Low Power under 3000 revs & motor system failure - Alfa Romeo Forum
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(Post Link) post #1 of 38 Old 12-10-12 Thread Starter
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Low Power under 3000 revs & motor system failure

Hi everyone, can anyone offer advice on what might be the problem with my Alfa 147 JTD M Jet 2004....

It starts fine, no smoke, but the motor control system light has come on (after I accelerated hard going up a hill) and now it is low on power under 3000 revs - I can put my foot to the floor and it has little effect until 3k then it goes great.

We have checked the egr valve, its working fine but have fitted blanking plates anyway.

Any ideas? Thanks in advance....
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Disconnect the maf sensor electrical connector its a bit awkward but only takes a few minutes.If it then runs better its the maf
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Turbo over boosting and going into limp mode ? However, this normally resets when you restart the engine. Need codes read to be sure.
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Check the small vacuum pipes that connect to the turbo actuator, and verify that the actuator is working (watch the little rod while someone starts the engine: you should see it drawn back towards the actuator capsule).
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Thanks for the replies, we'll try the MAF sensor and see how it goes!!
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2nd VAC pipes the VGT in turbo is stuck in large mode (which works at 3000 rpm) and not going to small mode (which works from 2000-3000 rpm) it'll be underboosting till revs rise.

Does engine shudder when you switch it off? That would prove vac leak.

If it does then check all VAC hoses for leaks (or just replace them all with cheap silicone off ebay loads of posts on size I used 3mm) also at back of engine hoses coming from VAC unit (just trace hoses to it, also hose comes from behind where throttle body would be on petrol to same vac unit).

Lastly while in that area I'd suggest cleaning and greasing the VGT arm from where vac hose ends to turbo as these can get dirty and stick.

If you find issue with car door open and hand to key you can just see VGT arm, turn car on and then after a few seconds off and make sure arm moves about 1" and if there was a judder on turn off that it's gone.

Lots of other posts on here about this including quite a long one I posted in earlier this year so have a search and if you can't find or get stuck come back and ask here

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(Post Link) post #8 of 38 Old 13-10-12 Thread Starter
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That's great, thanks for all the info guys, really helpful, I'll be out there tomorrow trying all these things and I'll let you know how I get on!!
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(Post Link) post #9 of 38 Old 14-10-12 Thread Starter
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Help!! During my investigations I have just snapped off the vacum connection on the boost control solenoid!! Tried searching for for a replacement boost control solenoid on the net but none found - does anyone know where I might find one? Thanks..... By the way, following your advice I can see that the turbo actuator isn't going in like it should when started, so this may be the cause of the original problem........
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Yep will be cause, either vac leak or arm gunged up usually...

Alfashop can get them but iirc it's a special order from pierberg so 2 weeks. When I did exactly the same I files out a gap below pipe connector (if it's top one) little flange below it. I then glued broken bit of plastic on and wraped round with electrical tape and glue though glue and a material tape may be stronger (just over 1 tight covering) then I thinned down one edge of vac hose so it would go into gap I created under pipe. I superglued the plastic over split and carefully popped vac hose on so it went on past the break. Then I used some electrical tape to create a small sealed area round hose and filled with superglue, once dried wrapped with electrical tape on vac hose and round top of vgt solenoid to take some pressure off brake from vibration and weight of hose although at some point the break re-opened as I'd popped hose past it with glue then built glue round hose end area it never re-opened and lasted for 3 weeks till new one arrived.

I've kept it as spare as the repair is so sturdy I think it would last for years.

Anyway I guess it's top hose you broke as it's not as sturdy as lower one so with a little mucking about with a thin file and glue you should easily be able to effect a lasting repair till you find\get a replacement the new one I got from peirberg looked like plastic top was made from a different material and looks like it won't go brittle so easily

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Also if arm not moving are you able to move it back and forward by hand?
 
