car running terrible! help

1992mustangLX

New Member
Jun 13, 2007
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My car sat for a few days and i went to run it today and its running horrible!! It cant get out of its own way, it will barely rev past 3000rpm and the exhaust is popping like crazy. I can floor it while driving and it barely accelerates, i mean barely! I bought a code scanner and i am getting the wierdest code! CODE 678 and in the book it says its a problem from 2nd to 3rd gear which makes no sense! this is how the code reader flashes, flashes 6 times,7 times,8 times then 1 time, then repeats. Anyone have any ideas? Im thinking its the ignition somehow. PLEASE HELP!
 
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Foxes (as indicated with your username) don't have 3 digit codes. Those started with the 94's.
What year is your car?
 
Sounds more like a code 67 and a code 81. Neither one of them would cause the problem you describe.

I would remove the TFI module from the distributor and have it tested at the local auto parts store. You may need a special socket to get the module mount screws loose.

Code 67 - clutch not depressed (5 speed) or car not in neutral or park (auto) or A/C in On position when codes where dumped. Possible neutral safety switch or wiring problem. This code may prevent you from running the Key On Engine On tests. You can generally ignore this code, since it has no effect on engine performance.

The computer wants to make sure the A/C is off due to the added load on the engine for the engine running tests. It also checks to see that the transmission is in Neutral and the clutch depressed (T5, T56, Tremec 3550 & TKO)). This prevents the car from being driven while the computer is in test mode. Key On Engine Running test mode takes the throttle control away from the driver for several tests. This could prove hazardous if the computer was jumpered into test mode and then driven.

The NSS code 67 can be bypassed for testing. You will need to temporarily ground computer pin 30 to the chassis.

Computer pin 30 uses a Lt blue/yellow wire. Remove the passenger side kick panel and then remove the plastic cover from the computer wiring connector. Use a safety pin to probe the connector from the rear. Jumper the safety pin to the ground near the computer.
Be sure to remove the jumper BEFORE attempting to drive the car!!!

The T5 neutral safety switch has nothing to do with starting the car. The clutch safety switch controls whether or not the starter cranks the engine.




Code 81 – Secondary Air Injection Diverter Solenoid failure AM2. The solenoid valve located on the back side of the passenger side wheel well is not functional. Possible bad wiring, bad connections, missing or defective solenoid valve. Check the solenoid valve for +12 volts at the Red wire and look for the Lt Green/Black wire to switch from +12 volts to 1 volt or less. The computer controls the valve by providing a ground path on the LT Green/Black wire for the solenoid valve.

With the with the ignition on, look for 12 volts on the red wire on the solenoid connector. No 12 volts and you have wiring problems.

With the engine running, stick a safety pin in the LT Green/Black wire for the solenoid valve & ground it. That should turn the solenoid on and cause air to flow out the port that goes to the pipe connected to the cats. If it doesn't, the valve is bad. If it does cause the airflow to switch, the computer or wiring going to the computer is not signaling the solenoid valve to open.

Putting the computer into self test mode will cause the solenoid valve to toggle. If you listen carefully, you may hear it change states.

If you do not have catalytic converters, you can ignore this code.

TAB & TAD solenoid valve eliminators – eliminate codes 81 & 82 and 44 & 94

Don’t do this if you have a catalytic converter H pipe. The catalytic converters must have the air from the smog pump or they will clog up and choke.

See www.Newark.com for the resistors to replace the TAB & TAD solenoids

http://www.newark.com/jsp/Passives/Wirewound/OHMITE/43F82RE/displayProduct.jsp?sku=64K8974
If the link fails do a search using the park number
82 ohm, 3 watt wirewound resistor, 94 cents each.
Newark P/N 64K8974
Ohmite part # 43F82RE.

Pay a visit to your local Radio Shack to get some heat shrink and some crimp on tap terminals. They do not stock the resistors. Or you can use the Ford connector pin kit from AutoZone.

pRS1C-2266040w345.jpg

18 gauge crimp on taps Catalog #: 64-3053

Put the resistor inside the heat shrink tubing and crimp the connectors on. I would choose the Ford pin connectors since they should plug in the TAD wiring. That way you haven't modified the wiring so it is easy to re-install the TAD solenoids if emissions testing comes to your area.

