Sick '94 GT

[343wc]

Hi all, I'm new here and need help! I'm an old guy (66) and my wife's 94 GT is giving me fits. I'm an old hot rodder and this "new" stuff makes me crazy....so I hope some of you will take pity on me and give me some direction before I lose what little sanity I have left!

We bought the 94 new and it now has 77K miles on it....except for a clutch and 3 batteries we have never had a problem with it till last October. Then it started running rough on mild acceleration and idle, sometimes it would shut off when idleing but could be started up instantly. I ran some BG cleaner and it was no help. It was intermittent and didn't matter if it was cold or hot. The CEL and ABS light would come on momentarily and go right off again and recently the clock would have to be reset. One time I was behind her when it did it and black smoke came out of the exhaust, just a puff. Except for a K&N air filter and side pipes the car is stone stock. Since I knew my tech limitations on new cars I took it to some recommended shops around here in Stafford, VA. The first shop changed the fuel filter, ran BG through the intake and changed the IAC....It ran good for 3 days then started to act up again. The second shop was the Ford Dealer and they changed the Ign module and stator....again it ran good for 3 days then acted up again. The last shop changed the battery, starter, ign switch in the steering column, repaired a corroded electrical connection in the alternator harness and changed the ELM (remanufactured). It ran good for 2 weeks and then started to run bad again! Again, I'm an old hot rodder and used to drag race an A/A in So Cal in the 60's....I run and maintain two street rods that are non computer cars and I have no problems, so I'm not really mechanically stupid....I just don't get the computer cars! Anyway today I read on the internet that my problems point to a bad IAC....the post also said that to check it just take it off and have someone turn the ign to "on" and the IAC should move 1/2". I did that and the little white bellows inside the IAC moved about 1/8".

I don't want to start replacing parts that have already been replaced but I have bought new parts over the years that didn’t work so I thought maybe the IAC is a bad new part?

Any help or direction will be much appreciated, thanks in advance,
343wc

 

[ProKiller]

clean the MAF. when was the o2 sensors last replaced? the clock problem was probably a bad battery so thats good you have that changed. double check all your grounds and vacuum lines too. when was the last time you checked or replaced the dizzy cap/rotor, plugs, wires?

 

[343wc]

Thanks for your response,
I will clean the MAF, break clean OK?....I have never changed the O2 sensors....cap,rotor, plugs changed 10K ago, never replaced wires....I am going to change plugs again this weekend, read them to see if clue is there. Grounds have been taken off, sanded, dielectric grease applied, reinstalled all grounds....checked vac lines, none found bad.

 

[Chythar]

Definitely do a search on the forums for "clean MAF", it's easy to do with rubbing alcohol and a q-tip. The 94-95 cars are sensitive to engine vacuum, so cracked hoses could cause a problem. The computer can store problem codes even if the CEL isn't on, so a code reader could give you more insight as to what's going on.

Finally, are you still in SoCal? If you're not that far from me, I might be willing to pop by and take a look.

 

[343wc]

Thank you Chythar,

I live in VA....thank you for your offer though.

I think I'll clean the MAF and recheck the vac lines again while I'm changing the plugs. We tried to pull a code but it must not be storing any because we found none!
chuck

 

[xr8d302]

Lots of guys from VA here that might be able to stop by and check it out for you

My initial thoughts were a ground problem but it looks like you've already got that covered.

As for Cynthar's advice, definitely read up on the easy cleaning methods for the MAF, and you'll be surprised how much it can do for the driveability of your car.

Good luck,

 

[343wc]

I did not know about the MAF....I have a K&N air filter and clean & oil it once a year....for 16 years, did not realize oil from K&N could mess up MAF! Who knew? I'll clean it.

You all have given me some logical things to look into that might be my problem....I'll work on these next week and let ya know if it helped.

Thanks again for helping,
chuck

 

[knightmare90]

Auto stores also sell MAF cleaner now too. It's designed specifically for the purpose of cleaning MAF.

 

[HISSIN50]

You got no codes at all? You should see 111's. If you didn't generate any codes at all, there's an issue and we need to get to the bottom of that FIRST.

I'm not familiar with the acronym ELM. Is that another way of saying EEC/Computer?

