'92 Lincoln Continental air suspension malfunction

Previous owner replaced all four air shocks. Compressor failed soon after. I replaced the compressor and burned fuse. Rear was not holding air and compressor running too much. I was leaning towards the possibility of air lines not sealing properly and causing leakage...but...before diagnosing

*that* problem fully, I took it for an inspection sticker...and the real fun began.

During the inspection, the idiot masquerading as a mechanic jacked up the front of the car, neglecting to turn off the suspension control as required. (This wasn't his only faux pas, just the most serious at this point.)

After this, the right side stayed up overnight and the left side deflated (the front slightly less than the rear). I started it and the left front came up but the left rear stayed down. I moved the car in an attempt to get the system to equalize but it did not. Then I reset the switch and tried again- the LR stil did not come up, and the RF over-inflated. Now the left front and right rear are holding air and appear normal. The left rear is apparently not getting any air at all and is completely deflated while the right front is over inflated- holding it and will not deflate as it should.

Unfortunately, my Chilton's is rather sadly lacking in specific information on troubleshooting the air suspension system. I'd be grateful if someone could provide a few more details on the operation/control of this system.

If I didn't know that the system was funcioning normally (at least as far as pressure being directed to the appropriate components) I might think that the LR and RF air lines had been switched at the compressor. What else could account for this? Only the control module?

And just how much pressure will the LF hold before it pops? Just curious, I know I'll need to bleed it off before I let the compressor run again.

Reply to
Wrongway Napolitano
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Before you go broke with nothing to show for it!

Lugnut

Reply to
lugnut

There seems to be a booming aftermarket for that stuff and I saw a number of different companies with similar kits while I was looking for more detailed information, but those are the best prices so far.

However, I'd kind of like to figure out what the problem is. The major assemblies have already been replaced and are only about a year old and have less than 1,000 miles on them. They should last for quite some time yet...if I can get to the root of the control problem.

I have a '91 with a bad motor but the air ride was working perfectly before the motor crapped out. Plenty of spare parts but I'd rather diagnose the problem accurately instead of just blindly swapping parts until it works.

Call me hard-headed, I like to learn the hows and whys. Problems with this suspension in cold weather are not unknown and the intermittant/inconsistent nature of the symptoms suggests that it could be rectified if I can pin down the problem. I've been reading this group off and on for years and I know there are some good techs here who should be able to point me in the right direction.

Reply to
Wrongway Napolitano

If I were to guess based on the premise that the "idiot mechanic" caused your new problem, I would say that he messed up on of the front height sensors. It sounds from your description like only the front or one corner of your vehicle was raised. Where did you go for the inspection, Jiffylube?

If one side height sensor is not reporting accurately, the air suspension control module may accept it as correct height info and deflate one side of the car's airbags. It seems like the most likely possibility from a remote guessing standpoint.

There's still the previous problem of the rear not inflating properly. As you said, you may have a leak in the supply line to the rear. If the rear corners are capable of holding air (even if they aren't at full height), then the air bags and individual air solenoids are probably good.

Or if it is very cold where you are perhaps you have some frozen moisture in the system. Moisture may have even damaged a component from expansion. If you are up to it, visually inspect all underbody components, perform simple line integrity tests (remove lines and see if they hold pressure/vacuum), and apply B+ and ground to the two-wire airbag solenoids and check operation.

Toyota MDT in MO

Reply to
Comboverfish

No, it was a local garage but not my usual guy- his dyno was broken and he couldn't do it. LOL, I didn't say he was an "idiot mechanic", rather an idiot *pretending* to be a mechanic. I don't know where all the *real* mechanics have gone, we used to have some very good ones in this town. Now they seem to have been replaced by glorified parts-swappers[1] who just keep putting in new parts until they eventually get what was broken. And half of them are jibbering in broken English that you can hardly understand, with a silly smile as they hold out their hand for more money.

[1] The only difference(s) between them and me is that they have a garage and lift and I don't...and I have more scruples than to charge people for "fixing" things that weren't broken because I didn't know how to diagnose the problem correctly.

Yes, after a little experimenting today I'm thinking that the RF ride-height sensor is hosed. Maybe the LR too?

The temp here in MA finally got above freezing today. I jacked the LR and disconnected the air line, got a hiss from it. When I let it down it was sitting higher than before, almost normal.

Then I jacked the RF and bled the air out. I let it down and started the motor, then flipped the switch in the trunk. The LR deflated and the RF came up.

So, the LR will act on a signal to deflate, and the RF will act on a signal to inflate. Vice versa? Don't know, and that will be hard to say at this point, without a Super Star II tester or equivalent that plugs into the suspension diag connector. Lacking that, it looks like I may have to just start swapping parts anyway.

Reply to
Wrongway Napolitano

On Feb 17, 2:54 pm, Wrongway Napolitano wrote:

I can't keep my lousy dyno running; I feel his pain ;-)

That's old school (so it seems)... but certainly MA has their share of really good techs given their near-CA level of emissions regulations

-- it's simply harder to fix emissions failures if the failure tolerences are tighter, therefore the better techs really shine in these so-called 'green states'.

There is only one rear height sensor. The front two are the major input regarding side-to-side height control.

A Snap On brick (MT2500) scanner with appropriate cartridge will access this system adequately for your purposes. I still think you should check the system out as outlined in my last post. I can add a couple of general ideas to get you going... The biggest problem with these systems, while hard to state factually, is compressor failure. A bad filter/drier, moisture, corrosion, age, bouts with depression, etc... these can all make this garbage part fail quickly. One trick I read about is to have the four corners really low, then turn on the key and let the system try to pump up, then blow shop air into the filter inlet (filter removed) or schrader valve if equipped. See if the car raises evenly now. If so, you are probably dealing with a weak pump. Also, pull off an air outlet line at the pump, then while it is running try to block off the output with your finger. If you can seal it off, the pump is too weak. If you can't hold pressure with all of your might, then it is probably adequate. I have not tried either of these tricks but trust their value as diagnostic aids. If you can get the system fully pumped up with the above method or by standard system operation, turn off the system switch and fully raise the car on four jackstands. Inspect the airbags, lines, solenoids etc this way with soapy water and a flashlight. There should be no leaks on a properly functioning system. You should also be able to remove the lines from the four air solenoids and check the solenoid inlet fittings to see if the solenoids aren't holding air in the 'off' state.

Toyota MDT in MO

Reply to
Comboverfish

Thanks, good to know. I don't recall Chilton's mentioning that. I might have got a little agitated looking for something that wasn't there.

OK, I'll do those tomorrow. The compressor could be weak. It came out of the '91. It *appeared* to be working adequately there, and initially it was inflating all four shocks in the '92 even from dead flat.

Couple more data points- I checked the rears and they had NOT been replaced as I was told, and the left one looks pretty crappy, could very well be mostly kaput. If I don't do the conversion to springs I'll probably order new ones. The ones in the '91 probably aren't worth the effort to swap out.

Second thing is, I jacked the front (both wheels) and activated the system. Compressor ran for a couple of seconds and shut off. Shut the ignition off and waited. Theoretically, both fronts should have deflated but neither did.

Reply to
Wrongway Napolitano

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