Idle problems/stalling

[djj624]

Here's what's going on. 87T with minor mods. Whenever I'm driving and come to a stop weather it's in stop and go traffic or stoplight/stop sign the car starts to idle very low and usually stalls. scanmaster shows it dips down to 550 rpm and fluctuates back to 650 then 600 then 575. Once I'm stopped for for a couple seconds if it doesnt stall it idles up at 600 to 650 still fluctuating but stays running, a little rough but stays. When I'm driving it's obviously fine and also when it's in park the idle is better around 650 to 700 then goes up to 750 and back down to 650 just fluctuating still but idles much better compared to a driving stop. Any ideas?

Galaxy S7 Edge

 

[Chuck Leeper]

Standard ? coming: Do you have data logs, Scanmaster readings, details of what's been done to the car?

 

[djj624]

The cars mods are, 3in dp w exhaust system, external wastegate, 255 walbro fuel pump, hot wire kit, k&n filter, scanmaster, audible knock detector, boost and temp gauges, standard mods nothing radical. Didn't check all the readings on the scanmaster except for idle during cruising and parked and tps wich is at .42.
Since iv had the car for about 2yrs now iv done the scanmaster audible knock detector, replaced the old external wastegate and installed the fuel pump. Besides the obvious spring cleaning.
Galaxy S7 Edge

 

[GNRick]

Remove the iac valve and spray it with carb cleaner. Then remove the up pipe and spray out the throttle body. Wipe it clean with a rag. IAC should be in the 20-30 range. Also make sure you don't have vacuum leaks. Blm should be 128 +/-10.

 

[djj624]

Will do. Thanks

Galaxy S7 Edge

 

[earlbrown]

What does your IAC reading say while all this is going on?

 

[djj624]

Ok so iac was at 57. Readjusted iac to 16 and tps to .42 . Rpm now is at 700 to 750 at idle. Doesn't seem to be stalling or dropping idle at stops much anymore. Thing that's weird is the iac drops from 16 down to to 7 slowly at idle in park. Is this normal or should it be a steady 16/17?

Galaxy S7 Edge

 

[djj624]

Here is a quick video of the scanmaster values, car warmed up and in park. Again you will notice the iac is low but when the car is restarted is back up to 17 just slowly declined down to 5 then back up to ten or so.

Galaxy S7 Edge

 

[djj624]

Anyone?

Galaxy S7 Edge

 

[GNRick]

Blm of 150=vacuum leak

 

[djj624]

I'll start the search. Thanks. What should blm be at?

Galaxy S7 Edge

 

[69RSCLONE]

128

Sent from my SM-G935V using Tapatalk

 

[69RSCLONE]

Higher than 128 equals lean, computer adding additional fuel. Vacuum leak, exhaust leak, o2 sensor.

Sent from my SM-G935V using Tapatalk

 

[GNRick]

Lots of good info http://www.vortexbuicks-etc.com/

 

[Frederickdav]

Does it still have the original chip? I tried all kinds of "fixes" on my 87 T to no avail. Then someone on this board suggested a new chip. That made my car run like brand new!

 

[djj624]

Thanks Rick that's actually the site I used to fix the iac and tps. It is s great help. Frederick it is the stock chip (plan on getting a tt) but a chip unfortunately will not fix my vacuum leak issue. Once I solve that then I'll get the chip. I know how much better the car will respond with it.

Galaxy S7 Edge

 

[earlbrown]

Oh god, get rid of that chip YESTERDAY. It's burned for gasoline that we just don't have anymore.

If the chip is original, I'm guessing the injectors are too?

If so, time for a package deal on a new chip and a set of 60's. You'll think you have a different car.

 

[djj624]

Pretty sure I found the leak. This black step down T was cracked at the one end. Anyone know if I need this specific part or if I can use s regular T. Looks like it feeds one of the hard line vac lines going to the dog house, then another top the boost Guage them another going towards the air filter with a check valve on it.

Galaxy S7 Edge

 

[GNRick]

That's not a factory T so any T should work. Best way to find leaks is with a smoke machine. You can make your own. Just Google it. You might also want to zip tie the hoses so they don't blow off under boost.

 

[djj624]

Found a couple issues. Fixed that one. Then rotted rubber lines at the hard lines on the dog house. Also map sensor vacuum line rubber shot as well as vac line not even plugged into the map sensor. Although after fixing these issues blm only dropped to 146. Still an issue somewhere.

Galaxy S7 Edge