405 GTX '96 stalling problems

Hello all,

I have a problem with my 180K mile 405 which has today escalated to the
point of being unmanageable and before I go throwing sums of cash at it
I figured I would ask here.

The car drives normally however when pulling up to junctions or lights
and lifting off the throttle the engine dies. It will restart however
it wont idle. It also has a stutter which I had thought I had cured
when I replaced the plugs and HT leads however this has returned as
well. The fault is also intermittent and I can't get the error codes
off the ECU as it doesn't appear to start the diagnostics.

Any help would be nice, even if anyone can point me in the correct
direction for diagnostics.
--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

I don't know if it's in any way related to what is causing your problem but
I have had a very similar problem on a VW that turned out to be the EGR
(Exhaust Gas Recirculation) system.
The pipe for the EGR valve had split, and was letting in to much air,
causing a very lean mix.
The car seemed fine most of the time, but would stall when pulling up and
rev the pants off itself when you put your foot down..

If it's not the ECU, I would take a guess at either a crankshaft/engine
speed sensor of some kind! - or an air leak.
The ECU can only work with the info it gets given from the sensors, so it's
either a faulty sensor, or something is fooling a sensor - i.e. air leak...
that the ECU has no control over.

You don't say what engine you have..

Andy

 

Change the Idle Stepper motor

Pete

 

Mine did exactly the same, and it was caused by a vacuum leak. Open the
bonnet. Right at the front near the bonnet catch, is a sensor connected to
the intake manifold, via a thin piece of tubing. I suspect it's the MAP
sensor.

Anyway, my tube had split. Duct-Taped it up, and all was well again.

 

Hi,

Duct Tape is wonderful. Say, at least as wonderful as WD40. It cured the
exploded expansion tank of a friend's 750 Stinger for over 300 miles ! I
could tell you the story if you wanna have some fun.

 

That's been done when it failed last year.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

Nik&Andy wrote:

Its the 2.0 litre 8P magnetti marrelli fuel injected version.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

I have spotted this and will have a look at the condition of the pipe.
The intermittent fault would hint at an electrical fault though.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

The Stepper Motor Electrical Connector can give trouble.
Give bothconectors a good clean with Iso Propyl Alcohol.

Pete

 

Nah, mine was also intermittent. The split opens and closes depending on
what's moving around, and the Idle Control Valve will try and compensate for
the leak. It'll only stall when the ICV is closed, and the split closes
too - meaning the engine gets no air. At least, that's what I rekon

 

I found a split in the MAP tube and cut the tube back to get rid of it,
the car has been running fine since.

--
Martin:
"For a minute there, you bored me to death."
VTR1000 Firestorm
TDR250 http://ukrm.net/BIKES/Yamaha/tdr250.html
martin dot smith nine zero three at ntlworld dot com

 

Hurrah !

 

What a useful resource!
This morning my 405 2.0 GTX auto estate displayed the same symptoms -
reluctant start, failure to idle.
The quick solution was to jam some kitchen paper between the clip and
the throttle cable holder to keep the revs to 1000.
After reading these submissions, I took a look under the bonnet.
No obvious signs of split tubes (there are several) and all
connections looked good. I gave them a powerful glare and then started
the engine. With no problem - except that the idle was too high. I
removed the kitchen paper which brought the revs back.
It seems to be running fine now. No doubt the threat was enough! I fix
PCs the same way.
Is it possible that the ECU could, in fact, be faulty? I know these
things can become unreliable as they start to fail. And is the ECU
just that little cylindrical thing on the offside of the throttle
body? (Magnetti Marelli).

 

Look closer, and move them about with the engine running. The split in mine
was VERY hard to see !

As above, the pipes bend and flex slightly when you turn, and when your
engine moves in it's mounts etc. The split may well be opening and closing !

Not really. They're just a lump of solid-state electronics. There's no
moving parts, and not really anything to break.

No, that's the idle-control-valve, which are known to go faulty. Remove it,
and give it and it's connections all a good clean. Or just replace it if you
can't be bothered !

Has the engine-management-light ever come on ? Mine did a few times, before
I cured the split. I guess it was because the ECU was getting wierdo results
from the MAP sensor.

 

The ECU is located in the scuttle panel under the black plastic cover where
the pollen filter is.

Remember they are CODED before trying to swop the ECUs.

Make sure both ECUs have the same keypad code BEFORE changing them.