Alfa 147 JTDm 150hp - EGT problem (GTB project) - Alfa Romeo Forum
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(Post Link) post #1 of 6 Old 05-03-14 Thread Starter
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Alfa 147 JTDm 150hp - EGT problem (GTB project)

Hi,
I'm new to the forum and I'm not a real alfa owner (hope I didn't break some rules).
I'm here to try to resolve a problem on a my friend car.
I'm a computer science student, I've a good experience on engine tuning (mechanical part) and I'm well prepared on the ecu tuning side.
Some months ago we planned a GT2056 turbo (Trim 55) upgrade due to original turbo failure (broken vnt actuator and noisy turbo), we built from scratch the exhaust manifold and adapted everything else.
Stock turbo back exhaust without cats and stock intercooler, upgrade of both were surely planned but not yet installed.
GT2056 was choosen only because I had one used unit available.
Started tuning the part-throttle and quickly realized EGTs were sky high, with almost stock injection and boost pressure of 1.5 bar 900C were archived after no more than 15 sec at WOT.
Considering that installed turbo started making some very strange noise even at low boost (no surge) we planned to swap to a brand new GTB2056 (Brera 210hp) thinking that the high EGT problem was related to bad custom exhaust manifold design.
After that we finally installed the GTB on the stock exhaust manifold.
Started tuning the VNT maps and actually I was really surprised having better spool than stock with no sign of compressor surge.
MAF started giving error due to max flow reached so I planned to switch to speed-density (MAP).
Anyway the problem was that with completely stock injection and 1.4 bar boost (a bit more that stock) we still had EGT higher than 850 on a 20 sec. pull.
After that we double checked everything:
- IAT ~70 max after a very long pull and heatsoaked
- EMP ~1,3 bar
- changed the EGT sensor with different type and make
- no boost leaks
- EGR closed physically & on the ECU
- no sign of smoke from the exhaust
Having no idea of what the problem could be the stock turbo was reinstalled.
With stock turbo EGT went down a bit (780C) on a 20 sec. pull.
Finally found a possible problem: timing belt slippage anyway EGT went down to 760-770C.
Before adjusting the phasing with the dedicated tools we checked it with the old soldering tin method and we also found that the glow-plug was white coloured. (normally black)

Having no experience on JTDm engine (have worked a lot on TDIs) I'm really struggling to understand if those EGT figures could be normal or not.
Some time ago I've read somewhere that maximum EGT on factory cars (OEM recomended) must stay below 750 and every car I've seen until now stayed below that temp. even with FAP\DPF installed.
Considering that the car is running an empty turboback exhaust excl. final silencer I'm pretty sure the EGTs I'm seeing are very strange.
(I think I'll easily see more than 800 on a very long pull)

The car is the "no-DPF" version with the old injection system (1400bar).
Have anyone measured the EGTs on that car?? Maybe ori & mapped?
Thank you and sorry for such a long post, I've tried to write everthing useful!!
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EGT's of around 800 C with standard turbo is normal.
I think the 2.0 JTDm engine starts to decrease power when EGT exceeds 850 C.

But with a GTB2056v installed and no change in injection rate I'd expect lower EGT instead of higher, so that's strange.

I have an EGT at a long run of around 900 C, with GTB2056v, FMIC, open exhaust, ducati injectors and 105 mm3 injection rate.
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(Post Link) post #3 of 6 Old 06-03-14 Thread Starter
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Hi, thank you for reply.
EGTs with the GTB2056 have been higher than the stock unit probably because of low boost\IQ...
Anyway are you sure about that EGTs??
800C on stock map + decat seems to be very high...
I have a Golf Mk4 1.9 TDI 130hp remapped to ~180 and EGTs never reach 850 C even on a very long pull...
Regarding to the exhaust, for "open exhaust" did you mean the stock one without cats\dpf?
Thank you!!
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What was the original GTB you used off of? and any pics of installation?

I cant help on the high EGT sensor readings as its out of my depth, one of the best to answer already is, the only thing i have noticed from your post is "changed the EGT sensor with different type and make" why? and do they need callibrating or even checking for that matter upon installation?

Wayne
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(Post Link) post #5 of 6 Old 07-03-14 Thread Starter
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The EGT sensors doesn't need calibration, it was changed due to failure of the first one and I decided to change the type & make to be sure the readings are realistic...it's one of the cons of using cheap chinese probes...
The GTB2056v I used is the Alfa Brera 210hp one.
I'll upload some pics asap...
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Sorry want reading fully, read the GTB part and then read, in my mind at least the firts turbo was a GTB2056, it was infact just a GT, sorry

Wayne
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