ddire333

Make sure the coding plug for the ecu is setup right / has ground, had same issue as you on none cat 87, someone had installed coding plug backwards and then ECU was looking for an O2 signal which it was not present = add more fuel all the time.

kamaro

I just did that, it was OK.

kamaro

As I said earlier, what I have noticed is that the engine was struggling to get any air while idling, I already put a brand new idle valve and I just took off the intake and re-tested the valve again using 12v battery, it opens fully when I apply power so I assume its working ok. What I also noticed is the throttle door is fully shut and it has a small adjustment screw to control its limit, is there a procedure to adjust the throttle door in order to get the correct idle air?

Geo55

I really don't know why your engine is running rich at idle (and wouldn't try to guess), but what I do know and am certain of, is that the people that are trying to help you know their S*@t. Given their years of experience, I would listen and appreciate..

Speedtoys

You are entirely incorrect.

Let's go back to my post:
"just tell us what you did/didn't do."

In that...are the MAF and idle air valve new?

kamaro

What I did so far :

1- tested the NTC II sensor, OK.
2- tested fuel pressure with vacuum and without : OK.
3- smoke tested the intake : OK.
4- checked ignition sparks on all 8 plugs : OK.
5- checked the throttle switch as per WSM : OK.

The air valve is brand new and I bench tested it yesterday,it fully opens when I apply 12v to its terminals, and closes down when no power. The MAF was supplied to me as "rebuilt" from someone in UK years ago, I had it in its box in my garage since the past 5 years or so. thats why I only assume its OK but can't be certain.

thanks,,,

kamaro

I was googling around and I came across JDS Porsche in UK, they have a very nice and detailed troubleshooting procedure for the MAF, I went to the garage and started the troubleshooting and found that my MAF has no output signal, I sent it to Mike @ JDS and I got it back from him the same week, not only I got a fast service, but he did a very good job on rebuilding it, the MAF looks brand new and very well cleaned and detailed. I also got a set of new injectors from Roger @ 928srus. After installing the rebuilt MAF and the new injectors the car started right up and idled smoothly for the first time since 20 years or so. I drove the car around and everything seems to be working very well. After about 10 minutes between idling and driving around the block I removed a couple of spark plugs to have a look and found they look a rich just a tiny bit, no smoke out of the tail pipe though. I can't take the car for a longer drive simply because I noticed that my brake reservoir is leaking past the lower O ring between it and the master cylinder, until I got that fix I will take it for a longer drive and hopefully it will continue to run as good. Thanks to everyone here for all the tips/ideas.

Speedtoys

"My car is a Euro spec with no catalytic converters or O2 sensor"

It will run a little fat like this, and that is just fine...

But this is back to the beginning, understanding what a "full rebuild" did/did not do.

That it was as simple as a MAF refresh is both wonderful news, and..not entirely unexpected. A 30+ year refresh project replaces everything..nothing gets reused.


Have fun!!!!

kamaro

​​​​​​What I meant by full rebuild us I took the engine back to bare block and built back from there. all new seals, hoses, gaskets .. etc .. along with neq water pump, timing belt, Porken tensioner .. I have some pics and some info that Im planning to share with you in a separate thread. My problem is that I'm doing everything alone in my home garage, so its hard for me to take photos, upload them and write up a thread all at the same time, also English is not my mother tongue and clearly Im not a good speaker in that language.

Speedtoys

Oh ya..of course.

But a full rebuild is more than just the metal parts. Everything needs touched.

I really cry when I see people do a top end, and then have IAC issues..because it was "fine before"..but still 30+yrs old, and then a month later, is no longer fine.