Stainless exhaust pipe diameter on JTD, what size should I pick?!

[dusanGT]

According to ePER, price (in Germany) of original MAP sensor (2.5bar) for my 147 1.9 JTD 8v is 89.10€ and price of original MAP sensor for 147 1.9 JTDm 16v (seems to be 3.0bar) is 76.57€. It is much better than price for Bosch PSA-B and PSP sensors.
But I have serious dilemma: Is only change of 2.5bar MAP sensor with 3.0bar MAP sensor quite enough for overboost problem resolving or this is only first step? Is the change the corresponding parameters in remap second step.
Best regards. Dusan.

[Cuore_Sportivo_155]

it would depend on the amount of overboost you have. if your overboost goes over 2 bar (boost pressure) you'd still get overboost problems. Mind you, 2 bar boost is a LOT, and I'm sure you're not far from destroying your engine there....

[dusanGT]

My map is with 1.56bar pressure (2.56bar with atmospheric pressure) and I think that the 3.0bar MAP sensor is good enough for overboost problem resolving. Have you Cuore_Sportivo_155 some different opinion about this.
Thanks. Dusan.

[Pud237]

I think the problem with the 2.5 and 3.0 bar MAP sensors is they don't quite give the same readings (in Volts) at lower boost levels. For eg, when the 2.5 bar sensor is reading 1.5 bar (0.5 boost, 1.0 atmospheric), it might give, for example, 3 volts. But when the 3.0 bar sensor is reading 1.5 bar (0.5 boost, 1.0 atmospheric), it only gives 2.9 volts. Close enough for the car to run, but definitely fine tuning required to get the fuelling correct for the different MAP sensor.

I'm sure Jasons has said this somewhere too.

[Cuore_Sportivo_155]

the fueling is determined by the air flow meter, the boost sensor is there to protect the engine against too high boost...

[Cuore_Sportivo_155]

Originally Posted by dusan

My map is with 1.56bar pressure (2.56bar with atmospheric pressure) and I think that the 3.0bar MAP sensor is good enough for overboost problem resolving. Have you Cuore_Sportivo_155 some different opinion about this.
Thanks. Dusan.

I think it will work with fixing the overboost, if like Jason reported the 0.3-ish volt difference at atmospheric pressure is not enough to trip an alarm in itself.

I will be getting such a sensor myself in good time, just no need now as I run a standard car...

[dusanGT]

This is crucial question: is the role of MAP sensor in setup of diesel/air mixture together with MAF sensor or MAP sensor have only role in protection of the engine against the overboost.
For N/A petrol engine manifold pressure is about 1.0bar (atmospheric) and what is the role of MAP in that case? What is your opinion?
Cheers. Dusan.

[dusanGT]

I download from Bosch some pictures, drawings and diagrams (given bellow) for two MAP sensors:
a) 2.5bar MAP sensor with approx. 1.8V per 1bar (0.3V+4.5V/2.5bar is signal voltage for 1bar pressure)
b) 3.0bar MAP sensor with approx. 1.5V per 1bar (0.3V+4.5V/3.0bar is signal voltage for 1bar pressure)
I think that 0.3V as a difference in readings from both of MAPs is to small comparing to the signal of 4.5V (6.7%) as a reason for big trouble. Is it correct?
Original 2.5bar MAP is in orthogonal position regard to the intake manifold. Because of fixating hole location, 3.0bar MAP must be in paralel position regard to the intake manifold. Exact?
Thanks for your opinions. Dusan.

[Cuore_Sportivo_155]

Originally Posted by dusan

This is crucial question: is the role of MAP sensor in setup of diesel/air mixture together with MAF sensor or MAP sensor have only role in protection of the engine against the overboost.
For N/A petrol engine manifold pressure is about 1.0bar (atmospheric) and what is the role of MAP in that case? What is your opinion?
Cheers. Dusan.

