Symptoms of Vats Not Disabled
Thread Starter
Teching In
Joined: Oct 2017
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From: Indiana
Symptoms of Vats Not Disabled My build is almost done. I'm trying to start it for the first time. I had a friend disable the VATS but it was his first time. I think maybe he did it wrong. I put up a PSI wiring harness so A lot has changed from the donor Avalanche.
The engine Hits immediately maybe 1 cylinder then nothing. It will pretty consistently hit on first rev but then just acts like there's no fuel present. I've purged the fuel system and even went to speedway and got a new LS fuel pump/ regulator set up.
I have limited diagnostic tools but my OBD2 reader registers Engine speed. O2 sensors, TPS, the Throttle body reacts to throttle input. ECT. I'm stumped.
All Help appreciated.
The engine Hits immediately maybe 1 cylinder then nothing. It will pretty consistently hit on first rev but then just acts like there's no fuel present. I've purged the fuel system and even went to speedway and got a new LS fuel pump/ regulator set up.
I have limited diagnostic tools but my OBD2 reader registers Engine speed. O2 sensors, TPS, the Throttle body reacts to throttle input. ECT. I'm stumped.
All Help appreciated.
typically the "SECURITY" light will be flashing right after the engine stalls. That's always been the dead give away to me.
The next time you jump in the vehicle, turn the key to the run position but DO NOT START IT.. Watch the security light. It should be illuminated. Just wait for it to go out/off before you try and start the vehicle. Try that and see if it will stay running. Starting the engine, or attempting to start the engine, before the light goes out will cause it to stall immediately. I had a 99 Tahoe that would do this. I had to tell my kids when they borrowed it to wait for the security light to go out before starting it or it would strand you for 10 minutes while it reset. If you waited for the light to go out, no problems. This was on an all stock Tahoe that has never had a tune. I finally paid the credits just to delete VATS permanently.
If your security light never goes out, then VATS has not been deleted.
The next time you jump in the vehicle, turn the key to the run position but DO NOT START IT.. Watch the security light. It should be illuminated. Just wait for it to go out/off before you try and start the vehicle. Try that and see if it will stay running. Starting the engine, or attempting to start the engine, before the light goes out will cause it to stall immediately. I had a 99 Tahoe that would do this. I had to tell my kids when they borrowed it to wait for the security light to go out before starting it or it would strand you for 10 minutes while it reset. If you waited for the light to go out, no problems. This was on an all stock Tahoe that has never had a tune. I finally paid the credits just to delete VATS permanently.
If your security light never goes out, then VATS has not been deleted.
Thread Starter
Teching In
Joined: Oct 2017
Posts: 25
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From: Indiana
Hooked the HP Tuner up today, Verified that VATS was deleted. It wasn't but now is. Checked several times. The VATS page says passed after key on. I double checked everything. Took Injectors out and cleaned each one individually. used my Pressure vessel to put cleaner with pressure on it then with 12volts applied injector passes fuel. Then put injectors back on rail without putting injectors back in intake. bypassed fuel pump relay and jumpered injectors and proved injectors passed fuel when fuel pump was pumping.
Double checked pressure regulator and confirmed that pump and pressure regulator were hooked up correctly.
I put a new pump and regulator from speedway on it. last week. Purged the fuel rail through the schrader valve on the passenger rail. Of course had bubbles and air, ran it until it was spraying clear fuel. THE ONLY THING I HAVEN'T MEASURED IS FUEL PRESSURE. I will do that tomorrow. I don't have my own fuel pressure gauge and the one I ordered had the wrong fitting.
Used the Old cheap spark testing tool to confirm that I have spark.
Still hits on first RPM then won't start.
I did get it running for 10 seconds or so on starting fluid.
IT still acts like it's not getting fuel. When we were watching the fueling PWM on the HP tuner during cranking and the average %pwm increased as expected.
Checked AIT, MAF, O2 sensors, and Engine temp. All of them work. Rpm reads correctly.
I am completely stumped.
ANY Help would be appreciated.
Double checked pressure regulator and confirmed that pump and pressure regulator were hooked up correctly.
I put a new pump and regulator from speedway on it. last week. Purged the fuel rail through the schrader valve on the passenger rail. Of course had bubbles and air, ran it until it was spraying clear fuel. THE ONLY THING I HAVEN'T MEASURED IS FUEL PRESSURE. I will do that tomorrow. I don't have my own fuel pressure gauge and the one I ordered had the wrong fitting.
Used the Old cheap spark testing tool to confirm that I have spark.
Still hits on first RPM then won't start.
I did get it running for 10 seconds or so on starting fluid.
IT still acts like it's not getting fuel. When we were watching the fueling PWM on the HP tuner during cranking and the average %pwm increased as expected.
