Technical Multipla woes! maf, map, egr scratch head

[scottley]

More woes with this multipla of mine, i think i must have bought an absolute dog with this one.

Cut out last week and wouldnt rev over 2000rpm, like limp mode but nothing on the OBC. For starters is that normal? Does the OBC not pick up on this stuff?

We put it on a reader and nothing found, disconnected the MAF (OBC picked that up ok) and it ran ok, took it for a long test drive and it seemed ok but still a little sluggish. Put a new MAF on (How much!) and seemed ok for the first mile or so then it packed up and reverted back to limp mode.

Lef the new MAF on and stripped off the EGR (OBC got that too) and cleaned it out and replaced. Went like a dream, low rev pick up was best its ever been. Then it died and wouldnt start. Got it going after a few goes and took it back to the garage where its been ever since. Then things got worse, put it on a different reader and it gave a glow plug fault code.

After discussion we decided it shouldnt have anything to do with the plugs but as a prcess of elimination we'd change them anyway. How i wish we hadnt, got thre out so far and the threads on 1 is godd the other 2 are looking iffy. The third just spins, you can see the thread but it aint coming out for love nor money. Cant get to it as anyone who has tried will know and to take of the inlet is a real PITA. We dropped the enigne out last night as im damn sure the heads gonna have to come off to get it out or have it helicoiled.

All that work and its probably nothing to do with the original fault anyway!

So watch this space and ill let you know how it goes

 

[urchin]

that sounds like a proper multipla making one job into 3!!!

back to your original fault, have you checked the plug above the passenger footwell where the throttle pedal plugs in? I had the same sort of symptoms as you and lots of random fault codes in the end someone mentioned this plug I thought it was a long shot but cutting the plug out and joining the wires direct cured the problem worth a try and I wont cost you anything.

 

[cooky257]

Not sure why no fault codes show up because thats definately the best way to find out whats going on. Anyway a couple of thoughts, only a correct genuine bosch maf will do,I tried an ebay one and it was rubbish, no power,not revving properly. Also sometimes cleaning the egr isn't enough, the soliniod part corrodes quite badly internally and sticks.
Having eliminated those as the culprit, I would also suspect the Map sensor or maybe the crank sensor. I would expect fiatecuscan diag software to help me out at bit on those items.

 

[scottley]

Thanks for that advice, ill look into it.

So far he has managed to get the offending plug out and hopefull will be able to recut a new thread with the head in situ. Its a good job we dropped the engine as the stuff that has to come off to get the manifold off is ridiculous. You just cant get to anything on the back of the engine at all.

Fingers crossed he can get the threads cut and new plugs in and then get the engine back in by the end of the week as we are supposed to be off on our holidays int he car next week. Although even if he does get it back in we still havent sorted the original problem.

Going back to the lack of fault codes, he has 2 diagnostic machines and although th car iteslf didnt give any clues with EML's the 2nd computer did mange to read the glow plug fault so once this is sorted its possible it may show where the problem lies? Although if the glow plug fault still shows it could be the relay?

Is it at all possible for the glow plugs or relay to cause the limp mode effect??

 

[Devious]

If a plugs threaded, is it not possible that youre loosing compression, thus throwing it into limp mode?
Just a thought.
Ta

 

[widemouthfrog]

The heater plugs are in the inlet manifold, so wouldn't affect combustion chamber compression, but you're right, they might give you a loss of turbo boost pressure.

 

[scottley]

It would probably cause a problem but sadly the threads knackered on removal.

Got them all out now, could they have designed anymore stuff to come off it ge tthe manifold off? I see now why he chose to drop the engine out. Going to re-tap the threads adn stick a new set in and put the lump back in and see what happens.

There are a couple of electric sensor on the back of the engine, under the manifold near the injectors, not a chance of changing them with the engine and manifold in place. Do these ever fail??