RX7 LS1 wont start, please help. (& I searched)
03-16-2008, 01:56 AM
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RX7 LS1 wont start, please help. (& I searched) Ok, let me give you the run down. 86 RX7 with 99 Camaro SS LS1. There are no emissions on the engine. The engine is stock with no modification. I had the harness modified by a respected member over on the v8rx7forum who has many other cars he wired running fine. It cranks, but will not fire. When I check I don't appear to get spark or fuel. I have done a lot of looking at other posts and have tried all that I could find. Here is where I am at.
1. Ignition on is hooked to a relay with a wire fused direct to the battery and a activation wire that gets 12V when on and ~10V when starting.
2. Power constant gets fused 12V direct from the battery.
3. Coils get ~11V when ignition on and ~10V when starting.
4. Spark plug wires give not spark with the "screwdriver test", but coils get ~11V when ignition on and ~10V when starting.
5. Pin 20 and 57 get 12v constant and pin19 gets 12v ignition-on on the Blue PCM plug. All still get power while starting.
6. Ground from battery runs to passenger side frame rail directly, and motor is grounded on both sides from frame rails.
7. The three ground wires from the harness are grounded to fire wall.
8. All ground spots were sanded to bare metal and dielectric applied.
9. Pins 1 and 40 on both red and blue PCM connectors get ground.
10. One oddity is blue pin 54 (map sensor ground) didn't show a ground, is that normal at ignition on or is it activated by something else?
11. I replaced the crank position sensor with a new one and no change.
12. I unplugged the MAF once to see if I could get the "limp mode" thing and no luck.
13. Fuel pump will prime at ignition on, but does not run while starting.
14. Running power directly to the injectors will active them. They all flow.
15. Using OBD2 scanner I get only 2 codes.
A. Code ? (EVAP pressure low)
B Code P1336 (Crankshaft position variation not learned) which should not prevent me from starting and I can't get rid of it until I do.
16. The PCM is stock with no code removed (VATS still intact). I have a new one on the way from Wait4me Performance, but will not arrive till late next week.
17. All sensors are there and plugged in.
18. There is fuel pressure at the rails, but I don't know how much. What are the threads on the shrader valve? 1/8 NPT?
19. The battery is a new Red Top.
20. Yes the PCM plugs were tightened down.
Anyone with suggestions please help. I am soooo close and almost at whits ends.
(Not the most recent picture.)
1. Ignition on is hooked to a relay with a wire fused direct to the battery and a activation wire that gets 12V when on and ~10V when starting.
2. Power constant gets fused 12V direct from the battery.
3. Coils get ~11V when ignition on and ~10V when starting.
4. Spark plug wires give not spark with the "screwdriver test", but coils get ~11V when ignition on and ~10V when starting.
5. Pin 20 and 57 get 12v constant and pin19 gets 12v ignition-on on the Blue PCM plug. All still get power while starting.
6. Ground from battery runs to passenger side frame rail directly, and motor is grounded on both sides from frame rails.
7. The three ground wires from the harness are grounded to fire wall.
8. All ground spots were sanded to bare metal and dielectric applied.
9. Pins 1 and 40 on both red and blue PCM connectors get ground.
10. One oddity is blue pin 54 (map sensor ground) didn't show a ground, is that normal at ignition on or is it activated by something else?
11. I replaced the crank position sensor with a new one and no change.
12. I unplugged the MAF once to see if I could get the "limp mode" thing and no luck.
13. Fuel pump will prime at ignition on, but does not run while starting.
14. Running power directly to the injectors will active them. They all flow.
15. Using OBD2 scanner I get only 2 codes.
A. Code ? (EVAP pressure low)
B Code P1336 (Crankshaft position variation not learned) which should not prevent me from starting and I can't get rid of it until I do.
16. The PCM is stock with no code removed (VATS still intact). I have a new one on the way from Wait4me Performance, but will not arrive till late next week.
