Still need help - Cold issues on an 82 - SOLVED!

[So Cal Mark]

I seriously doubt the regulator is the problem. Have you removed the vacuum hose to it and checked for leakage?

[majicwrench]

If the car runs well cold with the temp sensor unplugged that means there is probably enough fuel available to get the job done, so pressure is not likely an issue. If the pressure was not up to snuff unplugging senor and driving system full rich would not help much.
SInce problem occurs cold, checking O2 sensor is not going to help much, sensor will not read cold.

Any air leaks downstream of AFM will lean out mixture. Once engine reaches operation temp, and O2 starts reading, computer can then compensate, but when cold computer cannot compensate because it cannot read O2.

Same with plugged injectors, when cold injector opening time is pre-programed into computer. By disconnecting temp sensor you make computer think car is really really cold, and it opens injectors up longer. Again, once warm, and computer can read O2, computer can now compensate for plugged injectors.

Good luck,
Keith

[4babycar]

Well I was able to get the regulator off this morning, replace with a known good and re-assemble. Everything is still the same.

Thanks for the thought process Keith. So, if I a read that correctly, the suspect areas should be a vacuum leak between the AFM and the plenum or a clogged injector? I have searched for a vacuum leak all around multiple times and the only one I can find is a failed vacuum advance, which I disconnected and plugged. I have even removed the air intake hose and inspected the underside. I bench cleaned the injectors but that has now been 4 months ago. I have tried removing a fuel injector plug (systematically through all 4) and then running and it is noticeably worse so I figure they are at least firing somewhat.

Keep the ideas coming. I am going to take the afternoon off and go on the local ride but will be back at it tonight/tomorrow.

Thanks again!

[majicwrench]

There are lots of suspect areas......!

Air intake system, tween AFM and engine, not really familiar with fiat FI (mine is carbed) but ANY hose that connects to that boot can be leaking un-measured air into system. Clamp off hoses and try. Even oil fill cap need to be in place.

The FI system uses mostly the AFM, the Temp sensor, the Throttle position sensor, and then the O2 once warm to decide on mili-second opening of injectors. It's all pre-programed into ECM. TPS not likely cause it runs well warm.

When you cleaned inj 4 months ago, did that help?? Was it doing this poor cold thing then??
By a "known good AFM" did you take one off a functional car??

[4babycar]

Ok, I guess I should have said conditions rather than areas. Yes, there are lots of areas to check for leaks.

To answer you questions, I did not check the running of the car before cleaning the injectors 4 months ago. One hose was cracked so I took them off, cleaned them and replaced the hoses before I tried to start it. I am suspecting that this issue was going on before then because the PO, who I only spoke to once, said the car had an AFM problem when I bought it. Yes, the AFM was a working one from another working car. The issue was the same.

I will try again tomorrow to see if I can identify any vacuum leaks and go from there.

[majicwrench]

Next quick question.... how did you clean the injectors 4 month ago??

[surfingfreeman]

Hey Michael
I also have what i think to be the same problem, at least symptom-wise. I turn it over in the morning it fires right up but when i put the car into first or reverse and let the clutch out with a load on the engine and reach the friction point with clutch it starts to idle rough and will stall unless i push the clutch in and rev the engine to about 3K for a couple of seconds the it is good to go. I am waiting to bring the car in for it's 40K timing belt change and have the mechanic figure it out, i have only had the car for 5-months and the seller mentioned there being a probable AFM issue that was causing the trouble but it sounds like you already looked at this. My mechanic mentioned there being an expensive diagnostic piece of equip that can verify if there is an AFM problem, anyone know what this is? In the meantime the way i deal with the problem is i let the car idle for a couple of minutes in the morning and then rev it to 3K for a couple of seconds and then it is usually fine. I will be interested to hear how things work out! Good luck.
Mike

[surfingfreeman]

Hey Michael
Have you read the section on FI and AFM function, might be worth a look
http://www.artigue.com/fiat/books/Artig ... 124_MM.pdf

[4babycar]

Thanks everyone for your help and suggestions but I was able to solve the problem this evening! I am sure many of you can understand how excited I am!

I know you all are wondering what the solution is so I will fill you in. The problem came down to being the favorite little gremlin in the electronic distributor..... the magnetic pick-up. The clearance gap for the pick-up was so far out of spec. I am surprised it ran at all. Once I adjusted the clearance, it ran great.

All I have to do now is replace the master cylinder, re-re-re-bleed the brakes, install some rear seat-belts, replace the vacuum advance and finally, enjoy!

Thanks again everyone I really appreciate all of your help.

[dantye]

Thanks everyone for your help and suggestions but I was able to solve the problem this evening! I am sure many of you can understand how excited I am!

I know you all are wondering what the solution is so I will fill you in. The problem came down to being the favorite little gremlin in the electronic distributor..... the magnetic pick-up. The clearance gap for the pick-up was so far out of spec. I am surprised it ran at all. Once I adjusted the clearance, it ran great.

All I have to do now is replace the master cylinder, re-re-re-bleed the brakes, install some rear seat-belts, replace the vacuum advance and finally, enjoy!

Thanks again everyone I really appreciate all of your help.

