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Old 01-06-2011   #1
resurrected1988
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1988 to 1990 TPI

Hey


I havent been on the site in a long long time. But I am a owner of a 1988 Trans am GTA. I recently have been doing lots of work to it and I left off with one problem.. The engine that I put into is is exactly what was in it, BUT...Instead of it being a 1988 305 Tuned port injection..it is a 1990 305 Tuned port injection... I met a guy who reporograms computers and he took mine and adjusted the computer and deleted the cold start injector and some other things cause I told him its a 1990 engine going into a 1988 car...

My question to you guys is this...Ive heard that The distributors are different??.. I dont know if thats true or not, But I noticed that the oil pressure plug is different and I have to switch the 1988 oil pressure switch over from the 1990.. I turned the distributor with the igniton on and well, it sparks alright lol... I just dont see why it would have to be swapped.. I have the old 1988 engine and a 1988 350 with aluminum heads so I have may parts to play with I just wanted to ask somebody what I need to do with a engine that came out of a 1990 Speed density Firebird and put into a 1988 MAF car.. thanks

Zadrian

Last edited by resurrected1988; 01-06-2011 at 01:41 AM.
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Old 01-06-2011   #2
george88gta
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Re: 1988 to 1990 TPI

The basic iron should be the same. If you used the 1990 TPI setup, then you did the right thing by having the cold start injector deleted. If you used the 1988 intake and TPI setup, you didnt accomplished much and may have caused a problem. The car is setup for MAF, not speed density. I seem to recall that you just cant swap a speed density engine ( complete) in to a MAF body, without major mods. Bottom line is that the easiest way is to swap over all the 1988 TPI stuff to your new engine. No ECM mods, etc.
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Old 01-06-2011   #3
merc3065
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Re: 1988 to 1990 TPI

No, you can't just swap it in without doing some major mods...

The mechanical/moving parts are all the same. The sensors, intake and fuel system are where the differences will come in.

As you've probably noticed, the oil pressure sensor is different, the fuel rails from a 90 do not have the 9th injector (cold start). The TPI manifold has an extra hole in it for the MAP sensor. The intake ducting is lacking the Mass Air Flow sensor in it and is a single piece.

Im not so sure about the distributor though...For some reason, there appears to be a difference between a trans am and a GTA in terms of drive train. An MSD pro billet will fit an 87-89 GTA, but will fit an 87-92 trans am...That sounds kinda fishy...

On the back of the distributor there should be 2 wire hookups. 1 for a 2 pin, 1 for a 3 or 4 pin (cant remember which). These then plug into the remote ignition coil that sits on the back near the distributor hold down.

If you want to swap to speed density, get a SD TPI plenum, computer, harness and sensors.
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Old 01-07-2011   #4
resurrected1988
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Re: 1988 to 1990 TPI

Hi, thankyou for your replys.


The engine itself was pulled from a 90 and put into my 88.. I have the mass air sensor. I have everything needed. What I did was I didnt have the computer for the car. So I got a 1988 Trans am GTA computer with a 5.7L engine.. I had the chip reprogrammed for the 305 TPI with the deletion of the cold start injector so I can use my 90 engine and not have to change anything. Im goign to change the oil pressure sensor bot other then that my main concern was the distributor. It looks exactly as you described and is identical to the 1988 one.. I would swap them just to play it safe but the 1990 engine has a brand new distributor. If anyone has any other input I would greatly apreciate it, thankyou
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Old 01-07-2011   #5
YumikoGTA
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Re: 1988 to 1990 TPI

I think the chip has to also be programmed as to what the type of transmissions the car has and exactly what differential gearing it has.

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Old 01-07-2011   #6
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Re: 1988 to 1990 TPI

Don't have to do anything with the differential gearing in the chip but manual/auto is optional. Only difference between the auto and manual chips in terms of coding is the manual chip will allow for the shift light to come on and neutral safety switch check. Automatic chip controls torque converter lockup and park/neutral safety switch check.

If the programmer knew how to delete the cold start injector, he more than likely knew that the engine was a 305 and changed the hex code for the engine size as well.

If the distributor is new, use that one, keep the 88 as a spare.
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Old 01-17-2011   #7
resurrected1988
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Re: 1988 to 1990 TPI

Thankyou for all your info.. I do have one more question.. I I have the engine harness installed, With the exception of a few grounds and the oil pressure sensor and the reverse sensor.. I tried to start the car and The fuel pump dont turn on and the starter wont turn..

Im thinking this is cause a a few things are not connected. and I think that the oil pressure switch not being connected is a result of the fuel pump not coming on.. I dont have a security light on anymore so I know is not a vats issue.. But the wait on getting this car running is killing me!
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Old 01-17-2011   #8
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Re: 1988 to 1990 TPI

VATS can still be an issue even without the security light.

You need the oil pressure switch connected otherwise it'll kill the fuel pump. Kind of a safety feature to save your engine or if the car flips or something in an accident and oil pressure drops.
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Old 01-17-2011   #9
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Re: 1988 to 1990 TPI

Just remembered. If the car had VATS installed in it you still need to bridge the starter relay to completely bypass the VATS system.

I have this issue on my notchback even with my 88 non vats computer and removal of the rest of the vats passkey system.
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Old 02-04-2011   #10
resurrected1988
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Re: 1988 to 1990 TPI

Quote:
Originally Posted by merc3065 View Post
VATS can still be an issue even without the security light.

You need the oil pressure switch connected otherwise it'll kill the fuel pump. Kind of a safety feature to save your engine or if the car flips or something in an accident and oil pressure drops.


Thanks. Could you tell me how to Bridge the starter Relay?
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Old 02-04-2011   #11
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Re: 1988 to 1990 TPI

You have to connect the large gauge green and yellow wires together up where the starter relay is. It's upper left driver's side, against the firewall.

I cant remember if you do it on the connector side or just to the wires. it's been a long time since ive been in there.
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