Mondial T - rough idle, tach way to high

Hi,

I have a 1990 Mondial T (i.e. motronic 2.5) that idles rough, seem to overheat right cat and the tach is most of the time showing 4500 when idle (engine revs are around 1000 I would judge) cold as well as fully warmed (fans kicked in). To start I need to press the gas pedal a little bit.

After checking sparks I can see that I have sparks on all cylinders on the right bank and the left bank.

I did a second test run after checking the spark and occasionally when you drive with a bit of engine rev the tach will show real rev (over 3000) and it will run fine with a more "turbine sound" compared to the stuttering when she misses. When driving with even gas she will stutter and "pull" most of the time though.

I am thinking crank sensor issue - am I way off?

I will lift her up and check the connections for the crank sensors, anything else I should look at?

Cheers, Niclas

 

Thanks for all the help!
I ordered the Kia crank sensors and will pick them up and install them tomorrow (a tip if you are in Sweden, Thurebergsbil in Upplands-Väsby carries spare parts to older Kia models, I had to call quite a lot of Kia dealerships to get hold of the sensors).

I will definitely take a second look at the vacuum hoses, in fact I fiddled with them to check if they were lose and that could have accounted for the better running at the second test run.

Alternator is on the rebuild list in the major service I plan to do next week...
...and I am ebaying after Stabilant 22a for all connectors and ground points, I will make sure to give ECU ground an connectors a good clean and some Stabilant when it arrives.

The right O2 sensor has been spliced on to the Ferrari connector, probably a good idea to redo that work and measure the sensor at the same time - I was though under the impression from My Ferrari 348 that the O2 sensor only come at play when the engine is warm?

Of cause I can have several issues at play at the same time...

Cheers, Niclas

 

Thanks for the optimism Dave!

I exchanged the crank sensors, but there was no change in the engine behaviour unfortunately.

Tomorrow I will have a go at accessing the status of the alternator, there was quite a lot of crud around the front of the engine due to a small oil leak (seem to originate from one of the couplings for the oil lines) and the alternator was quite dirty.

I started to determine which cylinder is out by pulling a spark plug cap, starting the engine, and noting the difference. I would say that removing cap from cylinder 1 made little or no difference while removing the cap from 2 worsened the behaviour. I will continue that tomorrow.
I also removed spark plugs to take a look at them to try to determine which cylinder might be out (they are brand new so they should be only affected by the current running) - by some brain dead behaviour I started on 4 and worked forward instead of following the order I used when disconnecting the caps. 1 was clean with a little petrol film while 2 had a little bit of soot build up already and a petrol film, I will check the rest tomorrow.

One funny thing though - I noted that the spark wires are dressed with heavy duty fuel lines and has a small tape on them with a number - I thought the previous owner might have numbered them to make sure they are on the right place but taking a closer look I realised that it is decimal number on them with values typically between 6,17 and 6,22 (5 on cylinder 4). Sounds like some measurement to me...

Cheers, Niclas

 

I measured the voltage over the battery to 12,9 volt with the engine off and with the alternator on idle to 13.5 going up towards 14 and over when revving the engine. When revving the engine I saw the voltage drop initially for half a sec and then pick up.

I recorded a shaky mobile phone video and the engine was definitely running nicer today - and for the first time I got a Slow Down light! Slow down 1-4 lit up just after I shut down the video.

Link:
Mondial T, rough idle - YouTube

Cheers, Niclas

 

Hi again - just a short update,

I disconnected the battery (I have done that 2-3 times before over night to make the ECU re-learn with little improvment.)

I then cleaned the terminals of the alternator with my Dremmel, the ground connections on the fire wall and also the ground strap between the engine and the subframe.
The strap seem to be in good condition, I noted that the connections was drenched in copper paste and a the surfaces was a bit dull.
I am not sure about the usage of copper paste on the ground strap, the stuff I have does not list is as being conductive - only corrosion inhibiting and facilitating easy removal of bolts and nuts.

I removed the MAF's, cleaned them with electronic cleaner (non-residue stuff) and calibrated them to the factory default 383 - they read 470 and 475 (lean compared to factory default if I am not mistaken). If I get the car running ok I will tune it based on the O2 reading as described on this forum later.

While I was waiting for the MAF's to dry I changed the air filter and cleaned the connections for the O2 sensors.

Yet to do is to clean the ECU grounds on the cam covers - I can not for my life find them though ... ...and then I will clean the grounds under the dash as well and start her again.

I will take a look at the Thermocouple ecu's as well - and try disconnecting them if she still runs bad.