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Two flat pin connectors.
One 82 ohm, 3 watt resistor.
One piece 3/8" heat sink tubing 2" long.
Two pieces 3/16" heat shrink tubing 1 1/2" long.
Solder the pins onto the resistor leads using electrical solder.
Slide the 3/8" heat shrink tubing over the resistor.
Slide the two pieces of 3/16" heat shrink tubing over the two wires, leaving the flat part of the pins uncovered.
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It helps to have the resistor leads straight and not bent as shown in the first picture when you apply heat to the heat shrink tubing. That way, the tubing shrinks more evenly.
Finally, apply heat to shrink all the tubing uniformly.

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Bend the leads to fit the spacing on the female TAB & TAD connector sockets.

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Push the connector pins of the completed resistor assembly into the empty female TAD or TAD connector sockets on the wiring harness. The resistor assemblies replace the missing solenoids: one resistor assembly per solenoid socket.

Do not crimp on the pins and wrap the mess with electrical tape and say you got the idea from me. If you do, and I hear of it, I will say unkind things about your intelligence and family heritage. Do Quality Work!

This information is for informational purposes only and is intended for use only on off road vehicles. It should not be used on any vehicle operated on public roads.

Operating a vehicle modified in such a manner on public roads is a violation of the EPA codes regarding modification of emission controlled vehicles.
 
thanks guys, i appreciate the detailed replies! It helps a lot! I am gonna replace the tfi module on the distributor as that was my initial though being the ignition, because it doesnt seem like a fuel problem and it breaks up a little when driving so ignition is my my first thought. I had to order the part cause there is no store near me that had one in stock so i will get it and put it in tomorrow and let you now how i make out. Hopefully thats what it is. Thaks again!
 
Foxes (as indicated with your username) don't have 3 digit codes. Those started with the 94's.
What year is your car?
Ya that what i thought to, however when reading the manual on the scanner it says it will beep once between codes. and when i run the scan it doesnt, it just beeps 6x,7x,8x,then 1x. The last beep i thought was signifying the end of the code, and according the user manual if it was 67 and 81 it would beep 6x7x, 1x , 8x1x , 1x. That why i thought it was wierd. I read it a few times to make sure i was doin right and got the same result every time. Maybe i missed the beep every time or something caus ei was concentrating on making sure i counted them. I am going to assume it was an error by me which is likely being that i was quite frustrated. According to Jrichker if it was code 67 it bc the ac may have been on which is very likely becaus ei leave it on vent went driving to keep air circulating and dont think i shut it of so i can ignore that code. Code 87 can be ignored if i dont have cats and it turns out i just took the the factory h pipe out and put in a off road x pipe and dont have cats so that can be ignored. So it makes sense. So like stated before i am gonna go right to the tfi module.Thanks for the help everyone
 
New update on my situation.

So i replaced tthe tfi module on the distributor to rule that out thinking might be the ignition. Nope it didnt do a thing.

I checked my tps sensor thinking it might be improper throttle response. Nope, the voltage was fine. .94v and at wot it was 4.7v (is that low? i think its right but not sure thought it would be slightly over 5v @ wot.

Checked fuel pressure and is adjusted to trick flows recomendation with 24# injectors at 41psi. So thats fine.

I have spark going to all wires and cylinders.

So I have the basics fuel and spark. The only thing left is ignition some how. Im thinking its faulty in some way but i know its not the tfi module now. I have mentioned this before but the timing does not advance when i plug the spout back in after timing it and im thinking its related somehow.

Anyone else have any other ideas for me?
 
I had the same thing happen to me. I read the codes, replaced sensors, new TFI, swapped distributors, new plug wires........... It turned out to be bad gasoline. When I pulled the fuel filter off, I let it drain into a plastic bottle. About half of what was in the bottle was gas, the other half I am thinking was rust and water :mad:

I drained the tank, got some new gas, and she ran like a champ.

I headed up to the gas station where I got the bad tank and guess what? Boards on the windows and tumbleweeds in the parkinglot.
 
New update on my situation.

So i replaced tthe tfi module on the distributor to rule that out thinking might be the ignition. Nope it didnt do a thing.

I checked my tps sensor thinking it might be improper throttle response. Nope, the voltage was fine. .94v and at wot it was 4.7v (is that low? i think its right but not sure thought it would be slightly over 5v @ wot.

Checked fuel pressure and is adjusted to trick flows recomendation with 24# injectors at 41psi. So thats fine.

I have spark going to all wires and cylinders.

So I have the basics fuel and spark. The only thing left is ignition some how. Im thinking its faulty in some way but i know its not the tfi module now. I have mentioned this before but the timing does not advance when i plug the spout back in after timing it and im thinking its related somehow.

