[Julian]

Just to finally follow up to this thread. After taking my bad Alternator to 2-3 different stores for testing, I was convinced it was dead. I didn’t want to spend the money to see if it was just the voltage regulator or the whole alt.
In general, it was a shortcoming of 87-93 Mustangs to have an under-powered alt (75 Amp). Further, from the factory, the mustangs came with incorrectly sized wires for the alt that had a history of burning up. Anyway, I upgraded my alt to a 130 amp with 4 gauge wires and the problem was resolved.

[Julian]

Hi,

Have you tried hooking ti up to a scanner? Sometimes codes are set, but they’re not major enough to trigger the CEL. Maybe that’ll be a starting point to tracking down the MPG.

Good luck.
Julian

[Julian]

pull a spark plug. have it connected to teh spark plug wire and but the base of the plug on the metal of the engine. have someone crank the car normally (no hot wiring) do you see spark?

[Julian]

pull a spark plug. have it connected to teh spark plug wire and but the base of the plug on the metal of the engine. have someone crank the car normally (no hot wiring) do you see spark?

[Julian]

Just wanted to give a quick follow up. I had a couple of hours to play with the car. Here’s what I did:

1. I unplugged the battery for about an hour to clear all the codes.
2. I replaced the metal filter and grommet of where the PCV plugs in to the passenger side bank (it would come out too easily). The valve itself is new. (This didn’t fix the rough idle)
3. I hooked up a vacuum gage to the unused port on the vacuum tree which is on the firewall. It gave a reading of 20-18. Only when the idle would drop and be rough, the vacuum would then drop to about 15. When I revved the engine—the reading would drop to 0, come up to about 25 and within about 2 seconds steady itself at 20-18.
4. I hooked up the fuel gage as well. At idle, it showed about 33-34. With vacuum removed from the regulator—it’d go up to about 45 if I remember correctly.
5. I kinds heard a hiss by the upper intake manifold. I played with the vacuum hose going from the Upper Intage Manifold (UIM) to the Charcoal Canister and it seemed the hissing would change. I pulled off the hose and it didn’t look like it was tight on the air inlet on the UIM. Plus, it was old and cracked. It seems like the hose is the same size diameter as what I had in the garage, but the difference is is that the tip is wider than the rest of the line. Since I don’t have an expender, I couldn’t make my new hose work. However, I did just cut off the outer most piece of the original hose and pushed it back on to the manifold and clamped it better than it was before.

The car seemed to idle better. The vacuum no longer dipped to 15 but stayed at 20-18 for a while. Also, it sounded good enough to take for a ride around the block—and it seemed the hesitation was gone. Fingers crossed that’s the end of that issue. When I have some more time—I’ll run the computer diagnostics again to see if the codes cleared too.

Just curious—I noticed that one of the caps on my Charcoal Canister is missing. Can that cause any issues as far as vacuum? I looked online and it’s a 1.50$ part with $10 shipping 

Thank you for all your help!

[Julian]

Just wanted to give a quick follow up. I had a couple of hours to play with the car. Here’s what I did:

1. I unplugged the battery for about an hour to clear all the codes.
2. I replaced the metal filter and grommet of where the PCV plugs in to the passenger side bank (it would come out too easily). The valve itself is new. (This didn’t fix the rough idle)
3. I hooked up a vacuum gage to the unused port on the vacuum tree which is on the firewall. It gave a reading of 20-18. Only when the idle would drop and be rough, the vacuum would then drop to about 15. When I revved the engine—the reading would drop to 0, come up to about 25 and within about 2 seconds steady itself at 20-18.
4. I hooked up the fuel gage as well. At idle, it showed about 33-34. With vacuum removed from the regulator—it’d go up to about 45 if I remember correctly.
5. I kinds heard a hiss by the upper intake manifold. I played with the vacuum hose going from the Upper Intage Manifold (UIM) to the Charcoal Canister and it seemed the hissing would change. I pulled off the hose and it didn’t look like it was tight on the air inlet on the UIM. Plus, it was old and cracked. It seems like the hose is the same size diameter as what I had in the garage, but the difference is is that the tip is wider than the rest of the line. Since I don’t have an expender, I couldn’t make my new hose work. However, I did just cut off the outer most piece of the original hose and pushed it back on to the manifold and clamped it better than it was before.

