Here we go again: Idle and hesitations problems 1.8 16V

[mwahlgreen]

Hey

Sorry if I sound to much of a new comer, but as a matter of fact this is my first car and I'm struck even as I have worked on cars for years. (mostly electric cars and Audi A2's) I have also other PUG owners at hand, but so fare no luck, just more ideas for what to look at next.

Here is a little info on the car:
PUG 406 SR 1.8 16V, XU7JP4, Motor: 8BLFYE, Electric system SAGEM, Produced Mar 1999

Have connected the car to PP2000 and get the following error in the Engine ECU:

Intermittent fault: mixture regulation auto adaptation - lower stop (/).

This fault can be caused by:
- Damaged connection or harness
- Faulty control unit calibration

The troubleshooting here not that easy with this very little info to go on.

What I feel in the car is the following:
- Cold start in wet weather can be a problem on the first try.
- Idle is not steady, ever.
At cold it oscillates +-100rpm and might stay at 1200-1300 rpm for a while, when warm it oscillates at 850-900 rpm
- It hesitates until 3000 rpm and then shots away, might be a feature and not a bug

Here is this road so fare:
- no PUG service since 2008, maybe the oil have been changed at some point, I have no history of it.
- I have bought the car in Aug. 2013
- Changed the following items in this order
-- Tires (off topic)
-- Oil (Castrol something) + filter
-- Gear Oil (Total something recommended for this PUG)
-- Fuel filter (original or same as fitted)
-- Spark plugs (Bosch FR8LD+U, FR8LDC is recommended by Haynes, but hard to get)
-- Air filter (original)
-- Pollen filter (Bosch)
- Clean the ICV (it was not that bad looking and a test in pp2000 shows it works)

The oil in the car was BLACK and sluggish and the change made the car more quiet and I have a new batch (oil+filter) for changing in 6 month.
The old plugs were not showing any signs of error other than expected wear and tear after 80k km.
The new spark plugs and the air filter means that the kick at 3k rpm are more distinct to feel.
Havn't run it long enough to see if the plugs+air filter have done anything to millage (between 9(city)-13(highway/freeway) km/l)
Air filter have given the car more of a roar.

When I had my session with pp2000 some tests were done:
- MAP sensor values reads Atmosphere pressure, when not started. At idle it stays at ~500mBar. It lowers at acc. (Seems normal)
- Advance adjustment oscillates 0-30 at idle as well as ICV follows +- 5 steps around step 10. Blank 0 at throttle conditions
- ICV oscillates at step 10 +-5 steps in idle. Static at throttle conditions.
- Lambda sensor seems to oscillate between 0.2-0.8V as it is suppose to.
- Butterfly valve sensor stayed at 11.3 when pedal was left in idle and wire is loss. Otherwise it seems to read correct numbers (should it go all the way to ZERO?)
- Funny fact: Revs are returned to idle if you hold it static at 1500 rpm or 2000 rpm for a couple of sec's without any readout at the speed sensor.

And I have read a lot of forum posts about this subject by now, but not even Google can help me with the fault massage from pp2000 above, so I seem to be rather lost.


So the BIG is what to do next? As I'm not rich, no need to say changing everything, as it is not an option


Here is my own ideas:
- Check for air leaks after the throttle body (change gaskets between throttle body and intake manifold or even between intake and the block)
Air leaks before the throttle body is not a problem, since now sensors here.
- Check MAP sensor for soot if intake manifold are taken apart.

Further plans for the rest of car:
- Clean throttle body from the back and maybe intake manifold.
- Change coolant.
- Change break fluid.
- Leak test and refill A/C.
- Change timing belt.
- Fix air intake and move it higher and away from left wheel arc. (hose is broken at inlet and risk of hydrolock).

My location: Lyngby, Copenhagen, Denmark.

Don't be shy to ask any questions and I will replay with all info ranging from pictures to videos if need.
And I will follow up if there is any changes.

To you from
Electric Engineer
Mikkel Ø. W.

[steve_earwig]

My god that's a lot to digest, and you've already covered everything my simple understanding of these things can come up with. Apart from checking/cleaning the injectors.

Intermittent fault: mixture regulation auto adaptation - lower stop (/).

This fault can be caused by:
- Damaged connection or harness
- Faulty control unit calibration

Could that be "I can't make the mixture weak enough"?

[mjb]

WOW! *THIS* is how to ask for help! Excellent job. Just... wow

I'm going to presume this condition's existed since you acquired the car?

First thing I'm going to suggest is to disconnect the battery to reset the ECU's adaptations (where it tweaks the map slightly based on sensor data). Don't use PP2000 before this, as you don't want to kill power as the ECU is writing to EEPROM. If you want to be really safe, there's a procedure for "properly" disconnecting the battery - you can search for it on this site (although I suspect it's just open bonnet, key out, wait 15 mins for the ECUs to go into standby)

Bosch MP ECUs only need a second or two to lose their adaptations and are resilient to unexpected power loss, but I have no experience with Sagems. In fact, you may even need to use PP2000 to reset the adaptations.

In any case, once that is done, clear the fault and see if it pops back up.

