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1982 928 us
 
Join Date: Mar 2008
Location: NH
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??? -- no cat , whats setup going on there? running bigger diameter of pipes will slow exhaust flow not getting enough back pressure. or replaced with cheaper test pipe/cat gutted doesn't have baffles/air for back pressure . running idle up to half its getting by not needing as much air to fuel ratio but its calling for more air at full throttle and not enough time for it to make air. a smaller engine wouldn't be noticeable /wear and tear on other parts modify/changing exhaust system . but...

pcar is a big v8 engine and to add no dummy , just try to get one over on it,lol. it knows.

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1982 Porsche 928 us
Old 10-10-2013, 05:07 AM
  Pelican Parts Catalog | Tech Articles | Promos & Specials    Reply With Quote #21 (permalink)
928: Serial Enabler
 
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Euro had/has no cats.

We've run one here for years with no cats, Y to 3 inch single.

He has other issues.

Its got one on him, but the mention of interior tide line is interesting.
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Old 10-10-2013, 03:01 PM
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Hi Blaize..... just found your thread on here..... does the voltmeter still vary when you hit the throttle ?
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Old 10-11-2013, 09:23 AM
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1982 928 us
 
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alternator, adequate parts in it, harness/connections
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1982 Porsche 928 us
Old 10-15-2013, 12:59 PM
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Quote:
Originally Posted by John Speake View Post
Hi Blaize..... just found your thread on here..... does the voltmeter still vary when you hit the throttle ?
I installed this voltage stabilizer on my 82, it worked great. No more bouncy voltmeter.

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1982 Porsche 928, Auto, 4.5
http://i72.photobucket.com/albums/i166/hethaerto/928Mist2.jpg?t=1305333945
Old 10-16-2013, 04:56 PM
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It came with extra wiring to install grounds around the engine. That really helped out the roughness.
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1982 Porsche 928, Auto, 4.5
http://i72.photobucket.com/albums/i166/hethaerto/928Mist2.jpg?t=1305333945
Old 10-16-2013, 04:58 PM
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Universal Car Vehicle Voltage Stabilizer Fuel Saver Regulators 3 Earth Cable | eBay
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1982 Porsche 928, Auto, 4.5
http://i72.photobucket.com/albums/i166/hethaerto/928Mist2.jpg?t=1305333945
Old 10-16-2013, 05:00 PM
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LOL, can't be serious.
Old 10-17-2013, 02:27 PM
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Quote:
Originally Posted by Danglerb View Post
LOL, can't be serious.

Yep, I bought it, installed it, installed the extra ground wires around the engine, and it worked as advertised. It's just a rechargeable battery pack. It calmed my voltage needle down, and that was what I wanted.
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1982 Porsche 928, Auto, 4.5
http://i72.photobucket.com/albums/i166/hethaerto/928Mist2.jpg?t=1305333945
Old 10-17-2013, 02:48 PM
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1982 928 us
 
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? gas tank/vent lines venting. unscrew gas cap a bit. tank maybe sucking itself in.

passenger charcoal canister /vent lines venting . disconnect so the crankcase can vent out. canister maybe clogged.
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Old 10-22-2013, 05:54 PM
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Quote:
Originally Posted by John Speake View Post
Hi Blaize..... just found your thread on here..... does the voltmeter still vary when you hit the throttle ?
Nope, it was the speedo and that seems to have gone away completely. The injectors were pretty dirty and horrible spray patterns, all refreshed and back in today, no practical change in performance. It is a monster when cold, VERY fast and butter smooth, and over the course of 5-8 min of driving it falls apart and eventually gets to where it has barely got enough power to be safe in traffic.

Whatever it is is totally temperature dependent. Drove it today until it was fully heat soaked, and really down on power. driving around floored for the length of a city block and only hitting 25 MPH. Let it sit in the shop door idling while the emissions machine warmed up, and in 5 min at idle it actually improved. Not close to fixed mind you, but when I drove in, holding the brake and flooring it produced very little power, after idling 5 min, it was trying to spin the tires.

Have ordered a fresh temp sensor II as a matter of course, and going to go over all the vac hoses and diaphragms in the morning. Cant say I am close to figuring this one out though.......
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Old 10-28-2013, 08:57 AM
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I had a similar problem where I was getting a misfire for a long time.

It ended up being a NON-OEM fuel pump relay. It was new, but not OEM.
Might be worth taking a look if you haven't already.
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Old 10-28-2013, 11:54 AM
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Anyone know how this problem was resolved.
I have an '83 with exactly same symptoms.
Spare computer, ignition module, and AFM changed with no help.
Old 05-07-2015, 02:24 PM
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Euro 84 uses a MAF and LH injection, 83 has almost nothing in common.

Most common issues; "note issues, not issue"

Vacuum leaks.
Bad ignition wires.
Dirty injectors.

Computer, ignition module, almost never fail, AFM different issues. (related to the 83 model)
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Old 05-08-2015, 06:36 PM
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Thanks for the reply Danglerb.

