DrZOOM

Hi guys. I just got a 1989 Mustang GT Cobra. My buddy abbandoned it so I picked it up for $500.00. Its got 127,000kms. Shes solid but dirty and neglected.
Today I changed the oil so I could drive it. Friggin tar came out of it and I dont drive cars with oil like that in them. I put Mobil 1 synthetic in it. Changed the plugs too.

I just want to ask you guys if these are symptoms of something that typically goes wrongon these cars.

The engine wont idle when its cold. Its very lumpy and rough. The RPM surges up and down. When it goes down. It shuts off unless I hold the gas pedeluntil itwarms up. While holding the gas to warm it up,it stays running but its very rough and still surges up and downabout 100-200RPM.

When its warm. It idles very low and weak. It still surges but alot less. Evey 10-20 seconds when warm. It will almostshuts off but usually doesnt.It surges up higher then idle and comes back down to idling roughish.

When its hot. It stillsurges but only 1 or 2 times every 2 minutes. Idle is rough.Feels like its rich but no black smoke.Hitting the throttle now hot, it will burbble a bitas she climbs in RPM. It almost feels like its missing whilereving up. She climbs fast but it feels rough and burbely.

I drove it HARD today. **** does it go! But,.............Its not a smooth trip up the RPM`s. The engine seems like its missing. Even out the exhaust you can hear it gurgling and missing as she climbs up the RPMS. I dont know if its related to my idle problem because the timming is definatly off too.
Iheard pinging on my drive so I immediatly came back home. Tomorrow I will do the timming.

I dont have a repair manual yet so I cant go specing thesensors to see if they are all ok just yet. Is there any online manuals for the 5 O`s with specs andECU codes?

Just wanted to ask in case these symptoms sound like a common issue on these cars that I should look at first.

Tomorrow I will make sure timming and all the other basics are good before going nuts on it.Timming alone cantmake it run this bad. Or can it?

Thanks.

5.0 lou

no such thing as an 89 cobra

5.0 lou

i say timing

93 LX FiveO

first of all.. do a FULL tune up

plugs, wires, cap, rotor, fuel filter, air filter

set the timing at 10* and go up from there if the engine smooths out

clean the maf and iac sensors. ill attach a pic of locations.

some people will say run codes before u do anything but these are things any mustang owner should do at one point and time anyway...

[IMG]local://upfiles/46009/02FDA58EF3C1416B9771DEDA7ADC0BF3.gif[/IMG]

mattdel

thanks for using my pic

yah, definately do a full tuneup. i also suggest that you get rid of that synthetic oil.
while alot of stores and counter guys will tell you that its best, when it comes to an old engine, synthetic oil can actually cause problems.

secondly, while you are checking the timing, be sure the harmonic balancer is good. if the timing marks are jumping around wildly, you more than likely have a bad balancer and/or timing chain issues.

also, i HIGHLY recommend you run a bottle or two of Seafoam through it over the next couple of weeks. It will help greatly, and it will eliminate a few driveability concerns.

The idle issues you are experiencing are probably caused by carbon deposits inside your intake. The seafoam will take care of most of it, but just to be sure, pick yourself up a spray can of MAF cleaner and go to town on the MAF.
There are 2 wires inside the MAF sensor. If either one of them is even remotely close to looking black in color, its dirty.

DrZOOM

Ooops. Sorry. I was told it was called a Cobra.

-Fuel filter, Air filter, and plugs are allready done. Wires are recent (1 year old and almost no miles).

Friday I will get the full tune up done. I agree with the back to basics. IAC. Can I take it off to clean it? Does the gasket survive most times or should I get a spare before taking it off?

WOW. That was fast responce time. Thanks guys. Keep it comming.

DrZOOM

What is Seafoam?

mattdel

The IAC can be cleaned, yes, but most of the time it will need to be replaced eventually.
Do yourself a favor and grab a gasket, just incase.

Seafoam is a product available at your local autozone, www.seafoamsales.com
You run it through a vacuum line, and it cleans out your intake and valves.

There is a specific procedure to follow when using it, for it to be most effective. Ask me when you get it, and I will explain it to you.

tplwhitegt

Did you drive the car at all before you changed the plugs? The firing order is 1.3.7.2.6.5.4.8 if memory serves me correct. Check to make sure no wires got pluged onto the wrong cylinder. I also agree about the full tune and timing check. If all is well with the firing order and the tuneup is complete and there is still a problem check for a vacuum leak, on a car this old it is a very high probability. A vacuum leak will create just about all of the things you are discribing. There is also an idle air control adjuster that can be purchased from several companiesthat fits between your throttle body and the I>A>C> valve itself that you can adjust the amount of air that is bypassed around the throttle plate. These things have worked wonders on lots ofMustangs I have had problems with. Oh also do not forget about the S.P.O.U.T plug located near the diststributor.

92hatchLX

Yes there is such thing as a GT Cobra. It's theCanadian version of the GT, I don't think that the LX 5.0 got the cobra sticker on the back. Anyways, it's got the same 5.0 HO motor just like the rest of us (besides those of you that have the 93-95 cobras).