kmascotto

No, both knock sensors are new (again only a few years old). The wire that you are refering to, which is wraped, is the MAF connectror.

kmascotto

The TPS switch is working properly

worf928

And, at least for the WOT-side on the switch, can’t cause the cold-start issue.

I think you have two issues: lean idle and cold-start. Interrelated, but curing the former, might help/change the latter.

Do you have the ability to smoke test the intake? (Inexpensive, but useful, smoke machines available on ebay, etc.)

Do you know how to test basic ISV operation from the LH connector? (Instructions in my inspection guide on the openroad dot site.)

EDIT: You tested idle switch. Have you tested idle-switch at LH/EZK when cold AND warm? Or just one or the other? If so which one?

kmascotto

So just to recap, I’ve got two issues going on.

1) The original reason for my post is, the car will not go through the high idle circuit on startup, actually it won’t even stay running for the first few minutes after start up. Once the engine has a small amount of heat...it runs perfectly.

2) The second problem that cropped up after the first issue was the lean running condition. As seen in the video

kmascotto

I agree there are two different issues.

I have the pressure tester for the intake (as per Dwaynes intake refresh) I can test again...maybe something has changed.

I'll have a look at the ISV operation (its new too) as per your write up.

I just replaced the TPS because the switch was not seating properly at idle (car wouldn’t idle when it was warm). (eg. no click) That fixed that issue. But correct me if I’m wrong...but wouldn't that mean the switch is functioning properly?

worf928

The new switches (as in ‘new’ since Porsche Classic got the part) need to be set-up more conservatively than originally. They need more ‘slack’ between the initial plate movement and the ‘click.’ Else they will work when cold but not warm. I doubt that is your problem but checking idle switch operation when cold and when at-temp will rule out any idle switch weirdness.

I have more diagnostics to describe, but that description will require a real keyboard as opposed to an iPad’s touchscreen. Thus, will need to wait until I’m back from Camp928.

worf928

And I assume that it held steady pressure when last tested.

Cold-start lean pretty much has to be false air, ISV, or no warm-up enrichment. Or, funky electrical gremlins.

Once the O2 loop kicks in, is the idle close to 14.x?

Stock injectors?

kmascotto

Yes, stock injectors (cleaned a few years ago)

I posted a video above which will give you an idea of the AFR at difference RPMs

I cant remember how long it held pressure when I last checked it, but its easy to do so I'll try again. Ill post a video when its done.

worf928

I watched it. But was it a warm run or cold run?

kmascotto

it had been running for a minute or two. you should be able to see the temp guage is still cold

GregBBRD

In the simplest of terms, the late model 928 fuel injection relies on the MAF and the water temperature, when completely cold.
After a few minutes of running, the O2 sensor gets warm enough to modify the "base information", that the MAF provides.
There's a limit to how much the O2 sensor can modify this signal.

Your issue is a textbook aged "MAF" providing a signal that is too lean to correct, completely.
Terribly lean on start-up and then too lean for the O2 sensor to completely correct.....although the O2 sensor helps.

BTW....there's a huge variance in what the word "rebuilt" means in each and every part you will buy.
In the case of MAFs, there's a huge variance.....and even the very best of the "rebuilders" can have a MAF slip buy that doesn't respond correctly.

Your car (in my shop) gets a different rebuilt MAF off of my shelf...long before you typed your first post.
And yes, I understand that this is way easier, for me than you...I've got a shelf full of these items....you probably do not.
So, your other alternative is to beg/borrow a Sharktuner from someone, hook it up, go drive it 10 miles, and actually see what the O2 sensor correction factor is.

Shirah

For my own knowledge Greg, I thought I read that to use a Sharktuner you need PEMs, or maybe I mis-understood.
Also how does the Sharktuner tie in to get an O2 reading?
Really interested in these two answers. Please and thanks

Kent, as an fyi, my Canadian(Florida-Snowbird) neighbor who has since returned home has a Sharktuner and he lives in Toronto.
He has a Koenig Specials (silver). He hasn't posted in a while.

kmascotto

I switched the MAF out with a good used one...there was no change

kmascotto

Fred?

Shirah

Yes, Fred