Checked AIT, MAF, O2 sensors, and Engine temp. All of them work. Rpm reads correctly.
I am completely stumped.
ANY Help would be appreciated.
Thread Starter
Teching In
Joined: Oct 2017
Posts: 25
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From: Indiana
Spent another day in the Garage with the 5.3l still not starting.
went through all my wiring and did find a little goof, But nothing that really made a difference.
Friend came over with the HP Tuner and we ran some log files. What we observed was the Injector PWM command increases up to 50 msec and as soon as the engine fires the fueling goes to 1ms. Which of course is too low.
So something in the fueling table is or ECM control routine is shutting down the fueling.
My buddy is posting the log file on a HP tuner forum.
Anyone else ran into this??????
If im not mistaken vats disables the injectors. U should still be able to crank it with starting fluid. Im betting its still a vats issue. Look all over the tune there are vats disable tables all through out.
First is under OS tab.
Check in engine diag tab.
Check in fan and system tab toward the end.
U will most likely need to do a rewrite entire to fully disable the vats. Starter fault codes will make it do the same as well.
First is under OS tab.
Check in engine diag tab.
Check in fan and system tab toward the end.
U will most likely need to do a rewrite entire to fully disable the vats. Starter fault codes will make it do the same as well.
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Verdad Gallardo Well hell. I have never had this issue but i have a 74 caprice we 5.3 swapped with a e38 and psi harness. I fisabled vats in it and cant get it to fire the injectors either. Never had this issue before. Did u ever figure yours out??
Thread Starter
Teching In
Joined: Oct 2017
Posts: 25
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From: Indiana
What are starter checks?
Here is what I've done, since my last post.
I ran over my wiring again. and found that I had broke my brake wire when I buttoned things up. (that shouldn't be a deal)
I took the ECM to a Professional shop in Speedway Indiana and had them program the ECM.
It's been so cold I haven't been able to work much. But I really want to get this thing going. With the reprogrammed ECM It did pretty much the same thing.
Fires on the first Revolution or so and then stops. I can get it running on starting fluid
The Only thing I havent measured twice is the fuel pressure, I'm going to do that today.
I think i might have found my issue. Im headed to shop to try this.
But anyways check and make sure the maf sensor pigtail isnt swapped and with the front cam sensor. I wanna say they look the same and could be used vis versa. I read that the injectors will not fire if cam sensor doesnt read or goes bad.
But anyways check and make sure the maf sensor pigtail isnt swapped and with the front cam sensor. I wanna say they look the same and could be used vis versa. I read that the injectors will not fire if cam sensor doesnt read or goes bad.
Thread Starter
Teching In
Joined: Oct 2017
Posts: 25
Likes: 0
From: Indiana
Jan 6 Update.
Went and got a fuel system tester and I'm Not happy. My fuel pressure is 19lbs, far far less than the 58 PSI required. Here's the problem, I went to speedway motor and bought these Items
https://www.speedwaymotors.com/Speed...PSI,41791.html
https://www.speedwaymotors.com/Walbr...ump,65378.html
and a bunch of an6 connectors and such to go along with it.
My first pass I hooked the pressure to the return side and so On, I found that out and reversed it.
I've got a bit over 1/3 of a tank of fuel and the pump doesn't run out of fuel, It continues to pump with the schrader valve out and I purged all the air out of the lines.
when I bypass the fuel pump relay the pressure comes up smoothly to 19psi and stops, It doesn't jump around, It doesn't dip or move, It acts like its regulating to 19 psi and then when I hit the purge on the Pressure test fixture a spurt of fuel comes out and pressure drops to 0.
Any ideas. Did I get a bad regulator, did I foul it up by hooking it up reverse ?
Went and got a fuel system tester and I'm Not happy. My fuel pressure is 19lbs, far far less than the 58 PSI required. Here's the problem, I went to speedway motor and bought these Items
https://www.speedwaymotors.com/Speed...PSI,41791.html
https://www.speedwaymotors.com/Walbr...ump,65378.html
and a bunch of an6 connectors and such to go along with it.
My first pass I hooked the pressure to the return side and so On, I found that out and reversed it.
I've got a bit over 1/3 of a tank of fuel and the pump doesn't run out of fuel, It continues to pump with the schrader valve out and I purged all the air out of the lines.
when I bypass the fuel pump relay the pressure comes up smoothly to 19psi and stops, It doesn't jump around, It doesn't dip or move, It acts like its regulating to 19 psi and then when I hit the purge on the Pressure test fixture a spurt of fuel comes out and pressure drops to 0.
Any ideas. Did I get a bad regulator, did I foul it up by hooking it up reverse ?
