Wierd electrical problem: Delta integrale evoluzione 1

[prc87]

Help!
My auto electrician and I are struggling to remedy a wierd electrical problem.

Symptoms. Car cold starts OK, but idle jumps to 2000rpm. Warms up and runs OK, but idle remains high until shut ignition down. Sometimes at warm restart idle returns to normal at 850rpm, other times idle remains high at 2000rpm. Disconnect wire from idle air controller while car running and idle drops immediately to 850. Reconnect plug and idle climbs back to 2000rpm. Throttle position sensor perfect at 0.5V. Factory diagnostic shows IAC at 90%, when it should be 0-5% when warmed up. It's almost as if the ECU thinks the car is not warm...mmmm...something or some sensor is obviously confusing the ECU.

Any and all suggestions gladly received!

Many thanks in advance.

[sparehead3]

Hi Peter,
I was going to suggest having a look at evoforum but I see you're already there ...

Steve

[prc87]

Thanks Steve, appreciate you steering me there. Another member sent me a private message with the same suggestion, so I registered and asked the question. Thanks!

[Neil Lewis]

Sounds to me like the "standard" integrale problem; a malfunctioning temperature sensor.

After-market sensors are about £5 in the UK (Fuelparts WS1044 for an Evo; Intermotor sell one too; sorry don't know that part number).  Don't buy them off Ebay, you'll just get the same sensor at three-four times the price!  Original Fiat/Lancia ones go for about £25.

However, in my experience it's more likely to be the wiring than the sensor.  The AMP connectors are not waterproof (although they are meant to be when new), the rubber boot perishes, watre gets in and the terminals corrode.  That's enough to change the resistance the ECU sees and car thinks the engine is cold and over-revs the engine at idle.  The worst sympton is not being able to stop at roundabouts after a blast down a dual carriageway; very worrying!

So check the terminals first; brush the pins on the sensor and the sockets in the AMP connector with some "trike" solvent using a small brush.  Serious corrosion may need some small strips of wet&dry paper.  Put a smear (really just a smear) of copper grease in the connector before you put it back together.  If the connector is too far gone the same connectors are used on most BMWs so they're easy to find in breakers yards.  Snip them off the BMW and solder the wires to the snipped off wires on the Lancia; polarity isn't important.

Changing the sensor can be done with the engine cold using a deep 19mm socket.  Not much water will run out but if the engine is even slightly warm, you'll be sprayed in the face with antifreeze.

Neil

[prc87]

Neil

Thanks for your detailed explanation - most helpful! We had been wondering about wiring and connectors. I'll let Nathan (foreman at my service specialist and overseer of the auto electrician) know on Monday.

-prc.

[Neil Lewis]

I realised after I wrote that, while I had the Evo part number correct, I had described how to remove the 8-valve sensor.

The Evo temp sensor is mounted underneath the water manifold on the gearbox side of the engine.  So it's a bit obscured by all the pipework around there and probably will spray some water out.  Not enough to consider draining the engine though.

Neil

PS
Also look at the Idle Control Valve thread in this database.

[prc87]

Thanks Neil (and others!)

I've trawled through this forum and Evocorner and have found several threads that talk about the same sort of problem I'm experiencing.

It seems the TPS may need further adjustment, and/or the air temp sensor may have been knocked, and/or some wiring/plugs might be faulty. We put a second ICV on the car and the fault remained, so VERY unlikely to be that part.

Car is going back in on Monday - will let you know how I get on!

-prc.

[prc87]

update.

After about six hours  trawling through forum databases and postings, the general consensus seems to be that the TPS on my car is incorrectly adjusted - and this is affecting ECU outputs (including ICV signal).

The factory manual states the TPS voltage (engine warm, at idle) should be 0.5V, but common experience states that 0.25-0.27V is much more appropriate. Indeed others with exactly the same symptoms as my car has demonstrated have found the car returns to normal acceptable behaviour after the 0.25V adjustment is made. Strange but true!

Fingers crossed when the car goes in tomorrow morning - will be checking all AMP connectors and cleaning them with connector cleaner at the same time - I'll let you know how I get on.

[Neil Lewis]

update.

The factory manual states the TPS voltage (engine warm, at idle) should be 0.5V, but common experience states that 0.25-0.27V is much more appropriate. Indeed others with exactly the same symptoms as my car has demonstrated have found the car returns to normal acceptable behaviour after the 0.25V adjustment is made. Strange but true!

I've recently fitted a new TPS to my 8-valve and, since someone broke the club's F&L Tester, I had to set it up with a multi-meter.  From my experience with other ECUs (where the sensor range is usually 0.5 to 4.5) I set it to 0.5 volts and the engine idled really roughly.  I tried adjusting it by "feel" and it ended up set exactly at 0 (zero) volts and it's been like that for three months now.  Seems to work just fine.

I was worried about getting the over-boost at full throttle but, set at zero, it over-boosts just fine too.

BTW I found the setting has to be done with the engine running or the voltage fluctuates too much.

Neil

[prc87]

Neil et al

What a difference a day makes.

I drove the car in to the city today - 28km mostly motorway (100km/h) except for first 4km suburban and the last 1k CBD. I was under instructions to present the car if the ECU light came on. Well it did, so I presented the car!

Told Nathan and the team about my research (0.25V TPS, clean connectors etc etc) and he got to work. Collected the car car tonight to find:
1. TPS no set at 0.24V
2. ICV reconnected
3. all AMP connecters thoroughly cleaned
4. car idling smoothly at 850rpm

Wonderful, just wonderful!

Nathan has installed his Fiat Lancia Diagnostic Tool inside the passenger area so that I can monitor performance (including immediate knowledge if the red light comes back on).

Fingers crossed though the problem has been resolved and I can get back to enjoying my car with confidence.

A BIG thanks to all who made suggestions!

-prc.

[prc87]

Final update

After running the car through a few stone cold start cycles, we have discovered the car is rough for the first 30+ seconds after ignition. Throughout experimentation, the TPS has been adjusted to 0.28V (warm, idle, ICV disconnected), and the startup behaviour seems to be MUCH better.

I'm going to try 0.30V to see whether a couple of more millivolts improves the situation further, or makes it worse again.

Anyway, problem appears to be fixed and I can get back to enjoying the car!

Thanks for all your help and suggestions.

-prc.