When I switch on the key I used to only get lamp test for brakes and the 3 red lights in the tach - lately I get lamp test also for the slowdown lights - but I have not seen the check engine indicators at any time. I read in a thread on another forum that lack of light test would indicate a faulty ECU...?

Cheers, Niclas

 

Well, thanks to you Dave my cam cover grounds have now magically appeared - I can not understand how I missed them!

Anyway, just got an hour to work on the car today (I was ordered to the beach, quite a waste of time I would say.)

There was a bit of green fluff on the connections and I noted that the ground points were painted red and not clean metal. I understand that the idea is that the pointy washer should penetrate the paint and give connection but I decided to polish away the paint (I rather do a yearly routine of polishing the grounds then hope that the washer provides adequate connection). I also polished the connectors and gave the whole assembly a nip of connection spray.

One cam cover ground to go and then I will hunt ground points under the dash and see if I can reach the bulbs for check engine lights. The weather guys has promised rain and cold weather tomorrow so I should be able to avoid the beach and get some work done...

Cheers, Niclas
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Hi,

Time for a update, I removed the alternator and had it renovated - it had a broken "diod bridge" according to the renovator. Unfortunately they put it together wrong so the attachments points did not line up and I had to take it back for adjustment (they did a mark on the front and the body on one of the ridges but a previous renovator had done the same markings on another ridge so they aligned them wrong).

While I was waiting I had some time over and removed the exhaust to check the cats and they look fine. I also checked the light bulbs on the annunciator strip by removing the plastic window and they are all there at least, but I could not remove them with the tools I have (the light assembly seem to move inwards when I touched the bulbs) - or do I need to remove the dash to change them?

With the alternator finally assembled I started her up again today.

The tach works now as it should and I think she runs better but a bit nervous on idle around 1000 rpm.
I let her idle 10 minutes and checked the cat temp regularly, the left cat reaches around 180 C / 334 F while the right goes up to 270 C / 530 F but it stayed there, previous it started to glow.
After 10 minutes of idle I did a test run, right away the engine stayed on 2000 rpm - occasionally it would drop down to normal idle if I revved it lightly. Giving a bit of gas revealed only that I will need a new clutch... I stopped occasionally and checked cat temp but it stayed steady on the temp above, on the second stop I got the slow down light 1-4 when idling so I shut down the engine waited 10 minutes before I started, I needed again to give gas to get her to start and the 2000 rpm behaviour was still there.

I suspect that bank 1-4 might be running in open loop due to the high rpm and warmer cat...?

Here is a link to a video after 10 minutes idle:

Mondial T after 10 minutes idle, renovated alternator. - YouTube

Cheers, Niclas

 

Hi again,

After switching sides on Cat ECU's and then the ECU's with the issue with rough running and hot cat still on the right I moved on to measure the resistance of the ignition cables (all having around 6,12 to 6,35 Kilo Ohm), I decided to measure the fuel pressure from the fuel regulators before I go on with switching ignition modules etc...

...and now I am confused!

I had the wife to control the ignition key since I bought an el crappo pressure gauge that basically just has a cone that you insert in the fuel line you want to test.
I measured at the fuel line that goes into the fuel rail from the regulator and got no pressure on ignition key position one (as expect as I understand) but also on position 2 I got no pressure (waited 10-15 seconds) and even a 1-2 seconds of cranking yielded no pressure - and no fuel either (line was dry when I removed the gauge)...

I tested both sides separately since I only have one pressure gauge and need to hold it in the fuel line and I got the same behaviour on both sides.

I put back the fuel lines after applying liquid thread sealing designed for fuel/oil/gas and had the wife to crank it and after 3-4 seconds the engine started to ignite.

Funny enough it run like a sewing machine for 10-15 seconds before it started to stutter and idle rough as usual...

Should I attempt to measure the feed to the fuel regulator just to check the fuel pumps or did I do something wrong perhaps?

Cheers, Niclas

 

Hi,

After reading some treads on issues with idle air valve I decided to clean mine with MAF cleaner and switch sides - they seemed clean already before I cleaned them and switching did no change.

Then I measured the output from the O2 sensors with my multimeter in line with the connection - positive terminal on the output connection and negative on the contact since I wanted to see their behaviour when connected. The left sensor achieved 465 mV and held steady there but the right was all over the place, jumping several times per second from 50 mV to 1,2 V to 350 mV to 0 etc and then it would sway around 260 to 370 mV for 5-10 seconds and start jumping again. From what I have figured that is not an expected behaviour...?
I will replace that one and see if I get another behaviour from a new sensor...

Cheers, Niclas