Can someone help me understand how this would result in the engine running fine after warm-up? Just learning.

I have a problem with my '81 FI that seems identical to what 4babycar initially described and have gotten some advice via another topic, but have just been putting up with it. However, I just noticed, when checking electrics upon reinstall of the center console, that when the ignition was turned on just short of the start position - with the fuel pump running, I got a small gas leak under the car around the fuel pump area - in 10 seconds it would make a puddle about a foot in diameter. Once the engine is running, you can let it set and idle and the leak appears to stops, but is perhaps just slower. Obviously, I will be promptly checking clamps and replacing hoses as needed to eliminate the leak, and will post here if this improves cold-running.

Is it possible that the pressure differential caused by such a small leak could create this cold running problem?

Any observations in the meantime will be appreciated.

Thanks!

[rlux4]

First off, as you may know by now, the fuel pump shouldn't run until the engine is cranking. If it runs with the key in the "on" position before the engine is running the power to it has been modified. The signal should come from the dual relay after the flap in the AFM opens. This is a safety issue: engine not turning (as in an accident), then the fuel pump stops pumping.
Second, in answer to your question, if the fuel leak is also causing a pressure leak to the point where you're getting less than at least 30 lbs. at the injectos, then it would cause the car to run poorly. Either there's not enough pressure to get through the injectors, or the fuel leaving the injectors isn't in a mist-spray. Optimum pressure at the fuel rail should be around 35-40 lbs.
Ron

[dantye]

First off, as you may know by now, the fuel pump shouldn't run until the engine is cranking. If it runs with the key in the "on" position before the engine is running the power to it has been modified. The signal should come from the dual relay after the flap in the AFM opens. This is a safety issue: engine not turning (as in an accident), then the fuel pump stops pumping.
Second, in answer to your question, if the fuel leak is also causing a pressure leak to the point where you're getting less than at least 30 lbs. at the injectos, then it would cause the car to run poorly. Either there's not enough pressure to get through the injectors, or the fuel leaving the injectors isn't in a mist-spray. Optimum pressure at the fuel rail should be around 35-40 lbs.
Ron

Thanks.

So could this be caused by a stuck relay, a defective ignition switch, or would it have to be a mod? I assume that if the AFM flap was stuck, it would not run well, if at all. This ignition switch sequence has been like this since I first got it running a year ago and has logged more than 1200 miles; What puzzles me is that the fellow who initially got this running for me is primarily a Brit car pro, but has owned and worked on a number of Fiats and Alfas. I would have thought he would have noticed such an issue. If this was a safety shortcut, taken just to get it running, that would be a serious concern.

I am a retired electronics guy and have manuals and wiring diagrams. I have fixed several lighting circuit issues, so I will first try tracing these circuits before placing any blame.

Thanks again.

[rlux4]

You shouldn't assume that the flap isn't stuck. As an example: when I first got my car it had an issue that Mark suggested may be flap related. I removed the boot, moved the flap a little and it moved freely. Later, after a lot of wasted time I opened things up, and found that the flap would stick about 1/2 way through it's travel. I now pay closer attention to what Mark suggests. The tolerances in it's plenum are pretty tight and it would stick on built up gunk. So we need to do a periodic checking, cleaning and lubing on this.
Also, it's easy to check if you're dual relay has been bypassed. Use a test light and put it on the brown with white wire at the dual relay, it should be energized when you turn the key on, this comes from power supplied from the ignition switch through an inline (critical) fuse behind the main fuse panel. Then put the light on the green with black stripe wire, it should be energized when the engine is turning (cranking or running). If you have power to the relay, and no power out, it's a bad relay and someone has bypassed it, probably by tapping a "key on" hot wire to the green with black stripe wire that goes down to the fuel pump.
Ron

[dantye]

You shouldn't assume that the flap isn't stuck. As an example: when I first got my car it had an issue that Mark suggested may be flap related. I removed the boot, moved the flap a little and it moved freely. Later, after a lot of wasted time I opened things up, and found that the flap would stick about 1/2 way through it's travel. I now pay closer attention to what Mark suggests. The tolerances in it's plenum are pretty tight and it would stick on built up gunk. So we need to do a periodic checking, cleaning and lubing on this.
Also, it's easy to check if you're dual relay has been bypassed. Use a test light and put it on the brown with white wire at the dual relay, it should be energized when you turn the key on, this comes from power supplied from the ignition switch through an inline (critical) fuse behind the main fuse panel. Then put the light on the green with black stripe wire, it should be energized when the engine is turning (cranking or running). If you have power to the relay, and no power out, it's a bad relay and someone has bypassed it, probably by tapping a "key on" hot wire to the green with black stripe wire that goes down to the fuel pump.
Ron

I will check all of this thoroughly and see what I find.
With an unheated garage, I have just begun to get "shop time" up here!
Guess my radio install will have to wait a bit Thanks!
Dan

[So Cal Mark]

one of the most common mods I see is that an owner opens the AFM and "tweaks" it to make the motor run better. That changes the adjustment of the fuel pump switch in the AFM allowing it to make contact constantly.
You really should start your own thread on this, probably will get more replies that way