What kind of differences are there with the pre 90 (MAF) TPI induction systems vs. the MAP style systems? I want to convert an older vehicle (pre 87 bolt pattern heads) from Q-jet to TPI; I think the only thing that will fit is a MAF type intake system.

Can I just plug the cold start injector hole and be done with it? Are there other concerns/problems/impossibilities with trying to convert a MAF intake to MAP mode? Would I need to drill/tap any holes or install any additional vacuum nipples? Help....I'm clueless on this. Thanks

 

Yes it can and I used a tee to get vacuum to my MAP. You could drill and tap a hole for a barbed fitting to feed the vacuum signal to the MAP.

 

Cool....it's just that simple huh? How did you plug the cold-start holes and fuel rail?

 

Well there is a lot more to it. I asumed you were talking about the TPI unit itself. You would have to convert to the 7730 computer. You would have to convert the wiring harness or get one from a 90-92 car. You could leave the ninth injector in place but not hook up the wiring. If you did remove it you can put a freeze plug in the runner inplace of the injector. You can get a cap for the back of the fuel rail. You would need to get the proper knock sensor and probably some things I'm missing.

 

You assumed correctly, I know about the computer part already. I was just wanting to know how hard it was to convert a MAF intake to be speed-density ready.

I was also wondering how much difference there was between the harnesses. I was hoping that adapting a MAF harness to a speed density system wouldn't be too hard, but I guess that's asking too much from GM.

 

The later the maf car the easier it gets. On my 1989 model it was not hard at all. Every year you go back the more involved it gets.

 

if you got pre 87 heads dont you need to get either a corvette TPI base or change the heads to 87plus?

 

When changing to aftermarket heads you should get an aftermarket TPI intake anyway so you dont choke off your new heads with the stock intake.

There is a huge difference in the 85-88 harness vs the 89 and the 90-92 harnesses. In 1989 GM integrated the car harness with the engine harness so they're all in one wire loom. Before that it was two separate wire looms. But you can still rewire the earlier ones to work with the speed density system.