could the plugs im using cause it to be running rich and therefore causing the plugs to carbon up? i have NGK BPR5ES, if so would you recommend i switch to the Bosch plugs, WR7DC or WR8DC, the motor is stock.

Thanks

try it! i believe the higher the number the hotter the plug..porsche recommends the bosch wr's. a hotter plug may help burn off more oil or gas without foulling -J

hey i just picked up the Bosch WR7DC+ plugs and am going to try to put them in tomorrow, i was wondering if adjusting the fuel/air ratio would help me out as well, since it appears that it is running rich.

You shouldve gotten the WR8DC--hotter plug. but it shouldnt be that much difference. the problem lies elswhere and the plugs will just help counteract that rich tendency. DO you have a manual? im not totally sure about your 79' but most airflowmeter box's have an adjustment screw on the top corner to tune in air-fuel mix. i think its hex head. I would remove the A.F.M. first and totally clean it and check that the "flapper" valve is moving freely. this device tells the ECU how much fuel to add according to amount of air flowing thru the "flapper" valve. so if its malfunctioning that would throw everything off. the flapper valve controls an internal rheostat switch that could be faulty as well. it could also be as simple as corroded or wet connectors to the AFM! give it a good looking over and get a manual..theyre avaliable on disc now for cheap..highly recommended! ;)

Watch my Video I made when I changed my injectors. It's CIS like your car. I also changed my plugs. Towards the end of the video, it shows where and how to adjust your A/F. You'll need a very long 3mm allen. Push down and clock to richen and counter to lean.

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The carbon on the plugs is probably due to the extra fuel provided during cold starts. If they are carboned after warming up to operating temps, you should check your A/F mixture, check for worn valve guides or check for excessive blowby into the intake.

ok yea i was going to pull it apart and clean it first then put it together with the new plugs and try possible adjusting the air/fuel to see if this would make a difference. I do not have a manual and have hear that i can get one on cd for cheap but just dont know where to get it from. The video is a great help. I will check the other stuff as well.

Thanks

check EBAY for cd manual....or 928 m ot or spo rts...or 928 intl. your on the right track...probably a faulty AFM....or as i said before..could even be a bad connection! Many problems ive had were just simple electrical connections! It cant hurt to clean that AFM anyway after 30 yrs of service! may have never been serviced before! good luck, keep us posted!-J ;)

Roger sells Jim Morrisons CD collection this is the one you want Roger@************

ok thanks you i will try and get my hands on a manual asap...as an update, i didn't have much time yesterday since the cars outside and the sun was going down in bout 40min and i had to try and move the car anyways, so i didn't get to pull apart and clean the air flow meter, or mess with the air/fuel ratio. I put the plugs in to see where i was and i started it, it turned on and i ran it for about 30-40 min, and drove it around the block a few times. The idle was extremely low, on the virge of dieing out, but wen i gave it gas it responded well after it warmed up, just wouldn't idle more than 100rpm's. When i was driving it 1st gear would almost shut off even when i gave it 2500rpms and slowly released into it, then it would go after a few seconds of what seemed like chocking for fuel. I pulled the plugs after it ran for a while but the sun was down so couldn't do much, but they where no where as nearly carboned up as the previous plugs, but where slightly carboned up. I know i should still take the other steps and clean the air flow meter and prob adjust the ratio, but is there anything else i should try as well?

Thanks

stay on track and work with the AFM..and idle adjustment on throttle body....go to autozone and get a air fuel mix meter...that will help you see what happening in real time..but i heard the 79 dosent have an O2 sensor? maybe someone else knows how to hook one up to your 79? good luck.

79 does not have an O2. Buy a Innovate Wideband O2 with Gauge and you will be loving life with your CIS and knowing exactly what it's doing in realtime from "Inside" your car. The kit comes with an O2 Bung that you can have your local Muffler shop weld in. If you you look at the video i posted, you can see the gauge working and that's how I adjust my A/F Ratio.

Here's also a link to my thread on how I installed mine with pics:

Porsche 928 Forums dot com - View topic - Pics of my First 928 and Current Project

Since it accelerates alright, don't mess with the A/F mixture just yet. Clean the air sensor plate and look for any vacuum leaks. After that, adjust the idle and give it another test drive. Then, if it still carbons the plugs, adjust the A/F mixture. The slight carboning can be caused by the crud on the air sensor plate which could also adversely affect the idle.

ok thanks ill try those tips and try to get one of those meters, i just realized that the one vacuum advance that comes off the distributer is not connected, and i can't seems to remember or find where it goes.

Thanks

that disconnect on distributor can cause HUGE idle and surging problems! take a pix and post it.... your talking about the spark plug distributor? or air distribuor? if its the distributor cap for ignition it should connect to the closest vacuum outlet on throttle body. If off the air distibutor it connects to either the brake booster( on drivers side between 2 air tubes) or a switch that connects to smog control and carbon canister...( this ones in the very front of air distributor) you could plug either up with a cap and see how she runs..good luck ;)

i will try and post a pic tomorrow, but the one from the spark plug distributer cap is the one that is disconnected. I thought it went to the throttle body, but didn't see any openings but im sure there is so ill look and post pics, may be a few days though since the temp dropped pretty low here. If im looking from the front of the car that would mean its on the drivers side? and will it be on the back side of the throttle body closest to the drivers side? sorry if that confusing i know pics would be most helpful.

Thanks

P.S. i ordered the cd manual

drivers side is drivers side no matter which way your looking.....there will be a vacuum port on the front next to idle screw...now im going by mid 80's model car..but i believe it should be the same. if just one vacuum port is open that will cause your engine to not start or start and surge w/ rough idle. :)

Finally
 

Hi, sorry for the long time lapse, just had alot of snow here and no time with school. Finally got out today to work on the car, i was able to connect the vacuum advance from the distributor, clean the AFM, all plugs cleaned as well, then adjusted the A/F slightly and the idle. It starts up & runs, throttle responds great after it warms up, doesnt seems to be misfiring either. So i let it run for bout 15-20 min and checked over everything and off i went. When i went to drive it tho, same problem occurred in bottom of 1st gear, it wants to dies out (not as bad as before), but after a few seconds it slowly picks up then goes and through the rest of the gears it fine, but then once i go back to first at low speed it wants to die out. It occurs only when i engage 1st gear and start to take my foot of the clutch, otherwise if its stopped its fine, but when i ease of the clutch to start goin thats when it occurs. I don't know wut to check now, im thinking air/fuel still possibly but dnt see how. Any help would be greatly appreciated. BTW have an exhaust leak in two spots if this is any contributor to the problem, before muffler and where the cat would connect to the rest of the system back to the muffler, and it appears that there has been a cat delete.

Thanks

Have you checked the ignition timing on this car?

N