matt968

Checking to see if anyone in the Baltimore, Philadelphia or Washington DC area has the JDS tool or Porsche tool and can perform the adaptation process on my 89 S4?
I can come to your location or meet somewhere....if it ever stops raining here!
Feel free to email me.
marzy1027@gmail.com

Thanks.

davek9

Curious as to what "adaption process" you are referring to?

If you disconnect the battery it will automatically reset and relearn on an S4.

Dave K

matt968

I read on the JDSPorsche website under the "Spanner User Manual" to perform this function anytime work is performed on the inlet system or as a routine service item for Porsche technicians. It is suppose to recalibrate the LH for proper idle (675 +/- 25rpm for automatics).

I performed an intake refresh about 2 years ago and replaced everything except the ISV and throttle switch - I was not having any issues at the time with either item.
This past winter I did replace my ISV and throttle switch - mainly as a precaution, and since I was familiar with how to do it, I figured I might as well replace those 2 items and have everythingnew under the intake.

Now it starts and runs perfect from cold. Drives perfect. After driving and getting it warmed up, if I shut it down and restart it is just fine. However, if I let it sit for about 15 mins after being driven, again it starts perfect, settles into the correct idle but after a few seconds the idle slowly drops to around 550 rpm or so. If I then put it into "D" the rpm's start to repeatedly surge - like it is trying to bring the rpm's back up but overshoots and then tries to lower the rpm's. If I tap the gas or drive away it drives just fine and does not do it again.
After my most recent drive (about 15 mins) when I got home and put it in "P" the idle went to around 1,000rpm. When I put it in "D" it settled back to normal. This is the first time it has done that.

I disconnected both the LH and EZK connections and confirmed with an OHM meter the throttle switch is performing as specified in the WSM at both idle and WOT. I also checked the Temp2 sensor is within spec. (I replaced it as well for precaution).
I also checked fuel pressure while running and residual fuel pressure and both were in spec.
I have pressure tested the intake and do not believe I have any leaks. However, I may take it to my local Porsche mechanic and have him "smoke" test the intake to be certain.
Also, I have disconnected the negative battery connection for an extended period of time....usually anytime I work on the car I disconnect it as precaution.

Since I have no drivability, problems I figured I might as well start with the adaptation process first. Which does not make any sense to me anyway. You would think the LH would see the crank signal and adjust the ISV accordingly to hold proper idle?!?!

Any thoughts?

docmirror

You removed two parts which were working fine, and replaced them with new. And now you are having some idle trouble.

Think about it.

As far as adaption goes, after the battery has been disconnected, in the first drive cycle the LH/EZK will perform the adaption automatically. Drive normally, make sure the car comes up to normal temperature, and put on about 40 miles or more, the adaptions should be completed, provided you are using bone stock chips in the ECUs. If you are using aftermarket ECU chips, I have no idea.

matt968

I agree. Usually it's the last thing that was disturbed or touched. And it is completely stock.

Based on what I read I assumed I had to use the Porsche tool to do the adaptation process.

I will try disconnecting the battery again and taking it for a longer drive....if it ever stops raining in the mid-atlantic.

Thanks for the reply!

Mrmerlin

when you drive the car make sure to do a few full throttle pedal to the floor runs up to about 5500 rpm use the lower gears

worf928

chart928s4

I am not an expert on LH behavior, but this doesn't sound like a learning/programming issue. As Docmirror points out, it's usually the last thing you touched.

You may not have installed your TPS with the correct clocking position, i.e. with the bolts loose it needs to be rotated on the shaft so it just clicks before tightening the bolts to the throttle body. Idle misbehavior after an intake refresh is often caused by missing the subtle TPS positioning. However, your observations are not what I noticed when I was having trouble - my idle was great cold, then slowed to a crawl and stalled when warm.

I haven't had any trouble with my ISV so I don't know it's misbehavior modes. But that also can contribute to idle issues.

