Stalling when slowing down to turn

[arbailey]

I have an issue with my '88 speed density coupe. It is heavily modified (cam,heads,intake,etc) and runs awesome but has one issue. Now and then as I slow down to a stop to either pull into my driveway, or make a turn, it will stall. It idles & runs great, but I can't figure out the stalling issue. I want to eventually give the car to my son, but I don't want him killed because the car stalls as he trying to make a turn and he gets hit by oncoming traffic.

The car has the following mods and is still speed density:

Explorer Upper, Explorer Lower (Ported to Fel-Pro 1250), Thumper E7's w/GT-40 valves (Ported to Fel-Pro 1250), Comp Cams XE264HR cam, 65mm TB, 67mm EGR, 19lb injectors, Kirban AFPR, March Power & Amp Pulleys, K&N Filter, etc...

I'm not looking for "convert to mass air", I want to correct the stalling issue as it is the ONLY problem I am having.

 

[HISSIN50]

Is the VSS hooked up and functioning correctly?

 

[jrichker]

See the "Surging Idle Checklist” for help with all your idle/stall problems. Everything you need to find and fix idle problems is in there.

The first two posts contain all the updates to the fixes. At last count there were 24 possible causes and fixes for surging idle/stall problems. I continue to update it as more people post fixes or ask questions.

 

[arbailey]

HISSIN50 - I didn't check yet but from what I understand my car shouldn't have one because it doesn't have cruise control. Would adding one help? Is it even possible to add one?

jrichker - Great list! I'll check everything on it.

Thanks so much guys.

 

[HISSIN50]

HISSIN50 - I didn't check yet but from what I understand my car shouldn't have one because it doesn't have cruise control. Would adding one help? Is it even possible to add one?

You're correct - AFAIK, it should not even have one.
Is the idle set fairly low? Since it sounds like it only happens while turning and slowing, I wonder if the additional load from the PS is causing the stall. The EEC/IAC do not increase the idle to accommodate the load of PS on V8 cars.

 

[arbailey]

I'll have to check it when I go through "the surging idle checklist", but I was thinking that between braking AND turning it's using enough vacuum to stall the motor(?) I even thought about adding one of those vacuum reserve canisters. Any thoughts on that?

 

[HISSIN50]

Does hitting your brakes cause the idle to drop? Any idea what your vacuum signal looks like? Stock is almost 20" at idle.

Turning should not use any vacuum (that I can think of).

Can you do some testing on a safe closed course?

I would brake but not turn. Stall?

Then turn but not brake. Stall?

Then do both (for a control to be sure the car will stall at that time).

Maybe you can narrow down which aspect (braking load/vacuum concerns or PS load, or both in tandem) are causing the issue.

I have not used an aux vac canister.

 

[arbailey]

Looks like I have A LOT of things to check & test.