LT1-LT4 Modifications 1993-97 Gen II Small Block V8

Install EFI connection LSX PCM

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Old Jul 23, 2010 | 02:15 PM
  #181  
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Anybody know how to change tac values in hp tuners? I am looking for a way to get my tac to work, before taking other measures.
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Old Jul 23, 2010 | 02:31 PM
  #182  
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Originally Posted by 97LT1
Anybody know how to change tac values in hp tuners? I am looking for a way to get my tac to work, before taking other measures.
tac (Throttle Actuator Control) or tach (tachometer)?
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Old Jul 24, 2010 | 09:11 PM
  #183  
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Originally Posted by v7guy
late to the convo, I know. to conclude you're saying the express van ECM (pt# 12200411) runs an old school SBC/LT1 firing order. so it sends fuel and reads O2 sensors appropriately bank to bank and knows what cylinder?
the van didn't run COP but has the capability, so you just assign the ignition to spark in the right firing order via efilive?

Just want to make sure I understand completely.
Originally Posted by S10Wildside
Yes


Yes


Yes, based on the 4x crank reluctor.


No, this will require a 24x crank signal and a calibration from an engine originally equipped with a 24x crank signal.


No, you cannot change the firing order with EFILive. HP Tuners supposedly supports this, but I don't know of someone who has tried this. The firing order (injectors and coils) are changed in the harness. The injector to bank assignments for closed loop fuel trims are changed in the calibration.
Ok this may have been answered in another part of this thread, but here's a question. Will this swap work like the express vans- i.e. single coil and a distributor? Reason being is I have a Digital 7 Ignition box with the HVC II coil, and would like to keep it. I am having troubles with spark at high rpm's, and also trying to get enough fuel in the engine via the PCM for any more than 15 psi of boost. So really I'm just looking to get rid of the OPTI and the LT1 PCM, and don't really want/need to go to the LS1 coils.

Thanks!
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Old Jul 25, 2010 | 08:11 AM
  #184  
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Originally Posted by Ponyhntr
Ok this may have been answered in another part of this thread, but here's a question. Will this swap work like the express vans- i.e. single coil and a distributor? Reason being is I have a Digital 7 Ignition box with the HVC II coil, and would like to keep it. I am having troubles with spark at high rpm's, and also trying to get enough fuel in the engine via the PCM for any more than 15 psi of boost. So really I'm just looking to get rid of the OPTI and the LT1 PCM, and don't really want/need to go to the LS1 coils.

Thanks!
The 2001-2002 Express Van uses the 12200411 PCM (also used with LS1 engines), a 4x crank signal, and a 1x cam signal. This results in single coil and distributor and tuning with EFILive, HP Tuners, etc. The problem with the LT1 is going to be the 1x cam signal from within the distributor. If your manifold already has a distributor hole (TPIS LT1 MiniRam or modified LT1 manifold), then you can use a Vortec distributor for the 1x cam signal.
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Old Jul 31, 2010 | 10:33 PM
  #185  
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Pretty close to finishing my DIY harness but have a few ????s Had 14 LT1 wires left over in the PCM harness RED 9, 12, 14, 20 CLEAR 11 BLUE 10, 20, 24, 30 BLACK 2, 5, 14, 20, 23. Also the LS1 harness RED 15 is Alternator L terminal what do I do with this, theres no LT1 match up? Hope to get some feedback soon!!!!
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Old Aug 1, 2010 | 08:37 AM
  #186  
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Originally Posted by RuQuicker97
Pretty close to finishing my DIY harness but have a few ????s Had 14 LT1 wires left over in the PCM harness RED 9, 12, 14, 20 CLEAR 11 BLUE 10, 20, 24, 30 BLACK 2, 5, 14, 20, 23. Also the LS1 harness RED 15 is Alternator L terminal what do I do with this, theres no LT1 match up? Hope to get some feedback soon!!!!
Bump to the top If we can get some info and finish the harness we can have the car at the track in about a week or two.
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Old Aug 1, 2010 | 11:03 AM
  #187  
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Alt terminal L is not used. Leave it alone.
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Old Aug 1, 2010 | 04:39 PM
  #188  
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What about the left over LT1 pcm wires.
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Old Aug 12, 2010 | 09:27 PM
  #189  
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Originally Posted by Ed Wright
People having a lot of Optispark problems need to look in the mirror for the cause. A new GM unit, or even better a Dynaspark, properly installed, with a sub 7500 RPM engine will run fine for many miles. Dowel pin engagement depth and cam end play are crucial as well as locktite on the rotor screws along with alumini pop rivets holding the blade on the rotor if you are spinning it over 6500. Don't buy parts store crap, nor any other brand aftermarket. No matter how pretty yellow or red they are.
Originally Posted by S10Wildside
TPIS did a 396ci LT1 comparison with LT1 PCM, high output coil, and MSD optispark and then LS1 PCM with individual coils. The gain was 28 hp and 17.5 ft-lb on the engine dyno. I seem to recall the engine being pulled to 6200 rpm.

TPIS also mentioned that the Delteq system slightly improves horsepower and torque compared to stock LT1 ignition.

Source is Street Thunder Magazine, May/June 2010. I can't link to the article because EFI Connection is not a paying vendor on LS1tech.
Wow. That's a pretty bold statement to make Ed.

I'm going to make this simple since I've been eyeing this new EFI system for a while, show me the dyno graphs.

The ONLY downside to this system, ignoring cost, is here on Long Island, NY I don't know anyone around that does LSX pcm dyno tuning. Which in my opinion is key to my whole LE heads and cam swap.
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Old Aug 13, 2010 | 11:58 AM
  #190  
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Originally Posted by Rob94hawk
The ONLY downside to this system, ignoring cost, is here on Long Island, NY I don't know anyone around that does LSX pcm dyno tuning.
Kaltech does LT and LS tuning there in Long Island.
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Old Aug 13, 2010 | 12:43 PM
  #191  
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Originally Posted by Rob94hawk
Wow. That's a pretty bold statement to make Ed.

