Any suggestions how to deal with a hesitation under load while the engine is cold?

 

PLUGS!

 

Letrr warm up!

 

I second that, Let it warm up. Drive it easy for the 1st few minutes. Have you done a tune up? check all the vaccum lines.

 

I second the plugs suggestion.....out of the cold garage I don't get this...and, BTW, my mechanic (Leif Johnson, well-known 928 mechanic in NW) tells me that my '85S 32V prefers the stock plugs over the fancier onces I had him install (engine missed a bit with the fancy platinums). He pulled them, went back to stock and all's well again. I guess some cars can be picky?

Harvey
'85S

 

I replaced the plugs only a few months ago. This hesitation only occured in the last few days. If I open the throttle at all wide, before the engine has warmed up, there is a gulping/sucking sound - like a carburetted car would sound with a faulty choke. It completely vanishes when the car has reached operating temperature. Thanks for the suggestions.

 

Check the resistance on the Temp II sensor...

 

OK, I'll ask the question...

What are you doing opening the throttle wide before the engine is warmed up?? Habbit or just playing around??

BTW......928s take a long time to warm up.......much more than most other cars......big engine, 9 quarts of oil, etc. My GT doesn't even begin to feel
normal until the oil temp comes up a little.......like at least 10 minutes of driving. Never really hesitates, just feels like not all the ponies are there, but then again I've never really opened the throttle wide when the engine was cold......don't know what it would do.......

 

Obviously, I never run the car hard when it is cold: this problem occured at any throttle opening, until the engine was warm.
However, I followed your suggestions, and replaced the expensive 4-prong plugs with OEM-spec plugs, and the problem appears to have vanished!
Thanks for the insights.
The internet is a marvellous resource for people working on their own with a relatively scarce product. (Fortunately, I live in the same town as Tony Harkin, V1UHOH!)
This is my second S4, and I still don't believe there is a better driving experience to be had for the money. I manage a BMW dealership, and have my pick of tempting cars, but use the S4 as my daily driver.

 

I really like that line.

 

Encouraged by the improvment shown by returning to OEM plugs, which cured about 90% of the problem, I bought a set of Denso Iridium plugs. Not cheap, but a noticeable improvement. The engine starts immediately, without any cranking, and seems more eager throughout the rev range.
The electrodes are needle-thin, which makes the gapping procedure a bit nerve-racking; but it's worth the effort.
The plugs are IW20, and the gap is .0028.

 

Hi,
I have been monitoring my engine's temperatures for nearly 12 months
The 928 does take a long time to get all systems to the correct operating temperature - especially the engine's oil!

It appears that about 30 minutes is needed to get near to an 80C oil temp in a cold start at below 15C. A regular visit to 80C is the minimum needed to keep the oil in a good condition

As the 928 develops very high oil pressure and has a high relief valve setting the oil filter can be by-passed for long periods especially if it is not an OEM filter ( MANN etc. ) The OEM filter has a high higher than normal by-pass setting too

Use only minimal revs until at the normal gauge temp. gauge setting is reached and then about another 10+ minutes will be needed for the oil temp. to catch up!

It becomes clearer why the S4 had flaps ( especially in colder climates ) when the cooling systems are fully understood

Regards