A Bosch Hammer will quickly show if either of those components is malfunctioning. So it's still worth finding one. But a double check of both ISV and TPS would be a good start.

matt968

I believe the TPS is set properly. You can hear the audible click as soon as the throttle plate is opened. Plus, I checked the connections at the LH and EZK multi-pin connectors with an OHM meter throughout the full range of motion of the throttle.
I can try taking it for a longer drive after the rain stops. I usually run it up to redline at least once when I take it out....what's the point of owning a Porsche if you don't!

matt968

PROBLEM SOLVED (or at least so far, so good!). FYI, this is for my 1989 S4:

I noticed taking longer drives (approx 30 miles) and being sure to run it through all rpm's helped the idle adaptation process. My occasional low idle condition went away.

My next issue was after starting from cold it would start and idle as it should...(during the warm up process the initial idle will be around 800 then slowly drop to the specified 675 +/- 25), however, after reaching full operating temperature, the idle would just smoothly and quickly change to approx 900 rpm. but it was not very stable. It would vary +/- 50pm. My assumption was that this increase in idle was right when the LH was switching from open loop to closed loop (upon reaching full operating temp.).

A fellow Rennlist member was having the exact same issue. And he had done the exact same thing as me...replaced the TPS and ISV and that's when his high idle issue began! He put his old TPS back in and that fixed his problem!

So, first thing I did was replace my new TPS with my original TPS. This made no difference.

Next step, I purchased a smoke machine and smoke tested the intake to verify no leaks. None were found.

Pondering the issue and thinking if it is receiving excess air and that is what's causing the idle to increase, there are two sources that will provide excess air DIRECTLY into the intake. The first is the EVAP system. It takes fuel vapor from the charcoal canister and plumbs it directly into the intake. If there is an issue with the electrical switching valve and the vacuum switching valve sticking open it's possible to have excess air drawn into the system...although unlikely both would stick open. My vacuum switching valve was sticking so I replaced it hoping this would fix the problem but it did not.

The other direct source of air to the intake is the Y shaped venturi that provides vacuum to the brake booster. It not only provides vacuum to the brake booster and other vacuum operated devices but it also takes metered air from just past the MAF, but before the throttle plate, and bypasses the throttle plate and ports it directly into the intake manifold.
In my mind, that venturi is a "calibrated" air bypass device. If anything is wrong with it, it will upset the calibrated air. I removed mine and plugged the 3 hoses and the idle dropped to the specified range! I removed it and reinstalled it 3 times just to make sure and it had the same results each time. With it connected it had a high idle; disconnected and the hoses plugged it idled as specified!
NOTE: I had previously checked the brake booster side of the system and was quite certain there were no leaks coming form that port of the venturi.
I ordered a new one form Roger and this seems to have fixed my idle issue.

Now I don't see how anything can go wrong with that venturi but I do know you could pull mine apart...one side slides into the other side. At one point I had even put some HondaBond around the two pieces to ensure it was not causing a vacuum leak. Again, my assumption is somehow it was allowing a little too much air to pass through the venturi and into the intake.

Anyway, after driving it yesterday so far so good for me.

Hope this helps someone else.

Marti

great reply, thanks for feeding back

any idea of the part number for this y piece venturi, when I looked up the Porsche PET I could not find a art number for it?

matt968

I do not have the part #, however, I got it from Roger at 928sRus so he knows the part.

skpyle

Hi Marti!

Item 1 in the PET illustration, 035 133 753 A

AutoAtlanta shows this part as currently NLA. Hopefully Roger has a lead on some.




FWIW, the O-ring inside the venturi is replaceable. The specs are purported to be: O-ring, 3/8" ID x 3/32" cross section, Dash no. 110.
The venturi tube on my Red Witch has a green O-ring. I have a sneaking suspicion that someone used an AC O-ring on it.






Note the green O-ring on the piece at the left.

SteveG

It may not be critical, but I would suggest looking for a metric numbers(s) when looking for a replacement for this. Understood it may not be available, is why you found what you found.

skpyle

Steve, I got those dimensions from Rob Edwards from a long ago Rennlist post. Good point about the metric dimensions.