Daft Question - solved!

2.4TE · Post by **2.4TE** » Sun May 29, 2011 7:56 am

Sorry, too much red wine when I was writing. BTDC.

Ian 2.2S · Post by **Ian 2.2S** » Sun May 29, 2011 7:59 am

Rich

I am quoting from a copy of a Porsche service manual for MFI cars. I have quoted all engine sizes for completeness.

All done at normal operating temp.

2.0 & 2.2 litre engines

Ignition timing at 30deg BTDC @ 6000 RPM .
On 2.0 and 2.2 litre engines always check ignition timing at idling speed.
0-2 deg ATDC at idle.
If setting is too late, surging may result.

Note:
If ignition timing is too late at idle, do not readjust until it is checked at 6000 rpm. Timing earlier than 30 BTDC will burn pistons.
If timing cannot be adjusted properly at both ends, remove the distributor and check advancement curve.

2.4 litre engine

1. Adjust ignition timing to 5 ATDC at idle (900+/- 50 rpm) with the vacuum line connected.
When the throttle is opened and the engine accelerated, the ignition timing must shift from retard to advance.
Check by disconnecting the vacuum line while the engine is idling. The ignition timing must be between 4 and 6 deg BTDC. This approx. 10deg timing variation is a result of the precise throttle valve synchronisation.
If the air-correction screws are opened too wide, the vacuum needed for ignition retard cannot build up. The timing may retard, for example, to only 3 ATDC. If the timing is now corrected to 5 ATDC, it will only change by 2 to 3 BTDC on acceleration.
The engine might have hesitation and bad transition performance.
2. (This seems to be just repearting itself!)
Let the engine continue to run at idling speed, disconnect the vacuum line and watch the timing change from late to early. When the vacuum line is disconnected the ignition timing should be at 4 to 6 BTDC.
3. With the vacuum line disconnected; check the the ignition timing at 6000 rpm. It must be between 32 and 38 BTDC.

Dwell angles for 2.4 are Bosch 38 +/- 3 deg, Marelli 37 +/- 3deg.

HTH

Ian

abzadams · Post by **abzadams** » Mon Jun 13, 2011 2:43 pm

Thanks for the tips. Been away in Moscow since these were posted. I spent some of the weekend trying the above, but still can not seem to get it.
It seems that there is very little movement in the first 2k. I timed it at idle, got it spot on to 5ATDC, when I removed the the vac line, the idle increased but the timing only shifted a couple of degrees. I presume that I am not getting enough vacuum at idle? Then it peed down with rain and had to stop!
So should I time it to 5BTDC without the vac line attached to make sure I get full advance? And should the vac line be plugged when not attached?

TIA

Gary71 · Post by **Gary71** » Mon Jun 13, 2011 4:19 pm

Vac line should be connected when setting up the idle.

All else fails I'd suspect the part you have most recently changed...

Your newly rebuilt distributor!

Ian 2.2S · Post by **Ian 2.2S** » Mon Jun 13, 2011 6:01 pm

Rich

Wot he said. Check vac line etc for leaks, if not it suggests advance mech on distributor may not be working correctly. Don't know if it make any difference if you plug the vac line when you disconnect it. Think advance curve on dist needs checking.
HTH
Ian

abzadams · Post by **abzadams** » Tue Jun 14, 2011 5:59 pm

Ian 2.2S wrote:Rich

Wot he said. Check vac line etc for leaks, if not it suggests advance mech on distributor may not be working correctly. Don't know if it make any difference if you plug the vac line when you disconnect it. Think advance curve on dist needs checking.
HTH
Ian

Ian, I think you are right! Just been out to the garage again for the last couple of hours. It seems that there is nothing until 2k and then the dizzy jumps to about 16 degrees (which is about where it should be). Loads of popping back through the intakes upto that point (lean?).

Does anyone have access to a testing machine or could possibly lend me a distributor to test, I would need a '003'? Just need to eliminate or confirm!

TIA

abzadams · Post by **abzadams** » Mon Jun 27, 2011 6:35 am

I managed to get some time in the garage over the weekend. Tim lent me a know good dizzy and I popped that in. Exactly the same thing happened. I timed it to 5ATDC and it idled fine. When I removed the vac line the revs increased but did not shift (exactly the same as my refurbed one). The timing marks as I blipped the throttle remained steady upto about 2k and then danced around like James Brown (!).
So I think it is something to do with a Vac leak, or the MFI is not set up properly. The problem I have is that I need to get it to Bob's to check the MFI side but it is underivable at the moment. My car doesn't have a tow hitch and I dont have a trailer!

abzadams · Post by **abzadams** » Sun Jul 03, 2011 4:49 pm

Bit of an update.
I was chasing down vac leaks and thought I would remove the TB's on both sides to clean and replace the 2 gaskets. Lots of gunk in the air bypass screws on both sides, carb cleaner did a great job! TB's are tight, squirt in the cleaner and it just stays there until the butterfly is opened.
Was just about to refit and thought I better do the the little pipe where the the dizzy vac line connects..... totally blocked! That's probably why I wasn't getting any retard on the dizzy!!!!
An in progress pic.

Plus I did notice that one of the return springs is broken, anyone know what the part number is? or could lend me one until I get one. The car is going to Bob's on Wednesday, and I don't think OPC would be able to get me one in time.

defianty · Post by **defianty** » Sun Jul 03, 2011 5:01 pm

Hopefully good progress Rich. Especially finding the block.

Ian 2.2S · Post by **Ian 2.2S** » Sun Jul 03, 2011 10:43 pm

Glad you seem to have bottomed the problem. Wish my TB's were as tight as yours

Ian

abzadams · Post by **abzadams** » Tue Jul 05, 2011 9:49 am

Success!
Got all the stuff back in yesterday, getting late so didn't start the car.
I watched for all the neighbors to go to work this morning and then went out and started the car.
Fired first time, a bit croaky to begin with, but then leveled out nicely. I let it warm up and then checked idle timing, had to adjust idle to spec 5ATDC then removed the vac line and for the first time watched the timing mark move to BTDC, infact bang on 5 degrees. Didn't do any more than that as I know the intake stack's are all pulling different values as I have had the bypass screws out to clean, and it is popping back through the intake on some of them.
So its getting trailered to Bob's tomorrow, for him to work his magic on the MFI.

Lightweight_911 · Post by **Lightweight_911** » Tue Jul 05, 2011 9:51 am

Excellent result Rich !

defianty · Post by **defianty** » Tue Jul 05, 2011 10:22 am

Good news Rich.

abzadams · Post by **abzadams** » Wed Jul 06, 2011 8:16 am

And off it goes to see the magician!

jury · Post by **jury** » Wed Jul 06, 2011 8:33 am

Nice one Rich

I guess that is the reasonably priced transporter