17. All sensors are there and plugged in.
18. There is fuel pressure at the rails, but I don't know how much. What are the threads on the shrader valve? 1/8 NPT?
19. The battery is a new Red Top.
20. Yes the PCM plugs were tightened down.
Anyone with suggestions please help. I am soooo close and almost at whits ends.
(Not the most recent picture.)
Last edited by necron3x; 03-16-2008 at 08:57 PM.
03-16-2008, 02:27 AM
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No the relay is only hot at run. The activation wire is a wire that was in the stock harness and was hot only at ignition on and starting. The relay is also brand new and it is a 30 amp.
Yes there is a learn procedure, that is why I have the P1336 code, but it should not prevent me from starting and the car can be driven gently while experiencing the code. In fact the car has to be running for a GM dealership to "teach" the PCM, or the car need to be able to go through the warm up stage three time without seeing the code again to get rid of it.
Not getting by the VATS currently, but that also should not be preventing it from starting. That should at least let it run for a few seconds. The new PCM I ordered will have that all tuned out along with all emissions.
Anyone know what are the threads on the shrader valve? 1/8 NPT?
Yes there is a learn procedure, that is why I have the P1336 code, but it should not prevent me from starting and the car can be driven gently while experiencing the code. In fact the car has to be running for a GM dealership to "teach" the PCM, or the car need to be able to go through the warm up stage three time without seeing the code again to get rid of it.
Not getting by the VATS currently, but that also should not be preventing it from starting. That should at least let it run for a few seconds. The new PCM I ordered will have that all tuned out along with all emissions.
Anyone know what are the threads on the shrader valve? 1/8 NPT?
Last edited by necron3x; 03-16-2008 at 02:34 AM.
03-16-2008, 02:58 AM
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No the relay is only hot at run. The activation wire is a wire that was in the stock harness and was hot only at ignition on and starting. The relay is also brand new and it is a 30 amp.
Yes there is a learn procedure, that is why I have the P1336 code, but it should not prevent me from starting and the car can be driven gently while experiencing the code. In fact the car has to be running for a GM dealership to "teach" the PCM, or the car need to be able to go through the warm up stage three time without seeing the code again to get rid of it.
Not getting by the VATS currently, but that also should not be preventing it from starting. That should at least let it run for a few seconds. The new PCM I ordered will have that all tuned out along with all emissions.
Anyone know what are the threads on the shrader valve? 1/8 NPT?
Yes there is a learn procedure, that is why I have the P1336 code, but it should not prevent me from starting and the car can be driven gently while experiencing the code. In fact the car has to be running for a GM dealership to "teach" the PCM, or the car need to be able to go through the warm up stage three time without seeing the code again to get rid of it.
Not getting by the VATS currently, but that also should not be preventing it from starting. That should at least let it run for a few seconds. The new PCM I ordered will have that all tuned out along with all emissions.
Anyone know what are the threads on the shrader valve? 1/8 NPT?
we had one where it wouldn't do anything but spin, then found out our vats chip was a few Hz off. fixed that and it fired right up.
03-16-2008, 09:45 AM
#6
7. The three ground wires from the harness are grounded to fire wall. Try moving these to the back of the left head, thats where they're supposed to be, and grounds can cause some really weird things to happen. Also make SURE you have power at the coils and injectors both at run and start, there's been several guys on here that thought they had power but actuall didn't have power when cranking. Just my $0.02
Last edited by ls1nova71; 03-16-2008 at 09:51 AM.
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03-16-2008, 01:05 PM
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If it is VATS then I am just going to have to wait till next week. Or if there is something wrong with the PCM in general.
I'm not sure how I will get a better ground at the back of the block, but I will give it a try.
When I tested the coils I had a friend put a voltameter on the pink wire in the main plug and touch the block then had him watch it as I turned the key on then start. It went from nothing at ignition off to ~11 at ignition on and finally ~10 at start. Same thing for the injectors. I pulled a couple plugs off and put the positive lead on the pinkish wire and ground to the block. The results were the same. Any problem with that method?
