Alfa Romeo Forums banner

1 - 20 of 27 Posts

·
Registered
Joined
·
346 Posts
Discussion Starter #1
She's very, very good. But when she's bad, she stalls out within a half-mile from home (warm or cold). This happens, maybe, 1 out of 15 times.

My "barn find" 92 runs quite well, mostly. She always starts up cold without issue and has easily run 30 miles a day with no problems -- warm and hot starting just fine.

But on several occasions she's stalled just a few blocks from home. After failing, she'll turn over just fine and maybe stumble for a second but seems to require a time-out of a half-hour or more before running again.

The Motronic temp sender was the obvious culprit. I swapped in one from my deceased 91 (which ran perfectly) without success. I bought a new one...still no joy. The wiring seems fine and I've cleaned the connector.

Fuel delivery is not likely to be an issue as it never starves for fuel when pushed hard and the idle is always even. (As part of its resurrection, I replaced the tank, pump, and filter.)

Mischievous fuel LEVEL came to mind, but after adding 5 gallons to half a tank -- taking it to well above 3/4 -- gave inconclusive results today. She made it home but almost died twice during the 1/4 mile run. Fetching the 5 gallons took about an hour...so I'm thinking the resting was more a factor than than the additional fuel.

Other items swapped in from the parts car: plug wires, "red stripe" relay, AFM, and Motronic ECU.

New parts installed: cap, rotor, and spark plugs.

The battery is brand new. Voltage reads correct running (14ish) and not (12ish) .

What are your thoughts?

I plan on replacing the aux air controller next.
 

·
Registered
Joined
·
2,994 Posts
Also air leaks in the intake bellows assembly. Your symptoms sound like an intermittent air leak. Check the bellows for cracks and the small diameter hoses for loose fit or loose clamping.

Barely possible might be water contamination in the fuel. Run fuel system cleaner/dryer through the tank.
 

·
Premium Member
Joined
·
15,850 Posts
Clean all electrical connections in the engine bay to start off with, to get that possibility out of the way. Easy to do. Protect the connections with dielectric grease.
 

·
Premium Member
Joined
·
26,994 Posts
So tell us about that fuel pump and tank swap did you put a new short hose just inside the tank cover when you did it? Did you do a new fuel pressure/flow/leakdown test in system?
 

·
Registered
Joined
·
1,785 Posts
Leaking connections at the intake boot didn't cause those symptoms on mine. Still good to correct though. I could only string this boot along for so long.
 

Attachments

·
Registered
Joined
·
346 Posts
Discussion Starter #7
Thank you all. Looks like I have a busy weekend ahead!

I was leaning toward a fuel delivery issue as the symptoms remind me so much of running out of gas. It not likely to be a pump placement issue as filling the tank didn't completely resolve the issue. The hose from the pump to outlet is new. Wouldn't a delivery issue cause some starving under load?

Yesterday afternoon's failure was a good example of the problem. Around 3 PM, I completed installing the stereo and took it out for a spirited drive of 5 miles or so. Frequently flooring it and manually selecting low gears -- essentially making it use just about as much air, fuel and spark as possible. No problems were observed. No hesitations, no starving, nothing.

I did notice the brakes were spongy, though. So I parked it, bled the rear calipers, and took it out for another drive. This time, I was often stopping hard to test the brakes but not heavily accelerating and found the brakes were much improved. After less than half a mile, engine warm but not hot, the car stalled as I came to a stop at an intersection and would not start again. (That's when I walked home, got my gas can, fetched gas, filled stalled car and got it home -- twice in less than a quarter mile it felt like it might be stalling.)

It may be worth noting that the stalling does not seem to occur under load. It seems to happen when the throttle is closed, typically when letting off the accelerator when preparing to stop.

I've yet to see the problem happen when, say, running the car on the driveway. I can start the car and let it idle until it reaches full temp without issue.
 

·
Registered
Joined
·
346 Posts
Discussion Starter #8
Forgot to add in the original post that the fuel pressure regulator was also replaced with a good one from the deceased 164b.

I've been reading CMalfa's thread with some interest. Sounds similar but differs in that he can usually start up again right away. In my case, it seems all bets are off until she sits a while.
 

·
Registered
Joined
·
1,785 Posts
Do these cars ever suffer from a hydro or vapor lock situation in the fuel lines? Maybe a tank pressure problem that builds over time and then subsides.
 

·
Registered
Joined
·
9,977 Posts
If it stalls only with throttle-off decel (or at idle), then my first suspect would be an intermittently failing the Idle Stabilizer. They key clue in this is it happens only with the throttle off. So, what controls the engine recovering to idle? #1 suspect is the IS, followed by perhaps the Min/Max Switch. Motronic coolant temp sensor? Highly doubtful. Even if it fails, I believe the ECU just subs in a default value, which may make the starting mixture wrong, but probably will start regardless. I'll have to try and disconnect mine and see if it will start.

Probably not a fuel delivery problem unless the FPR is leaking raw gas into the intake through the vacuum line.

I had the exact same symptoms and a new IS cured the problem. Check this thread:

http://www.alfabb.com/bb/forums/164-168-1991-1995/206282-diagnosis-idle-faults-164-a.html
 

·
Registered
Joined
·
346 Posts
Discussion Starter #11
I'd forgotten about your awesome article. I plan to check it all out this weekend.

The stabilizer was going to be my next swap after re-checking the crank sensor and min/max switch.
 

·
Registered
Joined
·
9,977 Posts
When troubleshooting, boil the problem down to the essentials. In this case, dies on throttle-off decel and won't recover to idle.

"It seems to happen when the throttle is closed, typically when letting off the accelerator when preparing to stop."


Almost certainly not . . .

