308 GTSi 2v - Intermittant miss..help

I finally got my car away from my mechanic....who did not fix the problem at all after new cats and a nice labor bill!!! Lesson learned.
My 80' 308GTSi 2V runs good and then for no reason will intermittantly miss on a few cylinders at idle up to around 2800 rpm. The tack will show a drop in RPM's as the engine misses. Seems to run good cold and then as is warms up, it gets worse. After a 20 minute run, it begins to run more eratic, missing fire more.
Someone told me to change the wires and extenders ( Has Cavis wires that look pretty new ).
I have read a ton of the chats on wires and I am still confused.
- On the 2V electronic ignition cars - will the Taylor or Accel spiral wound wires be the best choice?
- what is the best aftermarket ignition set up? MSD 6A, Nick's set up,, or is there something else I should look at for the 308 injected 2V model.

I love the car.....I just want to start driving it! Anyone know a great mechanic in San Jose, CA???

 

I had the MSD6A and the Accell red coils. It ran like a champ.

Have you looked at your plugs?

 

I pulled the #1 and #7 plugs and they look good - tan in color. They are Bosch plugs. I ordered the NGK "6" plugs from T.Rutlands which will be in on Wednesday.
Is the ground wire on the ECU a possible culprit? I read that in one of the chats.
The cars "supposedly has only 12K miles on it" according to the speedo. Would the timing belts cause this as well? How would diagnose?
I am used to working on American iron.....so I am really excited about learning about these thoroughbreds! Now if I can only get it running good so I can drive it!

 

It sounds exactly like one of your ECUs, specifically the one that drives the tach (I forget which one that is) is freaking out. 99% of the time this is because one of the TDC sensors is intermittant. Measure each sensor (there are 3) with a multi-tester. Each should be 600-800 ohms. They are usually more intermittant when cold as they expand when they get warm and then make contact. I had the same problem on our Mondial. The tach freaking out is a dead giveaway.

There are a couple threads on this, but I can't seem to find them. I'll search some more.

Birdman

 

In San Jose call ROSELLI FOREIGN (408) 297-0303 ask for Ezio or Robert they specialize in the older F cars like the 308's and Dino, I think they are open today good luck.

Mike

 

When I had this on my '80 308 finally I changed the crank sensors and that fixed it.

 

I would bet The ground wire for the ignition boxes is the problem..do this fix 1st as it will save you alot of headaches (now or later)

Run a new ground wire from the trunk where the Marelli Boxes ground to the bolt where the coils mount. The ground in the trunk is trouble and I have done this update on 6 308's to date + 1 user on FC did it 3 weeks ago and solved his problem.

 

The ground strap is definitely a good first thing to try. Hopefully that works. Beyond that, I am betting money that it's a TDC sensor. Read this thread:

http://www.ferrarichat.com/forum/showthread.php?t=102649

Birdman

 

OK..I put on the ground wire. Seems to run a little better, but still misses between 2000 - 4000 RPM. The tach is steady now and idle is better now with the ground wire, but it still has a miss.
I also noticed that the Electrovalves are not plumbed up, one has a broken nipple ( anyone know where I can get a new one? ).
I am heading to Italy for business on Monday, and hoping to go to the FERRARI factory while there. I will also look for a parts house...maybe someday it will come in handy.
Do you still think it is the TDC sensors?

 

Certain electrovalves have just open nipples....that is normal.

 

Just a thought ... Check your ingnition wires with an OHM meter. They sould measure about the same (difference in lenghths will give slighly different readings) . If one wire does not have any reading .. then it has an open or a break. Replace that wire. (I uesed Taylor 9 mm when I found 3 open wires). The spark will jump the gap of the break .. it would run but rough and miss when pushed. The gaps usally get worse due to carbon accumilation..

 

Suprised no one has mentioned the !@#$ connectors on the digiplexes. They vibrate loose, first you get misses, then one bank goes dead. Drive it home a couple of times this way on four and gasoline washes the walls of the missing bank and you have a rebuild to do. (I understand there was an unofficial recall/repair due to this years back).

Check out the threads re replacement distributor; easy to do.

Rufus

 

OK...I will change the wires, clean the disty capm and put new extenders this week and see if that helps. I will post the results as soon as I get it done.
Also, I will reseat the ECU plugs and clean them with Electrinics Cleaner.
I guess if that doesn't help, then I'm down to the TDC sensors or a fuel problem.
When I start the carcold ( after 10 sec of cranking ) the car sometimes does not rev up until 30 seconds or so, sometimes not at all. Would those symptoms have anything to do with the intermittant missfire?
Anything in the fuel circuit that I should check also?

