Got a new/old car tonight, need a little help

[Seanmay1]

got me a 86 GT tonight, 302 .30 over, has a mild cam, 24lb injectors (supposedly, they are blue) 373 posi 8.8, new T5 and king cobra clutch, converted to Mass Air, 65mm throttle body, cold air intake, ok biggest issue to me, the car wont idle right, it goes up and down and wants to cut off, my cousin also told me when he hit the brakes coming off the expressway it cut off, what all could cause this and how hard is it to fix ( i know nothing about fuel injected cars) if i cant fix it im just going to take all the fuel injection and stuff and sell it and throw a intake and carb on it. But i would like to keep it fuel injected. Next problem, heater hoses aren't ran to the heater core gonna hook em up and see why but if its bad how do i change that in these cars

 

[Seanmay1]

Also i want to change the brake booster i hear a little air when i hit the brakes and they aren't as good as i would like so i think thats the problem on that

 

[bloopbloob]

i'm guessing you have a vacuum leak and a bad heater core. heater core swap is apparently quite a PITA, which is probably why it's just plugged, as an easy fix.

 

[Seanmay1]

Well i will check for vacuum leaks in the morning, thats what i was thinking but my uncle said a vacuum leak wouldn't make it do that, but i wasn't sure, another question could i put the F cam in the car without doing any computer work?

 

[Arcane4565]

86 GT

..remove the idle air control motor.It's on the throttle body.Clean it well with carb cleaner,and check to see if the gasket is bad.This happened to me before.The 86 has a choppier idle than the 87 and up.(Stock cam was stronger,faster in 86 but was unpopular because of the idle).,But I guess your isn't stock.Also,check your plug wires,and plugs...Good luck,Jason

 

[ttop88]

Check this out. It has the answer to the idle. Nobody can tell you witch one or how many of these problams your car has tho. It is cheap to fix,But very time consuming.
http://forums.stangnet.com/showthread.php?t=698148&highlight=idle+checklist

 

[Seanmay1]

Alright im going through that list now, thats a lot of stuff lol, oh and when u give it gas the car is fine just wont idle worth a ****, my cousin told me its fast as hell though

 

[NKau]

To replace the heater core, you pretty much have to pull out the entire dash/speedo, which is easy, but just takes a lot of time with all of the little fasteners.

The idle I would suspect is probably a vacuum leak, but it could be a lot of things; go through the checklist and see what you find. I would check all of the easy stuff though; these motors are prone to leaking around the pcv valve. I'd start there, and check all of the other easy vacuum stuff.

I doubt your brake booster is giving you the braking problem. Fox brakes aren't the greatest to begin with, so if you have worn pads/rotors they just get worse.

 

[Mustang5L5]

Vacuum leak


Get a can of carb cleaner and start spraying around. If your idle goes up, you've found your leak

 

[Seanmay1]

if it was a vacuum leak it would run like **** wouldn't it? it runs great just wont idle it goes up and down to about 1k rpms and sometimes cuts off, other times it idles fine figured that out driving it today, car has a lottttt of power

 

[ttop88]

Trust us. You have a vac. leak or twenty. We all start with someone else's neglected car.

 

[Mustang5L5]

if it was a vacuum leak it would run like **** wouldn't it? it runs great just wont idle it goes up and down to about 1k rpms and sometimes cuts off, other times it idles fine figured that out driving it today, car has a lottttt of power

That's a surging idle.


Common cause is vacuum leak.

 

[bloopbloob]

Trust us. You have a vac. leak or twenty. We all start with someone else's neglected car.

+1!!! we're all on here to help one another with the same cars, and problems, and questions. we all aren't on here for the fun of giving someone bad advice. most people have been here a long time, and know common problems and how to fix them. it may not be the cause, but it most likely is. start there....

 

[methemike1]

Wouldn't a bad MAP sensor make it have an erratic idle?

 

[lang williams]

Do the 86's have the 87+ interior? the heater core in the older interior is a lot easier to access than the 87+ cars.

 

[Mustang5L5]

One other thing.


Dump the codes

Since it's a mass air conversion, the person probably didn't go the extra step to give it a functional check engine light. The 1986 SD mustang does not have this at all.

You could have codes and not even know it.

Run them and see what it tells you

 

[Seanmay1]

It rained all day today so i really didn't get to check anything, just drove it some, hopefully tomorrow weather will be good and i can really check things out, how do i check the codes? Another thing, i can hear a noise sounds like a grinding or scratching not real loud but noticable, at first i thought it was the transmission but it still does it when im sitting still so i think its the clutch, my uncle said it might be the throw out bearing, but the car is spose to have a new king cobra clutch in it

 

[Arcane4565]

..king cobra clutches sometimes scrape the T-5 bellhousing.......