Fox Restoring Health To Our Fox

[7991LXnSHO]

You first posted
"So the next place I am attacking is the motor. The goal is to restore the health for a factory fresh idle quality and throttle response. We're not looking to mod this car at all, and want to keep it as close to factory as possible."

Since you are new and are missing the point, just this time, I will try to be more clear than pleasant. - PLEASE JUST KEEP IT STOCK THEN! You do not need to make life complicated and mess up a stock car for no real gains.

Here are some details and good reasons why, besides federal emissions laws say do not remove smog parts-

If you are still not looking to modify the car, just put the long belt back on the pump and put new high flow cats on. Your problem should be fixed and look almost stock with a few more HP. I think the after market cats should free up more power than the air pump eats. Then you do not have to mess with the computer that Ford made work pretty darn well with the factory parts. If you are not planning on modifying the car a lot, if at all, there is no need to twerk with reprogramming the computer or replacing it. The computer tweaking needed to ditch the pump and use newer cats is a tremendous, tail chasing waste of time and money. What will you gain without a speed boat load of performance parts and a racing type set up? Neither the air pump nor the cats are eyesores as they are both tucked out of the way. Pypes brand cats are even stainless and I bet could be polished. It is not a big deal to fix the air pump codes your car is popping. The air pump system is simple to fix if it is all there. A catted H/X pipe (and cleaning the crossover tube if a code is still there, and then chasing cracked vac lines if that still does not do it) is a lot easier than rewiring for a Mega Squirt or a later stock style (but more powerful) computer and making it work with wide band O2 sensors. If you think it is truly easy to program one of these systems, you might have been born after the year 2000 with a computer in your hands. (Your poor Mama!) These systems can be learned, but it is not worth time just to a kill a couple of codes. And a little better gas mileage will never pay for the new computer system in an almost classic convert.

Listen to @jrichker. he will save you money and frustration just because he's a nice guy! I have printed and notebooked many of his help guides because they are better than any manual I can buy!!
Listen to @Gearbanger 101. When he reads the whole thing, he is right on too.
@89oem is looking out for you.
To paraphrase both Grandpas, If it isn't broke, DON'T fix it.
This can be the most helpful site you will find for Mustangs, but fools tend not to be harbored. (Search for missing lug nuts for a amazing read!) Do not be one of them.

I will try to be more concise and polite next time.

 

[Gearbanger 101]

Listen to @Gearbanger 101. When he reads the whole thing, he is right on too.

Hey, I resemble that remark!!!

 

[stoopalini]

Good advice ... my thought around removing the smog system and still keeping a clean burning motor is more related to part failure rates, and partly related to underhood clutter. I've owned many a high performance/muscle car, of which one was a 1996 Z28 which also had a secondary air injection system. The one way check valves and pump all went out on me at some point. I was told this is common place due to the exhaust gasses being corrosive. I did replace the check valves when they went out, but when the pump eventually failed, it was cost prohibitive to replace it. So I removed the entire system, plugged the holes in the manifolds (that system injected air directly into the manifolds), replaced the Y pipe with a Random Technology pipe with high flow cats, and reprogrammed the OBD-I system accordingly. It was an easy fix, I never had to worry about the smog system again, and it ran clean.

So my questions are related to me learning about the mustang's system. It sounds like removing the system and updating the cats isn't a viable option mainly due to the ECU not able to be reprogrammed within reason. The last mustang I owned (or Ford for that matter) was a 4-speed 1979 5.0 back in 1992, so I appreciate your patience while I learn this platform and get up to speed.

As I stated previously, I did put the stock length belt back in and the AIR codes are gone. I'm now getting codes related to both banks running lean (41 and 91). I understand this could be related to the AIR system as well, and will check the crossover pipe for buildup to try and resolve them. I also understand the self-check system does not continue to the AIR check if it encounters a lean code, so the AIR codes may very well come back after I resolve the lean situation.

I'm not concerned with increasing HP on this car, so my decisions aren't based on "how much power can I make" ... they're more related to longevity and reliability. This is my wife's weekend toy, when she can get away from our kids, so I would like it to be turn-key reliable and smooth running.

After replacing the stock length belt and engaging the smog pump again, I now hear a high pitched sound when the RPMs get above 4k or so. I assume this is the pump itself whining, as it wasn't present with the bypass belt installed. I wonder if this is a sign the pump will fail soon?

Thanks again for the input and advice, it is appreciated ...

 

[7991LXnSHO]

Get a mechanic's stethoscope and confirm which accessory or bearing is making the sound. After setting a while, you could have more than one dry bearing. You can also remove the belt and spin each thing by hand, but the up to speed test is more accurate. Pumps make some noise, but a real scrape after it is broken in is a bad sign.