 

OK...I changed the spark plug extenders and put on new wires. I used Taylor Spiro pro 8mm and they fit perfect. I put a thin coat of Dielectric grease on the wires and they slipped right in with no effort.
I took the car out for a test drive and it still runs the same!!! Still has a miss between 2-3K rpm and then does fine from 4K on up. It will idle good most of time and then it will miss intermittantly. If I turn the car off and then start it back up, it run OK until I rev it up to ~3K, and then the miss starts again.
After the test drive, I pulled the ECU plugs and cleaned them. I installed the plugs on opposite ECU's. This had virtually no improved affect on the car.
What is left? TDC sensors?
Just for kicks, I turned the Fuel Mixture screw clockwise 1.5 turns, and the engine idled higher and seemed to smooth out a little bit. I then turned the Idle Speed adjustment down to 1000 rpm. it runs better then before, but still has a miss.
Any ideas from anyone? I really want to drive this baby...

 

I don't pretend know what your problem, might be, but I once had a 1980 volvo 242gt (RIP) which did the same thing yours is doing. Would run fine up to about 2400 rpm then would miss..like it was running on 3 cyls..could not develop any power in that rpm and up. The problem got worse... it turned out to be the fuel distributor. Replaced it with a known good one and she ran like a champ. I think your injection system is similar to the 242 (constant drip) and I think you do have fuel distributor. Worth looking at if the other ideas don't work. good luck.

 

Gast308,
I'm telling you my friend, check the TDC (crank) sensors! It takes only a few minutes to pull the left side rear inner wheel well, pop the connectors off each sensor and measure the DC resistance with a multitiester. They only cost $100 each and take a few minutes to swap out. I'm betting you that is the problem.

Birdman

 

Turning the mixture screw clockwise will make it richer. 1.5 turns is a lot, this says to me you also need to check your airflow sensor plate height. If your sensor plate is too high you will never make it run good. It is easy to adjust, the plate should sit in the smallest part of the opening. You will see the opening is like a cone and then the angle turns vertical about 1mm then it makes a cone the other way. A cross section of the airflow meter will look like an hour glass. The plate should sit right in the vertical section, if it is too high you must move the stop down and then readjust the mixture. To move the stop down there is a steel pin just under the hex part of the fuel line fitting this is 1.5 inches from the mixture screw toward the motor. With a small punch tap the pin down until the edge of the plate nearest the the outside of the car is level with the vertical point. If you go too far you will have to take the airflow meter apart th drive the pin back up.

Larry

 

Birdman..TDC sensor check is next. I was trying to do all the easy stuff first. BTW, today I took out the ECU's and cleaned all the bolts and connections really good. There was some corrosion on the bolts/nuts. I also ran a ground from both ECU's ( using one of the hold down bolts ) to the ground screw on the cover plate. I also pulled all the connections on the coils and cleaned those as well and crimped down the connectors.
I started the car and it immediately rev'd up to 2500 rpm ( 500 rpm more than before ) and then dropped to 1200 rpm ( 200 more than before ) after the cats warmed up. That was better than ever before.
I took it out for a spin and it definately has more power and takes off nicely.
HOWEVER....it now has a definate miss at 2800 rpm. It idles good and was over 3200 rpm, it takes off good. Acceration above 3500 rpm is very good, no appearance of a miss.
Still think it is the TDC sensors?

Also, I ordered a new fuse block holder from your website about two weeks ago, paid via paypal. I did not get a confirmation that you recieved the payment. Can you check please? Thanks..Randy

 

I am ordering TDC sensors today.. I hope that is the final fix to the miss at 2800 to 3200 rpm!
Should I also get injectors? Are the seals reusable, as I do not see them in the pictures of new injectors?
Thanks,
Randy

 

Wow...now I know what a Ferrari feels like when it is running on all cylinders!!!!! AWESOME!!!
OK, I replaced all the injectors and cleanes all the connectors that I could see. I got the sensors from Rutlands....they are the newer version, so I had to cut the connector ends off the new sensors, and splice in the original connectors from the old sensors. I measured the resistance on all the connectors to insure that they were good.
The sensor on 5-8 was bad, the resistance measured infinity.
Using an 8mm socket and 8mm open end/box end wrench , I removed the Oil Filter for better access to the top sensor, and inner fender well for the bottom two sensors. was able to get all the sensors out with a bit of contorting!
After replacing all the sensors, I started the car up and the tach was not working and the engine was not firing on all cylinders.......now what???? I had replaced everything!
While the fender was off, I noticed that the connector that carries the sensor signal to the ECU's ( located between the coils and coolant overflow tank ), was very dirty. So I disconnected it and cleaned it out real good with contact cleaner. I also noticed a pin that appeared to be pushed back. I fixed the pin and hooked it back up.
I started the cars and................VARRRROOOOOOOOMMMMMM!!! It jumped to life on all cylinders....Wow!
So I took it out for a spin and man oh man......what a difference! It ran great. It idles nicely at 1000rpm and accelerated very smooth from idle to 5500 rpm.....YES!!!!! Ok, now I will settle down a little. We will have to see if it maintains the good running......I hope to see some of you guys on the road!! Thanks for all the help......

 

Congratulations!

 

Congrats, now you truly know what this forum is for! These guys are the best and have seen it all!

Now drive it!

 

CONGRATS! Doesn't it feel great when you finally find and fix a nagging issue?? I love that. Now drive it!

Birdman