Mondial fluctuating idle

Please help, I am having problems with my 87 mondial cab. The car starts fine when cold, but after it warmes up it develops a fluctuating idle. The problem is more noticable during the mornings or at night. When I drive the car it tugs and pulls during accelaration. I have cleaned the distribuer cab and changed all spark plug wires and plugs. I have changed all intake hoses. I clean and inspected AAV and it works fine, and I changed O2 sensor. What I did notice was the fluctuation is in sync with the frequency valve. What I mean is the frequency valve vibrates on and off as the car's idle. When I disconnect the frequency valve I notive a drop in power but the fluctuation disapears. I checked the ohms on the frequency valve and it measres 2.6 ohms and the connection from the frequency valve has a fluctuating voltage from 10.5 volts to 11.5 volts. My car is also running very rich . I have been reading every post possible to gather info but still can't figure it out. Please help!

 

Today, I kept checking the car for loose or dirty connections to see any change. I feel confused or maybe its all the fumes from the overly enriched exhaust I have been inhaling. I checked the TPS as per Carl Rose and was confused on the bridging of wires and were to connect the multimeter so I order a new TPS. The only shop down here that fixes imports left my car sitting for 3 months, so I got the hint and took it home. I think its pointless to have a nice car sitting in the garage. If I must I will change every part out, I just hope I don't have to.

 

I have been following Steve's recommendation to oleholy from " Protection Relay Conversion and Fuel Distributor Starting Alignment" thread since I think I have the same situation. I think my FV is going crazy and vibrating very loud, so I tried one of Steve's test to disconnect the green wire from the O2 sensor and the idle went to normal, and when I connected the green wire back the idle went up and down. I dnt know what that means and I did change the O2 sensor 3 months ago. Is there any other test I can do to confirme the O2 has gone bad. I am afraid the wires from the car have gone bad since they are 20 years old and they are very closed to the exhaust.

 

I hope I am doing this correctly, I checked the volts from the O2 sensor green wire at warm idle and the volts were all over the place. I got reading from .34 volts to .8 volts and mostly bettween .6 to .7 volts which I think that means the o2 sensor wants to run rich. That might explain why I smell like gas fumes. I still have the old O2 sensor, so I will try to change it out to see any difference.

 

Your good running when cold, or when warm with the O2 sensor unplugged are good signs that the basic K-Jet part of it is working OK. Few things you might try:

1. Measure the DC voltage on the single wire from the O2 sensor (relative to ground) while it is plugged in and the engine is at warm idle -- if things were working right, the voltage would be "wandering" slowly between 0.1V (lean) and 0.9V (rich) in a quasi-sinusoidal way. If it is just stuck at one extreme, or the other, that would be a sign of system badness. Or if it never gets to one of the extremes that would also be a sign of system badness. (Just saw your latest post and those results aren't horrible -- even if the engine isn't running well, at least the overall system is trying to do the right thing -- i.e., it's trying to keep the average O2 sensor voltage at 0.5V -- try test 2).

2. Measure the DC voltage on the single wire from the O2 sensor (relative to ground) while it is unplugged in at warm idle -- if it is stuck near 0V, but the engine is running well, that might indicate that your air injection system is either not working correctly, or it is "leaking" and letting air into the exhaust stream, or you have some other exhaust system leak -- which makes the O2 sensor signal (wrongly) indicate lean, so the injection ecu intentionally increases the duty cycle to the FV to add richness.

3. Measure the AC voltage (or duty cycle) between the two wires on the FV (while they are plugged in to the FV) and the engine is running at warm idle -- do this both with the O2 sensor plugged in and unplugged (and nothing wrong with trying the old O2 sensor if you think it might still be OK).

Perhaps from the measurements, it might give a clue...

 

Many thanks Steve for your reply, I connected the old O2 sensor and let the car idle warm and checked the single wire from o2 and it averaged .8dv it went up and down in the tenths at steady rate. The idle felt better and more consistante than with the other o2 that spiked from very low to very high dc reading, its like I had my meter set at random. How can I find out which o2 sensor is giving the correct readings? Is it the o2 trying to correct a bad setting or a faulty o2?

 

So I left the old o2 sensor on and checked the duty cycle, since It gave me a steady idle. I connected my meter 15 (-) and 8 (+) and let the car idle warm and got a 4.6 - 5.5 acv and with o2 single wire disconnect it stayed at a steady 4.7 ac volts. Does this mean my car is running at closed loop? I will try with the other o2 as soon as the car cools down.

