72 2.4 !!! help

rogman · 02-07-2015, 08:25 AM

guys I'm ready to pull my hair out!!! my 72 911t 2.4 runs great until at 180 degrees ???? car has been doing this for the past year just happened all of a sudden!! i have since replaced the entire ignition system with a clewett ign system which by the way was a great upgrade..... car runs and revs right up to 7k parked and also under load, until it warms up it will run fine then just start falling apart at 3 to 4 k RPM and then basically crawl home spitting an sputtering ....i have replaced all the fuel in the car i have sent the fuel pump out and have had it rebuilt i have also replaced the fuel filter and of course plugs and wires are new with the ignition system ..........i am at a loss and frustrated any help would be greatly appreciated guys..........thanks

pors1968 · pors1968's Garage

Is the coil been replaced.

zedsn · 02-07-2015, 09:57 AM

+1

rogman · 02-07-2015, 10:11 AM

yes when i did the electronic ignition it came with the 3 coil system.

pors1968 · pors1968's Garage

Carb or MFI and did you check distributor advance .

rogman · 02-07-2015, 11:15 AM

mfi and i no longer have a distributor with the new electronic system....oh and FYI the system is set up so the timing can me advanced or retarded by the turn of a switch and it is in time perfect.....

reddogmotrsprts · 02-07-2015, 05:25 PM

I'd quit revving it to 7k while it's cold and focus on debugging the problem while it's hot. When was the coil last tested or replaced? A new MSD 8222 is about $50; I'd pick one up just as a spare and then use it to confirm that it's not the source of your problem. I've seen a bad coil demonstrate these symptoms.

You say that the entire ignition system was replaced. Can you elaborate a little more on what this entailed? Was it a kit we can examine online? I'm assuming it's an optical distributor pick-up to replace points, but I've never seen a "3 coil system".

Matt Monson · 02-07-2015, 05:34 PM

Reddog, look up Richard's parts. Top notch Motorsports caliber stuff. I doubt it's the ignition system especially since his problem predates the upgrades.

reddogmotrsprts · 02-07-2015, 05:39 PM

Quote:

Originally Posted by Matt Monson

Reddog, look up Richard's parts. Top notch Motorsports caliber stuff. I doubt it's the ignition system especially since his problem predates the upgrades.

Thanks for the tip, where can I find this parts list?

19-911-65 · 02-07-2015, 07:18 PM

fuel vapor lock?

Porboynz · Porboynz's Garage

I had the same experience when I accidentally blanked off the MFI hot air hose, it ran OK when cold but was a rich running pig once warm. Went well on full throttle but anything else not so much.

bkreigsr · 02-08-2015, 05:39 AM

The MFI pump needs the hot air source from the headers so the bimetallic element in the rack will slide to adjust the mixture as the car warms up.
Bill K

Matt Monson · 02-08-2015, 07:23 AM

Quote:

Thanks for the tip, where can I find this parts list?

Clewett Engineering, The complete solution for ignition & fuel injection

RSBob · RSBob's Garage

How old are the spark plug wires?

I had a similar issue with my 2.4. The car ran great cold but when warm it started missing and losing power and it only became worse the warmer the motor. After 3 hours of troubleshooting, it was old wires. Not saying that is your problem but if you can put on a new set to test, that' some less variable

rogman · 02-08-2015, 08:25 AM

guys......i think we are on to something here!!!!!!! i had the whole engine rebuilt years back and never really drive the car far at all!!! and yes there is no hose going from the heat exchanger outlet port to the pump???? I'm not sure why?? this was a major rebuild from the ground up from a very well known Porsche shop in new england ?? i am seeing a hose about 6 inch's long that is coming off the front of the pump and is then bent back in-wards?? anyone know what type of hose i need to use to complete this application?? and yes i just put in brand new wires and plugs and thought i might have the gap set wrong and thats why it was breaking up possibly and when i took them all out to reset they were black as hell !!! very rich..... oh and for those of you who are interested in the ignition system it was from a guy name rich in California at a company called clewett engineering.com he has been very helpful in answering questions and it was not hard to install at all...it did take a bit of tI'me as i wanted a very clean install but i think it was part of the fun putting it in anyway....check out his site....and yes the 3 coil system works awesome 1 coil for every 2 cyls keeps a fully charged and ready to go spark which I'must say until my car warms up to 180 it runs as if its brand new!!! especially cold starts they are not a problem now at all!!!! hope its just this hose!!

Porboynz · Porboynz's Garage

The correct hose has an inner and an outer as a form of insulation. Its available from our host. Any flexible hose is better than none at all, try your local parts supplier for a flexible metal tube of the correct diameter and if it solves the problem then order the correct items.

There are many posts and opinions on bypassing the bimetal thermostat permanently or with a choke cable arrangement. I figure if its not broke I won't fix it and left mine stock.

billh1963 · billh1963's Garage

It sounds like it may be your MFI. But, If it's not the MFI, take a look at the wires going from your tachometer and ignition switch.

Two years ago my 914 (with a 6 transplant) tachometer had an intermittent short once it heated up. When The tachometer finally failed the car would not run. That was a b!tch to figure out....replaced the tach and problem solved!

On my MG MGC the car would die once up to temperature. Turns out that age and vibration had broken several copper strands in the ignition wire. Once everything heated up it couldn't carry any load (amperage).

So, check your wires. This is just a shot in the dark; but, The wires are 40+ years old and could be a source of the problem

rogman · 02-10-2015, 06:28 AM

thanks guys for all the insight ......i am out of town on bizz but will be back in a couple of weeks and will look into every suggestion and post my results!!!!

rogman · 02-14-2015, 06:47 AM

guys also the fitting coming off the air cleaner appears that there should be some type of hose going some were to that as well?? any thoughts....yes mfi

Porboynz · Porboynz's Garage

The T shaped plastic hose fitting at the rear of the air cleaner housing has one large braided hose to the oil reservoir via a tube above the oil filter console. Its the return hose for any fumes blown out of the engine breather, via the oil reservoir. The other side of the T fitting is blocked off on my 72 Euro build. Then there is the smaller diameter tube that drains any oil in the base of the air cleaner down onto the road, or onto your headers if you are moving at pace. Must fit a catch bottle one day, its the greeny in me.