Initial Throttle Position On Motronic 1.3

[mhyphenl 10 1 Cars]

My car is finally complete but running like sh1t3. Checked for air leaks and sensors and all fine, everything has new seals, gaskets and things like throttle body has been thoroughly cleaned. Played with moving the timing forward and back a tooth with interesting results, all worse but had to make sure I'd got that right too. I think the combination of throttle initial position and air screw is wrong as when it's warm the idle is very low and stalls when I dip the clutch but the air screw is unscrewed quite a lot! I've read the injection section in the Haynes and there is setup info for jetronic etc but no Motronic, it just says 'throttle initial position is factory set' but what do you do if you know you've changed it? Where do you start with setup? Will the Jetronic setup help as a starting point?

[luggy 13]

Just realised which section it in

 

Just to clarify its got a CAS, SAD and Knock Sensor or CAT?

 

Go for the Jetronic setup.

Edited March 19, 2014 by luggy

[mhyphenl 10 1 Cars]

Yup, although Haynes insists it should have a double barrel on it!

[luggy 13]

Yup, although Haynes insists it should have a double barrel on it!

 

That'll be for the 16v dual butterfly with idle control valve, you haven't got either!

[welshpug 1,626]

the 8v 405 would have a double butterfly.

[luggy 13]

the 8v 405 would have a double butterfly.

Edited March 19, 2014 by luggy

[mhyphenl 10 1 Cars]

Yes, I think because its a DKZ they were fitted to 405 as well weren't they! Thats where the Haynes info has come from. Any way, mines got the standard Throttle body, Cam position sensor, cat with lambda, SAD etc, all of which seem to be working. No vacume advance on the distributer as spark is set by ECU but a normal rotary dis cap and arm (which I've set up so there's good contact!)

 

So do we still say jetronic setup!? Haynes says, with engine at temp, with air screw fully in and 4 turns on the initial position screw from touching, revs should be about 600RPM, then unscrew air screw until I get 900-950 RPM?

 

If at this point the gasses are wrong then it's tamper with the AFM spring time?

Edited March 19, 2014 by mhyphenl

[luggy 13]

Another option would be to adjust the dizzy angle to see if it improves the idle just make sure you mark it up before adjusting.

[mhyphenl 10 1 Cars]

I have adjusted the dizzy. I turned it as far as it would go in both directions, obviously it starts to get very lumpy at either end but I set it halfway between lumpy and lumpy This should mean the spark it happening when the rotor arm is in the middle of one of the contacts. As the ECU determines when the spark happens there's little more effect this can have I don't think.

It seems happy driving but the revs are too low at rest with the air screw about half way out, thats why I think the butterfly is too closed and needs setting.

[DamirGTI 327]

You can't change anything by rotating dizzy on a Motronic car ... ignition is ECU controlled , theres no mechanical parts inside the Motronic dizzy like on Jetronic one .

 

Throttle body adjustments are same on both the Jetronic and Motronic system .

 

D

[mhyphenl 10 1 Cars]

Thanks all,

 

As I say, all you can do on a Motronic with the dizzy is make sure the rota is in contact with a point when it wants to spark and that's it! I'll try the setup tomorrow and report!

[mhyphenl 10 1 Cars]

Ok, set up the throttle initial position as per Haynes and would not run! Very lumpy but got better by adjusting the AFM spring a few notches, this also solved the stalling when coming off the throttle and the engine management light actually went out occasionally! In going to start from cold again later to see if this has helped!

[welshpug 1,626]

you shouldn't need to touch the spring, you wind the screw to adjust the mixture.

[mhyphenl 10 1 Cars]

I'm not convinced the spring hasn't been touched before!? Anyway marked its position in case but seems to be running a lot better and the engine doesn't die when I dip the clutch. What I do have now though is the engine is very noisy under load, fine under tick over or very steady acceleration! It's sounds very clackety like a tractor. What's gone wrong now dag nammit!? Seems to be nice and quick.

[pug_ham 241 3 Cars]

If your engine management light is on, have you code read the ecu to see what is causing it?

 

g

[mhyphenl 10 1 Cars]

Yup, can't remember the number but it says air fuel mixture and to basically check everything! It fits because it goes out at certain times while driving! I think a session with a Gas analyser a d some fine tuning will sort that! It's this noise under load that bothers me now, it's not pinking I don't think!

[pug_ham 241 3 Cars]

Air fuel mixture hints at the Lambda not working properly as well imo but that usually gives a specific code.

 

g

[mhyphenl 10 1 Cars]

Ok, only fault code is 52, mixture control. It's always had this problem and an auto electrician explained that it throws this code when it cant bring the 02 into line by adjusting the fueling within certain perameters, ie ECU syas it's lean but unable to balance with the injector modulation. Normally means Air leaks, which we've checked, coolant temp sender which I'm sure I've checked but just bought a new one which I've checked with a multimeter, a saucepan and a thermometer and finally incorrect info from the AFM ie spring tampered with etc.

This knocking either sounds like pre ignition or big end barings. How can you tell the difference??

[pug_ham 241 3 Cars]

Has it got the correct afm fitted? A jetronic one won't be compatible with the motronic system.

 

Are the ht leads in the correct order on the cap?

 

Pre-igntion should clear as you get higher up the rev range.

 

g

[mhyphenl 10 1 Cars]

I think it's the right AFM, I'll get the number and check later. As for pre ignition, it does seem to sound smoother at higher revs but I don't want to push it and do damage! I'm not sure about any of the engine even though I've built it up from scratch! Could I have the wrong cam shaft? Crank shaft? Think it runs too smooth for the leads to be wrong!

[cybernck 400 1 Cars]

Go for the Jetronic setup.

On the other hand, I would suggest the opposite to all Jetronic users.

 

52 should be lambda sensor, as pugham said.

[mhyphenl 10 1 Cars]

Starting to think that of Motronic! Just noticed my brand new oil filler vessel and cap aren't a very tight fit! Possible leak? Also the Lambda was new but with so many issues since rebuild I've probably screwed it already! If you go on auto data it says check everything for fault 52 as its not a broken unit but an inability to bring the O2 into line due to one if many things!

I'm losing my rag with this thing!

[jackherer 543]

It might be worth getting the injectors cleaned/tested if you've covered everything else.

[mhyphenl 10 1 Cars]

Already done that one. Sent 8 injectors to be cleaned and used the best 4 which were all spot on according to the guy who did it, got the results sheet safe just in case I sell it

Also did valve clearances and all ok.

Am I right in saying that there is no knock sensor on a 205 with Motronic? I know the spec of Motronic 1.3 allows one but don't think it's used on a 205!?

[welshpug 1,626]

unlikely to be anything to do with a knock sensor given the code is mixture control.

 

you need to get it on a gas tester or some kind, or a wideband and see actually what's going on, but messing with the afm spring tension is the last thing you want to do on a Lambda equipped ecu.

 

have you confirmed its the correct AFM?