Overboost ...

[Dandu 0]

Hi mates,

 

I try to suppress the overboost via ECU. Does anyone know how (or where) to do it? I hope, there's a map I can alter easily.

 

Just a common question. Can anyone explain to me, under which conditions the overboost sets in? During my first tests with the engine the overboost only came up sporadically.

 

Bye Dandu

Edited June 24, 2010 by Dandu

[bales 1]

When I had mine it didn't ever overboost, it just maintained it at 7psi regardless of speed or gear.

 

I have heard it mentioned various times on here but everybody seems to experience something slightly different with each engine. I was told that the VSS sensor had something to do with it but mine ran identical with this unplugged or plugged in.

 

What does it boost to now 7psi? Easiest option is just a dawes type boost controller unless you are desperate to have the boost solenoid controlling it for other reasons?

[Henry Yorke 269 3 Cars]

I think the overboost was on the T16 engine, not the 8v one. I have not seen any overboost on mine

[Dandu 0]

We recently transplanted a XU10J2TE RGX (147 BHP) in a 205 CTi. The project lasted nearly 1 year. It was fabulous. The car / engine worked properly with an original ECU 204813. Boost gauge revealed an overboost (usually coming up at the moment you start to go forward [at lower revs]) of 10-11psi. Let's say for 5 seconds. After that, boost usually went down to 8-9 psi. It definitely felt like overboost and it appeared constantly.

 

You see, the car seemed to be set up properly. Thus, I saw a good chance to raise the boost. Everybody surely knows the RGX ECU doesn't have a chip, you can exchange. Another ECU has to be bought. RobTurbo gave me the chance ... and it works quite appropriate, not to say great. Quite early I felt a strong urge to adapt the maps in order to raise the boost. Fortunately I had some software (proper for the ECU, allegedly raising the boost to 1bar). The rumor said, the chip might be a bit faulty. The test confirmed it. After hard acceleration boost went up to 14psi+ at higher revs, resulting in an emergency operation of the car ... the boost was gone. After fiddling the maps, I was able to set up and test-drive some other chips. These chips worked fine, regarding the acceleration problem. But only sometimes the boost goes up to 14psi+ and ... you know, what happens. This effect always comes up at the moment, I start to accelerate. It feels like overboost (although it sets in irregularly now), but unfortunately I don't need it. Thus it might be a proper idea to get rid of it. But how? Is there a map, I can change? Is there a chance to release higher boost pressure (>1bar) with a special valve?

 

Bye Dandu

Edited June 24, 2010 by Dandu

[bales 1]

I think what your saying is that you bought a 'chip' for the ecu to increase the boost however it is overboosting (1.2 bar I think is the ecu limit) and the fuel cut is coming in regularly during acceleration.

 

I don't know of a specific way of bypassing the fuel cut, though personally I wouldn't want to do this as the standard turbo is well out is its effciency range at 1 bar anyway.

 

All I can say is that I didn't bother with a different eprom I just increased the boost mechanically with a ball and spring type boost controller and disconnected the solenoid. Mine was set to hit a peak of 1 bar (approx 15psi) and to be honest wasn't able to sustain it anyway due to the size of the turbo so would drop to about 10psi at higher revs.

 

I never had any issues with running lean and ran reliably like this for a year or so, wouldn't push the boost much past this without tweaking the fueling however.

[Dandu 0]

Hi bales,

 

it's not my intention to apply a boost >14psi. The first tuned software came from the same guy, who sold the engine to me. After getting to know, that it's not working properly, I decided to have a look at the software. Eprommer, tuning-software, hex-editor came into view again. It didn't take me a lot of time to figure out the differences between the standard software and the modified one. Visualizing the maps wasn't difficult as well. Thus, I could fiddle with the maps and .. you already know the rest.

 

Back to my problem. The easiest part would be to release the pressure (that exceeds the 14psi limit) with the help of a special valve in the inlet tract. But I'm still willing to do it via the maps. There might be a chance to suppress the overboost. I'm in need to alter the software anyway. Because, as you mentioned, it's the first step to raise boost and fuel injection. The second is to adjust the ignition timing. I definitely like to go this route.

 

I'm well aware of the option to apply a mechanical boost controller. But actually I also wanted to save the money. See it as a special ambition. By the way ... where exactly did you put the boost controller? Do you have an image?

