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  • Throttle Body Injection help needed

    I am working on a buddies vehicle that has throttle body injection.

    The injectors and throttle body are from 1988 mounted to a 350.
    The vehicle has started running super lean, and I'm wondering if the injectors are plugged from all of the years of mis-use before he had the vehicle.

    We put on a completely new fuel system, lines, tank, pump etc. The only thing left from 88 is the throttle body assembly. The old system was trashed and very dirty.
    O2's were replaced at the time we put the new engine in.

    I would like to replace the two injectors, but not sure if there is a cheaper way to go - such as a rebuild kit? I see Airtex offers an injector rebuild kit and also a throttle body overhaul kit that has the necessary gaskets, o-rings, etc.
    The injectors cost roughly $80 each, so at $160 plus the cost of a rebuild kit...it seems almost better to find a reman throttle body. I know Holley makes a performance unit for around 350, but that is out of budget.

    Has anyone rebuilt their existing TBI injectors, or had experience with replacing these with a better/more performance injector?
    What are my options?

  • #2
    is this a truck were talking about, i know my 88 k1500 throttle body was a little crappy i dropped a can of seafoam and cleaners in the areas and it cleared up fro awhile, before i let it come back i rebuilt the whole thing in shop class cause i was bored. it wasnt necessary but it worked tons better, if the injectors look that bad go to a jy and fin a tbi unit purchase em stick em in your pocket its you decision, but i dont condone the second choice. the stock truck doesnt need much bigger injectors unless you have some mods done to it. plus spacers, and porting would help open up more power also
    91 Trans am, 305, Lt1 cam, 24lb injectors, headers, SLP LM2, SW chassis, massive panhard, lowered, modded TPI, Tuned, 4.10s, Lincoln locked
    85 Z28 406/th400?/3.42 4th gen disc rear/4th gen dash
    00 Tahoe Z71........Stock
    97 K1500 lt4 cam, 1.6s, MPFI, Solid axled, IROKs,------winter beater

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    • #3
      It is indeed a 88 K1500 Rochester 220 throttle body, but this is supposedly also used on many of GM vehicles, including F-bodies.

      The original fuel system on this truck was full of crap, so I would believe the filters to be plugged up severely. Possibly the injectors as well.

      The only reason I wanted to go a bit bigger as we've added a towing/RV cam to it. With a carb this long block could pull quite hard. With the throttle body it seems choked down quite a bit.
      I know Holley makes a 670cfm throttle body, but that's out of budget.

      I will probably first try to replace the filters, do a basic tune up on it. I see that Jon at FIC sonic cleans the throttle body injectors. Not sure if anyone else tried this...or if I can just backflush the injector with carb cleaner.

      Anyone have a spare they want to sell cheap in the event this one is foobar'd up?
      Last edited by TrickyTransAm; October 30th, 2011, 04:34 PM.

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      • #4
        i may be wrong so check around but the 454 tbi's can be used i believe but the lack something on a certain year ill have to read through my old emails and check. is this a completely stock tbi if so the heads are a big problem right there. a set of vortecs with a carbed vortec mani and a tbi adapter did wonders on my friends truck, and then threw in a lt1 cam and it was sickening how much power we gained. i may be wrong but if you go bigger injectors i think you need to upgrade from a tbi pump to vortec style. i dont think the tbi one can keep as much pressure as needed throughout the fuel system and they are almost maxed on the trucks while stock.
        edit: i found my old emails
        Stock TBI pump flows 75lph and supports at best 250hp. The stock 1996 Vortec pump flows 155lph and can support up to 400hp
        http://www.tbichips.com/ultimateMODS.htm i talked to the guy in depth about tbi he has quite a knowledge and he willing to just educate you and not froce his products on you. give him an email he has lots of advice.
        Last edited by TylerT/AZ28; October 30th, 2011, 05:08 PM.
        91 Trans am, 305, Lt1 cam, 24lb injectors, headers, SLP LM2, SW chassis, massive panhard, lowered, modded TPI, Tuned, 4.10s, Lincoln locked
        85 Z28 406/th400?/3.42 4th gen disc rear/4th gen dash
        00 Tahoe Z71........Stock
        97 K1500 lt4 cam, 1.6s, MPFI, Solid axled, IROKs,------winter beater

        Comment


        • #5
          Originally posted by TylerT/AZ28 View Post
          is this a completely stock tbi if so the heads are a big problem right there. a set of vortecs with a carbed vortec mani and a tbi adapter did wonders on my friends truck
          We used a 76 350 short block and purchased a set of refurbished heads to match the 88 intake. Everything else is stock TBI. The goal was to get it up and running as quickly as possible.

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          • #6
            well if you had stock 88 heads that;d be a huge issue for performance. but you dont so your good.
            91 Trans am, 305, Lt1 cam, 24lb injectors, headers, SLP LM2, SW chassis, massive panhard, lowered, modded TPI, Tuned, 4.10s, Lincoln locked
            85 Z28 406/th400?/3.42 4th gen disc rear/4th gen dash
            00 Tahoe Z71........Stock
            97 K1500 lt4 cam, 1.6s, MPFI, Solid axled, IROKs,------winter beater

            Comment


            • #7
              Check the injector for a pulse of voltage from the ECM using a noid light before you buy other injectors.

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              • #8
                Will do. They seem to be working, but not very well. I have a noid light set, and I think the PCM is commanding correctly...but have a feeling the injectors are so mucked up from improper maint. over the years...that they just ceased to function.

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