She runs rough.

[GM 4 Life]

I posted this in the 87 forum, but was suggested to try here. My 87 has a rebuilt bone stock older "orange motor" 305 in it w/ the complete 87 tbi setup on it installed by the p o .It also has stock rebuilt 700r4 & 2:73 gear. The motor has less than 1,000 mi. on it, but has set for a couple of years. It has the following NEW parts installed by me: Oil /filter change, seafoam in the tank, complete tune up, egr valve, coolant temp sensor, rebuilt the tbi, replaced all vac. lines, t-stat,both fuel pumps, rubber fuel lines & fuel filter, new exhaust from manifolds to bumper. I also verified the correct timing.When cold it fires right up, but then starts idling down roughly & stalls if I dont keep feathering the throttle @ 1,800 RPM'S or so for like 5 min. It also runs rough while taking off from a stop & driving untill it's completely warmed up. When it does die it always fires right back up though. Once warm it smoothes out somewhat & has good power/pick up w/ no stalling, but its nowhere near perfect.The outside temp. seems to have some factor on this issue as it's really bad @ start up when it's 30 deg. or less. The fuel injectors werent replaced on the tbi nor the iac & they have 255,000 mi. on them. Could that be whats causing this or could it be one of the emission sensors? I am @ a loss here & dont want to start needlessly parts swapping on a whim. Thanks in advance.

[ChevyTech]

Did you unplug the set timing connector when you set the timing?

Did you check to see if it is setting any trouble codes?

You could try disconnecting and plugging the vacuum hose to the EGR valve and see if it make a difference.

[GM 4 Life]

RE: Did you unplug the set timing connector when you set the timing?

Did you check to see if it is setting any trouble codes?

You could try disconnecting and plugging the vacuum hose to the EGR valve and see if it make a difference.
I didnt know there was a timing connector. There wasnt any mention of it in my Chiltons when looking for the correct timing specs. Could you eloborate on this please. There are no trouble codes. The EGR valve was stuck so I replaced it, but will try plugging that vac. line.later today. Thanks in advance.

[ChevyTech]

Unplug the set timing wire, set the timing to zero using a timing light (strobe), re-connect the set timing wire, and then clear the trouble code.

To set the timing you must unplug the set timing connector, which is a single Tan wire with a black stripe/tracer on it. On some years (I think 1987) the set timing wire is tan with a white stripe/tracer. Doing this will cause the check engine light to come on and will set a trouble code in the computer.

On 1987s & square body Suburbans and full size blazers, the connector is by the brake booster.

Doing this will set a code 42 in the computer. Clear the code after you are done checking or setting the timing.

For the Small block TBI trucks, the timing specification is Zero degrees BTDC.

I think this may be the problem. If you did not do this the timing will be set around 20 degrees late / retarded.

[GM 4 Life]

Thank you ChevyTech for the heads up. I finally located the timing wire, it was electrical taped to the back side of the loom on the driver side of the master cyl,then behind the splash pan looking deal behind the master cyl. After setting the timing with a new light to the the specified 0 deg It ran some better, but not much, so I tried several different settings & finally found that @ 4 deg. she really smoothed out on the idle, good throttle response & power, no bogging, spark knock etc. I then cleared the 42 code. I just ordered my posi unit, 4:11's, seals & install kit. I'm fired up to get that done so I can move my money towards the build of my 454 i bought last week. But that wont be done anytime soon, so the reliable driveability of the 305 is important right now. She now lugs along smooth in traffic @ 45 mph with the 2:73's, LOL. Thanks again man.

[ChevyTech]

You’re welcome, and thank you for the feedback.