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LT1 in 84....Help Needed
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Joined: Sep 2010
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From: Prichard WV
LT1 in 84....Help Needed
I am dropping an LT1 from an impala into my 84. My question is transmission related. THe guy at LT1 Swap.com (who programmed my PCM) told me I needed to somehow let the LT1 know when the car is moving to avoid stalls at low speed. The problem is this: the speed sensor in the original 700R4 I'm using produces a square wave signal and the LT1 PCM is looking for a sine wave signal (or vice versa, I can't immediately remember). Common sense would say to put an LT1 speed sensor in the 700R4 BUT, will I not lose the speedo as it reads the different signal? I believe I read somewhere that a converter is available and I'm sure I'm not the first to encounter this issue, so those of you who gone through this please help me here. I emailed Jags that Run, (who sells a type of converter) with the same question I posted here. After 7 days, I got no response- so I'm taking this to the Corvette Experts. Any help is majorly appreciated.
Thanks,
Rich
Thanks,
Rich
Burning Brakes
Joined: Jun 2008
Posts: 895
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From: toledo ohio
i dont know too much about this since ive never tried the swap, but from what ive heard dakota digital makes a lot of convertor "boxes" for swaps, vss signals, and all that good stuff. try giving them a call.
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From: Prichard WV
I know they sell a conversion kit that converts a cable sending unit to a digital signal for their speedos but what I'm looking for is some way to run BOTH signals- one to the speedo and the other signal to the PCM. I don't know if this is even possible but I'm hoping someone out there has done it and overcame this issue.
Burning Brakes
Joined: Oct 2009
Posts: 773
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From: Minneapolis MN
Call some electricial automotive experts(shops) in your town.Curious what the answer is.Some here may know.Post pics of build if possible.This would be very popular
I would keep the cross-fire emblems on the side,keep it appearing stock & have it be a "sleeper."Does it start now?Have you started the build?Pics?Any other wiring nightmares?How did you resolve some of the wiring issues?
I would keep the cross-fire emblems on the side,keep it appearing stock & have it be a "sleeper."Does it start now?Have you started the build?Pics?Any other wiring nightmares?How did you resolve some of the wiring issues?
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From: Prichard WV
Right now, the crossfire engine is out of the car but the LT1 is still on the engine stand. It is reverse-wired, meaning everything on the motor is wired (sensors/injectors/ect.) and the PCM plugs are connected. The only thing left to do when motor goes in is to hook up the sending units and the hot wires to the PCM/ignition- loom everything up & it's ready. It looks loke spaghetti on top of the engine, but I figured it'd be easier to do while it is out of the car. The only stumbling block I'm facing is this square to sine conversion so the pcm recognizes the car is moving. As for pictures, I'm still in the planning stages- I want to have a clear idea in my head before I dive in. Pics will be posted as soon as I figure some things out. As for calling garages/shops in my area, it's a small town- no one would know what to tell me about it. I'll keep searching though- surely one of you guys have done this, haven't you?
Le Mans Master
Joined: Nov 2009
Posts: 6,882
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From: Bangkok, Thailand
I would think that street-rod conversion places could answer this question pretty easily. I haven't dabbled with electronics for a long time, but I don't see any reason why you couldn't take the output of the trans sender and tap into it for a signal to the PCM. It's just a matter of converting the wave type and a good electronics guy should be able to do that.
I'm certainly not voluteering him to do this, but Jim at DCS (http://crossfireinjection.net/DCS%20Contact.html) is VERY familiar with the stock CFI setup and when I spoke to him was obviously VERY sharp when it comes to electronics. I'd say contact him and see if he is able to help.
I'm certainly not voluteering him to do this, but Jim at DCS (http://crossfireinjection.net/DCS%20Contact.html) is VERY familiar with the stock CFI setup and when I spoke to him was obviously VERY sharp when it comes to electronics. I'd say contact him and see if he is able to help.
Melting Slicks
Joined: Jan 2005
Posts: 2,658
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From: Clifton Park NY
I'm not gonna have a answer to your question but the guys at thirdgen.org are very knowledgable with ecms and such.
Just a FYI, you could have saved yourself a lot of time and money if you had used dynamicefi's ecm. No changes to the wiring harness at all and would easily control a LT1, speed density set up
Just a FYI, you could have saved yourself a lot of time and money if you had used dynamicefi's ecm. No changes to the wiring harness at all and would easily control a LT1, speed density set up
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Joined: Sep 2010
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From: Prichard WV
I've been in contact with Dakota Digital - they told me if my 1984 700r4 has a reluctor ring, they can help me out. Can anyone here answer that question? The tranny is still in the car, but I'll crawl under and see if no one here can tell me. Thanks for all the input so far.
Rich
Rich
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Joined: Feb 2004
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I've been in contact with Dakota Digital - they told me if my 1984 700r4 has a reluctor ring, they can help me out. Can anyone here answer that question? The tranny is still in the car, but I'll crawl under and see if no one here can tell me. Thanks for all the input so far.
Rich
Rich
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From: Prichard WV
OK, I spoke with Jags that Run today. The solution they offer is a 40 pulse reluctor ring that mounts on the differental flange just behind the Driveshaft with a second speed sensor feeding the 95 pcm. Sounds logical,just need to check the flange and make sure it has room to fit(corvettes being a little different and all....). If this solution doesn't work, I'm just going to get a 4l60E and buy a signal converter box from Dakota Digital to feed the dash speedo. Thanks for all the advice- it pointed me in a few directions I wouldn't have thiught of going for information. I'll keep everyone posted and start a build thread with pics when I begin reconstruction - which is getting closer 
.
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From: Prichard WV
Change of plans..........AGAIN!!!! After realizing I have to address the TV cable issue, it has become glaringly obvious that my best move is to get a 4l60e and mate it to the lt1- that way, I have only one PCM- a couple different ways to go with the speedo fix, but that's down the road. By the way, this will be the last post here about this subject. I plan on getting some pictures and starting a build thead- a picture is worth a thousand words, eh!!!
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From: Prichard WV
I know, but everything from PCM signals to making the speedo work seems to be much easier if the tranny is a 4l60e- even though this adds $$$ to the project. I think things will go a little better.
