Injectors tuned - now a problem.. Help please.

[hansfreekit]

Hi All
I was wondering if any of you could shed light on a problem I'm having.
I have a 1989 320i convertible auto for a year now. She was running ok, but I decided to get the injectors tuned to see if i could get a bit more performance and for peace of mind seeing as I did not know if they'd ever been done.
I used 'Injector Tune' recommended on here.
They came back with a clean bill of health. So my mechanic put them back in for me. All good. I also changed breather hoses for good measure.
Now, she ran great for about half an hour but then I got pausing of the engine, like little stalls as I went along, then every time I stopped at lights it would stall. She started up ok but then it would keep happening.
Anyway the next day I drove it back to the garage about 15 mins away. Again she was driving fine while cold then as soon as we got to 15minute mark she started stuttering again and the occasional stall. We checked for any other air leaks, seemed ok, emission test, ok. A little test drive it had stopped.
I drove her around for an hour after that and everything seemed ok.
This morning another drive, from cold everything ok, then after 15 mins - stuttering, random rev-ing, the stall at lights...???
Now, the injectors don't seem to have any leaks (and report said the same) but all this has started since they were tuned and replaced.
Anyone have any ideas as to whats going on?
It had my mechanic scratching his head.
He said maybe to test the fuel pressure? (which he doesn't have eqpt. for)
Also he said there maybe shit in the fuel - but then why would it run great for 15mins from cold - then start playing up?
Thanks in advance
HF

[hansfreekit]

By the way its a M20 engine.

[Speedtouch]

Is the blue temperature sensor properly connected? Try measuring its resistance at the ECU socket:

http://www.e30zone.net/e30zonewiki/inde ... emp_Sensor

Also, check the engine-to-body earth strap and all electrical connections are clean and tight.

The symptoms possibly suggest a problem relating to something expanding as it warms up, so when it re-occurs after 15 minutes, try spraying WD40 or similar around the inlet manifold gasket; if it briefly raises the idle then you have a gasket leak.

I would also be checking and cleaning the idle control valve and TPS.

[Gavla]

Yip, sounds like a possible air leak / intake issue...

[Grrrmachine]

The trouble is that to get to the injectors, you had to disconnect all sorts of other stuff first, and anything you touched will now be a culprit.

I'd still be thinking that it's an air leak, since the M20 is a real pig when it comes to these, but also check your blue temp sensor wiring as Speedtouch says, using the Wiki method.

[hansfreekit]

Mucho Thanks for the ideas.
Will have a go at these suggestions.
Another E30 guy said that "mess about with the fuel rail loom at your peril" the round black plug from the rail to the ECU loom - under the intake - is prone to corrosion and is sensitive.
The old 'if it ain't broke don't fix it' spiel.
I was having overheating issues over the summer til I changed the radiator. Was wondering if the heat at times has maybe affected some wiring.

[Motorhole]

http://www.e30zone.net/e30zonewiki/index.php/C191

[hansfreekit]

A brief update..
Yesterday took her for a drive. 10mins in she starts stuttering, like kangerooing, the eco meter flicks to the left each time, no stalling this time. This continues randomly for about 5 minutes. Then it calms down until eventually she's running fine for an hour - then home.

Now, if this was an air leak, surely the problem wouldn't come and go. It would be constant right?

cheers

HF

[hansfreekit]

..Also I think this is beyond my local mechanic's level. At the moment he's like "ooh I dunno mate". (he put the injectors in) He's brilliant with the mechanical stuff, but this is like E30 knowledge innit.
Anyone know any good E30 mechanics in East London / London - who could help me with this stuff? Maybe repair the C191 loom.
I'm not adept enough for wiring jobs.

Cheers
HF

[hansfreekit]

nudge.

[jimbom30cab]

check the DME relay (and fuel pp relay) are in and tight

a similar problem was on here recently and it was a dodgy DME relay

[aceifty]

did you use the standard injectors, if so check the fuel pressure at the same time change your fuel filter.

i had a similar problem on my R32 Skyline (i know it is a different car) changed the fuel pump and filter and now she drives perfect.

also check the the relays as above ^^

[hansfreekit]

Ok, I'm trying not to get too excited but I think I've cracked it.
I let her get warmed up, then I checked each hose clamp for slack. BOTH clamps on either end of the rubber boot had half a turn of the screwdriver in them. So I tightened them up as well as all others - which also weren't tight tight.
I took her for a spin around town, no stuttering! Great.
So then I took her on the motorway for a proper test. Just got back and it hasn't happened once.
So its possible that air was getting under them once the engine was warm and the clamps had expanded a bit.
Fingers and toes crossed that this is it.
I'll keep you posted.
thanks for the input peeps.
I know steps to take if this ain't it.
(small fist pump)
HF

[hansfreekit]

So i spoke too soon about cracking it.
the problem returned the day after. So, i took to Lusardi,s in Hackney to get some diagnostics on the electrical system. It turns out that the Idle control valve actuator was a bit noisy intermittently. (The three pin connector on the bottom of the the T-shaped valve )
So it was replaced with a 2nd hand part (thanks to Andyp a fellow zoner) and the interference was silenced.
So the ICV was sending a ,part throttle, message to the ECU instead of an ,idle, message - and this was causing problems as the car had been setup with this fault unchecked..
So the idle speed could be reset from the ground up again - so to speak - and the ECU is not getting confused causing the stutter and stalling.
Apparently! (You learn something new everyday)
This seems to have done the trick.
So Thanks to Eddie at Lusardi,s garage Hackney for his help.
And to andyp for supplying the part.
HF

[Martinaston]

Could be the flow and return fuel lines have been mixed up.