 

Bye Dandu

[bales 1]

Hi bales,

 

it's not my intention to apply a boost >14psi. The first tuned software came from the same guy, who sold the engine to me. After getting to know, that it's not working properly, I decided to have a look at the software. Eprommer, tuning-software, hex-editor came into view again. It didn't take me a lot of time to figure out the differences between the standard software and the modified one. Visualizing the maps wasn't difficult as well. Thus, I could fiddle with the maps and .. you already know the rest.

 

Back to my problem. The easiest part would be to release the pressure (that exceeds the 14psi limit) with the help of a special valve in the inlet tract. But I'm still willing to do it via the maps. There might be a chance to suppress the overboost. I'm in need to alter the software anyway. Because, as you mentioned, it's the first step to raise boost and fuel injection. The second is to adjust the ignition timing. I definitely like to go this route.

 

I'm well aware of the option to apply a mechanical boost controller. But actually I also wanted to save the money. See it as a special ambition. By the way ... where exactly did you put the boost controller? Do you have an image?

 

Bye Dandu

 

I can't help you with anything to do with adjusting the maps as I have no experience with that.

 

However employing a valve in the inlet tract is very counter-intuitive because in effect that is what the wastegate is for, you could adjust the wastegate spring pressure to open at 14psi but then you would need to disconnect the boost solenoid in order for that to work - and then you may aswell have a mechanical boost controller.

 

Putting an extra valve either before or after the boost solenoid makes the ecu control pointless as it is no longer having a direct control on the feed to the wastegate and therefore the boost pressure that the MAP sensor is seeing and therefore the values in the ecu will be wrong and sending the wrong signals back to the solenoid and so on! phew...if you see what I mean. It is a closed loop system and you would be making it open loop by adding an extra valve in.

 

It sounds like you need to sort the map out rather than start trying to add extra valves in - plus the MBC's are only about £15 over here so much cheaper than messing with ecu's.

 

My MBC is just in the wastegate feed line.

[Dandu 0]

Hi bales,

 

I think, I know what you mean. But I suppose, an additional valve might work, although I completely have to agree to you ... it's not perfect. The better idea is to alter the maps. And I believe, I'm on the best route to do it.

 

Much thanks for your comments,

 

Bye Dandu

[Dandu 0]

While I was checking the different software (chips), the MAP sensor recently decided not to work properly anymore. Does anybody have a spare one, I can buy? Have a look at: http://forum.205gtidrivers.com/index.php?showtopic=121697

 

Cheers Dandu

Edited July 1, 2010 by Dandu

[Jamal 2]

Hi!

 

I have got a rebiult engine with std management, and parts.

After solving the last faults my ecu is fault free.

 

At 2000rpm the boost goes up to approx 1 bar for 5-7secs, and after it settles at 0,6-0,7.

This overboost is always working between 2000-3000.

 

I have this infos from a french manual called Revue technique:

SURALIMENTATION (XU10 J2 CTE)

Suralimentation par turbocompresseur avec refroidissement de l'air d'admis

sion par échangeur thermique air/eau.

TURBOCOMPRESSEUR

Marque et type :GarrettT2.

Pression de suralimentation:

- 0,3 bar a 3 000 tr/mln é vide.

- 0,65 bar á 4 500 tr/min á vide.

- 0,9 bar á 3 000 tr/min á pleine charge.

Pression de commandé de la soupape régulatnce : 1 bar.

Déplacement de la tige de la soupape régulatrice : 3 mm.

 

And found somewhere, that if the wg is linked directly into the inlet, the max pressure has to be approx 7PSI

Mine is doing approx 5.5PSI in that mode. So later will adjust the wg's spring again

 

Hope it helps.

[Dandu 0]

@Jamal: Much thanks for your information.

 

.. in the meantime I got new trouble. But let's roll the story back. The last software worked fine - proper boost: 13-14 psi, no overboost. You could say: "Problem solved." But unfortunately it worked fine for just a moment. All of a sudden the boost went down. From then on I had no proper boost values anymore. Suddenly the engine diagnostic light sporadically came up. I supposed, the ECU (200219) broke down. Replacing the ECU with a standard one (204839) supported my conclusion, everything worked as expected (standard overboost: 10psi, standard boost: 8 psi). I assumed, that the MAP sensor from the other ECU didn't want to work properly anymore. But after replacing the MAP sensor the situation didn't change. Unfortunately from now on the other ECU (204839) works improperly as well. No repeating behaviour, sometimes overboost of 8 psi, sometimes standard boost of 5-6 psi, sometimes the pointer of the boost gauge shivers. It seems like the car doesn't want me to raise the boost. Does anybody have an idea, what's going on now? It seems like something else went out of order. But what?

