Mondial runs badly 20 minutes after starting

IMO it sounds like fuel supply. Firstly, ignition performance is strongly dependent upon throttle position (manifold pressure), as a good spark is much harder to generate under high compression than light throttle. The fact that backing right off doesn't restore smooth running tends to tell me its not the ignition.

Secondly, I assume that the FI system has a "full-throttle" circuit (like carbs have power jets), and it is therefore quite possible that under the conditions you experience, the "normal" fuel supply circuit is having problems. By going to full-throttle you are probably activating a separate second supply circuit which may explain why it goes when floored but not when not (?).

I'd check-out the FI system. How it could be temp-related I'm not sure, but these engines DO take a long time (at least 10-15 mins) to get up to full operating temp. Maybe there is a sensor for the FI that kicks in/out at that stage & that is what is playing-up. Do you have the '8' electrical diagram?

 

Have you checked the ignition advance curve? What is your CO set at? Are you sure that the throttle plate and TPS are set correctly? Has the EGR valve been checked?

 

It sounds like fuel problems, email me with your # and I can talk you through the tests or can reccomend a shop in your area that is very good with your type injection system.
Larry

 

Check your PM.

 

I went thru the same thing with my 82 Mondy it was driving me crazy, 20 - 30 minutes while driving it the would do the things you have describe, changed -fuel filter, coils, injectors, cap/rotors,plug wires,plug extenders and even the fly wheel sensors and still run bad after 20 -30 mins. of use.
It turns out that I had bad Catalytic Converters (original one's) when they get hot it would plug the exhaust flow - the technician used a pyrometer gun and confirmed that the Cats were bad.

Randy

 

I'm confused on this one.

What temperature was the technician reading? Off the heat shield or the can?

 

Paul,
This happened to me a couple of times. Chased down a problem with the ignition / fuel systems, fixed same, then still had a problem. Solution.....change the oxygen sensors. When the car isn't running right, this can kill an oxygen sensor quickly. You fix the base problem but still have the symptoms. Change the O2 sensor.

Tom

 

I think he was blowing smoke up your skirt on this one. Way too many variables to test it that way.

If the cat was bad, a simple HC/CO test on the exhaust system would confirm it.

 

Paul,
Oooops. I forgot.
I'm not depressed. It was time to move on and i'm looking forward to my new ride, MINI Cooper S, due in mid-April. In the meantime, i'll keep pondering your problem and see if I can't come up with something.

Have you looked at the ECU? If yours is located where mine was....in a well in the floor of the trunk....it might be wet. This area is prone to leaks and any water settles in this well. A few months ago, I pulled mine and discovered it dripping with water. Dried it off, repaired a couple of wires that had broken due to corrosion, replaced the O2 sensor, and it was good to go.


Tom

 

FWIW: In the parts manual, TAV 14 it doesn't show a TPS (Throttle Position Sensor) and that seems to be standard on the 2 valve injection. No Oxy sensor either as was earlier noted, although I have seen similar problems occur in the case of a fouled or bad oxy sensor many times. I wouldn't put the cats out of the picture entirely just yet, I believe I would also check the WUR as it can easily cause mixture variations, which would cause the Cat Cons to become plugged. In Randy's case, did the cat cons get replaced? And how did that effect the problem?

 

I am quite sure the advance should be much less at idle. 30 degrees sounds like what it should be at and above 3400 RPM. (At least it is on a 308GT4 but I doubt your Mondial is far different). It could very well be a sticking advance system. This could explain why the engine runs well at higher RPM but not at lower.

Gerrit

 

I am not sure about the early fi in your car but my 86 had a frequency valve ,and a relay with a fuse on the top of it . The relay is in the trunk and the valve is on th fuel distributor. The valve is what sets the fuel pulses for the system to work ,if it gets out of wack or if the fuse goes bad the car runs like you are describing ,,but I can't figure the 30 minutes after car is started,this is a tough one ,you must let us know what the fi guy finds
dazed and confused DAVID

 

While I wont discount the other possible culprits, such as ignition, (from many angles starting with the flywheel sensors, on), I would mention the text found in the book I have ben using that has been more than helpfull.
The manual mentions the fact that the WUR has a more correct nomenclature in calling it the Control Pressure Regulator. This is derived from the fact that it has many more functions than just the Warm Up Cycle, which include low manifold pressure enrichment, which fattens the mixture during sudden opening of the throttle, getting the signal for that function from the vacuum line after the throttle plate, and also an altitude adjustment, which gets its signal from the sensor line before the throttle plate. The book is very clear on it changing the fuel pressures, and the resultant as the result of two inputs for the source of heat. The first being of course the bimetalic arm that is acuated by the electrical connection to the ignition, (doesnt hurt to check electrical connections). But the second is the proximity to the block as a direct source of heat. This makes me wonder, would any changes in block temp, air flow around the regulator change the output? I would think so, as if it is dependant on motor heat, any changes in the way it percieves or recieves this heat may very well effect it's running and would take a while to appear. It may be worthwhile to check the condition of th two hoses that run into the TB for leaks, as they can really make a differance I can tell you from experience. A small, hidden split may be all it needs in what the unit recieves in signals, and as a direct result, what it sends out in pressures.
As to the need for a flame proof suit, LOL, the Bosch system has been on virtually every European Auto Makers at one time or another, and a few on the shores on the other side of the big ponds (Japanese), so it may be possible to find assistance from a wide variety of sources.
So it might nothurt to wiggle a line or two, and check the electrical connections.
Disclaimer: Just gladly sharing information, no referances to sales in any way, shape or form.
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In addition to all the excellent suggestions so far (Especially the vacuum line leaks) you should take a careful look at the polarity of the primary (low voltage) connection of the coil/s (sorry, but I'm not very familiar with the exact type of ign. coils on your car). I am assuming that you have one or two "cylinder-type" coils with a king lead and distributor/rotor arm etc. If you do not, or the low volt connectors are keyed to prevent incorrect connection then ignore the comment.

If you (or someone) has inadvertantly reversed the low voltage coil connections so that voltage is flowing in reverse you will eventually have the symptoms you have described, and also problems re-starting when hot .

The issue is not immediately apparent because it takes some time for the spark plugs to erode to the point where the spark will not make it across the gap, so the problem develops over-time.

Failing that you should try & borrow some new ign. coils from somewhere and try them just to eliminate this as a potential source of the problem. The dialectric insulation in the ign. coil can break down when hot, weakening the spark at the plug itself.

Last point, make sure everything is clean. An amazing amount of crud builds up in all the tubes, passages & vents over 20 years (and not just in the driver) Sometimes just a good clean can do the job.

Good luck, these problems are a pain in the @?@@ until you find the root cause, and then suddenly very rewarding !

RF.

 

Great ideas, RF.
I am certanly with ya on that one, especially the very last, LOL. How true!!!
Sales diclaimer, Blah Blah. Samo Samo.
Kermit