suspected air leak (not SOLVED!)

Sat Oct 10, 2009 5:17 pm

running rich

Sat Oct 10, 2009 9:44 pm

Dazdabomb wrote:running rich

Got it in one!
I see that Bosch super 4 plugs have been fitted. Lose them! I've no doubt that it runs better on them while the engine is being over fuelled, but, when the problem is solved, it will not run properly.

Sat Oct 10, 2009 10:34 pm

i use bosch super fours, and although there is no difference from standard it dosent cause any problems

Sat Oct 10, 2009 10:47 pm

asmith88 wrote:i use bosch super fours, and although there is no difference from standard it dosent cause any problems

If your sig and avatar are anything to go by, you have an iS with a M42 engine, not a M20. Completely different combustion chamber design!

Sun Oct 11, 2009 1:07 am

Supafly; I have checked the resistance of TPS today, it seems to be working fine. I even swapped it with a spare one, it didn't make no difference. I will check each of those other things which you have mentioned too. Thanks.

Brian; Can the Super4's actually be the cause? It's weird that Bosch would make an item that isn't good for the car, since its a well trusted brand. I have just ordered a set of NGK's, so will replace anyway. Also I will peel back the rubber on C192 plug tomorrow and have a look at the wire for corrosion. How likely is this the cause and is it common in M20's?

I can hear popping and burbling from the exhaust when throttle is held down. Over-fueling.

Sun Oct 11, 2009 10:45 am

Bosch weren't thinking of M20s when they designed the super 4 plug; they were thinking more of four valve per cylinder engines, which is why they should be OK with asmith88's M42.
Corrosion of wires under the C192 rubber boot is so common as to be considered normal!

Sun Oct 11, 2009 7:59 pm

I have checked the C192 plug. In it are the wiring for the sensors and injectors? Well the pins looked clean, and no signs of corrosion on the on the wires...

I thought it could be the o2 sensor but I have just checked and found out my car doesn't have one.

So what now?

Sun Oct 11, 2009 11:26 pm

quick bump before im off

Thu Oct 15, 2009 1:45 pm

same problem with me, i think may be tps or injectors

Thu Oct 15, 2009 5:25 pm

What happens if you open the oil filler cap while the engine is idling ?

Thu Oct 15, 2009 7:53 pm

There is major hesitation when I take off the cap. The whole engine starts shaking.

Also the first start off the day, the car idles at about 900rpm, then goes down to about 750 when warm. Is that normal? I thought it should be higher at cold start.

I am waiting for NGK spark plugs to arrive so I can see what difference it makes.

Thu Oct 15, 2009 9:47 pm

Hmmm, when mine was running rich at idle taking the oil cap off made the idle improve...

So is this car running rich or lean at idle ?

From reading all this I'm thinking that the mixture isn't the issue here.

Fri Oct 16, 2009 11:20 pm

GOOD NEWS. IT IS NOW SOLVED.

I cant believe it, it was the spark plugs. I changed them to NGK B6PRES, started it up and the juddering and slight missfiring completely dissapeared, to a normal stable solid engine idle. After alot investigation, head scratching, parts swapping, and many mechanics giving me many different false solutions... I am happy I am managed to get to the bottom of it EVENTUALLY. I have to thank Brian for mentioning that Super4's are rubbish on M20's, otherwise I would not have ordered the NGK's.
However, I only quickly started her up for a few minutes and turnt it back it off as I was freezing outside, so will check if it is still smelling fuelly tomorrow.

But right now I am happy and feel relieved...

Sat Oct 17, 2009 6:51 am

Is there anything that brian doesnt know about E30s? The guy is a bloody legend.

Sat Oct 17, 2009 10:30 am

m_jermyn wrote:Is there anything that brian doesnt know about E30s? The guy is a bloody legend.

You're in love!

Sat Oct 17, 2009 12:20 pm

Sshhhhh

Sat Oct 17, 2009 1:43 pm

m_jermyn wrote:Is there anything that brian doesnt know about E30s? The guy is a bloody legend.

Sorry totally not topic related !!!

Brian and Willnz are like the human e30 encyclopedia.

Thank you very much for answering all our questions.

Oh Willnz, you should post some pics of your many many e30s. Do you have or had owned all models of e30s ?

Cheers guys

Sat Oct 17, 2009 1:59 pm

m_jermyn wrote:Is there anything that brian doesnt know about E30s? The guy is a bloody legend.

Slightly OT, but what does Brian actually do for a living?

Sat Oct 17, 2009 2:09 pm

has to be a auto electrican

Sat Oct 17, 2009 2:49 pm

m_jermyn wrote:has to be a auto electrican

No he's not!

Sat Oct 17, 2009 3:06 pm

Brianmoooore wrote:
m_jermyn wrote:has to be a auto electrican
No he's not!

Although this might be common forum knowledge, it's something I haven't read so of course I'm curious. The depth of your knowledge base says to me that you haven't learned it all just by tinkering with your own car(s).

Sat Oct 17, 2009 3:36 pm

I shouldn't have spoken too soon. Went out for a drive this morning, everything seemed good as mentioned before.

A hour later, driving back home, waiting in traffic, I started to feel the car juddering at idle again. Reached home, opened the bonnet, and I see I am back to square one, the engine juddering like it used to.

I am not going to give up, but I am not going to try and hastly find the answer, just had enough for now. When I get my enthusiam back again, then I will carry on from there.

Sat Oct 17, 2009 3:52 pm

Brianmoooore wrote:I've no doubt that it runs better on them while the engine is being over fuelled, but, when the problem is solved, it will not run properly.

Are the new plugs sooted up?

Sun Oct 18, 2009 12:23 am

I checked a little ago, they are not sooted. Just little brown around the tip, but mostly clean. Also I am starting to think its intermittent now aswell.