Mallory 685 doesn't work with LT1 pcm
08-09-2011 | 11:38 AM
#1
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Joined: Jun 2006
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From: Lancaster, tx
Mallory 685 doesn't work with LT1 pcm I have been having trouble getting my car to fire up while the mallory 685 box is connected. If I use the by-pass it fires right up. This is the second box in two weeks, and I have went over the wiring several times. I called Mallory and the tech line rep told me that the mallory box was not compatible with the LT1 pcm. WTF!!!!! Someone please help. I know there are guys using the box. Why won't mine start?
08-09-2011 | 08:23 PM
#3
On The Tree
Joined: Jan 2002
Posts: 104
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From: Raleigh, NC
What year is your car?
You might call Century Performance. That's who I got my MAL685 from and their phone tech support is great. www.centuryperformance.com
A great resource for OBD1 guys is Jim's Performance in MD. Jim helped me over the phone through the MAL685 and a retro fit from HEI to small cap and LT1 style coil, so he's pretty up on his wiring with that box. http://www.jimsperformance.com/
You might try grounding the case of the box. That helped with longevity in my car.
I went through several boxes when I had the MAL685 under the hood. For me, they were super sensitive to water. I moved the box to inside the car and haven't had a problem in years.
It sounds like you are having luck making the box work at first, and then it dies over time. I have seen some of them that randomly adjust the start retard as the box cycles. You might want to check that if I am interpreting what you are saying correctly.
You might call Century Performance. That's who I got my MAL685 from and their phone tech support is great. www.centuryperformance.com
A great resource for OBD1 guys is Jim's Performance in MD. Jim helped me over the phone through the MAL685 and a retro fit from HEI to small cap and LT1 style coil, so he's pretty up on his wiring with that box. http://www.jimsperformance.com/
You might try grounding the case of the box. That helped with longevity in my car.
I went through several boxes when I had the MAL685 under the hood. For me, they were super sensitive to water. I moved the box to inside the car and haven't had a problem in years.
It sounds like you are having luck making the box work at first, and then it dies over time. I have seen some of them that randomly adjust the start retard as the box cycles. You might want to check that if I am interpreting what you are saying correctly.
08-09-2011 | 10:28 PM
#4
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11 Second Club
Joined: Jun 2006
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From: Lancaster, tx
The car is a 97, OBDII, the box comes on, the start retard is set at .01, I will check out the guys over at Century Performance and see if they can help. Thanks for the input
What year is your car?
You might call Century Performance. That's who I got my MAL685 from and their phone tech support is great. www.centuryperformance.com
A great resource for OBD1 guys is Jim's Performance in MD. Jim helped me over the phone through the MAL685 and a retro fit from HEI to small cap and LT1 style coil, so he's pretty up on his wiring with that box. http://www.jimsperformance.com/
You might try grounding the case of the box. That helped with longevity in my car.
I went through several boxes when I had the MAL685 under the hood. For me, they were super sensitive to water. I moved the box to inside the car and haven't had a problem in years.
It sounds like you are having luck making the box work at first, and then it dies over time. I have seen some of them that randomly adjust the start retard as the box cycles. You might want to check that if I am interpreting what you are saying correctly.
You might call Century Performance. That's who I got my MAL685 from and their phone tech support is great. www.centuryperformance.com
A great resource for OBD1 guys is Jim's Performance in MD. Jim helped me over the phone through the MAL685 and a retro fit from HEI to small cap and LT1 style coil, so he's pretty up on his wiring with that box. http://www.jimsperformance.com/
You might try grounding the case of the box. That helped with longevity in my car.
I went through several boxes when I had the MAL685 under the hood. For me, they were super sensitive to water. I moved the box to inside the car and haven't had a problem in years.
It sounds like you are having luck making the box work at first, and then it dies over time. I have seen some of them that randomly adjust the start retard as the box cycles. You might want to check that if I am interpreting what you are saying correctly.
08-10-2011 | 03:55 PM
#7
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Joined: Jun 2006
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From: Lancaster, tx
Yeah, I used the msd harness part number 8877. I wired it black to black, green to white, red to red, and yellow to orange. I am really close to sending this box back for an msd 6. I am going to keep working with this one for at least the remainder of the week. What part number is the msd 6? Does it have a window switch and high speed timing retard?
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08-14-2011 | 01:40 PM
#8
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Joined: Jun 2006
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From: Lancaster, tx
Well, I took a test light and checked each wire coming from the box to the wiring harness, each wire is hooked up correctly. Again, I connected the by pass harness and the car fired right up. WTF!!!. I just got off the phone with summit and they are going to send out box #3. The sales rep apologized and stated "we'll get it right this time". I surely hope so.
On another note, I took the car out and sprayed 50 down the tube....for those who say you can't feel or tell the difference with such a small shot is full of $h!t. It was by no means a rocket car, but it definately added a power you can feel. I sprayed from 65 to 120 and then from a dead stop. I can't wait to get that 150 shot going.
On another note, I took the car out and sprayed 50 down the tube....for those who say you can't feel or tell the difference with such a small shot is full of $h!t. It was by no means a rocket car, but it definately added a power you can feel. I sprayed from 65 to 120 and then from a dead stop. I can't wait to get that 150 shot going.
