Where Should I locate a water/methanol injector when I can't find throttle Body Spacer

Asked by Apr 09, 2014 at 08:20 AM about the 1999 Pontiac Grand Prix 2 Dr GTP Supercharged Coupe

Question type: Car Customization

Ihave H2O/Methanol injection kit, I'm to place the injector after the mass air sensor which is in the front of the throttle body. All TB spacer for this vehicle say's won't fit supercharged.
Any Simple Ideas?

6 Answers


Try AirRaid, I believe their TB spacer fits supercharged engines about $120.00. Shouldn't give any clearance issues. Setting the timing is going to be an issue with the boost/quench balance on a supercharged engine. Good luck!


A TB spacer is no benefit on any forced induction engine, whether it is turbo or supercharged. The injection kit will have to be mounted in the intake tube to be in front of the TB.


Hold on....the TB spacer alone does nothing, agreed. But you must install a TB spacer in order to port the methanol at the right place, which is after the MAS but before the TB. Installing it as you described will put the injector before the MAS, which is not recommended. Doing so will pretty much negate any value to the methanol kit as the ECM will simply compensate for the increased density. The MAS location on the Pontiac forces you to use a spacer. All TB spacers are not equal. The supercharged GTP has a slightly different throttle body so you need the spacer that's specific for that setup.

1 out of 1 people think this is helpful.
Best Answer

the TB spacer will be after the TB. it goes between the TB and the intake manifold. he said the methanol has to go before the TB.


The methanol injector has to go after the MAS. After that it can go anywhere - after or before the throttle body. You could even tap the intake plenum if you wanted to (or were nuts) and install a series of injectors. But the common way to do this is to buy a TB spacer and tap it for the injector. Many cars have the MAS well upstream of the throttle body so there are places to tap into the air flow, between the MAS and the TB. That's not the case on the Pontiac, where the MAS is virtually bolted right into the side of the TB. You must use a spacer, or tap into the intake plenum.

1 out of 1 people think this is helpful.

Norm is right. From the guy who asked Question.

Your Answer

Add photo

Related Questions

  • 2000 pontiac gtp 1 answer

    My mod list: 3.4 supercharger pulley,ported supercharger,ported lower intake,1.9 ratio rockers,throttle body spacer,cai,colder spark plugs,160 tsat,shift kit,zzp headers,3 inch downpipe exuast,res...

    2000 Pontiac Grand Prix GTP



  • grease nipples 2 answers

    I take my car in to get servicing and I pay for lubrication of my vehicle and one time I decided to look under my front end and with the wheels turned so as to get a look to find grease nipples and I ...

    2008 Pontiac Grand Prix Base


    Maintenance & Repair

  • Does anyone know how well a throttle body spacer works on a 305 pontiac 5 answers

    do they add any significant boost in power or fuel economy or would I be wasting my time?

    1992 Pontiac Firebird Base


    Car Customization

  • 2" spacers

    I have a 88 Pontiac Fiero, I want to install 2" spacers to make the tires look bigger from the rear.. I know 4" spacers will probably break my wheel bearing or Ivan my axle... is it the same issu...

    1988 Pontiac Fiero Formula


    Car Customization

  • Should I modify my original 389? 17 answers

    I have a numbers matching 66 GTO; I have been thinking about boring 30 over, roller rockers, dish pistons, and a cam. Is this a mistake? Should I keep it original?

    1966 Pontiac GTO Coupe


    Car Customization

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 3,749 nationwide Grand Prix listings starting at $879.


Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Reputation 3,980
#2 Tom Demyan
Tom Demyan
Reputation 2,660
#3 munron
Reputation 2,070
View All

Related Models For Sale

Used Chevrolet Impala
799 Great Deals out of 34,708 listings starting at $799
Used Pontiac Bonneville
6 Great Deals out of 674 listings starting at $1,599
Used Chevrolet Monte Carlo
12 Great Deals out of 1,692 listings starting at $2,300
Used Pontiac Grand Am
1,665 listings starting at $1,995
Used Chevrolet Malibu
1,077 Great Deals out of 85,119 listings starting at $1,995
Used Ford Mustang
396 Great Deals out of 44,403 listings starting at $1,000
Used Jeep Grand Cherokee
888 Great Deals out of 69,215 listings starting at $1,300
Used Chevrolet Camaro
309 Great Deals out of 38,867 listings starting at $1,250
Used Nissan Maxima
359 Great Deals out of 25,313 listings starting at $1,400
Used Honda Accord
887 Great Deals out of 82,090 listings starting at $999

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
14 Great Deals out of 472 listings starting at $1,200
2007 Pontiac Grand Prix For Sale
3 Great Deals out of 536 listings starting at $2,000
2006 Pontiac Grand Prix For Sale
8 Great Deals out of 633 listings starting at $1,999
2005 Pontiac Grand Prix For Sale
438 listings starting at $5,900