88horserider

I have a 88 mustang gt with trickflow upper & lower intakes w/spacer, 70mm tb, 19# inj....im having a problem with it running very rich (eyes & throat burning rich) and hesitation during acceleration, popping out the exhaust occasionally. I have pulled the plugs and only found the 2nd one from the left front mildly wet with fuel but i wouldn't consider it bad, all the others looked very good. It also has a whistle at idle that goes away with the crack of the throttle. If i drive it around town the hesitation and exhaust pops seems the worst, long distance on the open highway it seems to clear up for a little bit but the problems seem to return soon... I think it may be a vaccum leak somewhere but have had no luck finding one atleast not out easily accessible. Im just curious if this is a common problem or maybe definately symptoms of the suspected vacuum leak. Any advise on how to attack this problem?

dawson1112

Have you pulled any codes?
http://www.dfwmustangs.net/forums/showthread.php?t=7908

I would think if its running that rich you would have set a dtc in the computer.

Could be a dirty or faulty maf. I would think that the 02s would pick up the rich condition and cut fuel back, but not necessarily.
Possibly a faulty ect.

That whistling is pretty typical of a cai if you have one.

Classic73Garage

If you know you have a vacuum leak and you are running rich I would check the vac line off the fuel pressure regulator. A broken line will cause it to run open. I would also check the ones under the manifold

88horserider

thanks for your post, that really helped get me started. here is what i found:

I Have pulled several codes out of it: I got 31,81,82,95 from koeo...... i kept getting 95 from continuous monitor, & 21, 31, 91 from koer. 21 was ect sensor so i replaced that this morning and code went away. it still has a bad fuel smoke out the exhaust and slight engine flutter which is intermittant by the way. i see that 31 is egr related but it has no egr on it with a block off plate, the main one that confuses me is 91: 02 sensor indicates lean-driver side. How can that be so when its running rich as hell, with a smoke cloud behind it when i snap the gas. Im also not sure about the secondary air codes: 81, 82 is that the smog pump because it does not have that any more either?

to add to it, the cylinder balance test indicated cyl# 6 failed the test.

88horserider

dont laugh but im not mustang savvy yet so can you tell me what the "cai" is?



I would think if its running that rich you would have set a dtc in the computer.

Could be a dirty or faulty maf. I would think that the 02s would pick up the rich condition and cut fuel back, but not necessarily.
Possibly a faulty ect.

That whistling is pretty typical of a cai if you have one.[/QUOTE]

dawson1112

cai is a cold air intake. If it has an after market one on it they tend to whistle.

Classic73Garage

If it is throwing a lean code the computer will try to compensate for the "lack" of fuel therefore making it run rich. It is tricking itself into thinking there is a fuel problem

dawson1112

when was the plugs , wires cap and rotor replaced last?

It seems that a fowled plug would cause the balance test to fail and create a lot of black smoke due to un burnt fuel entering the exhaust. Un burnt fuel means a lot of extra un burnt o2 in the exhaust on the side that is fowled . Computer sees this as a lean mix adds more fuel to it causing even more un burnt fuel.

I may be wrong I'm not as savvy about the ecm's fuel strategy as some of the other guys on here. But it makes sense to me lol .

88horserider

i just bought the car last weekend, and all that (plugs & wires) was supposedly just recently changed. I pulled the plugs to inspect them and they all looked good except 1 which was the 2nd one from the left front, it was a little wet but i have seen a lot worse..... To my knowledge, that cylinder is not number 6 it would be more like 2 or 3. (cant remember which side #1 is right off hand)
As i drive it, it will clear up for a little but goes right back to doing it again. so i suspected the ignition coil. Well i changed that today and it seems to be a little worse lol.

This car is fresh off a rebuild by 8000 miles so im told, would a stuck valve or valve set too tight cause this problem anybody????

dawson1112

get a compression test done . check that #6 injector to see if its working . You can usually hear the injector clicking by using a long screw driver and holding the blade on the top of it and putting the handle you your ear.

Failing the power balance test says its either lack of compression on that cylinder , a dead miss from fowled plug or not enough fuel to ignite properly .