Can The Wrong Camshaft Be The Cause?

[mhyphenl 10 1 Cars]

I have recently solved a long standing issue regarding lambda readings and my car is now a dream compared to what it was, now getting 35mpg rather than 25mpg. However the idle now seems a little rougher, slight misses and blips, just feels uneaven when sat at the lights etc. The plugs, leads, rotor and cap are all fairly new, (3years but only about 2000 miles).

 

Could it be the camshaft. It's the only bit I can't say for sure is for the DKZ engine! Someone gave it me out of a 1.9 engine but thats all I know. I can't change any timing / fueling as that's all done on the ECU! Or could it be Ign amp / coil related?

[welshpug 1,661]

has any of the throttle stop or air bypass been tinkered with?

 

I doubt there is a significant difference between the 122 and 128 bhp camshafts.

[mhyphenl 10 1 Cars]

Hi Welshpug,

 

I must admit, they most certainly have been moved in the almost endless effort to correct the lambda issue. Does that have any bearing on Motronic other than idle speed which is about 950, i don't get any issues with revs dipping when i come off the throttle as I had the whole throttle body apart and cleaned. I'm sure you're right that the differences are small, the only thing that alerted me was it having its own part number in servicebox!? Could be the ignition amp as I think that's original. It seems random rather than a problem with a specific plug/lead.

[Miles 331 1 Cars]

Sounds like issue's else where, I used to run a high comp 1.9 engine on Motronic, went well, Good MPG and std emissions, Is it a Bosch amp and good coil, I know the cheap Ebay things are pretty cr*p

[petert 588]

DKZ cam has different exhaust timing (giving less overlap period) and less total lift, Thus why they're popular in turbo applications. A D6B cam does sound a tad rougher in comparison. If your inlet and exhaust lobes have the same lift it's most likely a D6B cam.

[mhyphenl 10 1 Cars]

Ok, so this is more of an issue when hot. Does that sound like those differences would do that?

 

I'm keen on getting hold of the correct one, it can't hurt. Can anyone suggest a good source or does anyone have one? I'm happy to let whoever have mine which is in great condition!?!

[welshpug 1,661]

how old is your lambda and have the injectors been cleaned?

 

have the valve clearances been checked?

 

 

I really doubt the cam would make much difference, I run a mild upgrade on mine and its not noticeable at all.

[Anthony 1,003]

How bad are the symptoms that you're describing? It's been a while since I've driven a Motronic 205 but from memory they're not silky smooth idling like you'd get from a modern car, and certainly the ever so slight roughness and missing that you're describing is "normal" on Jetronic models. It's most obvious if you reverse up to a wall and listen to the exhaust note, and is more pronounced when the idle mixture is leaned out.

 

I would imagine that if you got given the cam separate to the engine itself then it's almost certainly a D6B cam that you've got, given that I'd guess they probably outnumber the DKZ's by over 100:1 here in the UK. There's a good thread here about identifying which cam you've got.

[mhyphenl 10 1 Cars]

Sounds like issue's else where, I used to run a high comp 1.9 engine on Motronic, went well, Good MPG and std emissions, Is it a Bosch amp and good coil, I know the cheap Ebay things are pretty cr*p

 

I have to be honest, I think the amp and coil are original, which at 23 years old might be part of the issue! It's smoother when cold and accelerating but you can feel it when driving along at low revs as well as at tickover!

how old is your lambda and have the injectors been cleaned?

 

have the valve clearances been checked?

 

 

I really doubt the cam would make much difference, I run a mild upgrade on mine and its not noticeable at all.

 

The lambda is brand new and the injectors are the four best after having 8 properly ASNU cleaned etc so I'm quite sure they're as good as can be, valve clearances spot on last time I checked. The misfire feels quite random, i would say not one particular cylinder so I guess coil and amp may be more likely, as above i can still feel it under constant low speed. I'm happy to try a good coil and amp, should they both be bosch?

[Tom Fenton 1,542]

If you can put up with it I'd leave the D6B cam in, the engine will perform better.

[Miles 331 1 Cars]

Was it a Bosch Lambda, I know the cheaper pattern ones can cause issues

[mhyphenl 10 1 Cars]

Was it a Bosch Lambda, I know the cheaper pattern ones can cause issues

 

Yes its a Bosch one and only about 3 months old, had my multimeter on it when I was sorting an issue with the wiring to it and it flips between 0.35 and 0.55 volts a few times a second. I had a fiddle with the amp and coil connectors a bit this morning and it did seem better, although it was bloody cold and probably never got up to temp which is when it seems worse.