John Speake

Contact details for Louie Ott were on the menu on the page I sent you, but here it is.....
http://www.performance928.com/cgi-bi...cgi?form_id=27

John Speake

Just make sure you only link pins 30 & 87 or you can damage the LH ECU

Lizard928

Tony,

I mean no ill intentions with this. But your posts are getting significantly harder to read, which will in turn cause a lot of people to just skip them.

As well this topic is 4 of more new topics on the SAME issue. It is impossible for most to keep track in our head as to what has been suggested and what has actually been tested.
I would recommend linking ALL your other topics into the origonal post and keeping this one topic alive until the problem is solved.

A MAS is not a part. A MAF is. MAF stands for Mass Air Flow sensor. It is on your model attached to the lower air filter housing via a rubber sleeve and 2 hose clamps. It then sits in the U shaped piece which the throttle body attaches to. It is sealed to this with an O-ring.

Now you know its location. I would also like to mention that all pertinant vacuum leaks should be eliminated FIRST. Inspect the O-ring where the MAF sits and ensure that it is in as new condition. If it is not, then REPLACE it.
Verify all of the rubber sleeves connecting the outter air boxes to the runners are in good condition with no tears and are properly clamped. As well inspect and ensure that the rubber sleeve connecting the throttle body to the central distribution tube is again in good condition with no tears.
You will need to remove each one and inspect it in your hands.

Once all of the above is performed, and you are confident that there is no vacuum leaks, you will need to adjust the CO setting as per the factory manual. If you MAF is seriously out of calibration then you will be unable to get it set properly. However you will need to get the car started first to be able to do this. even if it requires you to hold the throttle open slightly to keep the car running.

I would recommend in addition to following the manuals for setting the base CO and idle. That you look at Porkens website as he has a lot of information on his site for this year.
As well a board search is always a wise idea!

Lizard928

John,

On the LH 2.2 cars (which is what Tony has), the manual states that the MAF must be adjusted to set base CO%.

AFAIK the LH 2.2 does not have any self learning or real adaptive power that the later cars had/have.

davek9

Tony if it were my car I would not start adjusting the mechanicals (unless I knew they have been changed) until I have checked and verified all the electrical devices are working, MAF to computer, WOT to computer, Temp sensors, etc.

Fuel pressure (31 PSI seems OK) as your gauge may be off a bit like said normal is 36, but how have you confirmed it is running out of fuel when you accelerate?

Are you watching the fuel pressure, it would be easy to install a gauge on the Fuel Rail to do just that, before you spend money.

Start by eliminating the things that are working and you will find the one that is not.

Edit: read that you removed the Air Pump, should be just fine,
if you plugged up the vacuum line.
DaveK9

John Speake

Hi Colin
My apologies, I forgot the 85/86 US cars with O2 loop are different ..... :-(

You are correct that LH2.2 as fiited to those cars does not have "adaptation".

Tony H.

I hope to clear up the thread!!

I did not ask about the fuel relay. I am trying to find out how to fix my car that was someone else trying to fix there car ot their relay issue not me.

My issue is exactly as I mentioned my car will start but not rev up to speed when the gas pedal is pushed down.
It acts like a starved engine of fuel, but every one seems to say 30 or 31 PSI is ok at idle, so we moved on to MAF and the possible adjustment there of.

I am not real sure if I can adjust it, and if I could how much to adjust it, or what is used to adjust it.

I hope this clears up my thread and my issue, I have checked as much as I can for vaccume leaks and found not issues.

Thanks Tony H.

Tony H.

I hope to clear up the thread!!

I did not ask about the fuel relay. I am trying to find out how to fix my car that was someone else trying to fix there car ot their relay issue not me.

My issue is exactly as I mentioned my car will start but not rev up to speed when the gas pedal is pushed down.
It acts like a starved engine of fuel, but every one seems to say 30 or 31 PSI is ok at idle, so we moved on to MAF and the possible adjustment there of.

I am not real sure if I can adjust it, and if I could how much to adjust it, or what is used to adjust it.

I hope this clears up my thread and my issue, I have checked as much as I can for vaccume leaks and found not issues.

Thanks Tony H.

Tony H.

Sorry for the double post the site keeps making me log in over and over!!

Mrmerlin

Here is some reading for you to do before you touch your car this will get you up to speed on most of the issues your having


https://rennlist.com/forums/928-foru...2-pinouts.html
https://rennlist.com/forums/928-foru...art-third.html
https://rennlist.com/forums/928-foru...-85-86-us.html

Mrmerlin

https://rennlist.com/forums/928-foru...s-awesome.html

Tony H.

I read some threads on MAF adjustment, I think this may be over my head, it seems as though there are a lot of items involved with adjusting the MAF things I do not understand, I do not know how to set the adjustment of the MAF.

Alot of the threads I read talked about 02 sensor, also setting base CO level, things I just do not understand, I do not think I will be able to do this, but I thanks all who have answered me, my car smells rich when started and some one mentioned in a thread that may indicate 02 issues, and also the computor needs to re-set itself after the battery has been diconnected well my battery has been disconected hundreds of time in the last 2 months.

I am at a loss and do not know what else to do or more so how to do? Just seems like I am waisting your time and driving myself nuts along the way, Porsche is beauitful but I think you have to be a cerified machanic to own on or have a second on just like it that is perfect ot repair you other one with trial parts, but why would I need to fix mine if I had a good one.

Thanks for trying if I find out anything else I will update the thread.

Thanks again Tony H. the ***.

I am pretty sure all of my computors are ok but I am not sure of the wot to computor mostly becuase WOT to computor is not something I understand as well what is WOT?

the flyin' scotsman

Tony.............dont despair.

You dont have to be a certified mechanic to work on a 928 but it sure helps to have the basics then we can lead from there.

If the issue is the MAF take yours off and try it on a a good running car.............if the symptoms follow then you've found the issue. If there isn't a local 928 send the MAF to someone you trust..............hell send it to me...............its worth the 'stamp'. If its bad we'll send it away for rebuild.

dprantl

LH brain, this is the computer in the car that is responsible for firing the fuel injectors. It controls how much fuel is pumped into the engine and has a bunch of sensors to tell it what is going on. With input from the O2 sensor once the engine is warmed up, it tries to keep the Air/Fuel mixture ratio cycling around 14.7:1; not too rich or too lean.

WOT is Wide Open Throttle. There is a switch that is bolted to the throttle body that has a connection to the LH brain. When you press the gas pedal, the throttle switch rotates. There are three states that the throttle switch can send to the LH brain:

- You are at IDLE, not pressing the gas pedal
- You are CRUISING, pressing the gas pedal, but not enough to signal WOT
- You are pressing the pedal more than 3/4 of the way, so the LH brain gets a WOT signal

If this switch is malfunctioning, the LH brain may be being told it is in CRUISING mode when you are actually not pressing the gas at all. This causes idle issues.

Oxygen Sensor. This sensor helps the LH brain monitor the fuel/air mixture. It doesn't become active on a cold start until the coolant warms up past 60 deg C or so. So, during cold start it is normal for the car to run a little rich. You can easily test the O2 sensor by disconnecting it to see if there is a change in the way the car runs/idles.

MAF, Mass Air Flow sensor. This is another sensor connected to the LH brain. It tells the brain how much air is going into the engine so the brain can input the correct amount of fuel.

Dan
'91 928GT S/C 475hp/460lb.ft

Tony H.

Great info on the letter symbols and what they stand for, this switch you talk about on the trotle body is it something i change or does it need to be adjusted?

Thanks Tony H.