 

Correction on post 4 and 6, I measured the dcv from the o2 sensor disconnect, the single wire that is connected to the o2 is were I got those readings. I tried and connect meter on the #2 and ground and got different reading nothing nothing I can pin point. I want to know if I am doing these test correctly or wrong?
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You said this a little strangely -- so let me suggest the following:

To measure the O2 sensor output with the O2 sensor plugged in, you would touch the "+" probe of the voltmeter to the wire end connected to pin 2 of the injection ECU and the "-" probe of the voltmeter to ground.

To measure the O2 sensor output with the O2 unplugged, you would touch the "+" probe of the voltmeter to the wire end that you removed from pin 2 of the ECU (not to pin 2 on the ECU) and the "-" probe of the voltmeter to ground.

Near 0V DC may be a legitimate measurement. Measure the O2 sensor output unplugged at warm idle as described above (it may be near 0V). Then, while still keeping the "+" probe touching the wire end, reconnect the wire end to pin 2 and see if the value changes.

 

Thank you Steve once again for your input, I think it is the air injection system at fault. When I changed all the hoses the T connection was rusted so I changed it with a T connection I picked up from Home Depot. The original cost as much as a hyper-flow cat so I used a cheap sub.
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Has anybody else have this problem and how did you fix it, since I cant find a T connection with the same inner diameter.

 

It's still a fairly ridiculous price, but www.allferrariparts.com shows 109887 for about 1/2 that price.

But as long as the "T" fits OK (i.e., no air leaks), I don't see why a hardware store substitute couldn't work just fine. How about a (solderable) copper tubing water pipe "T" -- won't have the ridges on the OD, but, if the fit is tight, and with good clamps, I'd think it would be OK (this isn't a high pressure application).

 

Well, today I check all my connection in the air injection to make sure I did not have any air leaks. I used new hoses and made sure everything was snug and tight. I did notice that when I removed the hose a small amount of water dripped out of the hoses from the check valve. Is that normal or are the check valves bad? Well there was no change, after the car warmed up the idle fluctuated again. It made sense to me that I do have air leaking through the exhaust causing the o2 to think its lean and making the FV work harder to rich out the mixture, but why the fluctuation? How do I check the FV, I tried to pull the rubber from the FV connection but was afraid, and how do I connect it to my multimeter? Once again thank you Steve for your feed back, I know with your guidance we will fix the car.

 

I have noticed the sensor plate from the air flow sensor high and not flush, could this be the problem.
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It's certainly OK that you've verified that the air hose connections on your air injection system are in good shape, but that doesn't mean all is OK. If your "T" got fried because of hot gas escaping past a failed check valve, your cut-off valve could also be damaged. But you never really gave a direct answer about test #2 (which, if you did get 0V from the unplugged O2 sensor and the engine still ran pretty well, would give you reason to suspect the air injection system isn't shutting off completely -- especially if, with the O2 sensor plugged in, the O2 sensor voltage was trying to stay at ~0.5V average, but the engine ran worse). If you remove the air line from the air box that goes to the cut-off valve, and then physically block that air line, that would simulate a properly closed cut-off valve for warm-running -- so if the O2 sensor voltage increased when doing test #2 with this air line blocked that would be another clue. And the converse is true, if you blocked this line during warm-running and it made no difference at all in the bad behavior, you could eliminate the air injection system as being the causing the trouble.

But can you back up to the beginning please -- was the car running well and then this warm-running problem appeared, or has is never run well when warm when in your possesion? If you just unplug the O2 sensor, is the warm-running and warm idle improved?

 

I did the checks again, I did the test from service bullitin No 80-29
Test #7 2.3-6.5 acv fluctuating up and down o2 connected
Test #7 4.7 acv o2 disconnected
Test #8 .3-.8 dcv flutuating

At warm idle o2 disconnected getting (+) from the single wire from the o2 sensor and ground .02-.03 dcv

When I got the car I did the 30k service but I never drove the car before I bought it. When they deliverd the car I was not impressed with the performance and thought it was very sluggish compared to my bmw z3. I thought nothing of it since the mondial was the least performing Ferrari of the 80.
Thanks again Steve I feel we are very close to a fix.

