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Old 09-24-2007, 01:49 AM   #1
FlatBlackBurb
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crazy engine bogging... 350 TBI

okay so in my 87 chevy suburban with a 5.7 TBI, when im going up a steep hill or basically any hill... the engine boggs reallly bad. it only happens when the engine is at half on the temp gauge. at first there is a considerably loss of power, and i have to put my foot down even harder, and then it makes a ticking sound, almost like the sound of someone tapping on a muffler with a stick. and then the bogging starts. the engine backfires like crazy and almost dies. theres a huge loss of power and accelleration stops all together. the problems i mentioned here seem to be minimized when im crawling at like 5mph... but id rather get to the good part of a trail quicker than that.. its been doing this for a while, im going to get new spark plugs and see if that does anything... my spark plugs are fairly new though.


recent parts:

MAP sensor
ignition module
plug wires
fuel filter
fuel pump
starter
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Old 09-24-2007, 03:08 AM   #2
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Does it throw any codes?
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Old 09-24-2007, 07:02 AM   #3
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Sounds like a fuel problem to me.

My 88 used to do that when the fuel filter would plug up.
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Old 09-24-2007, 07:39 AM
Posted in reply to loafer's post starting "Sounds like a fuel problem to me. ..."
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FlatBlackBurb
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it did throw a code when i changed all of those parts out, only because one of the cables that goes into the MAP sensor wasnt in there all the way. now it doesnt throw any. and i just replaced the fuel filter too! could it be a spark plug problem? im going to get new codes today and see what happens.
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Old 09-24-2007, 12:17 PM   #5
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Is the tranny downshifting??
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Old 09-25-2007, 07:47 PM   #6
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I know this sounds a little crazy buy my K5 that is carbeurated started doing the same thing and it took my a whole year to figure it out. It was my catalytic convertor getting plugged up due to a header deteorating from the inside out. It is very easy for a exhaust shop to check it out.
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Old 09-25-2007, 08:07 PM
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if you can you might want to do a fuel pressure check...although I don't see it failing only when going up a hill...thats usually a carb issue not TBI. sounds like it should be throwin some definate codes.
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Old 09-26-2007, 07:37 AM
Posted in reply to newlyblzed's post starting "if you can you might want to do a fuel..."
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yeah i think im gonna take a look at the cat. i was just gonna cut the thing off anyway maybe that will fix things.
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Old 09-26-2007, 12:09 PM
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If you've got a pressure gauge, you can test the cat converter, tap the gauge in front of the cat, should be less than 5PSI with some throttle IIRC. I think some of the new stuff is 3PSI, but if it's plugged up, it's probably a higher number. Lot easier and responsible than removing a potentially working part. If the pressure isn't high, it isn't hurting performance.

You might also do the same test on your muffler, no reason it couldn't be screwed up, and a waste of time to blame the converter if the muffler is bad. Could be that the converter came apart and is plugging the exhaust up further downstream, etc.

Since it's this consistent, and pops through the TBI, at this point I'm leaning away from something electrical like fuel delivery, etc., although any cause that limits power based on engine load should likely be repeatable even on hard, prolonged acceleration on flat ground.

No difference if the tank is completely full or not? Problem subsides if you let off the gas?
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Old 09-26-2007, 09:50 PM
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no difference at all if i have a full tank or not. it does a little bit of bogging on flat surfaces but its mostly noticably uphill.... i think im just gonna gut the whole thing and weld on the muffler with exhaust dump after the manifolds.
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