My car runs great when starting, warm up and first 20 minutes after that.
If I turn it off it restarts instantly then begins missing badly especially under load .
Completely temperature dependent worse on hot days.

Don't think the three things you mentioned would only be a problem only when hot.

But I did change the plugs and ignition wires, cleaned injectors (all were good) and checked for vacuum leaks. Also checked Temp II sensor many times at sensor and computer plug and checked all terminal values at computer plug.

Fuel pressure and flow good- same when hot and cold. No fuel in vacuum lines at damper or regulators. Fuel pressure holds after shut off so injectors and cold start valve not leaking.
Relays appear good but think a bad one would cause no run not a miss.

Timing good - same hot and cold.

Live in the desert so no corrosion problems but did check grounds many times.

Any other ideas?
Old 05-12-2015, 10:32 AM
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Is the routing and hookup on all vacuum lines correct?

Bosch copper plugs and Beru ignition wires, full loom change or just wires, if so did you check resistance in all the plug connectors?

Throttle position switches working properly?

Check, maybe swap out coil with a known good one (I buy used from 928intl to keep them handy cheap).
Old 05-13-2015, 01:01 AM
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I checked all terminals at the computer plug which includes throttle micro switches - all good.

Also posted on Rennlist. This is my complete post:

I have owned my car ('83 928s manual trans. 90,000 miles) for past 25 years and with the help of this forum have never needed a mechanic. I love the simplicity of the Ljet.

However, for the past couple of months the following problem has developed and I can't find a solution.

It starts instantly and runs great during warm up and first 20 minutes after that.
If I turn it off it restarts easily then begins missing badly (not just a one cylinder miss) especially under load. Completely temperature dependent - worse on hot days. Never over heats and has never overheated.
The miss feels like bad plugs did in the old days.

Compression good all cylinders.

I changed the plugs and ignition wires, - fat blue spark hot and cold. Closed gap temporarily on plugs to 0.20 - no change.
Cleaned injectors (all were good) and checked for vacuum leaks. Also checked Temp II sensor many times at sensor and computer plug (even tried a substituting a 250 ohm resistor for the sensor), and checked all terminal values at computer plug.

I have spare AFM, ignition module, and computer. Tried switching them all but no change. Green wire is like new, and connectors at both ends perfect. Pick up coil distributor readings hot and cold within specs.

Spare coil - no change. Voltage reading at coil terminals hot and cold OK.

Fuel pressure and flow good- same when hot and cold. No fuel in vacuum lines at damper or regulators. Fuel pressure holds after shut off so injectors and cold start valve not leaking. All injectors clicking when hot.

Replaced cat converter with "test pipe" no change.

New O2 sensor, disconnecting and reconnecting O2 sensor - no change.

Relays appear good but think a bad one would cause no run not a miss.

Timing good - same hot and cold. Battery voltage while running cold and hot good.

Disconnected tachometer terminal at dash pod - no change.

Live in the desert so no corrosion problems but did check grounds many times.

I found this thread at another site (mechanic with similar problem but he never posted the fix): [URL="http://forums.pelicanparts.com/porsche-928-technical-forum/769268-84-s2-missing-stumbling.html"

I wish it would just stop running - then fix would be easy. I'm thinking some wire, somewhere, maybe loose but where?

Any other ideas?
Old 05-13-2015, 07:40 AM
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Is the routing and hookup on all vacuum lines correct?

Bosch copper plugs and Beru ignition wires, full loom change or just wires, if so did you check resistance in all the plug connectors?
Old 05-16-2015, 06:20 AM
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928: Serial Enabler
 
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Bad vac leak at one of the intake boots?

Is it running rich when stumbling or lean? Clogged injectors, occluded fuel pump check valve, broken diagphrams in regulator or dampers?
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Last edited by Landseer; 05-17-2015 at 04:16 AM..
Old 05-16-2015, 02:54 PM
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(1) Heat failure is indicative of a ignition brake down and very common : So a close check of the Ignition is certainly in order . Check Spark when Cold , then when Motor is Hot and running Badly .
( look for weak spark when Its Hot and has the problem )
A bad Coil ( you have 2 correct ) well make the car run just as you describe .
Replace all the Ing condensers if you already have not done such . Could also be other things related to the Ignition the simple Key is if you have weak spark when It's Hot and failing .
(2)
Simple Water Vacuum Leak Test : Outside of the shop with motor running at idle Run Water
( Garden hose work just fine Low pressure ) all over the Intake area's , Vacuum Lines to check for a slow down at Idle , Steam out of "exhaust" is possible when a leak is bad enough .
If you have a Leak the motor well slow right down as water is sucked in the leak .
Naturally don't spray the Ignition wires and the like . Many are surprised to find a leak they missed
(3) Temporary Grounds :
Hook up some temporary Grounds at all the appropriate Places just as a test . Some alligator Clips and a long wire should do it > Lot's of grounds to check on the 928


Last edited by aluminum; 05-17-2015 at 12:22 PM..
Old 05-17-2015, 12:20 PM
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