(Post Link) post #12 of 38 Old 14-10-12 Thread Starter
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Hi Mr Mac, yes we can move it by hand, and have tried taking a feed directly from the inlet manifold on to the actuator so bypassing the bcs and now the arm moves....so does this mean its a faulty boost control valve or could it be the vanes sticking in the turbo? Thanks for the tips re a temporary repair, I'll give it a go!!
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Possibly but could also be leak on hose between solenoid and Vgt. Check hose carefully, could be wires to solenoid. There was a link on here to a foreign guide to take apart and clean solenoid but test it.

See if vac gets from one hole to other with it connected to car. Could just be now you've moved by hand it's moving and a clean and grease of rod and arm will help (maybe if dirty and sticking a little vac pressure wasn't enough to move it). Can FES not make solenoid operate? Or was that just egr? Think it maybe can so if you have obd2 cable maybe you can test valve more easily.

I'll look for guide
 
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Foreign but follow the pictures and translate with Bing Google or babelfish just paste in the url but pics are easy enough to follow.

Elektrozawór VGT (overboost) - operation manual
 
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With top off you may even be able to get a small metal tube out broken connector, glue in place and glue broken bit over tube
 
(Post Link) post #16 of 38 Old 14-10-12 Thread Starter
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Hi, thanks for the link, what is "FES"? I've ordered some silicone vacuum pipe to replace the current ones, just in case!!
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Fiat ecu scan - although they just changed the name.

Great software, can read and re-set codes and can check values like injector correction, boost pressure and all sorts (free version can log and graph 4 values on road which can be handy). With correct cable you can read ecu, abs, airbag etc
 
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Think you may need full version to do actuator tests (though can't remember for sure) full version can even write in new injector codes if injector changed.
 
(Post Link) post #19 of 38 Old 14-10-12 Thread Starter
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OK, I'll see if I can get hold of this software - is it something I can download from the net? Sounds like it would be useful !! I wont try the temporary fix as I have a spare 147 I can use until the new part turns up (think I may have sourced a 2nd hand one from a local scrap merchants who are breaking a 147 JTD). Thanks for all your help
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Need an obd cable as well and need a modded cable or adapters if you want to read abs, airbags etc.

Multiecuscan - Diagnostics software for Italian cars (Powered by FiatECUScan)
 
(Post Link) post #21 of 38 Old 14-10-12 Thread Starter
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Brilliant, thanks Mr Mac, this looks like fun!!
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I think I've got a problem with them little hoses. I've done full servicing few days ago and reset the error codes( .had p0238 while ago). Today tested if error code gets back on 4th gear 3000 rmp and hello again engine light... garage checked the hoses, but anyways I think its worth to give it a try as my car on swiching off shakes too hard (didn't do that before). Could you be more specific what hose measurements are? Inner diameter 3mm?? What length should i get to change most of the easy accessible ones/most vital? Could I get it from b&q or screwfix or etc? As I want to go to garage and sort it asap instead of waiting ebay delivery. Also any ideas how many labour hours it could take to change them and clean map sensor? Im trying to keep the cost down so if there is anything else i should buy with them hoses (like mini jubilee clipses??) Let me know please.
Thanks

Last edited by schranz; 16-10-12 at 08:56.
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3mmm internal diameter silcone hoses, but the garage may have something suitable, dont use 5mm as its too big

1 meter will do the lot = Ł2.50

the hose from the vacumm Reservoir at the back of the engine is difficult to get too and if you just pull it off may snap the connector - so its a ramp job i guess - the whole task should take about 20 minutes - theres pictures of all the pipes on the link above

just change the lot and have done with it, tiny cracks in the pipe and you end up with no boost at all within 2 weeks
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Oh blimey, I'vwe just ordered 4mm silicone hoses, will they work??!!
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The connection that may be a problem on 4mm will be top one on Vgt solenoid so try it for fit before testing it all. I was told 3mm and 5mm when I did it and discovered 3mm all round was what was needed 5mm was too loose. But I just popped a bit of 3mm on top solenoid connector and popped the 5mm over it which made a tight seal. You may get away with 4 but not sure, maybe need to do something like I did and pop a small length of 4mm inside the 4mm hose then connect to make fit snugger.

Or contact seller and see if they'll supply 3 instead
 
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