1980 Fi runs really rich

[forzaphil]

Good news, valentina at least starts. Problem is, low RPMs are really rough until about 3000 and then it starts to even out, but anything under that shakes the whole car. Light blue smoke puffs out the tail pipe no matter the number of RPMs and it smells like unburned gasoline. When i pull the plugs they have a black powdery deposit on them.

I checked fuel pressure: 40 psi with the car off and 32 while running. i raise the RPMs and the pressure goes up but then back down to about 30-32 which i think means the fuel pressure regulator is in good shape.

I'm going to go through brad artigue's troubleshooting guide tomorrow to figure out the rich mixture. Stuck Injectors? cold start valve malfunctioning? Gah! But a question that is bugging me is how my fuel pump operates. White w/ black stripe is ground, i know that, but besides that i have 2 other wires going to the pump. Green w/ black stripe, stock from the dual relay that SHOULD be used, and then another that the PO jumped from the far right fuse in the fuse box. the problem is, key on, engine NOT running runs the fuel pump continuously from both wires! i get the one from the PO but shouldn't Green w/ black stripe only activate the pump when the AFM flap opens? I'm wondering if that causes it to run rich? gah! it's overwhelming sometimes.

Thanks all in advance.

[majicwrench]

"shakes the whole car" sounds like a cylinder or two not working.Will it idle at all?? get it idling and pull injector plugs one at a time and see if all are even. Or ground the plug wires one at a time. If one or more cylinders don't contribute, run compression ck.
Blue smoke == oil. COuld just be plugs fouled. Again, start by killing cylinders, see which one(s) dead.
Keith

[So Cal Mark]

the pump will run constantly with the extra wire connected to it. The PO may have tampered with the afm. You'll need the troubleshooting manual to check the system out. There are several possibilities including leaking regulator, leaking cold start inj, failed temp sender, misadjusted afm

[forzaphil]

In all humility and meekness I come to you all knowing knowledgeable knowers of the Fiat Fuel Injection system with my symptoms and a plea for help. I have been on a frustrating spell of working on La valentina for the past month going through the diagnostics manual and I think i have my symptoms pin pointed at least (Runs rich, fouls plugs 2 and 3), but have some questions with things that seemed odd while diagnosing.

So, good news is that she starts and runs, just not well. After starting it with clean plugs it idles like a dream for a little bit, then after time it degrades and starts to buck around. I pull the spark plug wires one by one and find that cylinders 2 and 3 aren't really contributing. When i pulled the plugs, 1 and 4 were black and wet while 2 and 3 had black sooty carbon deposits. 2 and 3 fouled!

http://s1105.photobucket.com/albums/h34 ... 010120.jpg

I just went ahead and installed new champion RN9YC plugs just to be sure i had the right heat range etc. Since I did that today, it didn't really start bucking on me, but i also never revved it past 2000 rpm like i had been doing previously. My suspicion is that the Air to fuel mixture is very rich. It starts to back fire every once in a while as i rev it up and the exhaust smells like unburned gas. So anyway, after going through the FI Diagnostics manual, i have a couple of questions.

1. Does the Coolant temperature sensor resistance ever reverse polarity somehow? it sounds weird, but after running the engine for about a minute and a half, i checked the resistance for the coolant temp sensor at the ECU harness (pin 13 to ground) and it read -400 ohms. and started to make it's way to zero. after hitting zero it started to climb more and more as the engine cooled. (-400 to 0 to 400 to 800 etc. at bout a few ohms per second.)

http://s1105.photobucket.com/albums/h34 ... 010115.mp4

http://s1105.photobucket.com/albums/h34 ... 010117.mp4

It seemed really weird to me that it would ever be negative, but that's what it showed. all of the other resistances like in the AFM and the air temperature sensor all check out, and i'm sure the mutlimeter works just fine.

As if it weren't weird enough, i unplugged the connector to the coolant temperature sensor in the T in front of the engine block after the car had been running for a bit expecting it to die, but it just kept running fine.

Checked cold start valve- doesn't spray when starter is not running. working fine.
Checked Fuel pressure regulator - doesn't leak fuel into plenum
Compression is 150 psi in all 4 cylinders.
Cleaned the Oil vapor separator that was super super gunked up.

Thanks so much for reading my novel. All posts and suggestions will be appreciated and welcome. Thanks in advance.

[majicwrench]

Can't have "negitive" ohms
Keith

[narfire]

How has the car run in the past? Is this a sudden occurance or the performance happen gradually? To me it sounds like the mixture is acting up..think Mark mentioned too much fuel? After checking the plug leads, perhaps pull the injector connectors off one by one when the car is running.(I use a set of curved needle nose) They can foul as well. I took mine to a fellow that checks/cleans them for about $25 each and sure enough one was pooched. If the O2 sensor is buggered I believe the computer defaults to an "average" setting,but pull it and have a look anyway. I suspect you will be replacing that if it covered in soot/deposits.
This post is timely as I thought I had a miss in my engine yesterday and its not electrical...time to check the injectors.
Chris

[azruss]

sounds like there is some money to be made here. negative resistance? i see a perpetual motion machine in your future. i see a couple of possibilities. first is a weak spark on 2 and 3. if you dont get a clean burn then they will foul fast. 2nd is bad injectors. If they are squirting and not spraying it could create these symptoms. also you may have frosted your O2 sensor with the bad mix. not convinced the O2 sensor is causing all this.

[jlferris]

I have an 80 model I bought from a guy who couldn't get it to run right (car was flooding badly and exhaust smelled like fuel). after considerable searching found the throttle position sensor to be stuck open thus dumping way to much fuel in, replaced it and car now runs like a champ not saying that's your problem but that's where i'd start looking.

