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Discussion Starter · #1 ·
I'm trying to get my car started after installing the AEM standalone and am not having much luck. The box has a file on it from RSI, but something is off with it. The car just backfires, won't start or idle. I'm hoping someone has a file they can share with me, so I can give it a try. If that doesn't work either, I'll know there's another issue somewhere. My car is a twin turbo 2005 with 1000cc injectors and dual fuel pumps, but I think any Gen 3 file will work to at least get it started.
 

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Discussion Starter · #2 ·
anyone? I think I just need to have the correct ignition settings. Can't find them online anywhere. Crank/cam rising or falling edge? How many teeth? Ignition sync? I've been working on this for days now, still can't find the correct settings
 

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I can verify that the Gen 2 JTEC controller uses the falling edge of the notch to determine engine timing. That equates to 9 degrees BTDC for the firing cylinder and the notches are 3 degrees wide. Based on that alone, I would assume G3/4 follows suit.
 

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To add from the above:

The Gen3 manual says:

“The camshaft position sensor detects when a step down in the camshaft sprocket passes beneath it.”

“When the sensor detects the step down, the input voltage from the sensor to the PCM switches from low (0.3 volts) to high (5 volts). As the step up returns to the sensor, the input voltage switches back to low (0.3 volts).”

the ignition sync would need to be done to validate that the timing observed by the AEM is the actual timing (observed via a timing light). If that isn’t done, who knows what the offset could be. There are a ton of videos online about it still.

Unfortunately, not many using that system in 2022. I tried to dig through my logs and tune files but HPTuners (what I am currently using) dosent require any of that info you are looking for. You might have to hit up Dan C or Dan L to see if they can help get you straight.
 

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Hopefully this will help a little bit.
 

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Discussion Starter · #6 ·
Thanks for all that info. I bought a timing light hoping to check the actual timing, but quickly came to realize that the balancer doesn't have any timing marks. How do people check timing on these engines? the timing is currently set at 15* BTDC in AEM. Ignition sync is set at 4.953 teeth. AEM lets you advance or retard your timing, but you have to physically be able to check your engine timing and confirm it matches what AEM shows.
Here are a couple of screen shots of the file that RSI sent me. Please let me know if anything jumps out at anyone as being wrong. For example, I noticed the injector phasing was set at 0 for both injector 1 and injector 10. I'm thinking injector 10 should be 0.750.

Going off this calculation
The Viper has 10 teeth per cycle which is 72 crank degrees per one tooth. Therefore out injector tooth numbers would be as follows:
0/72 is undefined but we'll say 0
54/72 = 0.75
144/72 = 2
2.75
4
4.75
6
6.75
8
8.75

I have all those same numbers set for Coil Phasing. Injector phasing looks like it follows the firing order 1,10,9,4,3,6,5,8,7,2. So, to me it would make sense that injector 10 would be 0.750. I tried making that change, and nothing really changed. When I try starting the car, AEM is telling me I'm getting timing errors. Which leads me to believe the timing settings are wrong.
I noticed the options in the start screen say Crank Advance is 15 degrees. But ignition timing is also set at 15 Degrees BTDC. Does that mean that it's trying to start with 0 timing?



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You're way out of my comfort zone now. I just put a timing tape on my damper in the past couple of weeks - mainly for leakdown reference marks to know which one is up on compression.
 

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Discussion Starter · #10 ·
I called AEM and they sent me the base startup file for Series 1 Gen 2 viper. I copied all the settings over. Still no luck starting. I'm beginning to wonder if the AEM box itself is bad
 

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If you can’t validate where your timing is to begin with there is no telling what the computer is trying to do (and that’s even if it would fire up on a gen2 file anyway, which I would be skeptical of at best).

I’d pick up a TDC tool (several kinds available and inexpensive as well) and validate the timing before I went after much else.
 

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Discussion Starter · #12 ·
I'm not trying to start it with a Gen 2 file. Simply using the timing settings from that file. From the research I've done, Gen 2 and 3 motors use identical timing indicators, firing order, etc.
I agree, I do need to confirm the actual timing. I'm assuming that's where my problem is. If AEM is commanding 15 degrees but in reality it's actually 0, that's most likely where the issue is.
 

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Discussion Starter · #13 ·
You're way out of my comfort zone now. I just put a timing tape on my damper in the past couple of weeks - mainly for leakdown reference marks to know which one is up on compression.
Which timing tape did you get? I found a Mopar one, part number P4529070AB. Can't tell if it's the right size for the Viper Damper. I also found some MSD ones that come in various sizes. I guess I'll just get those.
 

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Use anything you can wrap around the OD of the damper (string, flat measuring tape) to mark, then lay flat it to measure the circumference around the damper. Divide that by Pi (3.1416) and that's the Diameter of the damper. My Gen 2 is 7.0" and that's also a standard Chevy diameter.

You need to find some spot on the upper side of the damper that is easy enough to see and that has some fixed reference protrusion close enough that you can set the "0" mark right on it with #1 at TDC compression. I used the cam sensor up top.

Then I used the bottom of the balancer (BDC) to mark where I can see it underneath the car with a socket on the crank bolt as reference for leakdown testing.
 

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Discussion Starter · #15 ·
OK so I've installed the timing tape and was finally able to use the timing light. I lock the timing in the AEM timing wizard and set it at 0*. When cranking, the timing is jumping all over the place. It'll be at 0 degrees on one revolution then be completely off on the next. So I guess that confirms my suspicion of my timing being completely wrong. Now, the question is how to fix it. I don't think the sensors are faulty, because the car starts on the factory ECM. So that leads me to believe either the settings in the AEM box are wrong or the AEM box itself is faulty. I don't think there's much else left.
 

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Remember - the Viper engine is a 90 degree crankshaft with a 72 degree firing interval. You have to work from a 720 degree cylinder cycle and follow the firing order. It's in the pdf attachments I posted earlier. The only time the cam sensor is used is on the first 1-2 rotations to be sure the fueling strategy is on the correct interval. After that, all timing is off the crank sensor. The plugs fire twice per cycle.
 

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Discussion Starter · #17 ·
Yeah I got all that set up, and confirmed the AEM Gen 2 file had the same values. Found this in another forum post

So, in crank degrees, it fires as follows:

0
54
144 (+90)
198 (+54)
252 (+90)
342 (+54)
432 (+90)
486 (+54)
576 (+90)
630 (+54)
- plus another 90 degrees gets you back to 720.

So, let's do some math here. The Viper has 10 teeth per cycle which is 72 crank degrees per one tooth. Therefore our injector tooth numbers would be as follows:

0/72 is undefined but we'll say 0
54/72 = 0.75
144/72 = 2
2.75
4
4.75
6
6.75
8
8.75

So those values get assigned to each coil and injector, in firing order. So I have
1 = 0
10 = 0.75
9 = 2
4 = 2.75
3 = 4
6 = 4.75
5 = 6
8 = 6.75
7 = 8
2 = 8.75
 

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I have an AEM compueter with a turbo tune in it.
 

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V1. I am selling it, sooooooo
 
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