svo-ed

KURT: I really like your take on the throttle being and "AIR" peddle rather than a gas peddle. For the 928, the gas is controlled by the computer, not the peddle. It is funny to think that the gas peddle controls only air.

I will check the pressure. I have been thinking it would be nice to permanently install a gage on the end of the passenger side fuel rail.

Changing all three relays couldn't hurt (like you said: if no improvement, then I will have spares!)

Melo928: The car is not really drivable. I have only stayed in my general neighborhood because it runs so sporadically (and poor). It has extreme hesitation on acceleration...As you push the accelerator peddle it coughs and sputters and the engine runs worse and then loses power...I have tried mashing the peddle to the floor and it usually continues to sputter and almost stall, but a few times when I put the peddle to the floor the complete power of the engine unexpectedly kicked in and pinned me back in the seat for a few seconds of smooth power (the way it should run)....then it begins to sputter and hesitate again.

You can not maintain a steady driving speed. I don't think it is in limp mode. There were times when I needed to put it in the Low 1 gear (it is an automatic) just to sputter my way up my driveway, barely making it.

Thank you all for your help. I will be sure to revisit this post to let everyone know what the end result is. I think the solution needs to be in the archives for future members.

Ed

Mrmerlin

first restore the old parts to new condition,
make sure the timing is correct.

NOTE installing a fuel rail gauge SB for testing purposes only.
The gauge has failed on a atleast one car and caused an engine fire.
the ball and cap are the best solution

svo-ed

I was just getting ready to send Kevin from Injection Labs an email to get a quote to rebuild my MAF.

Who might you recommend for a MAF rebuild?

Thanks.

Ed

Melo928

Check also cam timing while doing twin dizzy. It sound like there is more involved than just MAF.

I had a bad MAF and car had problems to keep steady idle and accellerations were a bit hesitant. But before that I had cam timing almost 180 degree wrong and car run but very poorly.

Fuel pressure is good to confirm as well. The fact that your car ran well at some point doesn't support cam theory.

svo-ed

Mr. Merlin,
Good point about a permanent gage being a fire hazard. I will test pressure and then remove gage per your advice.

Thanks,

Ed

Alan

You sure the exhaust isn't plugged up...?

Alan

Alan

This is of course not a 928 thing at all... thats the way internal combustion engines work for the most part...

'Accellerator' seems to be awkward - it may accellerate the engine but not necessarily the vehicle and we may use it more commonly to maintain velocity and perhaps almost equally to decellerate (engine or vehicle)

So indeed 'throttle' is much more accurate than 'gas pedal' - however of course we should refer to "unthrottling it" rather than "giving it some throttle" (maybe getting off the throttle - though we don't use it that way - rather the reverse...).

"Opening up the throttle" is really the most correctly descriptive term.

I suspect "air peddle" is just not going to catch on... "Give it some air" would usually imply using some sort of ramp...

Alan

Alan

Any news here - did you discover whatwas causing it? - EMWTK...

Alan

scarceller

I'm not a 928 expert but could this be IdleControlValve related? You could let the car idle and while at idle unplug the ICV then apply throttle and see if it now holds at a given RPM, say 2500RPM.

Alan

The idle stabilization valve adds some amount of air for idling when the throttle is closed - it can't take it away when the throttle is open.

Alan

John Speake

The Euro LH doesn't have an ISV with a control loop like the US 32v 85/86.

It has a thermostatic type air valve for warm up (under the runners), and also an air solenoid vale that helps stabilise idle when the aircon is switched on (this is the valve on the cross brace).

svo-ed

Hi Everybody,
I wanted to get back to everyone to update you all on the cause of the problem.

It turned out to be the MAF causing the problems. I sent the MAF out to Kevin at Injection Labs, and it came back repaired in about a week. Once installed, the car fired up and ran like new! And for only $265 it was a bargain! Kevin bench tests all MAFs, so you know for sure if it is bad.

Even a novice mechanic can pull and install a new MAF in 1/2 an hour. If you are having troubles with your 928...I say just pull the MAF and send out for rebuild.

The car has been a blast to drive!

Thanks again for all of the advice.
Ed

Mrmerlin

Glad you got the car sorted out,
enjoy your ride!