 

[Pokageek]

Subscribing

 

[Chythar]

You got no codes at all? You should see 111's. If you didn't generate any codes at all, there's an issue and we need to get to the bottom of that FIRST.

I'm not familiar with the acronym ELM. Is that another way of saying EEC/Computer?

Good point on the 'no codes' part, I missed that entirely. The plug under the dash is not used on the V8's; Ford saved some money by using the same dash and wiring for all cars, including the V6's. That plug is used only for the V6's. Our code reader hookups are behind the passenger shock tower, one large black one and a single gray plug. Yes, both are used.

 

[343wc]

ELM is on the invoice, $280, remanufactured? Could be EEC, whatever that is? I am going to try to work on it today and test drive it a while later today or tomorrow. The work needs to be done anyway so I'm not spending time/$ in vain.... Your comment about the codes makes sense too....I don't have a reader but my friend does and I'll see if he can stop by and check it out, under the hood, not the plug under the dash! Good info....thanks,
chuck

 

[343wc]

What a trip....now I remember why I don't like to work on that car! Changed the plugs, all were correct color. I gapped the old plugs at .052, like the book says and they were burned to .059-.060....I really don't know how many miles on them....I don't like to change them, my arms come out looking like a deer carcas that has been hanging awhile and the blood thinners don't help either. Anyway that's done.

The MAF....neat little deal....I had to buy a torx tip with a hole in it, weird, anyway it disassembled ok. When I first looked at it, it looked clean, but I carefully sprayed with MAF cleaner and carefully rubbed with a Q-tip. When I started the wires looked solid but after I cleaned them I could see the individual wire windings on the wire....I had to use a magnifying glass but there it was! The K&N filter is drying and I'll reassemble tomorrow....with no oil!

The vac lines looked ok except one going from somewhere under the passenger fender to a little valve then it disappears under the intake plenum? It's carbonizing, litterally falling apart and turning to dust! I don't know where it goes under the plenum and I will try to remove some wiring near the hood hinge to get access inside the fender to find the other end. I was a Buick mechanic in the '60's and remember one of the beasts had a vacuum accumulator tank inside the fender....was a real PITA to get to, I hope this isn't going to be the same drill?

One way or the other I'll road test tomorrow....I can't work on it past tomorrow....I have my wife's other car to get ready for three cruises and a show this comming weekend....I have the motor a little bit apart....I work on it a little while I'm cussing the Mustang....hehehehe

Thanks for your guys being out there to help....After we fix the Mustang I will probally not be back till I need more help....I don't know enough about the Mustang to contribute to the forum. Now if someone wants info about hot rods then please don't hesitate to ask me.
chuck the slacker

 

[Chythar]

I believe K&N filters need to have oil to trap dirt & dust correctly, but it's certainly OK for a short test. After you re-oil the filter, you may need to clean the MAF again to get any oil residue off.

The 94-95 cars are really sensitive towards engine vacuum. A cracked vacuum hose would be enough to get a rough idle.

The vacuum line you're talking about takes gas fumes from the tank and burns them at part throttle. The little valve is called the CANP (Canister Purge Solenoid), it decides when the gas fumes vent into the intake manifold. The other end goes into a charcoal canister in the fender, which stores the gas fumes until they're ready to be vented. If you've noticed a gas smell recently this hose is definitely damaged. You'll have to take off the passenger splash guard (and the wheel, of course) to get to the charcoal canister. It's not a bad idea, just replace all the vacuum lines whether they look good or bad.

 

[343wc]

Well the Mustang is still sick!
Test drove today....started up in driveway after reassembling parts and let idle for 30 min, no problem.....My wife drove the Mustang and I followed with my truck and we ran on Interstate above 2200rpm for 15 miles, no problem.....ran back on surface streets-stop and go-traffic lights-traffic-the whole deal, no problem. Parked and had lunch, 45 min. She started up and it malfunctioned leaving the parking lot-a lot of black smoke out both exhaust-she clutched it and rpmed up over 2K and it cleared ok....she drove 50 yds more and stopped to turn right and it did it again, black smoke, she cleared it the same way and had no more problem all the way home, 4 miles. It acts like a choke rod that is too short on a carb, when the engine cools down a little it cranks full closed and runs rich. Any thoughts?