MAP sensors on NA petrol engines can be used to determine fueling in a speed-density setup (together with an air temp sensor). For example the saxo 1.0, 1.1 and 1.4 engines use this setup. They don't have an AFM though, that would be redundant anyway...

You could determine fueling even without a map of AFM sensor, in an *****-n setup, and this is often used on cars with wild cams or individual throttle bodies (because of the lack of decent vacuum)

[Cuore_Sportivo_155]

Originally Posted by dusan

I download from Bosch some pictures, drawings and diagrams (given bellow) for two MAP sensors:
a) 2.5bar MAP sensor with approx. 1.8V per 1bar (0.3V+4.5V/2.5bar is signal voltage for 1bar pressure)
b) 3.0bar MAP sensor with approx. 1.5V per 1bar (0.3V+4.5V/3.0bar is signal voltage for 1bar pressure)
I think that 0.3V as a difference in readings from both of MAPs is to small comparing to the signal of 4.5V (6.7%) as a reason for big trouble. Is it correct?
Original 2.5bar MAP is in orthogonal position regard to the intake manifold. Because of fixating hole location, 3.0bar MAP must be in paralel position regard to the intake manifold. Exact?
Thanks for your opinions. Dusan.

have you got some bosch partnumbers for these? the big question is dus the fixation hole on the 3-bar sensor line up with the fixation point on the intake manifold.... but is suppose if the difference is small it could be adapted to work quite easily...

[dusanGT]

On the drawing bellow is given a possible location of 3.0bar MAP as a replacement of 2.5bar MAP. It is possible because both MAP haves same distance between pressure sensor and fixation hole.
I send you catalog number for 3.0bar MAP sensor later.
Best regards from Dusan.

[dusanGT]

0 261 230 042 - Bosch catalog number for 2.5bar MAP sensor
0 281 002 437 - Bosch catalog number for 3.0bar MAP sensor
Best regards from Dusan.

[Cuore_Sportivo_155]

I'll try to come up with some OE numbers so you can get the sensor from a dealer....

seems this is indeed the sensor that is used on the current JTD engines, available from ALfa, Fiat, Lancia, Opel and Saab dealers, or from motorfactors... and Mercedes...


List of OE numbers:
FIAT 73503657
FIAT 735036570
IVECO 504088431
IVECO 73503657
MERCEDES-BENZ 157 153 01 28
MWM 9 6120 06 9 0024
OPEL 24 459 853
OPEL 91 58 595
OPEL 91 96 671
OPEL 93 171 176
SAAB 93 171 176
SAAB 95 43 901
VM 45 96 2069F
VW 2R0 906 051 C

[dusanGT]

Tomorrow I will go in one autoparts shop here in Novi Sad, Serbia. Prices are approx. 30€ and 40€ for 2.5bar and 3.0bar MAP sensor for 8v and 16v 1.9 JTD Alfa. Mentioned sensors are not Bosch, of course, already some copy, but working copy... I will upload photos for these sensors.
Best regards. Dusan.

[Cuore_Sportivo_155]

I'm not sure I'd go with a copy, but if it works you have them for about 2/3rds of the price of the real thing....

why I wouldn't want a copy? Because with 1.5v/bar iso 1.8v/bar you're already at th edge of what the ECU will accept as a working sensor, IMO.. if the tolerances are a bit out on the copy (say 1.4v/bar) this could trigger a fault already at tickover....

[dusanGT]

Idea for MAP sensor change is following: 2.5bar in case of 8v sensor is 0.4+1.8*2.5=4.9V (close to the edge of 5V). But for 16V sensor 2.5bar is 0.4+1.5*2.5=4.2V (far enough from 5V). Even if 16v sensor is product of modest quality, difference between max. allowed voltage of 5V and overboost voltage of 4.2V is guaranty for avoid of overboost, I mean.
Next step is small change of diesel parameters in my remap.
Cheers. Dusan.

[jasons]

map sensors,

they both output near enough 2 volts on idle, they both max out to pretty much the same voltages, don'y read too much into the diagrams on the bosch website, all that says is they both start at the same voltage and end at the same (with minimal difference) but one measures in an extra 0.5bar.