You can get a piggyback chip that plugs in the computer and get it programmed to get rid of codes,






but a rebuilt smog pump is so much cheaper. And I think changing the pump requires r&r fewer bolts than the kick panel and computer involves screws.

I changed the pump on my 79 in work clothes over lunch, minus the tie, and only had to wash my hands and put the tie back on afterwards.

 

[jrichker]

Since much of your efforts have been directed towards the Thermactor Air System -TAS (smog pump & plumbing) I suggest that you remove the crossover tube and clean the carbon out of it. Clean the ports on the heads as best you can. Once you get good airflow through all the crossover pipe ports , put it back on, and clear the codes. Drive it for a while and dump the codes again. You may find that the code 41/91 has cleared.

 

[7991LXnSHO]

Since much of your efforts have been directed towards the Thermactor Air System -TAS (smog pump & plumbing) I suggest that you remove the crossover tube and clean the carbon out of it. Clean the ports on the heads as best you can. Once you get good airflow through all the crossover pipe ports , put it back on, and clear the codes. Drive it for a while and dump the codes again. You may find that the code 41/91 has cleared.

@jrichker
Any handy suggestions besides small hands to make the removal and replacement of that crossover tube easier?

 

[jrichker]

@jrichker
Any handy suggestions besides small hands to make the removal and replacement of that crossover tube easier?

Enlist the assistance of one of the female members of your family who has small hands. A suitable bribe will likely be needed..
Hopefully the price of the bribe won't be too extravagant...


Use a 1/4" drive ratchet and a 1/4" universal joint and extension. If you are lucky, the bolts will come out without damage to the ratchet or your fuzzy body.

 

[7991LXnSHO]

Hey, I am not a wookie yeti.
An on topic thread jack from my boy - Why do gorillas have such big noses? Because of their big fingers!

I think someone to hold the other end of the tube will be a good help too.

 

[stoopalini]

Before I remove the crossover pipe, I'm going to rule out other items due to the difficulty in getting that pipe out. It looks fairly rusted up as well, so I may just replace it if I end up removing it.

It seems a lean condition reported from both O2 sensors means there is extra air getting in somewhere, right? Wouldn't a clogged crossover cause a rich reading when the ECU is expecting to see the added air at the O2s? I'm having trouble understanding how it causes a lean condition; not that I don't believe you guys, I'm just trying to understand how the ECU would report lean if the extra air was not being injected into the heads.

I'm fairly confident I don't have a vacuum leak due to seeing 16in/Hg of steady vacuum at idle. I don't hear any vacuum leaks either, and if it were an exhaust leak I would expect the code only on one bank.

I don't have a fuel pressure test gauge yet, but applied 16in/Hg of vacuum to the fuel pressure regulator and it held it just fine. So it doesn't appear the regulator is bad. The car also had a new fuel pump installed a week before we bought it, and we've since put maybe 200mi on the car. I need a fuel pressure test gauge for my garage anyway, so will pick one up and test the pressure.

Considering I didn't get the lean codes when the smog pump was bypassed, could the diverter valve or TAD solenoid be faulty causing extra air to go into the heads when it's supposed to be directed to the cats instead? I think I'll test this next, considering it's easy.

 

[stoopalini]

Here's another interesting piece of info: I took the car to get inspected today, half expecting it to fail due to the lean codes, but it passed with flying colors. The tech commented that it was one of the cleanest reports he has seen.

 

[jrichker]

Glad to see you passed the emissions test. They can be difficult with older cars.

 

[stoopalini]

Just as an update to this: The car seems to be running great now. Even the cold start idle is working perfectly. I wonder if there was some build up in the fuel system, or some other location, which has been resolved just due to driving the car more? Either way, the car is running great now.

Just for grins, I connected a fuel pressure gauge to the schrader valve on the fuel line. I had 33 PSI at idle, with the vacuum line connected to the FPR. I shut the engine down and monitored the pressure. It only lost 3psi over the course of 15 minutes, so I think I'm fine there.

I'm still getting the strange noise when RPMs go over 3500/4000 or so, and am 90% sure it's coming from the smog pump (pulley maybe?). Considering the wife drives it most of the time, and she doesn't rev it that high, I'm not too concerned right now, but will dig into it at some point.

I haven't checked codes again since it started running good, but will do so later today when I have time. I'm hoping the lean codes are now gone, but we'll see.

 

[hoopty5.0]

@stoopalini Good to hear! I was wondering how it was coming since we seem to be chasing similar gremlins. I replaced an O2 sensor and did some other things and it runs much, much better.