jej3

Well, doing my "drive the car as much as possible" thing before a trip to SITM in a month. Today, car developed a really bad sporadic (low) idle this morning running errands. Came home, let the car cool down. Did the WD40 trick for the ISV and now the car is dying at idle (even after a hard 20 minute drive)

This wasn't my first time doing the WD40 trick and previously after longer drives or in hot temps, I'd get the sporadic low stumbling idle.

Right now, I'm leaning towards a full Intake Refresh (hoping a month of weekends is enough time!) as the car has had prior issues with starts after being warn without me blipping the throttle when it starts.

Last time I had real issues with the car was in 2012 (and it was resolved almost exactly 6 years ago) with the following:

• New Plugs
• New Caps
• New Rotors
• New Plug Wires
• New Temp II Sender
• New Temp II Sender Harness
• New 02 Sensor
• Replaced internal Fuel Pump with Strainer and changed Fuel Filter
• CEP Refresh - All new fuses, many new relays, deoxit on every terminal
• Ground Refresh
• New Rear and Engine Ground Straps
• Rebuilt JDSPorsche MAF and LH that were BOTH bad!!!!!

The thread from 2012 is here....

https://rennlist.com/forums/928-foru...-no-start.html

Any reason not to do a Top End Refresh? (Thinking it will take me 25-30 hours to do it all - not doing any powder coating)

That would be just barely enough time for SITM if I start tearing it down tomorrow and order parts on Monday.

Mileage is 179Kish, 1990 S4. Engine rebuilt by Porsche at 100K miles. TB/WP/OPG/MM/Fuel Pump done within last 20-25K miles.

What do you think?

PS - My pre-SITM maintenance interval which always happens before SITM was going to include:
- Oil Change
-Swap out Oil Cooler (not annual just leaking)
-Change Spark Plugs
-Trans Fluid Replace, Add Kendall Additive to fix reverse shift lag - per this thread (https://rennlist.com/forums/928-foru...o-reverse.html)
-Change Diff Fluid
-Change out the Petcock I use in place of Heater Control Valve and the short hose
-Change Spark Plugs

AirtekHVAC

jej3

Me, too, Ron! Come on folks... give me your thoughts

buccicone

Intake refresh. Checking all hoses, replace ISV...............

DR

Hi Trey,

I checked out that thread from 6 years ago, sorry I didn't see it so I could help you out. That was a painful read, sorry you went through that, but at least you go caught up on some items that probably needed taking care of sooner or later.

IMHO, given you haven't done the Intake refresh in all the years you have had it(IIRC), I also think it would be wise to go ahead and get it done. Had there been history of that being done I would say go in and just replace the ISV.

IF it helps you sort out what you want to get for the Intake refresh, go to my website and look in the left hand menu for "928 Specialists Kits", then select the "Intake Removal/Refresh Kit for 87-95 " . From there you can go down the list and select the items you feel you need. Or you can call us and we will step you through the options.

You should have no problems getting this done before SITM, since you have a great helper combined with your knowledge/experience, I think 2 weekends would be plenty. That includes taking your time to clean all the bits and pieces.

Let us know if you need any help,

Dave

jej3

Thanks, DR (and everyone).

Dave - I'll take a look tomorrow! Appreciate the vote of confidence on getting it done

FredR

Sounds as though the inlet manifold has not been off since the engine rebuild that took place- correct? If so when was that?

An educated guess suggests that your inlet manifold has not been off for 10 years and possibly longer so removal is a no brainer. I have had the inlet manifold off, items changed and the manifold back on in a long afternoon in 40C heat! I do not recommend that but it is doable. As to what you should do whilst in there depends on your sense of humour and wallet depth. The ISV & associated piping, breather pipes/ vac connectors/tubing and knock sensors are the minimum scope I would suggest. Flappy actuator, TPS, and CPS whilst at it are also good candidates if they are still original items.

jej3

Thank you, Fred. I think your educated guess is dead on. I'm getting ready to lighten my wallet

Meanwhile, my 15 year old and I took today to strip the spare intake and cam covers. We didn't get all the way through the original primer but some spots were bare aluminum. We primed with VHT High Heat Primer and then started to paint the intake VHT Bright Red High Temp Engine Enamel and the cam covers with VHT Low Gloss Black High Temp Engine Enamel. The VHT High Temp Clear glossed everything up. I was hoping for a low gloss black finish but I'm cool with it



We ran out of daylight today to finish it up but my plan is to order parts tomorrow, tear down (however far I get) and get injectors shipped to Witchhunter on Tuesday. They appear to have a 6-8 day backlog and with any luck, I'll get them back as I'm putting everything back together.

It's critical to me to have a shakedown week before the SITM trip. I believe it can happen thanks to everyone's input.

Cheers!

jej3

And I should add, my 15 year old is so psyched about the potential of having an engine we don't have to hide under a closed hood

928 at last

Hey Trey,
Just a slice of personal philosophy......I understand Witchhunter does great work, but for the sake of longetivity, I dropped a set of new Ford HP units in my '90 few years ago and have the originals in a bag to go out to Witchhunter at some (still undetermined) point in the future. Remember, you can't rebuild them, only clean and flow-test. My vote is for new. Likely a few extra bucks, but peace of mind too. The necessary "O" rings are available. Fair weather daily driver and three trips down to SITM over the years and all well. (And I'm running 2,100 miles (roughly) each time with a pause on the Tail of the Dragon.......).
First time 'round with my son assisting took three days (excluding waiting for the powdercoating). You should be able to do this easily in time for the event!
Best,
Rob.

928 at last

Oh, and my old ISV bench tested with no issues. Completely useless when installed. Go new.

Taguid

Check fuel dampers and fuel pressure regulator for leaks because that may be causing your idle problems but if you're doing an intake refresh make sure you get new ones.

jej3

Hey Everyone - just a quick update. Have everything taken apart waiting on parts to come in. Got busy with a bunch of clean up using Simple Green and my steam cleaner.





Also replaced the Petcock I have in place of the heater valve.. The old one had about 6 years on it and the short hose was looking "puffy"


New Hose, New Petcock closed to ensure NO HEAT whatsoever










A bit more clean up to do on the removed throttle body and possibly cleaning/painting the waterbridge. I also have a hardware tumbler that has turned all the hardware flat grey in color. I am probably going to soak it in some distilled vinegar and then bust out my nickel anode and plate the hardware before re-assembly.

Not really interested in going back with Yellow Zinc, just wanting clean, modest shine bits.

Stay Tuned! SITM is around the corner

Taguid

Hey where did you source the petcock? I have removed the vacuum part of my heater valve (which is new) and zip tied it shut. I'd like something like you have to possibly turn it on when is gets cold here which is about 10-20 days a year. TIA

jej3

It is a Four Seasons 84707 Shut-Off Valve.





The Petcock was originally introduced by JPTL here....

https://rennlist.com/forums/showpost...3&postcount=16