Thing is, you can interchange.

I also have a 3"+ intake where the maf is, as its little use giving good boost if the maf is off the scale early on.

Most boost gauges are fitted before the intake manifold, all this does is measure a serious restriction before the intake manifold (46/47mm) but does not measure boost (or turbulance causes) in the intake manifold.

This is the problem that causes overboost issues on mapped cars, get rid of the restriction, get rid of the turbo spiking.

[Cuore_Sportivo_155]

the 136 bhp i have measures in the intake manifold, around cilinder 3....

[dusanGT]

I am yesterday tried 3.0bar MAP sensor (instead of original 2.5bar), but without success. MCSF fault are still occurs at about 3000rpm in the 4th gear and around 2500rpm in the 5th gear. With 3rd gear all is OK, even if run on 4000+rpm. No problems with original map (1.15bar), but with map of 1.37bar and stronger I have MCSF. In case of very slow acceleration from 3000rpm to 4000rpm in 4th gear all is OK.
This is already becoming tiresome. Is there someone an idea for the elimination MCSF.
I am checked once more:
1) downpipe and free-flow exhaust (both cat are removed 8 months ago),
2) BMC-CDA 80-150 - it looks OK (5 months old),
3) Intercooler pipes - it looks OK (5 months old),
4) solenoid valve - it looks OK (5 months old),
5) MAP sensor - it looks OK (1 day old),
6) EGR valve is closed - it looks OK,
7) Intercooler - it looks OK and
8) turbocompressor GT-1749 - it looks OK (repair is made 5 months ago when changed the vacuum actuator, which adjusts work of VNT). But, It is possible that rod of vacuum actuator has the wrong motion, because it is taken from other turbine compressor.
Best regards from Dusan.

[Cuore_Sportivo_155]

I suppose it's time to measure how high your turbo pressure really gets. It's quite normal to build higher pressure in the higher gears too.

So is there no difference at all in fitting the new sensor?

[dusanGT]

Unfortunately no. With 3.0bar sensor MCSF error are appeared on few hundred rpm more comparing to case with the old 2.5bar sensor. After these holidays I will start the investigation about the real cause of my MCSF error. First step is exact measurement of the boost pressure and check of the vacuum actuator bellow the turbo compressor (i.e. the rod for changing the angle of vans).
Happy New Year. Dusan.

[Cuore_Sportivo_155]

just thought of something.... I have a 136 bhp with mechanical turbo pressure regulation, but yours is an electronic system, and very likely it uses the map-sensor signals to adjust the turbo prressure. If that's the case no matter what sensor you use it'll always go into overboost if you try to go over 1.5 bar, as 1.5 bar translates to 4.8v as far as the ecu is concerned

[dusanGT]

With 3.0bar sensor 2.5bar of pressure (atmospheric+boost) correspond to 4.2V, what is enough far from overboost... But with map which consist boost of 1.37bar I have MCSF. This indicates to other problem, especially if I have no MCSF in case of slow acceleration.
Cheers. Dusan.

[Pud237]

When you say you have MCSF, what is the reported error code?

[dusanGT]

After these holidays, I will perform (with my friend who is owner of diagnostic equipment) the detailed investigation about the real cause of my MCSF error and I will see error codes.

Before I repaired my turbocompressor in workshop, (vacuum actuator was replaced with new one) I have not had MCSF (even with 1.55bar boost remap and with 2.5bar MAP sensor). And I guess that the reason for the MCSF problem is originated since then. I doubt that the rod (for a change of vans angle) is too short, so the vans cannot be sufficiently open on the high revs.

Additionally, in this workshop I replaced overboost (solenoid) valve with new one. Our friend kgb told that the new type of solenoid (Pierburg) is not too good comparing to old type.

I emphasized that MCSF not appear in case of slow acceleration from 3000rpm to 4000rpm in 4th gear.

Best regards from Dusan.