 

Cheers Dandu

Edited July 11, 2010 by Dandu

[Dandu 0]

Perhaps I can make sume assumptions, you can answer to the negative. I suppose, the:

 

1. spring of the wastegate actuator (someone gave me the advice yet)

2. the boost solenoid or

3. the ECU (204839) is out of order.

4. Perhaps I've got a leak of air somewhere.

 

Especially the boost solenoid is interesting to me. Is there a chance to check it? How?

 

Cheers Dandu

Edited July 14, 2010 by Dandu

[Jamal 2]

First:

Read out the fault codes.

[Dandu 0]

That's the first thing I'll do next. .. Unfortunately the motor diagnostic light didn't flash, while driving with the standard ECU (204839). Thus I suppose, there is no fault code to catch. But perhaps the other ECU is worth an attempt. I'll report soon, promised!

 

Cheers Dandu

Edited July 15, 2010 by Dandu

[welshpug 1,661]

there can be several fault codes without illuminating the EML.

[Dandu 0]

Nice to know. ... I'll keep you informed. Thanks for your help!!

[Jamal 2]

there can be several fault codes without illuminating the EML.

 

Of course!

 

If minor problem is detected, the MIL lamp stays in 2-3 secs after engine start, and then goes out.

[Dandu 0]

ECU (204839, Bosch Motronic MP3.2) => 27. ... Unfortunately I couldn't find a document revealing its meaning. Bye Dandu

[welshpug 1,661]

vehicle speed sensor.

[Dandu 0]

Much thanks, welshpug. Do you have a reliable list of all fault codes? Google and co. come up with different explanations for fault code "27".

 

As far as I know, the vehicle speed sensor can't stay in relation with my current problem. Hmmm. ... Perhaps it's an old fault code. Today I'll delete the fault codes, drive around and check them again.

 

Cheers Dandu

[welshpug 1,661]

if its like the gti6 and s16 ecu's they give drivability issues such as flatspots and stalling, so its quite possible that it is contributing to your issues, especially if the ecu has an overboost facility.

[Jamal 2]

VSS is needed for the proper boost/overboost.

VSS fault was one of my problems. The other was te ECU's temp sensor. After fixing these problems, the car flies now

 

Edited July 17, 2010 by Jamal

[welshpug 1,661]

there you go, confirmed my thoughts

 

most of the codes are generic so would be the same across a lot of cars, what came before OBDII.

[Dandu 0]

Hey guys,

 

I feel sorry for my late response. But I faced some other trouble in between. Some days ago I figured out, that one of my axle collars got frazzled. It seems like, trouble is hunting me. But it will work out fine. Back to the boost problem ...

 

Your implications are pretty comprehensible. According to my researches (in the forum) the VSS is necessary for proper operating of the boost solenoid. In case I have trouble with the VSS, boost problems necessarily come up. Further on, I recently checked my fault codes again. Once again only the "27" was revealed. But ... I don't own a VSS, that can be linked with the ECU. There is only a mechanical link between VSS and speedo. Thus, my ECU has never ever got any idea of how fast the car went. People around me, driving the same engine, alleged that there is no need to link the ECU with the VSS. Thus, I drove without it from the first kilometer on. And at first I had no problems at all - boost at 8psi, overboost at 10psi.

 

Therefore I'm definitely confused. Can anybody explain? Does the ECU need the speed signal, or doesn't it? Is there a chance, the ECU does not immediately decline a proper operation of the boost solenoid (as soon as it recognizes the absence of a speed signal)?

 

Bye Dandu

[Dandu 0]

I see, my confusion spreads out. Just to summarize my current questions again:

 

1. Do I need a VSS (capable of being electronically linked up to the ECU, not only mechanically to the speedo) for a proper operation of the engine? Does it really influence the boost solenoid? I carefully suppose: "No, it does not."

2. Which task did the VSS (especially the electronical part) fulfill in a Peugeot 406, 605, Citroen XM etc.? I suppose: "It's possibly neccessary for ABS brake, traction control, perhaps hydraulics and so on."

 

Final question: In case I don't need a proper VSS ... what else might be the cause for my current problem "Lack of Boost"?

 

@Jamal: No offence .... but perhaps your trouble might have rather stayed in relation with the ECUs temp sensor? Is there a chance?

 

Bye Dandu

Edited July 22, 2010 by Dandu