Vortec Reliability after MPFI conversion and intake gaskets

[mistaake]

some pistol slap on cooler days right on startup......keeping my fingers crossed.

Maybe stop slapping the engine with a pistol if the banging noise is bothering you...

 

[ernjohn]

I'll add this: I bought my truck at 175k, a few hundred miles later I found the intake gaskets let go and it was knocking like there was a midget with a jackhammer in the engine. the oil looked like butterscotch pudding. the truck is now at 206k and oil pressure is good (55-60 psi cold and 35-40 warm @1k rpm) and still has good compression. I have put in the mpfi injectors (bosch). I did have a V2500 suburban many years ago and it seems things like fuel/brake lines/fuel pump/fuel filter are more the problem to reliability than the engine - except for bad electrical grounds which can affect any chevy regardless of year/model.

 

[Jrgunn5150]

My Yukon went 297, and drove just fine to the trade in on my Trailblazer. I put intake gaskets on at like 190, MPFI at 270

 

[superdave]

Mine has 177k with the poppets and no intake issues as yet. It's running fine, but I'm probably going to do both of these in the spring as preventive maintenance as well as a new distributor. I know there is no real advantage to replacing the poppets if they are functioning well, but after that kind of mileage, it's probably a good "while your at it" since I'll be digging into the intake. These are items I don't mind putting on since I can transfer them to a new motor eventually if and when this one croaks.

I have had a slight, external intake manifold coolant leak that was temporarily solved with GM coolant tablets. I know it's voodoo, but it has held for quite a while. I replaced all the hoses about 18 months ago and flushed everything prior to that. I do have the cold crank up knock (that GM installed) for a bit, but that is the only issue.

 

[carzan]

I have both and have cursed them both.

My 1990 5.7 with TBI I've had to do intake gaskets, injectors and distributor.

My 1999 5.7 vortec had the intake gaskets changed with 100,000KM less. Quit because the Crank position sensor failed. And simply would not start in extreme cold ...did the MPFI upgrade now it starts if it'll crank over. Block heater helps with the extreme cold starts.

What i'd really like is an LSx under the hood ...but I suspect they have some quirk as well.

 

[Ironhead]

Newby here, and I'd sure like someone to translate MPFI and SCPI.

 

[Jrgunn5150]

Newby here, and I'd sure like someone to translate MPFI and SCPI.

Multi Port Fuel Injection, I'm not sure exactly what SCPI stands for, but it refers to the "spider" style that Vortec's originally have.

In the Vortec, there are 8 injectors up in the throttle body, they fire, and fuel travels down a tube, that ends at the intake valve. There a poppet is actuated, and fuel sprays into the chamber.

Over time these lines Crack, leak, get up to all sorts of mischief because of the relatively high pressures they see.

An upgrade is the Delphi MPFI, I think it was for boats originally, but I know there was a class action lawsuit, and all California trucks got this upgrade. It relocates the injectors down by the valves where they belong, and is more durable.

It may run cleaner, or make more power, but I can't say since mine was all cracked and leaking and sacking tons of raw fuel anyway, so I didn't get to make an apples to apples comparison.

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[grampadirt]

MPFI Multi Port Fuel Injection (an upgrade to OEM)

CSFI Central Sequential Fuel Injection (OEM)

 

[Jrgunn5150]

I have both and have cursed them both.

My 1990 5.7 with TBI I've had to do intake gaskets, injectors and distributor.

My 1999 5.7 vortec had the intake gaskets changed with 100,000KM less. Quit because the Crank position sensor failed. And simply would not start in extreme cold ...did the MPFI upgrade now it starts if it'll crank over. Block heater helps with the extreme cold starts.

What i'd really like is an LSx under the hood ...but I suspect they have some quirk as well.

My LS quirk was the displacement on demand making it chug oil at a ridiculous rate lol.

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[thz71]

My LS quirk was the displacement on demand making it chug oil at a ridiculous rate lol.

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Huh? Most don't and those that do its easily deleted.