Trying to Start and Need Some Help
Trying to Start and Need Some Help Well, I tried starting my LY6/4L80E swap into my '72 Nova today with no success. After testing a variety of things, I know that I have fuel at the rail, I have spark, my injectors are not stuck, and I have voltage at the injector. I am pretty sure that my problem is that the injectors are not pulsing when trying to start. I came to this conclusion because a few cylinders fired once when I tried starting after I tested several of my injectors with a 9 V battery (this was the first time I had any sort of fire). I tested for voltage at the injector by unplugging #1 and testing with a multimeter while trying to start, however, I would imagine this is an incorrect method because I had a constant voltage in "run" and in "start" (it was 12 volts and actually dropped to ~10 V during start but still constant).
Are there any ideas about what could be wrong?
I know these type questions are asked a lot in this section, but any help is really appreciated. Thanks.
Are there any ideas about what could be wrong?
I know these type questions are asked a lot in this section, but any help is really appreciated. Thanks.
............"I tested several of my injectors with a 9 V battery (this was the first time I had any sort of fire). I tested for voltage at the injector by unplugging #1 and testing with a multimeter while trying to start, however, I would imagine this is an incorrect method because I had a constant voltage in "run" and in "start" (it was 12 volts and actually dropped to ~10 V during start but still constant)."
Battery should always present @ injs & coils in "RUN" & "START" . It is the GRND side of the coil & the injs which is turned on & off (in firing order) by the ECM.
When you caused several of the injs to "fire', do you mean that the cylinder ignited, or were you saying only that the injector fired? In either case, I'm assuming that not only did you apply batt(9v) to injs, but you also applied your own external GRND?? So, it may be that your ECM is not applying GRND sequentially, or any grnd at all. There is another, similar thread happening which is down the roster a bit.
https://ls1tech.com/forums/conversio...inj-pulse.html
Do you have VATS? Is your ECM receiving the 50Hz VATS sig which it needs?
Battery should always present @ injs & coils in "RUN" & "START" . It is the GRND side of the coil & the injs which is turned on & off (in firing order) by the ECM.
When you caused several of the injs to "fire', do you mean that the cylinder ignited, or were you saying only that the injector fired? In either case, I'm assuming that not only did you apply batt(9v) to injs, but you also applied your own external GRND?? So, it may be that your ECM is not applying GRND sequentially, or any grnd at all. There is another, similar thread happening which is down the roster a bit.
https://ls1tech.com/forums/conversio...inj-pulse.html
Do you have VATS? Is your ECM receiving the 50Hz VATS sig which it needs?
Last edited by gMAG; Dec 23, 2010 at 09:09 PM.
I asked the guy that tuned the computer to disable VATS from the ECM. I don't think I have a way to verify if it was, however, my understanding is that even if VATS is enabled the engine should still be able to run even if only for a few seconds, but I am not getting any type of ignition in the cylinders currently.
When I said the cylinders fired, I meant that the cylinder was ignited due to what I assume was fuel present from when I tested the injectors with the 9V. And yes, I had both the + and - terminals of the 9 V connected to the injector, so it should have been spraying fuel.
Also, what was confusing to me about when I tested the voltage at the injectors was that if the ECM applies ground only when the injector should pulse, then I wouldn't think I would be able to read a voltage at all times if I was reading at the two pins of the injector connector, not a constant external ground. But maybe I don't understand the electronics well enough, and that's why I made the thread
Thanks
Battery should always present @ injs & coils in "RUN" & "START" . It is the GRND side of the coil & the injs which is turned on & off (in firing order) by the ECM.
When you caused several of the injs to "fire', do you mean that the cylinder ignited, or were you saying only that the injector fired? In either case, I'm assuming that not only did you apply batt(9v) to injs, but you also applied your own external GRND?? So, it may be that your ECM is not applying GRND sequentially, or any grnd at all. There is another, similar thread happening which is down the roster a bit.
https://ls1tech.com/forums/conversio...inj-pulse.html
Do you have VATS? Is your ECM receiving the 50Hz VATS sig which it needs?
When you caused several of the injs to "fire', do you mean that the cylinder ignited, or were you saying only that the injector fired? In either case, I'm assuming that not only did you apply batt(9v) to injs, but you also applied your own external GRND?? So, it may be that your ECM is not applying GRND sequentially, or any grnd at all. There is another, similar thread happening which is down the roster a bit.
https://ls1tech.com/forums/conversio...inj-pulse.html
Do you have VATS? Is your ECM receiving the 50Hz VATS sig which it needs?
