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156 JTS 1.0 2003 - cold start idle surge

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2003 cold surge
3K views 15 replies 3 participants last post by  156and33 
#1 · (Edited)
Hi
Over the past few months I have noticed that the startup engine rpm is higher than I am used to. Th engine races momentarily to about 2000 RPM before returning to normal idle and otherwise behaving normally.
Recently, I had to replace a coil pack on #1 and did an ECU reset. First cold start was better, ~1500 RPM. Second start next day, back up high. Temperatures here are about 15Celcius.
No fault codes, no cracks in hose to air flow meter that I could see by quick inspection.
Worried about engine wear.
Where should I look next?

I made a mistake in the post title - can an Administrator change the 1.0 to 2.0 ?

Thanks.
 
#2 ·
I've had similar with my 156. When I called the RAC out their diagnostics came up with throttle issues. Mine turned out to a dirty throttle body. Very occasionally the engine management light comes on, but only when it ticks over high.

It is intermittent and a little annoying, but it's not fatal.
 
#4 ·
Still no joy.

I removed and cleaned the throttle body wih carby cleaner. Plenty of black residue around the lower part of the plate on both sides.
Reassembled and reset ECU?
First cold start, idle was normal, ~1500.
Second and third cold start, rpm races to 2500, before setting.
My scan tool, shows TPS percentage at WOT =100%, and 7.8% when engine warm but off.
I will recheck TPS%value when engine cold.

Can anyone provide further fault finding instruction? I can probe the signal voltages and even look at the signal with a DSO if needed (would be the first time).

Should the throttle plate shaft be lubed after cleaning?
What should the TPS % be when warm and cold?
Are there other likely causes, such as warn accelerator signal module?

I really don't like this high revving at all!!!!!

Thanks
 
#6 · (Edited)
Found a lot of oil residue under the inlet manifold, seems to be originating from the bottom of the throttle body where it joins the manifold. This could be a source of air leak. Anyone know an aftermarket supply for those large o-ring seal at the base of the throttle body?

Bad luck, snapped this pipe on the flexible air intake pipe. Managed to weld it back together but if anyone is wrecking a vehicle and could provide this shipped to Australia I would appreciate it.

Cheers
 

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#7 ·
Ok, the main cause of fast idle in these cars is an air leak AFTER the Throttle Body, and it's rarely the seal.
Just after the Throttle body you will find the plastic hose for the Brake Vacuum, it gets brittle, if it is broken or cracked, will cause the high idle.

The other main cause, and the usual, is right next to the Brake Vacuum line is the Crankcase Breather Valve. You will notice at the top right of the engine a soft hose going to the intake manifold attaching via plastic cylinder just behind the Throttle body. This valve is only supposed to open at high rpm, but the little "Golf Tee" valve gets gummed up or the spring under it get weak or broken. Thus at low idle rpm it will then open, causing the high RPM.

Here is a link with a little more info on it.

GUIDE - Breather valve replacement - Guides & How to's - AlfaDriver Forum

If you have any further problems or cant sort it, you can contact me as I am also in Brisbane and run my own Mobile Alfa Romeo Diagnostic and Servicing business, so if your stranded, can come to you.

I have sent you a PM with my contact details

Baz
 
#12 ·
NOT FIxed

Apparent fix of problem was only short lived. I have cleaned the PCV valve several times now, including the barrel as well as the valve with cleaner and polichsed any roughness on the valve. Seems to work for next start but not the one the following day.
 
#16 ·
No one has one that I can find. EBSpares are thinking about having something made. All other online suppliers that I looked at indicated that it was a discontinued product. Dealers in Melbourne have told me they never sold sny an there are no stocks in Oz.
The other thing I should add is that I have seen a leaking rocker cover gasket that Is relatively new. Perhaps that also points to the valve malfunctioning.
Squeezing off the hose did reduce the initial start up idle down below 2000rpm.

Can anyone source this item?
 
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