24X Conversion and Vats

[Neil350]

You guys that have done the conversion, did you have to disable vats in the LS1 PCM for the car to run? My fuel pump wont turn on and the car won't crank, so I'm thinking, the LS1 PCM may want the signal from the vats and not getting it, so it's not letting the fuel pump turn on and the starter to crank.

[eficonnection]

The 1993 car uses a VATS module that is probably not compatible with the LS1 PCM.

I think there could be two separate issues here...

Fuel Pump
Neil - The email you sent mentioned that you were not certain if the fuel pump was running. This post suggests that you confirmed the pump not running. Can you please clarify?

One way to test fuel pump operation is to apply 12v to the gray test/prime connector near connector C100 on the passenger side strut tower. EFI Connection harnesses contain this test/prime circuit just as the original harnesses do. If the pump runs, with 12v applied to the test/prime circuit then I would begin to suspect bad PCM or calibration issue. The pump should still prime with key ON even if VATS is enabled in the PCM and the VATS signal is not supplied to the PCM.

Starter
The 93 LT1 has neutral safety built into the starter circuit. Because you swapped from a 4L60 to a T56, you must be sure that the starter circuit running through the gear selector switch is rerouted to the clutch pedal switch. If you don't, the starter will never see 12v in crank.

[Neil350]

I thought I heard the pump turn on, this weekend I want to verify it with a fuel pressure gauge to be sure. I was wondering what that little test deal was, didn't see any thing that would plug in to it, thought I remember seeing it like that on the factory harness just wasn't 100% sure. When you turn the key, no crank at all, but every thing that's on a keyed 12 volt source acts normal, I used the factory diagnostic tree for a no crank no start to make sure it wasn't some thing else. What your saying about the starter makes sense though.

[ScottKnight]

When I first tried to start my project up, it would fire then quit. It would only run for like 1-2 seconds every time. I was pulling my hair out because I thought I had disabled the security in the calibration. After a couple hours of jacking around with wiring, testing the pump, fuel pressure, coils, etc., I finally looked in the tune only to find that it was still set to serial. Clicked it off and the car started right up :shiner:

[Neil350]

We ended up figuring why it wouldnt crank, issue with the T56 swap. Car cranks now, pops and back fires but wont run. We turned the serial off in HP tuners. I'm thinking I may have an issue with the coil pack harness going to the coil packs being on wrong? We matched the wire colors to those on my Sierra.

[ScottKnight]

By the sounds of it, you may have half of the cylinders wired wrong. Not sure what harness you started from, but the LS1 firing order is different than all previous GM V8's...for both injectors and coils, you need to swap 2/3 and 4/7 wires to make it run. You also need to visit the bank assignments for the injectors if you intend to do any closed loop fueling.

[eficonnection]

By the sounds of it, you may have half of the cylinders wired wrong. Not sure what harness you started from, but the LS1 firing order is different than all previous GM V8's...for both injectors and coils, you need to swap 2/3 and 4/7 wires to make it run. You also need to visit the bank assignments for the injectors if you intend to do any closed loop fueling.

He's good with the harness. It's a brand new plug and play build.

[Neil350]

The harness seems to work great with out issue, Mike sent the coil harness color guide and the coil packs are on right. In HP tuners we were able to make contact with the PCM, make the tuning adjustments, and also do stuff like turn the fans on, turn the fuel pump on from HP tuners so the harness has to be working just as it should.

[ScottKnight]

Almost has to be a fuel calibration issue, then. Granted, I am dealing with E85, but I had to make a LOT more adjustments to the startup portion of the tune than I first suspected. The result (and I still don't have cold starts anywhere near rich enough) is that I ended up with 20% higher in some places to the lower regions of the VE table to get a stockish LT1 to even run with a 2003 Z06 calibration. The startup and idle regions are right around 17-18%. Lucky for me E85 has a fairly wide tuning window so once I realized how lean it was, I could just throw 25% on top of the whole thing and start pushing down from there :D

[eficonnection]

The harness seems to work great with out issue, Mike sent the coil harness color guide and the coil packs are on right. In HP tuners we were able to make contact with the PCM, make the tuning adjustments, and also do stuff like turn the fans on, turn the fuel pump on from HP tuners so the harness has to be working just as it should.

Did you change the firing order in HP Tuners? You should not have.

Are you seeing spark on every cylinder?

[Neil350]

From the DTC.txt





[PCM] P0452 - Fuel Tank Pressure Sensor Circuit Low Voltage
[PCM] P0336 - Crankshaft Position (CKP) Sensor A Performance (Pending)
(Old) (Current) (Immature)


Continuous Tests
Misfire: Complete
Fuel System: Complete
Comprehensive Component: Complete


Once Per Trip Tests
Catalyst: Incomplete
Heated Catalyst: n/a
Evaporative System: Incomplete
Secondary Air System: Incomplete
A/C System Refrigerant: n/a
Oxygen Sensor: Incomplete
Oxygen Sensor Heater: Incomplete
EGR System: n/a

[eficonnection]

This problem turned out to be an ARP crank bolt that was too long and, because it bottomed out in the crank, did not tighten the 24x crank reluctor between the crank timing sprocket and crank hub.

The engine now runs.

Neil has the details.

[ScottKnight]

Funny that it could be that far off and not grind up the timing cover...or did it? At least with my method of installing the damper with an install tool, the damper would have been pushed back long enough to get it running and out on the road before it backed out. There would have probably been some serious carnage under the hood then :cry:

Glad you found it.

[Neil350]

It never ran, just crank and it would some time back fire. So no damage was done, I'm glad it didn't actually run because your right it may have caused some damage to the reluctor. Mike's customer service was phenomenal through this entire thing.

[eficonnection]

Funny that it could be that far off and not grind up the timing cover...or did it? At least with my method of installing the damper with an install tool, the damper would have been pushed back long enough to get it running and out on the road before it backed out. There would have probably been some serious carnage under the hood then :cry:

Glad you found it.

Scott...your method of installing the crank hub is textbook and really the best way. On the other hand, using the crank bolt to drive on the crank hub is questionable because you risk stripping the threads in the crank. Truth be told; until we made an install tool last year, we used the bolt method.

[ScottKnight]

Truth be told; until we made an install tool last year, we used the bolt method.
Should I really admit out loud that through most of the 80's until sometime in the early 90's I used a mini sledge hammer and and blocks of wood? :monkey:

[QC97Z]

Funny you mention that...that's what I HAD to use!
I used an instal tool and a deep well socket...until I ran out of socket. Then I had to *carefully* pound the damper on the rest of the way (ATI superdamper) with some wood and a hammer....Then i tightened the crank bolt!
You guys didn't just hear that....