in the MS that was set during the dyno tuning, however it fires the injectors immediately. The mechanic thinks that there is something inside the ECU that has fried. Is there a way to check if the CU has gone bad? Has anybody else run into this issue? I have search for several hours now and could not find a similar problem. Are there any MS guru's in the Chicago area that would be willing to give me a hand trouble shooting? Thanks, Marty Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 15, 2010 Share Posted July 15, 2010 Hook it up to an MS Stimulator board. Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 16, 2010 Author Share Posted July 16, 2010 Hook it up to an MS Stimulator board. Unfortunately, I did not get one with the car. Is there somewhere I could ship it to get tested? Quote Link to comment Share on other sites More sharing options...
Zmanco Posted July 16, 2010 Share Posted July 16, 2010 Unfortunately, I did not get one with the car. Is there somewhere I could ship it to get tested? Contact DIY Autotune - they sell kits and assembled too - maybe they do repairs? Matt is often on this board so may see this as well. But how do you know the injectors are staying open as soon as you apply power? I'd say it's far more likely that you have a wiring problem than the CPU is bad, unless the tuner is flat out lying to you, which is probably not the case. If the MS system was built using a Relay board, then I'd start with looking over all the wiring, looking closely for anything that worked loose, etc. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted July 16, 2010 Share Posted July 16, 2010 Injector test mode enabled in Megatune? Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 16, 2010 Author Share Posted July 16, 2010 Contact DIY Autotune - they sell kits and assembled too - maybe they do repairs? Matt is often on this board so may see this as well. But how do you know the injectors are staying open as soon as you apply power? I'd say it's far more likely that you have a wiring problem than the CPU is bad, unless the tuner is flat out lying to you, which is probably not the case. If the MS system was built using a Relay board, then I'd start with looking over all the wiring, looking closely for anything that worked loose, etc. I know they are staying open because they completely filled up the cylinders with fuel until it was hydro-locked. Fuel even got into the crankcase and the exhaust through a couple of open valves. We pulled the plugs and cracked it. It sprayed fuel across the room like a gieser! I need to put in some fresh oil and circulate it through the engine to clean it out. I am not sure how to clean out the exhaust. I aqm afraid to try and start it now. Quote Link to comment Share on other sites More sharing options...
goodoldjam Posted July 18, 2010 Share Posted July 18, 2010 I forgot to hook up quite a few of my grounds and the fuel pump would stay on instead of priming. Don't know if the injectors were open during this time. Found what i didn't hook up and it was back to normal. Probably a good chance it's just a wiring problem. Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 24, 2010 Author Share Posted July 24, 2010 Well I finally got a chance to get back into the garage this morning after delays for a track weekend and some minor surgery earlier in the week. On your advise, I starting checking on the wiring. I cleaned up a couple of grounds. Found and replaced 1 bad connector. When I was tracing the fuel injector wiring I discovered that the harness had fallen onto the rear of the exhaust manifold. Several of the wires had their coating melted. One was actually stuck to the manifold and possibly grounded to it. Looks like I need to replace the harnesses. Unfortunately, there is no part number on it. One of the connectors at the harness end had "P.E.D. 25" embossed on it. Any body recognize that? Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 24, 2010 Author Share Posted July 24, 2010 Well I finally got a chance to get back into the garage this morning after delays for a track weekend and some minor surgery earlier in the week. On your advise, I starting checking on the wiring. I cleaned up a couple of grounds. Found and replaced 1 bad connector. When I was tracing the fuel injector wiring I discovered that the harness had fallen onto the rear of the exhaust manifold. Several of the wires had their coating melted. One was actually stuck to the manifold and possibly grounded to it. Looks like I need to replace the harnesses. Unfortunately, there is no part number on it. One of the connectors at the harness end had "P.E.D. 25" embossed on it. Any body recognize that? Here is a picture of the connector if that helps. Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 24, 2010 Author Share Posted July 24, 2010 Well I finally got a chance to get back into the garage this morning after delays for a track weekend and some minor surgery earlier in the week. On your advise, I starting checking on the wiring. I cleaned up a couple of grounds. Found and replaced 1 bad connector. When I was tracing the fuel injector wiring I discovered that the harness had fallen onto the rear of the exhaust manifold. Several of the wires had their coating melted. One was actually stuck to the manifold and possibly grounded to it. Looks like I need to replace the harnesses. Unfortunately, there is no part number on it. One of the connectors at the harness end had "P.E.D. 25" embossed on it. Any body recognize that? Here is a picture if that helps. Quote Link to comment Share on other sites More sharing options...
Zmanco Posted July 25, 2010 Share Posted July 25, 2010 That looks a lot like the connector to the throttle position sensor from the 240sx that many of us use, but it would be near the throttle body, so not sure what it is on your car. Can you trace the wires? Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 25, 2010 Author Share Posted July 25, 2010 That looks a lot like the connector to the throttle position sensor from the 240sx that many of us use, but it would be near the throttle body, so not sure what it is on your car. Can you trace the wires? I found out that the injector harness on this car is actually from an SDS system. Mystery solved. Now to see if I can order a new one. Thanks! Quote Link to comment Share on other sites More sharing options...
Challenger Posted July 25, 2010 Share Posted July 25, 2010 Im not a megsquirt genius but it shouldnt matter if its an SDS injector harness should it? As long as the proper wires were going to each injector it should still work right? Quote Link to comment Share on other sites More sharing options...
WindyCityZnut Posted July 25, 2010 Author Share Posted July 25, 2010 Im not a megsquirt genius but it shouldnt matter if its an SDS injector harness should it? As long as the proper wires were going to each injector it should still work right? It doesn't matter at all. It has been running in this configuration fora long time. A couple of the wires got damaged and I want to source a replacement. Quote Link to comment Share on other sites More sharing options...
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