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Discussion Starter · #1 ·
Hello forum and thanks for having me on this forum. I've read a looot and learned many new things here for the past week or so.

I am back to the Italian brand , this time an Alfa 147 TS 1.6 that someone had forgot about for the past 5 years. (owned a Fiat Coupe 20VT some 15 years ago).
Car has been sitting in yard for the past 5 years as the previous owner could not have it started because of an IMMO / ECU problem.
Long story short. Got this car for free as the owner did not wanted it anymore. Got it started, fixed immo, fixed BCM box , brakes and now it runs and runs nice WHEN it wants :)
The problem is a rough / lumpy idle EXACTLY like in this video :
Sometimes , runs perfect and very nice, but most of the time like in the video.

What have I done and tested until now :
- Cleaned all coils
- Changed oil and filter (had a noisy "diesel start" variator, engine flush + new oil and filter cured it ... for now).
- Reset ECU and throttle body few times.
- Checked and cleaned the earths all over engine bay.
- Checked and cleaned Throttle body (was actually very clean).
- No codes on ECU,
- Checked all spark plugs and they are all ok except one that was cracked and had it replaced.
- Changed coolant sensor.
- Flashed ECU with 3 different software versions.
- Checked and cleaned MAF

Nothing helped, nothing changed.

Findings :
- If I reset the ECU while car is running , it will idle perfect for a few seconds. (This is very wired)
- If I unplug MAF still runs lumpy at idle like video.
- unplugging one coil at the time makes no diference, still as lumpy as hell.

Spent like the last 5 days all over the engine bay.

Any idea where to head from here ?

Thanks again for all the information you shared here.
 

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Fuel supply.
Moisture in tank perhaps.

When fault happens, will it still take throttle or os a rough idle all it's capable of?
 

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1st Sticking valve train usually hydraulic lifter charge hole blocked.if it's been standing for a while it would explain the rattle.
Warm up the car until up to temperature. Over a 15 seconds gradually increase the revs until 3000rpm then reduce to idle over 15 seconds. Another 15 seconds idling then repeat the whole process 20 to 30 times.
2nd How long is it taking to get up to temp on normal driving?
It should take no more than 5-6 mins or 4-5 miles on a TS. Any longer then the thermostat is sticking which will cause a lumpy idle up and down in a regular pattern as the ECU adjusts between cold and nominal running temp conditions. If it can't read what the thermostat is doing via the temp switch, it can't discern the difference!. Thermostats on many a TS that's been standing for a while tend to stick.
3rd pcv valve blocked, causing idle to fluctuate it's the little black plastic connection that attaches the breather pipe to the plenum after the throttle body. Carefully remove and give it a clean out with carb cleaner then refit.
There you go, if they don't cure it at least it eliminates a few more then it gets a little more complicated and pricey afterwards.
 

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Discussion Starter · #5 ·
1. Will definitely try this one tomorrow and see how it goes and if it makes a difference. With the old oil in it (which I think it was 5w30 ) it was making noise on lifters when hot, with the new oil 10W40 no more noise. Old oil was very clean though.

2. It does not take long to get warmed up. I have also changed the coolant temp sender on the thermostat, that is new, guess next step would be to take out the thermostat and check if is sticking. I will put the tester on it again tomorrow to check temperature readings. Can't drive around with it to much as I have no plates on it, need technical inspection first. So I take it for a spin on the dirt road across the street. Lucky I don't live in the middle of the town :)

3. PVC valve checked, tried to blow on it and it opens. When I try to suck air out of the breather pipe it closes, so I guess that one is ok.

Today I also took appart the throttle body and checked all the graphite paths and wiring and everything seems to be ok there.
On monday I also expect the new ECU and will try that also.
Tried to remove the O2 sensors from software and without O2 check it's running very smooth at idle. 2 new O2 sensors ordered also.

Thanks for the tips, will get back with some updates.
 

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Discussion Starter · #6 ·
Saga continues ... more unexpected things start to show up.
Found two cracked hoses that I have no replaced , but the idle is the same.
Working the speeder up and down as instructed by Grahameo does not help either.

If I take the car for a ride and drive for a few km when I stop and let the engine idle it will idle perfect ?!

If I drive the car a bit more harsh, over 4-5000 rpm it will start smoking badly and smells as burnt oil :(
If I drive it normally until 4000 rpm and not hard , no smoke no nothing.

So I think the rings might have seized because the car was sitting for the past 5 years ??
This might also be the cause of lumpy idle...

I have decided to stop investing money on it because if this is the case it will cost me more and more.

Thanks everyone for the help and tips.
 

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Discussion Starter · #8 ·
Well, yesterday I also changed the ECU (as I had it ordered last week) and spark plugs and MAF and O2 sensors.
Took some temporary plates and took her for a longer ride.

Smoke amount has now decreased, does not smoke so bad as before after the longer run.
Idle is getting better but not always stable.

I am also thinking timing might be off a bit .. as if I drive with the timing variator solenoid connected it will start making "prrrrrrrrrrrrrrrrrrr" (machine gun like) noise from the solenoid area.
If I drive with the solenoid drives smooth, I can just feel a bit of hesitation around 5000rpm.

Today I will try a bit longer drive to see how it feels after running for a longer period , thinking if it is oil rings seized they might come loose.

Also noticed "Low Oil Pressure" light coming when engine is hot and park the car letting it run at idle. Oil coming just fine in the top and oil level is also ok.
Bought the sensor to change today.

This car starts to be a pain but I simply love the way it drives and feels. Just like my old Fiat Coupe ... some strange nice feeling while driving :)
 

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When a car sits for so long it tends to brake itself apart over time especially an Alfa :rofl:

The timing for your engine was done 5 years ago according to the marker on your engine ( !!! ) you're engine is the 120hp model , use the lockers for your timing if you do the job yourself.

The variator solenoid sounds dead or surging for oil pressure, rebuild it if necessary. Using 10W60 fully synthetic oil will help your engine to run smother on the lifters, only con is it needs more time to heat up during cold starts.

Check for air leaks around the intake, hoses with some carburetor / oil spray on and see if it changes idle.
 

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Discussion Starter · #10 ·
The variator solenoid sounds dead or surging for oil pressure, rebuild it if necessary. Using 10W60 fully synthetic oil will help your engine to run smother on the lifters, only con is it needs more time to heat up during cold starts.
Can the SOLENOID be rebuilt ?
I took it apart and there is only a coil and a magnetic core actuated by the coil. What to rebuild here ?
 

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Another solenoid would be the cure. I've not heard of one failing before but nothing is impossible.
It also could be voltage/current reduction reaching it due to poor wiring/terminals.

Of more concern is the low engine oil pressure light illuminating. Again, it could be wiring or the switch itself but it could also be wear in the engine which would be costly and time consuming and really not viable. When the engine heats up, the oil thins and flows more easily. Oil pressure is simply resistance to flow. If it flows out of the bearings easily or has insufficient flow in the first place caused by a worn oil pump, then it would likely illuminate the oil light when warm when the engine idles.
 

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Discussion Starter · #12 ·
Of more concern is the low engine oil pressure light illuminating. Again, it could be wiring or the switch itself but it could also be wear in the engine which would be costly and time consuming and really not viable. When the engine heats up, the oil thins and flows more easily. Oil pressure is simply resistance to flow. If it flows out of the bearings easily or has insufficient flow in the first place caused by a worn oil pump, then it would likely illuminate the oil light when warm when the engine idles.

Does that :( Really don't wanna rebuild this engine. According to the invoice from previous owner this engine has only 80.000km on it.
 
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