Hesitation at >= 4K RPM

[73ess]

I posted this on the 911 Tech Forum, but am reposting here as obviously all the 930 experts are on this forum. Or perhaps most are.

I recently purchased an '88 930. 77K original miles with valve job completed at 57K miles. At the same time, it was converted to twin plug ignition, K27 turbocharger installed and aftermarket exhaust installed (GLH?). It starts and holds a steady idle at ~1K RPM. It accelerates fine from idle up to around 4000 RPM, but at and above 4000 RPM I'm getting some pretty bad hesitation. It feels as if the clutch is slipping, but I'm guessing it's something either ignition or fuel related. The car had been sitting for a couple of years without much driving, but I've already cycled through a tank full of gas and am still experiencing the hesitation. Also, after the engine is fully warmed up, the engine runs on for a few seconds before finally shutting down, after I turn the ignition key to off.

I haven't checked timing yet, as I'm not sure what the timing spec should be exactly with the twin plug ignition. Any ideas on what could be causing this? The typical culprits? A friend said it sounds like it's "dumping the wastegate". Not sure what he means by that. I'm definitely a 930 newbie.

[wjfk32]

Greetings:

Congrats on the car!!!!
Looking at your pics...No offense, it looks like the engine was under water....The engine needs some nice cleaning...
Now--Being the car was sitting for a long time. Mine was sitting for years also...
Change the oil,immed...change the gas-(empty the gas tank)..
Change fuel, oil filters.-injectors-expensive..Change plugs...and fuel accumulator...
Your pluger-fuel head might be getting stuck(gumming up at 4000rpms) mine did...Most likely that is the culprit..Your engine is starving for fuel. I Knew this, by using my HKS-AIC.-set it on TEST MODE..It immed dumped fuel when driving..(kick in the ass feel) . In off mode, the car had no pull. FUEL WAS NOT GETTING IN.It will cost u some money to replace parts...(Do it yourself and save some money-parts).
Put in Marvel Myst. Oil for both engine and gas compartment...Drive it--Open it up..Drive it....
Get the engine real hot and DUMP THE OIL/CHANGE IT Immed.

Hopefully-Things will work out..



Good luck!!!

Walt

(

[mark houghton]

Originally Posted by 73ess

Also, after the engine is fully warmed up, the engine runs on for a few seconds before finally shutting down, after I turn the ignition key to off.

A friend said it sounds like it's "dumping the wastegate". Not sure what he means by that. I'm definitely a 930 newbie.

Run-on after turning off the key...are you talking "dieseling" or just continuing to run normally for a couple seconds? The latter is normal providing the ignition kill delay circuit is working (let's ignition spark continue for a couple seconds, but shuts the pumps off immediately to clear residual fuel). Dieseling, of course, is not good. Do check the timing.

Unfortunately there are more than one possible cause. Your friend's comment about the WG dumping....well, a partially stuck open WG valve would limit boost and maybe cause the flat spot you're experiencing.

Do you have access to the gauge setup for testing your WUR pressures? Need to know that it's working properly so you're not chasing your tail in that regard, with maybe your boost enrichment portion of the WUR not reacting with the proper amount of enrichment.

[9dreizig]

Hi,
I am in the bay area pretty much every week. I'd be happy to hook up with you after work some night as it's always good to get another set of ears/eyes on the problem. I'm not an expert by any means but have some experience.

[73ess]

This evening I removed the intercooler on my 88 930 and found a few disconnected hoses, a cork plug and a loose wire in various areas of the engine. I need some help in determining where the hoses should go and more importantly, what the effect is on the engine performance with them disconnected as they are now. I'm guessing that some of them might have been disconnected in order to pass California emissions testing, but that's just a guess. Anyway, here they are. Any help very much appreciated!

Loose Hose #1 - Has a screw inserted in the loose end.

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200694.jpg

Loose Hose #2 - Also has a screw inserted in the loose end.

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200695.jpg

Loose Hose #3

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200696.jpg

Cork Inserted in Air Filter Housing. Why? Also, looks like a loose ground wire?

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200697.jpg

See hose slipped off, but not sure if done on purpose or just slipped off?

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200700.jpg

Should A Hose Be Connected to this Inlet Under Air Filter Housing?

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200701.jpg

Just a Full View of My Engine With Intercooler Removed

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200702.jpg

Looks Like a Torn Paper Air Hose in this Photo? But not sure.

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200704.jpg

What Is the Red Thingee and Should a Wire Be Connected to the Second Terminal?

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200706.jpg


Those are all the areas I could find that looked like possible contributors to my hesitation problem. Or maybe they are just disconnected for a reason. My engine has some modifications from stock. K27 turbocharger, not sure what model number , but here are a couple photos of it:

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200707.jpg

http://i11.photobucket.com/albums/a171/munkmunk/930%20Engine/P1200710.jpg

Also I have a GHL exhaust and twin plug ignition.

[AFM744]

If you can get your car down to me in Campbell I can get all that stuff sorted out for you. Ping me at x-1 (at) pacbell (dot) net. I'm around this weekend and I'd love to help!

[9dreizig]

Originally Posted by AFM744

If you can get your car down to me in Campbell I can get all that stuff sorted out for you. Ping me at x-1 (at) pacbell (dot) net. I'm around this weekend and I'd love to help!

I"d love to join you if it turns out that it's during the week.
Todd

[AFM744]

Steve and Todd, given my current employment status, it can be any damn time. (shrug) It'd be great to have both of you over.