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post #1 of 10 (permalink) Old 06-23-2014, 06:11 AM Thread Starter
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Engine timing?

2.0 8v twin spark FI in 105.

The engine doesnt really run smoothly. Under load the engine misses a bit and isnt too happy to rev, can hear it spitting a little.

I was under the impression that the motronic pretty much controls all this and there isnt much you can alter... Will rotating the distributors effect this?

Or is something else likely to be the culprit? I have all new leads, plugs, rotors and caps..

ta
Kev
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post #2 of 10 (permalink) Old 06-23-2014, 09:02 PM
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Hi Kev,

it's a good idea, if you haven't already, to check each dizzy is firing properly, just disconnect the HT lead from the coil on one and check the engine still runs on the other.. and vice versa. The lower dizzies especially develop a habit of shorting out through the rotor button = no spark on that set of plugs.

maybe check the VVT is operating - that makes them pretty unhappy under load.

re the dizzy timing - the motronic controls the advance / retard obviously, so it's not that critical where the rotor is timed relative to the cap as long as the spark is able to jump from the rotor to the cap electrode when the motronic fires. If you set the motor to TDC for #1 and the two rotors are already halfway or further across the given cap electrode it should run fine.

Vacuum leaks - the big rubber boot between the AFM and throttle can get some nasty cracks - particularly on the two small fittings that lead to the cam cover and oil vapor canister. The rubber couplings between the intake manifold and the plentum tubes go as well.

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post #3 of 10 (permalink) Old 06-24-2014, 12:26 AM Thread Starter
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Scott

Thanks for the reply.
Is it ok to disconnect from the coil? The coil will spit the spark wont it without the lead attached? (but no, i havent checked this yet)

Motor was set to TDC when i put everything together.

The VVT only kicks in above a certain rev range is that right? I can here the engine missing low down the rev range also, so i guess it would be this? (although i will check anyway)

There was a few plastic and rubber parts around the AFM that were split, but not right through, that i tried to fill and patch up....

Cheers
Kev
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post #4 of 10 (permalink) Old 06-24-2014, 07:28 AM
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Hi Kev,

You won't harm anything with the HT lead removed from one of the coils - it doesn't have a path to the ground so the coil will just sit tight until it does.

If you can see it arcing out of the nose of the coil - give the coil a good wipe over to remove oil/grease from the outside - that could be part of the problem.

running on one coil only isolates that side of the ignition - but the engine will still idle fine running on only one coil - if it runs worse on one than the other - that's a clue to start looking for issues there. You an drive it around on one coil as well to see if either system has issues under load. I drove my TS Super around for 6 months on one dizzy until I sorted the MS controller.

most TS engines I've come across have the rotor buttons glued on - you can buy replacements, but have to break the old ones off to fit them.

The VVT only kicks in above 1280rpm with more than ~40% throttle load, or so Festy discovered in his brilliant Motronic Deconstruction thread. Easiest way to test it is to disconnect it and see if the car drives any differently - if no difference - VVT isn't working. You want the ignition system proved first though.

what plugs are you running ? is the TPS switching correctly ? (it has contacts inside for Closed and Wide Open positions.) AFM flap isn't binding in it's travel ?

good luck ! let us know what you find

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post #5 of 10 (permalink) Old 06-24-2014, 07:59 AM Thread Starter
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hmm, ok well i can answer a few of those now..

The spark definatley arcs out of the coils, as i saw when id forgotton to plug the leads in when i first fitted! Although i had given them a reasonable clean..

The old rotors were indeed glued on and i had to carefully chip them off.. New ones werent glued in.. Could they be shifting a bit?..

The plugs i think, are bosch of somesort, single electrode.. The old ones i took out were quad though...

The others things i dont know the ansers to..
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post #6 of 10 (permalink) Old 06-30-2014, 03:51 AM Thread Starter
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OK, the VVT checks out fine.

I assume the engine needs to be running first before pulling one of the leads from the coil? ie not start it with pulled..

What should the spark plugs be gapped at? about 0.032 is the info i've managed to find..
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post #7 of 10 (permalink) Old 07-03-2014, 06:56 PM
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Hi Kev, you can pull the lead before starting - it will start fine on either ignition circuit independently if things are working as they should.

If you like a little more zing in your life, you can pull them while the engine's running. The motronic has a decent bite, as ignition systems go - got me through some heavy gloves and an insulated pair of pliers last time I did that

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post #8 of 10 (permalink) Old 07-04-2014, 12:03 AM Thread Starter
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im glad you said that! I pulled one of the coils and it wouldnt start! Not tried the other one!

However, im now concerned about my oil pressure.. The warning light comes on at hot idle, but not under load.. and its been suggested in another thread that i may have a problem Not changed the light sender yet though, so fingers crossed
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post #9 of 10 (permalink) Old 07-04-2014, 12:31 AM
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You might have found part of the problem then if it wouldn't start on one system. As long as the rotor buttons are on firmly they shouldn't cause an issue - but I'd look at gluing the top one on in particular at some stage..

what grade oil are you running ? I've found the newer 10W50 oils can make the engine a little clattery and give lower hot oil pressure at idle.

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post #10 of 10 (permalink) Old 07-04-2014, 12:48 AM Thread Starter
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i checked the rotor and it seemed pretty firm. I was a bit reluctant to glue it on as i had right trouble chipping the old one off!

im just running 10w40... I think 20w50 seems to be the recommended?
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