89blk_gt

I have an 89 mustang GT that is pretty much stock 5.0. Its had a problem with a hunting idle for years and I thought I had tried everything...well I got a suggestion from another site suggesting I change the Mass air flow sensor as it may be bad. Anyway long story short I installed a MAC 80mm mass air system thinking I'd try one last thing...after installing it won't hardly idle, runs awful... I thought the computer would just compensate but clearly I was wrong. Any suggestions on next steps? I am out of my league on this one other then putting everything back as it was. Thanks in advance. I've been reading the forum all night and I can't seem to find exactly the same scenario, so maybe I tried something really dumb?

15austin

What will work is on the vacuum tree that the brake booster hooks up to, there is a small spout that is plugged off. take off the plug and is should idle normal. Just something to try.

89blk_gt

Thanks, I'll give it a try but I am not even sure where to look for the vacuum tree, can you briefly describe it?

15austin

Right next to the brake booster. It has about 5 vacuum spouts on it. 1 goes to the brake booster one to the intake, one is plugged off take that plug off.

Boostfiend

Yep it's on the firewall right above the booster.

dudeboy

Time-out!

What are you telling this guy to disconnect?
If you can't NAME the part, then how would you know it should be disconnected?

Something smells fishy here...




Are you getting any diagnostic codes?
Is the MAF meter calibrated for your Injector AND ecu?
What brand is the MAF?
What ecu are you running?
What size injectors are you running?

jason

dudeboy

You are telling the guy to create a vac leak?

Boostfiend

Not tellignhim to disconnect, just telling him where the the line is. lol I thought the first guy might know what he was talking about. Ooops...

silver91gt

is the mass air meter calibrated for the injectors you are using?

89blk_gt

Thanks all...Here is what I know..the 5.0 is stock so I believe it still has the 19lb injectors, the mass air is from MAC Products Straight Shot Mass Air 80mm, they said I just take out the old put in the new and use my old sensor (which led me to believe the computer would compensate). As far as calibration, I didn't know to ask at the time, not what gets calibrated. Not sure what the 'ecu' is but should also be stock. I haven't tried checking the diagnosis codes yet as I don't have a means of checking that yet (I just installed this weekend and don't have the diag equipment - any recommendation if I should invest in the tool and what kind?). Just in case it helps, basically what it included was a new non-restrictive cone filter with air guard (chrome cover so that the air from the fan doesn't mess things up), a straight stainless steel cylinder with mount for the stock sensor and then that hooks right up to the throttle body assembly with a flexible elbow.