SOLVED:Truck boggs down when accelerating

1987r20_454

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I have a 1987 chevy suburban r20 454 with tbi. It would bog down when give it more than a quarter throttle. I thought it was because of an exhaust leak so I tried to repair it but broke stud. Because of that I put headers on it. When installing I found out the firing order was backwards. Fixed the timeing and drove around but still bogs down when accelerating but worst. I changed the map sensor thinking that might be too but still nothing. There is no check engine light and idles ok. Im just having trouble figuring out what could causing this and hoping you guys can help point me in the right direction

So update, I fixed the timing, so its running a lot better. It still feels like its restricted when giving gas so im gonna change the fuel filter, test the fuel pressures, and scan it for memory codes. It pops a check engine light when going 35 to 45mph now
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Last update. So I changed the fuel filter and learned it was clogged up. Now when I hit the gas pedal it takes off fine. It started having a miss fire now but I believe it could be the old plug wires that I haven't changed out but I can figure that out on my own. I really appreciate the advice you guys gave me. This truck has definitely been a good learning experience for old vehicles. Especially the tbi.
 
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Redfish

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I don't understand how it even ran with "the firing order backwards". I also don't see how an exhaust leak would cause the issue you describe.

My '87 TBI 350 required a new distributor, new Ignition Control Module, and new plug wires to get rid of a full throttle weakness. Truth be told, it was probably more about the plug wires but the distributor did make a difference.
 

SirRobyn0

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Pretty much two more ideas from me.

Lack of fuel pressure.

To much exhaust backpressure.

So step one, replace the fuel filter. Step two check the fuel pressure with a pressure tester, if you don't have one borrow one or buy a cheapy from Harbor Freight. Step three temporarily remove the oxygen sensor or pop the flanges loose at the manifold. Doesn't really matter, what your trying to do is create a massive exhaust leak before the catalytic converter. Take it out on the road, it should be extremely loud but if the power is back and bogging is gone then you need to replace the catalytic converter.
 

Ken B

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I once had a very old cat. That the Insides would shift and plug the outlet of the cat.
 

1987r20_454

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So when I bought the truck I already replace the fuel pump, fuel filter, both injectors, rebuild the throttle body. It also had the smog deleted and the cats removed. The previous owner also did duel exhaust. The only thing the exhaust have are mufflers. I did remove the old distributor and installed a new one. I was told I might be a tooth off so Im gonna mess with that and see if it helps
 

Matt69olds

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Does the check engine light come on with the ignition on, engine not running? If not, you may find someone removed the bulb. You may have codes stored you don’t know about.

Start with the basics. Check compression, lack of power or lack of compression could be timing chain. Put a fuel pressure gauge on it, make sure you have sufficient fuel pressure while driving. Check the ignition timing, there is a connector you need to unplug to put the computer in base timing mode. Read the instructions on the tune up label under the hood.
 

SirRobyn0

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So when I bought the truck I already replace the fuel pump, fuel filter, both injectors, rebuild the throttle body. It also had the smog deleted and the cats removed. The previous owner also did duel exhaust. The only thing the exhaust have are mufflers. I did remove the old distributor and installed a new one. I was told I might be a tooth off so Im gonna mess with that and see if it helps
Just remember just because it was replaced doesn't mean it can't be bad. Especially true of remain parts, and even at that there are plenty of low cost new fuel pumps that are junk. If the tank is not in great share (such as rusty) the fuel filter maybe plugged. I'm not saying that's the issue, I'm just saying keep that in mind as you go about diagnosing it, any thing for that matter, recently replaced does not always mean good even though it should.
 

JRichason

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Does the check engine light come on with the ignition on, engine not running? If not, you may find someone removed the bulb. You may have codes stored you don’t know about.

Start with the basics. Check compression, lack of power or lack of compression could be timing chain. Put a fuel pressure gauge on it, make sure you have sufficient fuel pressure while driving. Check the ignition timing, there is a connector you need to unplug to put the computer in base timing mode. Read the instructions on the tune up label under the hood.
I agree. Especially with the comment about the firing order being backwards. I would start with pulling the plugs out, inspecting them, and doing a compression test. I also wonder about what "bog down" means. I think that could mean different things to different people. Is it a sound, does RPM drop, is the engine misfiring, etc?
 

bucket

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So since it's now headers and duals, does the truck still have an oxygen sensor?

"A tooth off" doesn't exist on an engine where you can rotate the distributor wherever you want. What is your base timing set at? Did you disconnect the tan/black weatherpack connector when you were setting the timing?
 

sdewolfe

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Did you determine why the fuel filter was plugged? Have you checked the fuel tank(s)? Very fine rust particles will plug a filter in just a few miles.
 

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