94 Thunderbird Starts but won't idle.

[Baddog]

I thought there was a section for questions like these for other cars. May have overlooked it. Long day.

Move somewhere else if needed. Sorry for the inconvenience.

Over at a buddys house today and he has had a 94 Thunderbird 4.6L V8 parked in his garage for over a year now. It crapped out on him and started running rough and one day wouldn't start.

So I brought my Scan Gauge II over to see if I could pull any codes. Nothing came up. We put fresh gas in it and turned it over. It starts up when you give it throttle. It will Rev just fine and there is no vibration no shuttering nothing.

When I let off the throttle it just dies. No stalling no trying to keep going. Just dies. Cleaned the MAF and the IACV.

Did some trial and Error. I completely removed the IACV and unplugged the connector to it. There was no change in how the engine acted. While this was happening it threw a code. The MAF came up. So I started to become confused.

Would the MAF going out cause it not to idle? And how come when I unplugged the IACV it didn't change anything?

Or are both of them toast and need to be replaced? Don't want him to throw parts at it if it won't help it.

[green97gt]

first let me say fords are my least worked on manufacturer..so im taking your word it has a maf, etc.

i know on the 93 impreza i have, if you have the maf unplugged, the car will run, but not idle., as long as youve got the throttle plate open a bit, it will run, let it close and she dies real quick...i would unplug the maf and see if anything changes, then maybe find the specs for checking it with a multimeter. could also look for unmetered air, such as a crack in the plastic tubing after the maf.

always test parts to the max before replacing.

[Baddog]

Yeah we did unplug the maf and nothing changed. I left out some info I shouldn't have. I'm extremely tired. No cracks I checked for any vacuum hoses over and over again.

[httrdd]

What about a fuel filter? Maybe the maf code is coming up, but it seems that you need to force fuel into the engine and it cannot fuel inject itself on idle. I know that the maf code is coming up, but you already said that when you unplugged it it did not change.

[Huffer]

Is there anything to trigger throttle position or how that works in relation to the IACV?
Quite possible that the engine would die if the MAF is bad/going bad, it would be sending all kinds of odd signals to the engine and thus the IACV. Is the IACV even actuating at 0 throttle?

[Baddog]

When I had the IACV off the intake manifold but still plugged into the connector the IACV didn't do anything. So that's why I got confused when the MAF showed up.

[Huffer]

The IACV is supposed to open a little, allowing the car to idle - without it, and the throttle plate being closed, the engine is going to starve of air and will stall out.

[Baddog]

Yeah so since it's an $80 part we may start there and then work towards the MAF

[Huffer]

You could try holding your thumb over the hole where the IACV bolts in, start the car and as you release the throttle, allow your thumb to permit air in via the IACV hole, see if the car picks up the idle from that.