Also, what was confusing to me about when I tested the voltage at the injectors was that if the ECM applies ground only when the injector should pulse, then I wouldn't think I would be able to read a voltage at all times if I was reading at the two pins of the injector connector, not a constant external ground. But maybe I don't understand the electronics well enough, and that's why I made the thread
Thanks
I asked the guy that tuned the computer to disable VATS from the ECM. I don't think I have a way to verify if it was, however, my understanding is that even if VATS is enabled the engine should still be able to run even if only for a few seconds, but I am not getting any type of ignition in the cylinders currently.
When I said the cylinders fired, I meant that the cylinder was ignited due to what I assume was fuel present from when I tested the injectors with the 9V. And yes, I had both the + and - terminals of the 9 V connected to the injector, so it should have been spraying fuel.
Also, what was confusing to me about when I tested the voltage at the injectors was that if the ECM applies ground only when the injector should pulse, then I wouldn't think I would be able to read a voltage at all times if I was reading at the two pins of the injector connector, not a constant external ground. But maybe I don't understand the electronics well enough, and that's why I made the thread
Thanks
When I said the cylinders fired, I meant that the cylinder was ignited due to what I assume was fuel present from when I tested the injectors with the 9V. And yes, I had both the + and - terminals of the 9 V connected to the injector, so it should have been spraying fuel.
Also, what was confusing to me about when I tested the voltage at the injectors was that if the ECM applies ground only when the injector should pulse, then I wouldn't think I would be able to read a voltage at all times if I was reading at the two pins of the injector connector, not a constant external ground. But maybe I don't understand the electronics well enough, and that's why I made the thread
Thanks
(Goes out to garage @ 12:40A to verif this). OK, I've just checked my car...I only have 12v batt by one lead of voltmeter to inj harness & the other lead to CHASSIS grnd. With voltmeter connected to both pins, I see about 5v with key to 'run'. The grnd pin of the inj harness shows no grnd when checked to chassis (key to 'run'), but there MUST be some kind of current draw to see 5v. BTW, I'm using an analog meter at the moment.
Do you have 12v/key "RUN", or 5V, voltmeter across both pins of inj harness?
Do you see a constant 0 ohm grnd on 1 pin of the inj harness with key "RUN"?
No matter, it seems like you were firing the inj w/9v, therefore with 12v already proven, the grnd needed to fire might be missing.
About VATS...there could still be an issue with VATS. Reading from several prev threads, I've gathered that, depending upon the program used to disable VATS ( Hypertech, EFI Live, etc), sometimes the VATS disable doesn't "take" & VATS really isn't disabled.
Another thing about VATS...some people say that VATS (without the proper 50Hz signal) will disable the injectors. And, I've heard that VATS will disable the fuel pump. If the car will run briefly without the VATS sig, then that must mean that VATs only disables the fuel pump, therefore, you're running on residual fuel in the lines. If it disabled the injectors, then, obviously, the car would not run at all.
I don't want to come off as an expert here, I'm learning just as you are.
Last edited by gMAG; Dec 24, 2010 at 12:19 AM.
About VATS...there could still be an issue with VATS. Reading from several prev threads, I've gathered that, depending upon the program used to disable VATS ( Hypertech, EFI Live, etc), sometimes the VATS disable doesn't "take" & VATS really isn't disabled.
Another thing about VATS...some people say that VATS (without the proper 50Hz signal) will disable the injectors. And, I've heard that VATS will disable the fuel pump. If the car will run briefly without the VATS sig, then that must mean that VATs only disables the fuel pump, therefore, you're running on residual fuel in the lines. If it disabled the injectors, then, obviously, the car would not run at all.
I don't want to come off as an expert here, I'm learning just as you are.
Another thing about VATS...some people say that VATS (without the proper 50Hz signal) will disable the injectors. And, I've heard that VATS will disable the fuel pump. If the car will run briefly without the VATS sig, then that must mean that VATs only disables the fuel pump, therefore, you're running on residual fuel in the lines. If it disabled the injectors, then, obviously, the car would not run at all.
I don't want to come off as an expert here, I'm learning just as you are.
If VATS is enabled it will crank and attempt to start like normal, however it will fire and almost immediately die. Some people have claimed less than 5 seconds, I got more like one crank revolution. Inside HP Tuners (not sure about others) VATS has a Serial / PWM / None option BUT the PCM error codes need to be removed as well. If the codes are still enabled, VATS is still enabled... ask me how I know this...
This long winding road leads me to my next questions:
Do you have any codes? Those need to be addressed
What is your fuel pressure? If the standing fuel pressure isn't in the 55+ range that needs to be addressed
Who built your harness? If the answer is you - there may be something simple that was missed
Is your crank sensor plugged in? This is located behind the starter
Is the cam sensor plugged in? Located behind the intake on GEN III 24x engines and on the front cover for GEN IV 58x engines
Good luck, hopefully you will have a running engine for Christmas!
I'm working on a way to run mine on coal because I know that's what I'm getting.
Make sure you have ignition voltage in both "crank" and "run" stages. That little problem bit me for a week before I got clued in. Older cars originally equipped with a resistor wire in the ignition circuit may need to be rewired to achieve this....
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Verdad Gallardo Inside HP Tuners (not sure about others) VATS has a Serial / PWM / None option BUT the PCM error codes need to be removed as well. If the codes are still enabled, VATS is still enabled... ask me how I know this...
Good thing to know. thanks.
Good thing to know. thanks.
Alright, haven't been able to do too much the past day or two, but I do have a couple answers to questions from previous posts...
- I have about 12 V across the two injector connector pins AND across the injector power pin and motor/chassis ground. (key in run)
- There is no connection between ground pin of injector connector and motor/chassis ground. (key in run)
- Not sure of any codes present. I did try to set up a light on the malfunction indicator lamp wire off of the ECM, and after two short start attempts (1-2 seconds each) the light wasn't on. However, I am not 100% confident in my method of connecting the light, so that probably is not a useful result.
- I don't have an exact fuel pressure number, however, I do know it is building a fair amount due to the couple of fuel leaks discovered
. Also it should be plenty to at least ignite a cylinder due to the experience after testing injectors with a 9 V battery.
- I did the modification to the harness...this might be problem #1
- Camshaft and crankshaft sensors are plugged in. Crankshaft sensor is incredibly hard to reach well, but I am confident it is completely plugged in.
One thing I have thought about, mainly regarding the timing of things, is that when I got a few cylinders to ignite it sounded somewhat correct, which led me to believe that the timing of the spark was correct, which I would then assume that the ECM should be receiving a correct signal of when to pulse the injectors, however, I guess that also assumes that these events are timed from the same sensor.
- I have about 12 V across the two injector connector pins AND across the injector power pin and motor/chassis ground. (key in run)
- There is no connection between ground pin of injector connector and motor/chassis ground. (key in run)
- Not sure of any codes present. I did try to set up a light on the malfunction indicator lamp wire off of the ECM, and after two short start attempts (1-2 seconds each) the light wasn't on. However, I am not 100% confident in my method of connecting the light, so that probably is not a useful result.
- I don't have an exact fuel pressure number, however, I do know it is building a fair amount due to the couple of fuel leaks discovered
. Also it should be plenty to at least ignite a cylinder due to the experience after testing injectors with a 9 V battery.- I did the modification to the harness...this might be problem #1
- Camshaft and crankshaft sensors are plugged in. Crankshaft sensor is incredibly hard to reach well, but I am confident it is completely plugged in.
One thing I have thought about, mainly regarding the timing of things, is that when I got a few cylinders to ignite it sounded somewhat correct, which led me to believe that the timing of the spark was correct, which I would then assume that the ECM should be receiving a correct signal of when to pulse the injectors, however, I guess that also assumes that these events are timed from the same sensor.
One more thing I thought of, is there any possibility that a VSS sensor that is not plugged in could cause this type of problem? Mine is currently not plugged due to interference with the transmission cross member.
I couldn't think of an obvious reason why it would be the culprit, but I am trying to make sure all the bases are covered.
Thanks
I couldn't think of an obvious reason why it would be the culprit, but I am trying to make sure all the bases are covered.
Thanks
VSS won't cause a no start problem.
I'm not sure I understand your injector testing. There are two leads to each injector, power and ground but you say you had 12V on both???
If my memory is correct, they ground through the PCM. I'll check a schematic when I get home and verify. Yes it is the same ECM that came with the engine/trans out of a 2009 Van. It is an E38, so it was only made for the Gen IV engines.
As for the injector voltage, using a multimeter, I put 1 probe on the power (pink) pin in the connector and 1 on the ground pin and got 12 V with the key in run. I then put 1 probe on the power pin and 1 on an engine/chassis ground and again got 12 V. Also, I checked for amperage and got .12 mA (if I remember correctly) between the two connector pins with key in run.
Also, I used the multimeter to check for continuity between the connector ground pin and an engine/chassis ground and none was present.
Thanks
As for the injector voltage, using a multimeter, I put 1 probe on the power (pink) pin in the connector and 1 on the ground pin and got 12 V with the key in run. I then put 1 probe on the power pin and 1 on an engine/chassis ground and again got 12 V. Also, I checked for amperage and got .12 mA (if I remember correctly) between the two connector pins with key in run.
Also, I used the multimeter to check for continuity between the connector ground pin and an engine/chassis ground and none was present.
