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 of 1 people found this 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 of 1 people found this helpful.

Norm is right. From the guy who asked Question.

Your Answer

Add photo

Related Questions

Grand Prix

Looking for a Used Grand Prix in your area?

CarGurus has 2,828 nationwide Grand Prix listings starting at $1,991.


Search Pontiac Grand Prix Questions

Pontiac Grand Prix Experts

#1 Js08016
Reputation 4,330
#2 Tom Demyan
Tom Demyan
Reputation 2,940
#3 munron
Reputation 2,280
View All

Related Models For Sale

Used Chevrolet Impala
612 Great Deals out of 35,471 listings starting at $899
Used Pontiac Bonneville
5 Great Deals out of 538 listings starting at $1,799
Used Ford Mustang
683 Great Deals out of 44,980 listings starting at $750
Used Chevrolet Monte Carlo
10 Great Deals out of 1,423 listings starting at $995
Used Pontiac Grand Am
1,142 listings starting at $1,000
Used Chevrolet Camaro
345 Great Deals out of 31,319 listings starting at $2,500
Used Chevrolet Malibu
1,156 Great Deals out of 79,088 listings starting at $2,500
Used Pontiac Firebird
14 Great Deals out of 756 listings starting at $3,490
Used Nissan Maxima
329 Great Deals out of 24,429 listings starting at $800

Used Cars For Sale

2008 Pontiac Grand Prix For Sale
16 Great Deals out of 404 listings starting at $1,991
2007 Pontiac Grand Prix For Sale
364 listings starting at $5,499
2006 Pontiac Grand Prix For Sale
7 Great Deals out of 460 listings starting at $2,000
2005 Pontiac Grand Prix For Sale
5 Great Deals out of 374 listings starting at $2,350

Content submitted by Users is not endorsed by CarGurus, does not express the opinions of CarGurus, and should not be considered reviewed, screened, or approved by CarGurus. Please refer to CarGurus Terms of Use.