Inlet Manifold work - now "limp mode" - Alfa Romeo Forum
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(Post Link) post #1 of 4 Old 17-06-13 Thread Starter
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159 SW

Inlet Manifold work - now "limp mode"

Hi Guys,

Firstly let me just quickly introduce myself before I beg for help!! I'm Phil and I have owned a 159SW 1.9JTDM for about 18months. In that time I have been reading these forums religiously picking up lots of good info, I have gone down the route as many have of removing/drilling out DPF and having a remap to remove the regen and the EGR and boost the performance..... That has all been great with no issues for about a year now.

Recently inspired by a post seen on here the other week I decided it was time to take off the inlet manifold and try to do something about the leaky swirl-flaps, which I believe are like teh EGR and DPF a pointeless complication to the engine.

I set above removing the manifold from the car (an epic task, but not too complicated), cleaned out all of the gunk (there was plenty) and then decided that I would disconnect the flaps from the actuator (leaving the actuator electrically connected) and also remove the swirl flaps from the shaft that holds them into the manifold, then to finish the job I sealed the shafts into the manifold with exhaust paste..... so basically I no longer have swirl flaps, just 1 solid thin shaft in place of each flap.

After putting it back together, this took longer than expected as the woodruff key from the fuel pump disappeared into abyss!! I was confident that everything was connected, especially as I follwed a very thorough Vauxhall workshop guide as posted on here. I started the car (1st time) and found that it idled at 1500rpm had No turbo pressure and is limited to 3500rpm. If I press and hold the brake pedal the revs drop down to normal idle speed, but upon release it builds back up to 1500rpm.

So far I have tried the following (unsuccessfully):
Changed for a new MAP sensor because it appeared to be pressure related.
Disconnected ECU for a day to reset it.
Checked all vacuum lines.
Checked all electrical connections.
Used Fiat ECU scan to test all actuators and ensure they were functioning (they all were).
Used Fiat ECU scan to read fault codes (there are none).

Now I'm really struggling, my next steps are to follow the fault finding guides in the E-learn tool as there seem to be some useful sensor checks etc. If I can't find anything here then I think I'm going to have to do the job again and maybe try a new manifold with swirl flaps in place, but I don't really want to go here.

I have read on Vauxhall engines about people glueing the swirl flaps open with no issues (which is the same as what I've done), therefore I don't think my modification should cause this problem.

Any suggestions of what to check, would be gratefully received. I assume what I'm experiencing is "limp mode" but I don't understand why there are no faults recorded to give me a clue whats going on!!
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If I press and hold the brake pedal the revs drop down to normal idle speed, but upon release it builds back up to 1500rpm.
This may indicate your vacuum hoses are not good as the brake boost is affecting it.
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(Post Link) post #3 of 4 Old 18-06-13 Thread Starter
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Morning guys, in case anyone is interested or has a similar problem after an inlet manifold job, I managed to fix this last night. I was somewhat fortunate as I have no idea what the actual fix was.

I decided to remove and chack the throttle body using a Fiat ECU scan test on the actuator while it was off the car, all was well. At the same time I checked fault codes (for the umpteenth time since this problem started) this time amongst the sensors that were unplugged, there was MAP fault (this is a brand new MAP sensor).

I put it all back together and checked the faults again, still the MAP fault remained. I plugged in my old MAP sensor and the fault could be cleared. So I fitted that and gave the car a go..... and what do you know, all was back to normal and working fine!!

I don't believe it was actually the MAP sensor, because it behaved the same way with the old MAP after putting all back together the first time, thats why I bought a new one. I'm thinking along the lines of a plug/wiring fault. Removing and refitting the throttle allowed me to re-route some wiring that may have been incorrectly routed, and disconnect and reconnect a couple of vacuum hoses, and obviously reseat the throttle body.

Anyway currently problem solved.
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(Post Link) post #4 of 4 Old 18-06-13 Thread Starter
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Swirl Flap Modification outcome

Aside from the issues that I had on putting everything back together, I believe the actual modification that I did to the manifold will prove worthwhile.

I have a 2006 159 1.9 diesel, and the swirl flaps were leaking on top of the manifold. Rather than buying a new manifold, I decided to remove and clean the manifold as normal. At the same time unscrew the flap parts from the swirl flaps, this left me with a rod that could be withdrawn from the manifold (see "swirl flap.jpg").

I also disconnected the rods from the actuator mechanism so the flaps are no longer driven, and removed the bar that connects them all. The next step was to glue the remaining parts of the swirl flap (flap removed) back into their places in the inlet manifold, I chose exhaust paste to do this, some around the top manifold hole, flap pushed in, and then some on top of the flap/manifold to create a gas tight seal.

So now, I should have a pretty reliable manifold, with no swirl flaps to get stuck or leak and basically fail. The car felt very responsive low down the revs when I tested it, but this may just be placebo, I'm just happy that I have now removed all of the things that make modern diesels unreliable (barring the DMF).

Time will tell obviously if this modification holds, but I'm pretty confident. A fairly cheap fix, just labour intensive.
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inlet , limp mode , manifold , work

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