 

The problem with the bad idle started 3 months ago, I felt it was a mixture problem so I changed the o2, all the hoses, spark plugs to iridium, plug wires to taylor spiro wires, and cleaned the distributor cap. I recently put a bg 44k in the gas tank which I think made things worst. The car only runs well now with o2 disconnected, and when I plug it back in I feel that Im not driving but rather riding a horse.

 

Today I did as Steve suggested and closed the air injection past the plastic check/ cutoff. I started the car and the idle fluctuated when cold, I connected my meter to o2 single wire and ground while o2 disconnected and gave me a .5-.7 dcv and the idle stabalized as it warmed up. The car did sound different overall, and I am hoping this was the problem. I will check again tonight to confirm the numbers I got with my meter, and I also need to order the parts. If anybody has the cross reference numbers please post them for an 87 mondial cab 3.2. Ferarri has it as valve/check 121769 and valve/ cutoff 147390. Thanks once again Steve, I will keep posting to deny/confirm fix.

 

I love ferrarichat, it has become my #1 site. Steve Magnusson, thank you for doing what you do.
I fixed the air injection system with new hoses, check valves and cut off valves and it did make some improvement on the car, but that was only part of the problem. I am finding out this mondial is going to need alot more TLC. Lucky for me, I have Fchat and I am going to need some more help.
I have been reading several threads so as to check my car. I found out my slow down light does not light up in the dash, somebody took out the light bulb. I put in a new bulb but just like I suspected the light stays on and does not turn off at all.How I should I go about in fixing this? I did ordered a new Magnaflow cat, will this fix it? Is this also a cause for my mondi having poor performance.

 

I hope im getting my procedures correct, I turn the key and the slow down light lights up, then I turn the car on and the light is still on. I disconnected the thermocouple and measured the ohms between both wires and got 12.5 ohms, so I think the thermocouple is good, does this mean the ecu is bad. I price checked the ecu and well 1500, wow. I guess I should hope im getting my procedures incorrect and that the ecu is good.

 

Raul, I hope you get the bugs out soon. There are lots and lots of smart guys who know their F-cars extremely well on this site. Steve is definitely one of them. I'm sure you'll get her running smoothly. I wish I could help but I'm a rookie as well. From this one thread, however, at this rate, you're going to end up as a F1 World Champ before I even get out of Karting! LOL

Good luck.

 

Steve, I connected my multimeter to the o2 and ground, while o2 still connected to ecu and cold. I started the car and I got a reading of 5.4 v while warming up. As the car is warming up the dc volts start dropping slowly all the way to 54.5 mv and the idle and the multimeter are going up and down. I disconnect the o2 and get a reading from the o2 of 23 mv, would I be correct to assume that the car is running lean and I must have another air leak, or is this a fuel pressure problem. When I disconnect the o2, the car runs fine but the o2 reads lean, so what do I do next.

 

Thank you Jgoodman for those words of encouragement. I feel I’m pretty much on my own trying to fix this car. I am not a mechanic; all I have is Fchat and anybody willing and patient to guide me through the procedures. I did take the car to a mechanic, but the car sat there for months at the back of the shop. I don’t think the mechanic wanted to fix the car, I guess it’s not cost efficient.

 

The 5.4V seems oddly highish to me, but the output from an O2 sensor when physically cold is meaningless (and your air injection system would be running when cold anyway unless you've disabled it).

Don't quite follow this - are you saying that when "the idle and the multimeter are going up and down", the plugged in O2 sensor voltage is varying but never exceeds 54.5 mV?

Only if the O2 sensor is giving a meaningful value (and the air injeciton system is off, no air leaks, etc.).

This is unusual. At this stage, you need some other verification of the exhaust gas content at the O2 sensor location (i.e., upstream of the cat). Another test would be to manually turn the mixture screw to add richness in this condition (warm idle with the O2 sensor unplugged) -- if the O2 sensor voltage didn't increase to ~0.9V that would confirm that it could never run closed-loop properly.

 

Thank you once again Steve for your help, I have learn so much from your many posts and threads. I think at this point I am very close to fixing the car but I also think I’m killing the car. The car is not running rich anymore as before my cloths would smell like fuel fumes, but I checked the oil and the oil smells like fuel. I took the car back to the shop and I am hope it will not sit there for months. I know it will be something so simple I overlooked.