If it does, it could be the throttle. Dunno if this engine uses a motorised or mechanical throttle body off the top of my head, I suspect mechanical? First check if the throttle cable is too tight, preventing the butterfly from closing fully. If it's not, pull the flexible air pipe off it and have a look see if it's closed or just gunked up. If it seems to be mechanically prevented from fully closing, look for a tiny screw (might be an allen screw, recessed in a hole filled with gunk) which adjusts the closed position. There might not be one - I'm going from my experience with my V6... Aside, I haven't seen a 406 with 0-90 degrees reporting on the throttle pot

[mwahlgreen]

Could that be "I can't make the mixture weak enough"?

My idea as well, that is why I think it gets to much air (check for air leaks)

I'm going to presume this condition's existed since you acquired the car?

Yes, but not very noticeable in the late summer.

First thing I'm going to suggest is to disconnect the battery to reset the ECU's adaptations (where it tweaks the map slightly based on sensor data). Don't use PP2000 before this, as you don't want to kill power as the ECU is writing to EEPROM. If you want to be really safe, there's a procedure for "properly" disconnecting the battery - you can search for it on this site (although I suspect it's just open bonnet, key out, wait 15 mins for the ECUs to go into standby)

That is called the 3 mins rule : http://spidometrs.ru/s2/download/peugeot_manual.pdf taken from another tread in here Haven't cleared errors, as I don't see why that should help on an "Intermittent fault" which shouldn't put the car in any kind of "creep mode".

Bosch MP ECUs only need a second or two to lose their adaptations and are resilient to unexpected power loss, but I have no experience with Sagems. In fact, you may even need to use PP2000 to reset the adaptations.

Should be covered by the 3 mins rule.

In any case, once that is done, clear the fault and see if it pops back up.

I'll follow the manual later today for this.

If it does, it could be the throttle. Dunno if this engine uses a motorised or mechanical throttle body off the top of my head, I suspect mechanical? First check if the throttle cable is too tight, preventing the butterfly from closing fully. If it's not, pull the flexible air pipe off it and have a look see if it's closed or just gunked up. If it seems to be mechanically prevented from fully closing, look for a tiny screw (might be an allen screw, recessed in a hole filled with gunk) which adjusts the closed position. There might not be one - I'm going from my experience with my V6... Aside, I haven't seen a 406 with 0-90 degrees reporting on the throttle pot

Okay, then it reads out 11.3%... Then I have an idea what is the problem...
I'll investigate if the throttle potmeter (TP) is broken in the lower end of the scale.
The wire for the mechanical throttle is loss, I have even shortened it in its adjustment.
I'll also look into the throttle body if it is full of gunk, but I also cleaned it from the front with Electric cleaner when I cleaned the ICV. But the car don't run well in idle given this to run on

Everybody so fare: Thanks very much and sorry for the long tale, but I have been reading a lot about the subject and man some of the treads are long Some even just end with the owner selling the car

[steve_earwig]

steve_earwig wrote:Could that be "I can't make the mixture weak enough"?


My idea as well, that is why I think it gets to much air (check for air leaks)

I was thinking the opposite, that the mixture is so rich the ecu can't make it weak enough. The injectors on my wife's Toyota* were chucking way too much fuel in at one point, which was fixed by having them cleaned. This is why I said check/clean the injectors (although I know little about fuel injection, give me a carburettor any day )

*nothing to do with me

[mwahlgreen]

I think I would get this fault instead: "mixture regulation auto-adaptation - upper stop" if the problem was to little air/too much fuel, but that is just me, since googling "mixture regulation auto-adaptation - lower stop" doesn't get any hits or very low hits.
http://www.liontamer.net/forums/index.php?topic=2.0

I'll take cleaning the injectors into mind as well.

Thx again

[mwahlgreen]

Just to keep you guys reading this, posted:

I have looked into the TP part, nothing seems wrong with the readout (not actually had pp2000 connected), since there is no sodden jump in RPM's or anything while going from 850 RPM to 2000 RPM.

I have also had another look at the throttle body from the outside and cleaned it even more. No change in how the motor runs either.

I'll try some REDEX INJECTOR CLEANER in my next full tank and see if that makes any change.

Also the inlet manifold looks really black with some gunk in it behind the throttle body, so I'll look into how to take it of for a more rigid cleaning.
Anyone know where to find anything on the subject, except from servicebox?

[mwahlgreen]

Just to follow up:

I have now tried to make sense on how the Air intake temperature can read 40 degrees C at 20 degrees C.
To solve it I bought a new one. It reads the same... Took it of, it then reads -40C. Shorted the plug and it reads 130C.

I have no clue on how this can be 20 degrees C off with a newly installed sensor. My only guess is a faulty wireharness, but a sensor cable of going from -40C to 130C sounds ok.

My idle is still not completely still and my fuel consumption is driving me nuts, running below 10km/L at premium quality fuel.

[madmadmax]

never felt redex did much, millers eco max is the best fuel system clener i have come across get the big bottel and double dose it (don't let the bottal fall over as it leakes out allover the place) couple the fuel cleaner with an italian tune up shold show somthing.

if thers an improvment then its the injectors that need cleaning