Ron V

I can't tell if this is a bad ISV, or a vacuum leak. The car starts fine, and drives fine if I'm easy on the starts at a stop light. But if I stand on it at a stop light or when I get off the freeway it wants to stall at the next stop. Sometimes after it has stalled it will start with no problem and be ok if I'm easy on it. Other times I have to keep my foot on the gas to keep it from stalling. I'm going to be doing an intake refurb shortly so most of the culprits will be replaced.

the flyin' scotsman

You could try the WD40 trick down the vac line as temporary fix; when was the MAF rebuilt/replaced?

Ron V

I've tryed the WD40 thing dose not seem to help. I haven't messed with the MAF

Mrmerlin

when was the last fuel filter change? have you checked the dampers and FPR? for leaks either fuel or to hold vacuum? Are you installing new injectors ? The new 4 hole type from the ford Mustang

Ron V

Hey Stan, I have not replaced the fuel filter since I bought the car 3 years ago, and who knows when it was befor that. I'll start there. Have not checked for fuel leaks, but I don't smell any fuel. Was not planning on replacing the injectors. Is there an advantage to the Ford injectors you mentioned

the flyin' scotsman

you mentioned R&R the intake soon so that perhaps why mrM mentioned new injectors as it makes sense to replace or have the OEMs refurbished.

have you tried unplugging the MAF and observing the changes?

ZEUS+

Do you have fast idle when cold and idle flare up at start ? Have you checked ithe idle circuit of the tps ?

Mrmerlin

you can buy the newer 4 hole injectors off of Ebay for about 220.00 (You will be looking for the 19 # injectors) you will need to exchange the lower O rings for the correct size as the FMCo O rings are a bit smaller in diameter.
If your looking for leaks in the dampers this requires you to remove the vacuum line and see if fuel is dripping out OR pull a vacuum on them and see if they hold vacuum.
I would start with a fuel filter first.
on your intake dont forget to replace, both knock sensors, the TPS, the flappy vacuum pot, the hall sensor and the crank position sensor

dr bob

Most fuel-filter problems show up under load and not at idle conditions.

ISV comes into play when the idle switch is made with the throttle closed. Do a little ohm meter sleuthing at the LH brain connector to confirm that your open and closed throttle switches are working correctly. This is a relatively quick, relatively non-invasive, won't even get your hands dirty kind of check.

Ron V

Dr Bob, is there a write up on how to do this?

ibkevin

Humm.. I see an intake R&R in your future.. Tahoe will be here before you know it.

dr bob

Ron, I'm not instantly aware of one. Let me spend a little time with the WSM diagrams later today and see if I can get one going for you.

John Speake

Have you tried checking that you can hear the closed throttle switch click when you manually operate the throttle quadrant on the side of the inlet plenum ?

You should hear a quiet click as soon as the throttle starts to open just a few degrees, and then it should click again as you release the quadrant/cable. A sltcking or badly adjusted throttle cable can give the symptoms you describe.

the flyin' scotsman

to test at the LH plug:

the flyin' scotsman

once you get the intake off: