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94 3100 (N body) and 99 3100 (W Body) differences


AL

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One of the offers for my 89 was a 94 Grand Am with about everything wrong with it except the motor runs perfect... And my 99 GP needs a motor... He offered 350 cash plus his car... But I was wondering the differences between 94 and 99 that would cause problems with the swap... I know the motor mounts are different but those can be transferred... Did OBD2 add any sensors (I read somewhere about 2 knock sensors??)

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I can tell you that the upper motor mouns are very different, I believe i am correct on this. And the intake is different also. Egr will be different.

You are going from obd1 to obd2 (gen2) Is it really worth the work would be the question

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The transferring of motor mounts is just a few bolts while the motors are both out... I didnt know about the intake being different... Do you mean upper or lower or both? I am aware that I would be switching from OBD I to OBD II but I didnt know how in depth that would be... I havent read Bobs write up but maybe he can come in with a few pointers

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upper intake, egr, egr pipe and rear exhaust manifolds are different, but are simple bolt on swaps.

 

You have the change the knock sensor, and while the obd II 3.4 dohc has two knock sensor, I don't think the obd II 3100s do. if they do, there should be a pre tapped hole anyhow...

 

you may need to swap the injectors.

you will have an unused rear head temp sensor which could be blocked with a pipe thread insert.

the 94 should have ball and pivot rockers, while the 99 with have roller rockers. Unless you have the larger intakes(00+?) you won't have an issue.

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The timing covers should be different. I'm not sure if you'll need to swap them going N-body to W-body though. I believe the difference is only a mounting hole for an accessory/bracket.

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  • 4 months later...

ken, matt and robert(?) already covered everything IIRC...

 

only one knock sensor on a 99 3100 from what i can tell. not sure if the connectors are different or not.

 

injectors should be more or less identical, or at least they are in resistance and flow characterstics, possibly quieter on the newer ones.

 

n-body timing cover has a motor mount bracket on it

 

99 is expecting a single 3 wire coolant temp sensor(compared to a singlewire and a dual wire on the 94). just swap the 3 wire temp sensor in place of the two wire(should have the same threads) and leave the single wire in the rear head disconnected.

 

as stated: EGR, egr mount on the intake, the 94 won't have a TB with coolant running through it, the 99 should, 94 doesn't have the roller rockers, rear mani, EGR tube, blah blah bah....

 

i think that covers everything.

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