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Old 12-02-2012, 09:30 AM
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Thumbs up New Member with a question about an old truck

I'm not sure if this is the right place to ask this question, but here goes.

I have a 1994 regular cab K1500 with a TBI fuel injected 350 in it. It also has a 4 speed automatic that I think is a 4L60e. The truck has approx 210K miles on it, and I have owned it since bought new in 1994. I rebuilt the motor some time ago and made some "performance" changes at that time. I rebuilt it because it had enough blowby to push the oil dipstick out. The motor was bored 0.060 over. The heads and intake were mildly hand ported. I added long tube Hooker headers and flowmasters. I also put a mild cam from Comp cams in the truck. The Comp cams tech line stated the cam should work fine with the stock TBI. Several years ago, before the engine rebuild, I also added an old school Hypertech chip. Even when stock, the truck never had impressive power, but it at least got 14-15 mpg. Since the "performance" rebuild the truck picked up very little if any power. That was disappointing, but the main problem is the fuel mileage. I guess the cam change has screwed up the TBI injection because the exhaust pipes have a very black inside coating that makes it look like the motor is running really rich. The truck is also getting about 9 miles per gallon now. The truck is basically a farm/weekend dog riding truck at this point. It doesn't get driven much, but I would like to at least get the mileage back close to what it was when stock. Any suggestions?

I have thought about just removing the TBI injection and replacing it with a small 4 barrel carb. I think I could get a carb setup to run cleaner, make more power and get way better mileage. The problem with that is the engine and transmission computer control. I would have to get a stand alone transmission controller. What else would I need to do to convert to a carb? I know the intake manifold would need to be changed. What could I do for an ignition? Also, does anybody have any experience with a stand alone transmission controller on a basically stock truck?

I'm open to other suggestions for solutions. I've considered just going back to a stock cam, but I'm not sure there isn't something else wrong with the TBI. Are there any performance shops that deal specifically with the factory TBI fuel injection? Can a new chip be burned that would make the truck run right?

Sorry for the long email from a newby, but I would greatly appreciate any help or info. Thanks.
Old 12-05-2012, 08:02 PM
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no ideas?
Old 12-05-2012, 09:20 PM
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Not many TBI users here. You could have a new chip burned but you would need to find some one that specialize in that.

Most people swap to the newer LS platform. Your other option would be to swap to a stand alone fuel injection set up. You could buy a complete kit or piece something together and use a Piggy back system.

Companies like F.A.S.T. offer the Easy EFI and Edelbrock offer's the E Street EFI. These are kits for converting a carbed style vehicle's to fuel injection.

You could also do a 411 PCM swap which would give you the ability to control the transmission as well. Companies like EFIconnection offer kit's for the conversion.

This would give you the availability to tune your own vehicle to suit your needs.

Several companies offer a stand alone trans control unit including GM's Performance Parts division, TCI, JET, PA Racing. I know there is more but I can keep track of them all.

You could also do a Vacum modulator conversion to control the shift points. I believe Trans Go sell's a kit.


The best Advice I could offer would be to look at the overall cost of each option and what you can achieve with each set up.


If it were me I would Do an LS swap. I have seen reasonably priced complete pull outs with wiring range from $1500-$2500.

If your set on keeping the Old 350 in there then I would consider doing the 411 PCM swap or looking into one of the other fuel injection Kit swaps.

Good luck with your decision.
Old 12-05-2012, 11:31 PM
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The air flow of the stock TBI and air cleaner is barely enough for the stock 350. Are you still using both?

Where are you located?
Old 12-05-2012, 11:33 PM
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Originally Posted by 1FastBrick
Not many TBI users here. You could have a new chip burned but you would need to find some one that specialize in that.

Most people swap to the newer LS platform. Your other option would be to swap to a stand alone fuel injection set up. You could buy a complete kit or piece something together and use a Piggy back system.

Companies like F.A.S.T. offer the Easy EFI and Edelbrock offer's the E Street EFI. These are kits for converting a carbed style vehicle's to fuel injection.

You could also do a 411 PCM swap which would give you the ability to control the transmission as well. Companies like EFIconnection offer kit's for the conversion.

This would give you the availability to tune your own vehicle to suit your needs.

Several companies offer a stand alone trans control unit including GM's Performance Parts division, TCI, JET, PA Racing. I know there is more but I can keep track of them all.

You could also do a Vacum modulator conversion to control the shift points. I believe Trans Go sell's a kit.


The best Advice I could offer would be to look at the overall cost of each option and what you can achieve with each set up.


If it were me I would Do an LS swap. I have seen reasonably priced complete pull outs with wiring range from $1500-$2500.

If your set on keeping the Old 350 in there then I would consider doing the 411 PCM swap or looking into one of the other fuel injection Kit swaps.

Good luck with your decision.
411 swap for TBI truck? TPI, LT1, and even vortecs I have seen swapped, but never a TBI. Are you certain about that?
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