[SpiderJim]

Regards negative resistance try reversing your leads if you are using a DVM (digital Meter)

[forzaphil]

Thanks to everyone for the quick responses. I love this forum and how willing everyone is to help. The explanation as to whether it was a gradual degradation or happened over night is kind of a hard question to answer. A year ago, one night ran great, the next morning i couldn't get it to start. knowing my fuel pump had been really noisy i figured that was the problem (before i knew anything about cars or this forum) I had to wait 3 months to save up the 80 bucks for a new bosch fuel pump. installed new fuel pump, still couldn't get it to start, (Wore out the starter in the process, then had that rebuilt.) Anyway, after all this i realized that the white magnetic pickup wire to from distributor to coil had toasted against the exhaust manifold. i repaired it and finally got it to start, but it has run rough and fouled the plugs ever since. One last thing about the back story is that when i replaced the fuel pump i noticed there was an extra wire jumpered from the 1st fuse in the fuse box (#1 or A in brad artigues manual) to the pump. After researching in here i realized it was probably because the inline fuse for the pump had blown and the PO hadn't known about where to find it. So anyway, things I have done since then:

1. Replaced the magnetic pickup in the distributor and gapped it.
2. Checked timing: set to about 10 degrees BTDC where idle sounded smoothest (relatively)
3. Pulled fuel rail off and cycled all injectors to check misting. All spray, none drip or are clogged. Mist beautifully.
4. Checked cold start valve. No drips or leaks. only sprays while starter is running.
5. checked fuel pressure regulator. diaphragm is in good shape and keeps fuel pressure around 35 psi.

Question: Does the coolant temperature sensor resistance ever go to zero and then go back up? let's disregard the negative part of my previous post (sorry about that, a bit of a brain fart on my part. obviously resistance can't be negative ) Does the CTS resistance go down then back up as a part of it's path or does it just start high and then decrease as the engine heats up?

[rlux4]

Just the opposite, the resistance starts high and decreases as the temperature rises. The range should be 7,000 to 12,000 ohms at 14°F, 2,000 to 3,000 at 68°, and 250 to 400 at 176°. This information, and a lot of other good stuff can be found in Brad Artigue's maintenance manual, which has a section on the Bosch L-jetronic system:
http://www.artigue.com/?page_id=616
Brad has this and wiring diagrams that are downloadable on his site, and IMO are a must have for us Fiat owners.
Ron

[forzaphil]

Okay, that's what I thought. Thanks Ron (I have Brad Artigue's Manual and wiring diagrams. I love them very much and had my wife bind them for me.) I just wasn't sure if it went from

7,000 to 12,000 ohms at 14°F, 2,000 to 3,000 at 68°, and 250 to 400 at 176°

and then the resistance perhaps started to go back up again once it gets even hotter like around 190. It was a wild idea, but that's what mine seemed to do.

So after having looked through 112 posts on the forum on my search "Coolant Temp Sensor" I still haven't found a response to what my car seems to exhibit, so here is one last question before I start at the very top and go through the whole FI diagnostics manual once more.

What does it mean when the car seems to run really rich (fouling up the plugs) and neither the coolant temp sensor or a 330 ohm resistor (Thanks again Ron for this tip I found in other posts) inserted into the connector makes any difference when the Car is at operating temperature? Here is a video of the car running. Sorry it's so dark. I Also have some pictures of the temp sensor and my engine compartment.

http://www.youtube.com/watch?v=OGhr_ZSwGoE






Sorry to use these clickable thumbnails. I tried putting the full size image code in but the pictures were too wide for the forum. Thanks to all in advance! Any and all pointers welcome. Desperate and miss my beautiful car...

ps. should I repost this in engine and tuning? i realized it's probably in the wrong spot...

[rlux4]

As jlferris suggested, you can check the throttle position sensor setting very easily as per the instructions in Brad's manual. It wouldn't hurt to check your valve and ignition timing also, just to eliminate possible causes. It also wouldn't hurt, if you haven't done it already is to check for free movement of the AFM flap. It doesn't take much gunk in the plenum to cause them to stick.
Ron

[forzaphil]

Yeah, I do need to throw an ohmeter on the throttle position sensor to make sure it is not dumping in extra fuel on accident. When i open the throttle plate just a little I hear a click within the sensor, and up until now i have just been assuming that was the activating the circuit, but I will check it just in case. Thanks for the tip. I know ignition timing is about 10 or 12 degrees BTDC timed with the light as well as by ear as per Artigue's manual, but still need to check valve timing. AFM flap moves nice and freely as well. I appreciate the feedback everyone! I think i might have found something late last night that might be the source of my problem though. I saw a post with a beautiful picture of wiring on the coil, and decided I might very well be a Jackass.



Are my brown/white stripe wire and my pink wire to my coil reversed? From Brad artigue's wiring diagram it seems like the Pink wire whould be on the same terminal as red and brown/white stripe is supposed to be with black. Could these reversed wires be telling the injectors to fire at the completely wrong time when there is NO spark?

The Car is an hour away. I can't wait to go to it and try to prove my own idiocy. I am perhaps a major jackass and accidentally reversed the wiring...

[chrisfiat]

you have a bad coolant temp sensor, first of all resistence must NOT be read with voltage in the system, and second of all the sensor operation is linear , of sorts, meaning that it does not move as you describe, and third of all it is the second most imortent measurement device in the fuel map, the air fow meter being the first, but the temo sensor is most importent at idle. replacd it, clean the plugs and drive it hard to clean it out