1. CPS. Why only fail only at throttle-off?
2. Fuel pressure. Why only fail when fuel demand is lowest?
3. Connector hose in tank. Why only fail when fuel demand is lowest?
4. Fuel supply pump check valve. Check valve has no function with pump running.

On the ECU coolant temp sensor, nevertheless, I would check that the wires to the connector are not strained, even with normal movement of the engine. That was a known factory problem and I've seen reports of owners who thought they cured hard starting problems fixing that.

For a normal start, we don't use any throttle. If that's the case, and the IS is not working, it's not going to start. The half hour time period is probably meaningless . . . just whenever the IS cools down (whatever) and decides to work correctly again. Sometimes right away and eventually . . . . never. Also of note, I got no engine codes out of the ECU.

On the restart after stall, my symptoms were that the engine was sometimes difficult/impossible to restart using normal technique (no throttle) . I found that using medium throttle during cranking that it would reluctantly start and run badly for a few seconds until the excess fuel was pushed through the cylinders. Remember, the all idle air comes through the IS. If you try and start with the throttle closed and a failed IS, then no air to the plenum. Starting with the throttle open allows air in, but probably screws up the air-fuel mixture causing a poor start . . . but at least it starts.
 

·
Registered
Joined
·
3,932 Posts
Eric it looks like you have tried almost everything that I could think of. I have heard of the idle stabilizer going bad but fortunately have never experienced it so I am not exactly sure what the symptoms are. My first thoughts are that you have a fuel obstruction, since the symptoms sound so similar to what I experienced with a 1974 spider once. It sounds like you have changed most of that system out but I would still try pulling a fuel line just before the fuel injection system, extending the line to reach a 5 gallon gas can and let it pump several gallons to make sure the flow is strong and consistent. I was fooled once before with an initial burst of fuel that quickly tapered off due to a clogged fuel filter.

It could be an electrical issue effecting fuel or spark. In this area we have 4 choices if a real 'Afro Romaro mekanic' is required; Bob Heins or Heinz (Hitch House), Hans Milo (Smyrna), Charlie Grant (Hartwell) and Bart Miller (Cleveland).

I am in Kennesaw, neighbor and drive a red 1992, 164-S on Momo Aero's regularly and have since it was new. I'd be happy to take a look at it with you, if you like, perhaps late Sunday afternoon...

Mark S.
 

·
Registered
Joined
·
346 Posts
Discussion Starter #15
Update

Richard2 - you might be the winner of this "what the heck is wrong with my 164?" AlfaBB episode with your immediate suggestion of the crank position sensor...

I was convinced the problem was the idle stabilizer. All the clues seemed to point to it. So I swapped in the one from my deceased 164b this evening when I arrived home from work.

She started up as always but *stalled* after idling for about 5 minutes in the driveway! Completely new symptom (making me think temp sender again...likely wiring.) I was able to start it by giving it half-throttle but let it drop to idle? Bam, dead.

At this point, I'm thinking that somehow, gremlins had infested a perfectly good idle stabilizer which last saw service in February in a perfectly-running car. Unlikely. So I began to inspect the wiring to the temp sender for the 40th time.

Then I went to reseat the CPS connector nearby...the male side (leading to the sensor itself) disintegrated between my fingers so completely that the spades were left in their correct order. Wow. So broken.

After taking a forensic photo with my phone to preserve the wiring order, I plugged each wire into the female connector and tried starting the car "sidesaddle" (my personal term for "I'm so sure this car will start, I'm leaving my feat on the driveway -- away from all pedals.") Vroom - flawless start.

So, tomorrow will involve further testing.

Question: has anyone noticed a common auto parts store carrying replacement Bosch connectors? (Common = Pep Boys, Advance, Autozone, NAPA, etc.) I'd like to leave the old 164's engine bay wiring harness intact if I can.
 

·
Registered
Joined
·
9,977 Posts
Make a detailed check of the IS connector as well.

With the engine running, manipulate the CPS, Temp Sender, and IS wires some to see if you get any reaction. BTW, how's the upper dog bone mount? Nice and solid, or does the engine mover fore and aft a lot? Just reach down and give it hard tugs with the engine off. Check that the bolt is tight as well.
 

·
Registered
Joined
·
346 Posts
Discussion Starter #18
Bad to worse

Yesterday I swapped in the spare idle stabilizer and discovered the bad crank position sensor male connector. I plugged each wire from the CPS into their respective female slot. Order from the "top" (top = key ridge) is ground (bare), yellow, black.

After all of this, the car completely failed to start normally. I could get it to start by giving it half throttle but it died immediately after letting off the gas. So I gave up for the day out of frustration.

This morning, thinking that the maybe the replacement idle stabilizer was bad somehow, I put the old one back in. Still no start. I then rechecked the order of the CPS wires by comparing them to those on my old 164 (it's connector is in bad shape too and the wires are visible entering what remains of the connector.) I have the wires in the correct order.

For what it's worth, in the quiet of the morning, I am able to clearly hear the click of the throttle switch just as it opens...so that's out of the way. I also rechecked the temp sender connector and all is well. Plenty of slack in the wiring and no pushed back female connectors (I've experienced both in the past.)

Next step will be to swap in the CPS from the parts car. Maybe the current one died after getting a good dose of power or something.
 

·
Registered
Joined
·
9,977 Posts
If it's not running with the throttle partially open (not closed), it's probably not the IS.

Have you looked at the Air Flow Meter being dirty and the connections to it?
 

·
Registered
Joined
·
346 Posts
Discussion Starter #20
Installed the spare crank pos sensor. The car started and ran for about 3 seconds. But that was it.

Guess I'll have a look at the air flow meter next.
 
1 - 20 of 27 Posts
Top