I'm going to make this simple since I've been eyeing this new EFI system for a while, show me the dyno graphs.

The ONLY downside to this system, ignoring cost, is here on Long Island, NY I don't know anyone around that does LSX pcm dyno tuning. Which in my opinion is key to my whole LE heads and cam swap.
I don't give a **** what you do, it's your car. It is a proven fact that even a BigStuff3 or FAST XFI won't make anymore power below 7000 RPM than a factory PCM. That is if the LT1 PCM tuner has a clue about what he is doing.
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Old Aug 13, 2010 | 02:23 PM
  #192  
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Originally Posted by Ed Wright
I don't give a **** what you do, it's your car. It is a proven fact that even a BigStuff3 or FAST XFI won't make anymore power below 7000 RPM than a factory PCM. That is if the LT1 PCM tuner has a clue about what he is doing.
I thought for sure that a dedicated coil per cylinder even on a higher than stock compression engine would have improved gains all accross the powerband.
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Old Aug 13, 2010 | 02:24 PM
  #193  
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Originally Posted by C_Rules
Kaltech does LT and LS tuning there in Long Island.
I'll have to look them up. Thanx
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Old Aug 13, 2010 | 02:41 PM
  #194  
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Originally Posted by Rob94hawk
I thought for sure that a dedicated coil per cylinder even on a higher than stock compression engine would have improved gains all accross the powerband.
Why? If it does not misfire, and spark advance is correct, that is all there is.
NHRA Pro Stock cars have one coil and a distributor. If there was anything there I can assure you they would be using it.
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Old Aug 14, 2010 | 09:14 AM
  #195  
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Originally Posted by Ed Wright
Why? If it does not misfire, and spark advance is correct, that is all there is.
NHRA Pro Stock cars have one coil and a distributor. If there was anything there I can assure you they would be using it.
Point taken. I'll give your co. a call after my heads/cam swap is done.
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Old Aug 14, 2010 | 07:33 PM
  #196  
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Originally Posted by Ed Wright
Why? If it does not misfire, and spark advance is correct, that is all there is.
NHRA Pro Stock cars have one coil and a distributor. If there was anything there I can assure you they would be using it.
I agree with you Ed, about the first part of your statement....if you are getting a complete burn at the right time with an ignition then you will gain nothing by switching.
As for the part about Pro Stock.....aren't they limited to one coil and a distributor? I'm pretty sure it is regulated like the 500" limit. Again....not trying to argue your point about there being no need to upgrade....or even to argue about the pro stock rules....I could be wrong.
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Old Aug 14, 2010 | 07:41 PM
  #197  
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Originally Posted by Ed Wright
It is a proven fact that even a BigStuff3 or FAST XFI won't make anymore power below 7000 RPM than a factory PCM. That is if the LT1 PCM tuner has a clue about what he is doing.
I think you really hit the nail on the head above. People are always throwing out comparisons from one system to another, but who is to say they were both programmed with equal skill? It's like comparing tuned EFI to a carb bolted on outta the box with no jetting or adjustments.....or vice versa.
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Old Aug 14, 2010 | 09:10 PM
  #198  
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if you are getting a complete burn at the right time with an ignition then you will gain nothing by switching.
Exactly. The most accurate ignition system (or fuel management system) will use an engine position signal from the crank. With the optispark (or traditional distributor), the accuracy of the system relies on all of the variables from the crank sprocket, timing chain, cam sprocket, distributor gear, and so on. Amplify the inaccuracies by adding an aggressive camshaft. Comparatively, the LS1 engine has the most accurate method of fuel/spark delivery at all RPMs because the engine position signal is monitored at the crankshaft.

The testimonies of LT1 owners who have noticed improved idle and throttle response after swapping to the LS1 PCM may be directly related to the inaccuracies of engine position from the optispark distributor.

There are so many variables to consider for engine performance (obviously including tuning accuracy), but there is no denying the improved method of engine management with the introduction of the LS1 engine.
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Old Aug 16, 2010 | 11:10 AM
  #199  
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Originally Posted by 1961ba427
I agree with you Ed, about the first part of your statement....if you are getting a complete burn at the right time with an ignition then you will gain nothing by switching.
As for the part about Pro Stock.....aren't they limited to one coil and a distributor? I'm pretty sure it is regulated like the 500" limit. Again....not trying to argue your point about there being no need to upgrade....or even to argue about the pro stock rules....I could be wrong.
The rule book says maximum one distributor, nothing about coils.
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Old Aug 16, 2010 | 11:47 AM
  #200  
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Originally Posted by S10Wildside
Exactly. The most accurate ignition system (or fuel management system) will use an engine position signal from the crank. With the optispark (or traditional distributor), the accuracy of the system relies on all of the variables from the crank sprocket, timing chain, cam sprocket, distributor gear, and so on. Amplify the inaccuracies by adding an aggressive camshaft. Comparatively, the LS1 engine has the most accurate method of fuel/spark delivery at all RPMs because the engine position signal is monitored at the crankshaft.

The testimonies of LT1 owners who have noticed improved idle and throttle response after swapping to the LS1 PCM may be directly related to the inaccuracies of engine position from the optispark distributor.

There are so many variables to consider for engine performance (obviously including tuning accuracy), but there is no denying the improved method of engine management with the introduction of the LS1 engine.
Don't forget the water pump runs off of the cam sprocket. I've read on the innernet of the EFI Connect system taming radical cams at idle with LSA's of 107. How do radical cams run with the optispark?
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