Thanks
Given your question about the VSS sensor, I thought this might be useful...even though the question was already answered. It covers importance of sensors.
http://www.chevythunder.com/ls1_page_1.htm
http://www.chevythunder.com/ls1_page_1.htm
Yes it is the same ECM that came with the engine/trans out of a 2009 Van. It is an E38, so it was only made for the Gen IV engines.
As for the injector voltage, using a multimeter, I put 1 probe on the power (pink) pin in the connector and 1 on the ground pin and got 12 V with the key in run. I then put 1 probe on the power pin and 1 on an engine/chassis ground and again got 12 V. Also, I checked for amperage and got .12 mA (if I remember correctly) between the two connector pins with key in run.
Also, I used the multimeter to check for continuity between the connector ground pin and an engine/chassis ground and none was present.
Thanks
As for the injector voltage, using a multimeter, I put 1 probe on the power (pink) pin in the connector and 1 on the ground pin and got 12 V with the key in run. I then put 1 probe on the power pin and 1 on an engine/chassis ground and again got 12 V. Also, I checked for amperage and got .12 mA (if I remember correctly) between the two connector pins with key in run.
Also, I used the multimeter to check for continuity between the connector ground pin and an engine/chassis ground and none was present.
Thanks
I was re-reading the posts here, and noticed something...actually, two things.
1) I don't think that you've proven that the crank sensor leads have continuity between the sensor end of harness, and the ECM. Everything else has been done.
At the inj end of harness, there is DEFINITELY 12v on one lead, but the grnd has not been proven with a noid lamp?
You have measured across the two inj harness pins and have 12v in run. I believe that the only time this can happen is THAT momentary time when the ECM directs a ground to the individual injector being fired. Previously, you artificially created this scenario when you hooked up the 9v batt w/grnd to an injector.
So, with the correct signal being sent from the crank sensor, firing should occur.
2) Related to verif the leads on the crank sens...Have you checked at the ECM for grnds on ALL of the appropriate harness leads @ the connector & did you verify that the grnd coming from the crank sensor is on the correct harness lead at the ECM? I ask this only bec you mentioned that you had done your own harness.
3)Whoops, I said 2 items(lol)...might be a good idea, if you find nothing wrong with the crank sensor leads, to have someone recheck VATS to see if it's really disabled.
Sorry for the run-on!
Last edited by gMAG; Dec 27, 2010 at 03:04 PM.
Well I spent some time time today checking wires and voltages and have the following info:
- All of the injector grounds and coil wires have continuity back to ECM and are at correct position. This is the same with all wires coming from the crank and cam sensors.
- The 5 V references for crank and cam sensors have exactly 5 V at the pin. (key in run)
- One thing I didn't quite understand was that with the connector unplugged from crank position sensor, there was also 5 V on the crank signal pin. I would have thought there would only be 5 V if a signal was being produced??? (key in run)
I plan on getting a noid light tomorrow and with all of the previous things checking out, hopefully the noid light will lead to a decent conclusion. I guess it will tell me there is either a problem with the ECM (or sensor signals) or the injectors...
By the way, thanks for all the great help thus far
- All of the injector grounds and coil wires have continuity back to ECM and are at correct position. This is the same with all wires coming from the crank and cam sensors.
- The 5 V references for crank and cam sensors have exactly 5 V at the pin. (key in run)
- One thing I didn't quite understand was that with the connector unplugged from crank position sensor, there was also 5 V on the crank signal pin. I would have thought there would only be 5 V if a signal was being produced??? (key in run)
I plan on getting a noid light tomorrow and with all of the previous things checking out, hopefully the noid light will lead to a decent conclusion. I guess it will tell me there is either a problem with the ECM (or sensor signals) or the injectors...
By the way, thanks for all the great help thus far
TECH Resident
Joined: Jun 2004
Posts: 841
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From: Tampa, FL
If the program was done by Wait4me, I'd have someone else look at it. I've seen 3 or 4 now that wouldn't run because of that.
Try spraying starter fluid in it. If it runs while you spray it, then the ignition system is fine, it is the injectors not firing that is your problem (i.e. VATS)
Try spraying starter fluid in it. If it runs while you spray it, then the ignition system is fine, it is the injectors not firing that is your problem (i.e. VATS)
If the program was done by Wait4me, I'd have someone else look at it. I've seen 3 or 4 now that wouldn't run because of that.
Try spraying starter fluid in it. If it runs while you spray it, then the ignition system is fine, it is the injectors not firing that is your problem (i.e. VATS)
Try spraying starter fluid in it. If it runs while you spray it, then the ignition system is fine, it is the injectors not firing that is your problem (i.e. VATS)
Thanks