Anyone else have any other ideas for me?

That's why I recommended having the TFI module tested first. Throwing parts on a guess can get expensive. Your other part in the ignotion system that is easy to remove and test or replace is the ignition coil.
 
figured it out..

That's why I recommended having the TFI module tested first. Throwing parts on a guess can get expensive. Your other part in the ignotion system that is easy to remove and test or replace is the ignition coil.
yes i know but i planned on replacing everything anyways. I have put a lot of money into the motor so i planned on replacing all the other components any way. I have the original coil, distibutor, tfi, and everything else. Plus who cares because i spent over 4g on the motor there is no way i am not going to replace a $20 module for peace of mind. That and it took about 5 mins to replace, so a well worth guess to me.

It doesnt matter however because i figured out the issue.here it is.
ok, so when i was timing it i noticed it doesnt advance when the spout is reconnected. And when i accelerated the throttle the timing would retard. So i follow the wire from the tfi all the way to the coil and there was splice in the wire were the iodized supressor is suppose to be, and i figured it had to do with the pcm, so i look and it has a superchip tune on the pcm and the pcm is for a automatic transmission( i have a manual) and the tuner as well. So that missing suppressor burnt out the pcm. So i need a new pcm and i am going to replace the whole wiring. This discovery also revealed the root of other problem i was having, like reverse lights not working, ignition not working with the key, and the issues i was previously having with my timing.

If anybody knows where i get get the stock computer and a wiring harness for a 92 mustang lx 5.0 and 5 spd tranny., that would be great. Thanks for all the help.
 
yes i know but i planned on replacing everything anyways. I have put a lot of money into the motor so i planned on replacing all the other components any way. I have the original coil, distibutor, tfi, and everything else. Plus who cares because i spent over 4g on the motor there is no way i am not going to replace a $20 module for peace of mind. That and it took about 5 mins to replace, so a well worth guess to me.

It doesnt matter however because i figured out the issue.here it is.
ok, so when i was timing it i noticed it doesnt advance when the spout is reconnected. And when i accelerated the throttle the timing would retard. So i follow the wire from the tfi all the way to the coil and there was splice in the wire were the iodized supressor is suppose to be, and i figured it had to do with the pcm, so i look and it has a superchip tune on the pcm and the pcm is for a automatic transmission( i have a manual) and the tuner as well. So that missing suppressor burnt out the pcm. So i need a new pcm and i am going to replace the whole wiring. This discovery also revealed the root of other problem i was having, like reverse lights not working, ignition not working with the key, and the issues i was previously having with my timing.

If anybody knows where i get get the stock computer and a wiring harness for a 92 mustang lx 5.0 and 5 spd tranny., that would be great. Thanks for all the help.

The reverse lights are not connected to the computer. The switch on the side of the T5 transmission works the reverse lights. It has 2 studs that look like screws for connectors. Tremec 3550, TKO 500 & 600 use the same switch and location as the T5.
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Remove the wiring connector from the reverse switch and jumper the 2 connections inside together. Turn the ignition switch to Run: if the lights work now, the reverse switch was bad. Cost of the switch is $15-$20.

The ignition switches are a high failure rate item. There was a recall, but it was so long ago, I doubt that you could get it done for free.
 
The reverse lights are not connected to the computer. The switch on the side of the T5 transmission works the reverse lights. It has 2 studs that look like screws for connectors. Tremec 3550, TKO 500 & 600 use the same switch and location as the T5.
Remove the wiring connector from the reverse switch and jumper the 2 connections inside together. Turn the ignition switch to Run: if the lights work now, the reverse switch was bad. Cost of the switch is $15-$20.

The ignition switches are a high failure rate item. There was a recall, but it was so long ago, I doubt that you could get it done for free.

Yes i know the computer doesnt control the reverse lights but because the wiring is for a aod transmission that was originally in the car i dont think it uses the same wiring for a t5 tranny,but not sure. I know where the switch is but the previous owner cut the harness off which i couldnt figure out why he would do that and what i found explains it. The kid was a hack and did a bad swap. I meant to say the computer explains the timing issue and the poor performance and the wiring explains all my other electrical problems. I also already replaced the ignition switch. It is definatly a wiring problem somwhere and not a switch. I even replaced the clutch switch but again it didnt work. This was all before i knew that it had been a auto.
Thanks for the help, if any one knows where i can get the new wiring and the computer please let me know. Thanks!