Help after swap!

M

mk3-4-me

New Member
May 19, 2010
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Milwaukee, WI
Hey so I jet got done throwing a 92 7mgte into my 87. My motor got rod knock and then seized up on me, so I bought another motor.

I just hooked evrythin up, put the battery in and tried to crank it over. When I turn the key there is a loud buzzing noise from the round black metal thing right behind the brake system and next to the heater valve thing on the passenger side of the engine bay.

My tach also jumps up to 2k, and then will start jumping around to the buzzing noise, in between 2k and 0.

My battery has 12.7 ish volts, but when I turn the key the lights dim, and it buzzes. When I put a battery charger on it set to engine start, it does the same thing and 3 TEMS lights blink.

Idk what it could be, if you guys have any insight that would be cool!

Thanks
 
M

mk3-4-me

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May 19, 2010
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Oh ya forgot to mention that. When the charger is set to engine start, and I jumper the diagnostic box, it will continuously blink. And when the charger isn't on the CEL wont even light up, and everything else dims...
 
mk3_7m

mk3_7m

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Jul 21, 2007
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mk3-4-me;1710684 said:
What does the year have to do with it? I dnt need an 89+ harness do it??
Click to expand...

Well thats really dependant on your ECU to whether its grey pluged or yellow pluged. Yellow is pre.

Other than that does it crank? did u put hook up the starter motor?

I loved your description of the noise location. gave me the giggles.
 
M

mk3-4-me

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May 19, 2010
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It doesn't not crank... Like I said it buzzes and the lights dim... I have my 87 yellow harness and ecu hooked up to the 92 motor... So I dnt think that is a problem...

Yes starter is hooked up... I'll try cranking the pos. Cable on it tighter...
 
M

mk3-4-me

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May 19, 2010
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my coolant temp also jumps all the way up to a lil over H. starter is tight. idk what it is. theres a loud humming sound in the car, then when the key is turned is goes to the buzzing in the engine bay.
 
mkiiichip

mkiiichip

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Sep 10, 2007
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Haven't you been here long enough to know you should listen to JJ?

He never has much to say unless you ask the right questions. When he gives advise you can be sure he is spot on.

To put it simply, pre and post 89 are not plug and play.
 
M

mk3-4-me

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May 19, 2010
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So what dies that mean? How is or not plug n play? I had this problem befor with my 87 motor. I dnt think it has anything to do with the year... Why would it? What's a different plug on the post 89 vs the 87 motor?
 
90mkiiisupra400hp

90mkiiisupra400hp

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Mar 20, 2011
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Gardiner, Maine
I know of atleast one sensor that has a different plug on it, the cold start time switch on the thermostat housing. There are probly more but that is the only one off the top of my head, I did a 87 motor into a 90 with a 90 ecu and harness I just had to change a few sensors but I cant remember all of what I did, if anyone else can confirm other sensors that would probly be helpful...

Also if you seperated the engine and trans. and fortgot to put the plate between the two then the starter will not be lined up right and would possibly just bind instead of crank over, which would also cause the lights to dim while trying to start as the starter is using all that power.... not sure if this is your problem but it is a possibility
 
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Moy

Moy

It's broken...
Aug 6, 2008
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use the electronics from your old engine on the new one, along with a few of the sensors on the waterneck as the connectors changed... it SHOULD start up then

also make sure the ECU grounds on the intake manifold are hooked up and the start is in fact in the proper position so the drive gear will engage the teeth on the flywheel/flexplate
 
90mkiiisupra400hp

90mkiiisupra400hp

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Mar 20, 2011
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Gardiner, Maine
mk3-4-me;1710943 said:
Was a 87 7mgte with an a340e, pulled both out and threw the 92 7mgte with a r154. I bypassed neutral start switch thing...
Click to expand...
I see, I thought you just changed the engine not both, so there is no reason the starter shouldn't be lined up if it was all working before, like MOY said check the intake manifold ground wires
 
M

mk3-4-me

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May 19, 2010
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Milwaukee, WI
Ya those 2 that r together comin from under the intake manifold r bolted down.

That ground from the head on the back passenger side that connects to the body isnt bolted down, but I dnt think that is it. I'm gunna tighten it just to see but I dnt think it's it... Hopefully it's just that lol
 
90mkiiisupra400hp

90mkiiisupra400hp

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Mar 20, 2011
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Gardiner, Maine
Do you mean the 2 "groups" of wires under the intake? and the other ground on the passenger side shouldn't make it not run but its not a bad idea to hook it up, it's there for a reason but mine wasn't hooked up for a while untill I noticed it.
 
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