The car seemed to idle better. The vacuum no longer dipped to 15 but stayed at 20-18 for a while. Also, it sounded good enough to take for a ride around the block—and it seemed the hesitation was gone. Fingers crossed that’s the end of that issue. When I have some more time—I’ll run the computer diagnostics again to see if the codes cleared too.

Just curious—I noticed that one of the caps on my Charcoal Canister is missing. Can that cause any issues as far as vacuum? I looked online and it’s a 1.50$ part with $10 shipping 

Thank you for all your help!

[Julian]

Thanks collegeman and thanks wysetech! Funny you mentioned the higher then normal idle. I think I did get code 12- Idle speed control out of specified range. My code book I think specified that it was high. However, I ignored it for what I thought was the more important issue of Code 41 and the fact that I’m running under-drive pulleys 🙂

I’m still waiting for free time to work on the car, but gathering info for now 🙂 Besides looking at the O2 sensor, knowing that this is only happening on the passenger head– should I be focusing on something more particular– or things like the MAF and O2 ground, fuel pressure… could still be a problem? Wouldn’t those affect both heads?

Also, if I unplug that O2 sensor, would the computer switch to closed loop for that sensor? Same with the MAF? And if things improve at that point– would it make sense to pursue those further with testing?

Finally, one more question. The code puller that is used on the 89 mustang says to hold the clutch pushed in for I believe the KOEO tests. I know if I don’t do it– it complains of the neutral switch problems 🙂 However– does not holding in the clutch prevent/trigger other findings? I looked online for the extension code for the tester– it’s more expensive then the tester itself :):):) :woohoo: Would rather not buy it. Please advise!

[Julian]

Thanks collegeman and thanks wysetech! Funny you mentioned the higher then normal idle. I think I did get code 12- Idle speed control out of specified range. My code book I think specified that it was high. However, I ignored it for what I thought was the more important issue of Code 41 and the fact that I’m running under-drive pulleys 🙂

I’m still waiting for free time to work on the car, but gathering info for now 🙂 Besides looking at the O2 sensor, knowing that this is only happening on the passenger head– should I be focusing on something more particular– or things like the MAF and O2 ground, fuel pressure… could still be a problem? Wouldn’t those affect both heads?

Also, if I unplug that O2 sensor, would the computer switch to closed loop for that sensor? Same with the MAF? And if things improve at that point– would it make sense to pursue those further with testing?

Finally, one more question. The code puller that is used on the 89 mustang says to hold the clutch pushed in for I believe the KOEO tests. I know if I don’t do it– it complains of the neutral switch problems 🙂 However– does not holding in the clutch prevent/trigger other findings? I looked online for the extension code for the tester– it’s more expensive then the tester itself :):):) :woohoo: Would rather not buy it. Please advise!

[Julian]

One more question. While the car sat idling and I was checking different things, I noticed that the driver side exhaust had a water puddle behind it, where the passenger side exhaust– the side throwing the lean code, didn’t. Is a sign of anything? Has to do with the head being lean? Or, just a coincidence? 🙂

Thanks again!

[Julian]

One more question. While the car sat idling and I was checking different things, I noticed that the driver side exhaust had a water puddle behind it, where the passenger side exhaust– the side throwing the lean code, didn’t. Is a sign of anything? Has to do with the head being lean? Or, just a coincidence? 🙂

Thanks again!

[Julian]

makes sense to me. I ran a bottle of fuel cleaner about a month ago too– wonder if it dislodged something somewhere as well 🙂

[Julian]

makes sense to me. I ran a bottle of fuel cleaner about a month ago too– wonder if it dislodged something somewhere as well 🙂

[Julian]

Does it crank at full speed?

Since the battery is new– make sure the battery connections are tight– you can’t turn the clamps by hand on the battery terminals. And make sure they’re clean.

[Julian]

Does it crank at full speed?

Since the battery is new– make sure the battery connections are tight– you can’t turn the clamps by hand on the battery terminals. And make sure they’re clean.

[Julian]

Isn’t there a federal law/warranty that a cat should be good for 8 years or 80k miles– it’s a free replacement before then.

Just a thought.

http://www.epa.gov/obd/pubs/420f09048.pdf

[Author]

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