Thanks for the help guys;
I'm not sure how I will get a better ground at the back of the block, but I will give it a try.
When I tested the coils I had a friend put a voltameter on the pink wire in the main plug and touch the block then had him watch it as I turned the key on then start. It went from nothing at ignition off to ~11 at ignition on and finally ~10 at start. Same thing for the injectors. I pulled a couple plugs off and put the positive lead on the pinkish wire and ground to the block. The results were the same. Any problem with that method?
Thanks for the help guys;
03-16-2008, 04:17 PM
#9
If you have a digital volt meter, try hooking the red lead to the pink injector wire and the black lead to the other injector wire. Crank the engine and watch the meter. A digital meter should react fast enough to show an injector signal. If you have a signal, you may have stuck injectors. How long has it been since the injectors have been run? Vats won't keep the car from starting. It will just shut it off after about 3 seconds.
03-16-2008, 04:46 PM
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If you have a digital volt meter, try hooking the red lead to the pink injector wire and the black lead to the other injector wire. Crank the engine and watch the meter. A digital meter should react fast enough to show an injector signal. If you have a signal, you may have stuck injectors. How long has it been since the injectors have been run? Vats won't keep the car from starting. It will just shut it off after about 3 seconds.
not true as I said earlier. depending on what pcm you have, some will not start at all.
and seriously, what are the chances of having 8 stuck injectors?
03-16-2008, 08:20 PM
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That is what I did with the injector plug and I do get voltage.
Yeah I saw that, but he didn't have the same problem as I do. One he had spark and two his pump worked like it was supposed to. Also, as I said, to rule that out I ran voltage directly to the injectors (one at a time) using test leads while the injectors were off the engine and they all opened squirting gas into the bags I had over them.
Thanks though;
https://ls1tech.com/forums/showthread.php?t=881675 Read this post. He had that exact problem.
Thanks though;
03-16-2008, 08:56 PM
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03-16-2008, 11:58 PM
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There isn't really a seperate body and frame on those cars, unless more modification has been done than I'm reading about. I'm guessing he's just talking about a "frame rail" that's molded into the body.
The engine doesn't need all that much to start, and the fact that you don't have fuel or spark leads me to think that it's your VATS system acting up. I wouldn't beat yourself up over it until you get your new computer with the VATS turned off. Electrical problems suck, module problems are even worse.
The engine doesn't need all that much to start, and the fact that you don't have fuel or spark leads me to think that it's your VATS system acting up. I wouldn't beat yourself up over it until you get your new computer with the VATS turned off. Electrical problems suck, module problems are even worse.
03-17-2008, 01:06 AM
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Yeah sorry, there really isn't a "frame rail". It's just a unibody construction. That's where some of the weight reduction comes from. I am kind of counting on it being something up with the PCM right now. I can't wait for the new one to get here 
. I didn't put the grounds on the back of the block tonight because I can't exactly get to it, but I did check the continuity of the frame rail ground with a voltameter and it checks out with full 12V flowing.
. I didn't put the grounds on the back of the block tonight because I can't exactly get to it, but I did check the continuity of the frame rail ground with a voltameter and it checks out with full 12V flowing.
03-27-2008, 02:31 AM
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I thought I had the problem narrowed to the PCM so I ordered a new one tuned by Wait4me Performance. It came today and I was all excited. I got the PCMs switched and gave her a try, to no avail. It seems I am still not getting fuel or spark. I unpluged the the PCM connectors and put them back carefully and same thing. I then ran the OBD2 check, this time the only code it threw was P0335 (Crankshaft Position Sensor A Circuit malfunction). I have been searching around a bit and have found no good information on it. Unless someone can help my next move is to rebuy a new crank position sensor and swap them out... again.
