Aqualung

Ok, this is the story of my problem starting from the beginning. I am truely stumped so I hope you guys can help me. I have a 1989 5.0 Mustang H/O as tht title suggests. Well, I decided to go a little cheap on the fuel and get 87 octane. Which leads me to my first question.

What is the fuel octane rating of my engine? Does any one know? I dont have the owners manuel and m searches online have deemed fruitless. Would this cause my problems?

Ok, now to continue with my story, The first time I take it on highway afterwards I get a check engine light and lose power bad. So i barely limp it to a gas station and my initial thought is the fuel is the problem. So i refuel it(I was at about half a tank) with 91 octane fuel. It seems to run fine for a little while than i start having the same problems.

I limp it to my destination, and i had to take care of some stuff so I let it sit. when i finish, it is too dark to take a look at it. so I just try to start it to try to (mabey) limp it home. No dice. I try to start it and it turns over than just turns itself right off, no idle, no nothing. so I have to leave it for a few days. ( I am in the military and we where on an excercise so i diddent have time to look at it)

So when i finally get time to look at it I decide to try to start it, it starts right up, however after a few minutes of idle it starts to sound real sick. well, I can't keep it parked where it is i have to drive it home. So i get it home. after i park it at home and turn it off, it refuses to turn on again.

SO the first thing that comes to mind, was the IAC might be bad. so I talk to a mechanic buddy of mine, and he agrees.

so I clean the IAC. Nothing. So I buy a new IAC, nothing. It sometime idles like crap or doesent idle at all.

So I consult the Good ol' internet and i find somthing about the salt and pepper shaker looking connecters in the rear of the engine. so i clean those and ensure good connections, try to start up my car and it starts, idles like crap than eventually shust down. so i try again , It idles fine. I am so happy I Scream YESSSSSSSSSSSSSS and as soon as ifinsh that last S in YES the car dies.

oh and by the way if i press the accelerator, I usually have to pump to keep the engine running. if i keep it steady, it dies.

Soon after, I buy a diognostic code reader and try to figure out what may be wrong. I get 3 codes for KOEO 67, 29, 66.

67 is the neutral drive switch, 29 is inseficcent input from Either the vehicle speed sensor or the spedometer/odometer module. and 66 is Mass airflow sensor fault. so i think AHA! I know the answer.

So I go out and buy a new MAF and install it. still same thing. except for code 66 doesen't come up on my reader anymore.

To Recap:
symptoms: try to start engine and one of 2 things happen
1:engine starts than immeditly dies (unless I pump the throttle) or
2: engine starts, idles very badly than stalls
Corrective actions I have taken
1: change IAC
2: Cleaned contacts on "salt and pepper shaker" plugs
3: changed MAF


Sorry for the long post but that is the full story, if you need me to claryfy somthing for you just ask.

Oh and I NEED HELP!

mongolchuck

How's your fuel pressure? It may be the filter or the pump.

86GreenMachine

Code 67 is from parking it in gear.You may want to look at your Vechile speed sensor.It is located on the tranny.I have heard thatit can cause idle problems.Heres a pic,http://www2.partstrain.com/v5/includ...lyZWN0IEZpdA==

nacanitihs

my speed sensor was broken and it didnt cause idle issues. my speedo just bounced around. replaced it and no more bouncy speedo.

the 67 most likely just cuz you didnt hold the clutch in when testing. and i dont think you needed to buy a new MAF you could have just cleaned it w/ some carb cleaner. but oh well you have a new one now..

check ur fuel pressure. i believe it should be around 40psi. you could have a weak fuel pump.. or try replacing the coil. i had a similar problem once. mine crapped out (still sparked) but not strong enough... but i did have a 31 code (low evp voltage) tho..

and a bad IAC would just make ur car idle high it would still run. so you prob didnt need to replace that either.

toofst4u666

my idle got screwed up when my tps (throttle Position Sensor) went bad check that

Aqualung

OK, I checked the fuel pressure, with engine off and key on it reads 36 PSI. But, when the engine is on and idleing badly I am reading between 30-32 PSI and it is pulsating between the two. now I know thats low but could it be causing my problems? how would I adjust it higher or might it just be a bad regulator?

Oh and by the way it seems to start now, and stay running, but idleing bad for a minute or 2 before it dies. Not much but an improvement. reason for it improving? Not a clue.

Project85low13s

You should aquire a timing light any try to advance your timing a few degrees. When my 85' fox did this problem you are having i did that and it seemed to fix the problem, but however you also should look at getting an MSD Blaster coil for your spark and an MSD distributor cap and rotor set if you dont already have them, it seems to help. Both parts together should run about 50-75 bucks for both and very easy to install, just dont get plug wires backwards if u dont have a boock to tell what the firing order is.

nacanitihs

that unit is junk. mine crapped out after a year