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73-87 Chevy _ GMC Trucks => Suburbans => Topic started by: 87burb4x4 on October 20, 2014, 02:58:44 pm

Title: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 20, 2014, 02:58:44 pm: I have an '87 Scottsdale Suburban w/a 350 tbi... it's running very sluggish and weak. Everything I do to it makes it better but doesn't fix it. I have changed plugs, wires, cap, rotor, fuel filter (twice, clean on second change), rebuilt the tbi, and gutted the catalytic converter and had new exhaust put on it. The TPS was new when I bought it, but haven't changed that. The previous owner had a crate engine put in about 20k miles ago, along with a rebuilt 700R tranny, and went through the front and rear ends, which are .373 gears. I'm running 33 inch tires, so there should be no problem there. Trucks cranks, idles, and revs smoothly and sounds awesome. Once I get it out on the road, it's like I have something trying to pull me backwards and the exhaust sounds horrible. It doesn't pop, and has never smoked. Even after sitting for months this truck doesn't have the infamous Chevy valve seat leak. So I don't think there is anything wrong internally. Next on the list is to check fuel pressure. If that's not it, what else could it be? Oh, and I also OHMed the coil, and it checks out fine.
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 20, 2014, 03:15:51 pm: Also attempted to check timing, but could not find the wire you're supposed to unplug beforehand for the automatic timing adjustment. When checking time without unplugging that, where would the timing be on the tab?
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: VileZambonie on October 20, 2014, 09:38:50 pm: when you put the EST in bypass the timing spec is zero. There are several posts here on the subject. Have you scanned it? Any DTC's? Can you give us the values on your PID's at operating temp?
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 20, 2014, 09:58:19 pm: Have not scanned it yet, plan to do so ASAP. And quite frankly I have no idea what PID or EST is lol
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 22, 2014, 11:41:52 am: Checked codes and got a 32 which from what I have found is an EGR circuit fault
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: VileZambonie on October 22, 2014, 07:42:37 pm: Pull the vacuum hose off of the EGR valve with the engine running an see if vacuum is present at the hose.
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 24, 2014, 12:20:35 am: Got her fixed guys. EGR ports were NASTY. EGR Valve was toast. Put new one on, helped but still not there (again) and then checked time and it was way off. Got her dialed in and she's purring. Thanks to all that helped!
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: VileZambonie on October 25, 2014, 06:47:28 am: OK but what is your response to this:

Quote from: VileZambonie on October 22, 2014, 07:42:37 pm
Pull the vacuum hose off of the EGR valve with the engine running an see if vacuum is present at the hose.

Is there vacuum present?
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 25, 2014, 12:02:31 pm: I do not have a guage, but I cannot feel any vacuum. Will air pull from the EGR itself?
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: 87burb4x4 on October 25, 2014, 01:33:00 pm: After posting this, a check engine popped up. Came back another code 32. EGR circuit fault....
Title: Re: Got a sluggish 350 tbi that no one can seem to figure out
Post by: VileZambonie on October 26, 2014, 10:34:58 am: The EGR solenoid is most likely your issue. It is probably sticking open which causes the valve to hang open.