Are my plug wires bad and if so would that cause stalling after the car is hot? - Page 8 - Alfa Romeo Bulletin Board & Forums
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post #106 of 302 (permalink) Old 04-01-2017, 07:47 PM
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Does the distributor have one or two vacuum hoses to the advance unit? With the engine idling, pinch them off and see if the vacuum gauge climbs. You are right... very low vacuum reading at idle. Is the throttle body tight to the plenum? What about your idle o-ring on the side of the plenum?

Low vacuum can indicate late ignition timing, also. But you said you verified that.

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post #107 of 302 (permalink) Old 04-01-2017, 09:29 PM
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Hey, funny story. I forgot I still had the rear on jack stands, and realized I'd only put in a few drops of gas. Maybe it wasn't getting any fuel. So I dropped the car, put in 2 gallons, and fired it up.

At least it runs! But still stalls. Argh.

Cleaned and inspected the intake snorkus - no cracks or tears. Tightened everything down. Checked every vacuum hose.

So I'm wondering if it isn't an AFM issue. If I open the manual AAV all the way, the car will pull a strong idle. If I touch it at all, the vacuum will drop below 20" and the engine will begin stumbling. If I close it, the engine stalls.
This is sort of weird, because if there's a vacuum leak, that means unmetered air is getting it, which should cause it to run lean. But the AVV is designed to let in unmetered air, and the engine runs better with it open.
I've also opened up the idle bypass, presumably letting in as much air as possible when the AAV is open.

I also rechecked compression.
1-160
2-155
3-160
4-148
5-148
6-155

The driver's side bank is lower, which I chalk up to the fact that a couple of years ago I had the passenger side head rebuilt, and the seals were pretty crummy. I imagine the other side is a little leaky with the factory seals still in place.

So maybe it's a bum AFM? Or a leak elsewhere? Maybe it's an injector seal?

Grrr.
How does the fuel pressure and voltage to the pump look when the engine stalls? How long will the engine run before stalling? Does the engine now restart after stalling, or do you still have to wait?

Also, let's clarify a few things: by "manual AAV," are you referring to the hand throttle pull-lever to the left of the steering wheel? If so, I think that "manual AAV" is a misnomer, as the hand throttle lever acts on the main throttle valve, same as the throttle pedal (in other words, it doesn't bypass the main throttle valve like the actual AAV does). I'm actually not really sure why the GTV6 has a hand throttle, as a properly functioning L-Jetronic system will cold start just fine without it (it is very handy for testing/diagnostic purposes, though!).

You are correct that the idle adjustment locknut mechanism (on the side of the throttle body in the early GTV6 like yours and mine, on the intake plenum itself in the later cars) acts upon a throttle bypass passage, but this is a controlled bypass that the engineers accounted for (within a nominal adjustment range), and the airflow meter is there to keep the air/fuel mixture in check (when all is functioning correctly, of course!).

Semantics aside, when the engine IS running, your vacuum reading does seem to be low, but the idle seems steady enough in the video. You are correct to check for vacuum leaks, but I just had another thought: is the oxygen sensor connected or disconnected? I would leave it disconnected to make sure a bad sensor or shorted wiring isn't affecting things . . . . .

Does the engine still stall if you barely touch the gas pedal? In your latest post, you say that the engine will stall unless the hand throttle is all the way open---my '81 GTV6 is missing the plastic insert between the hand throttle cable end and the lever in the engine compartment, which means there is extra slop in the linkage. Even still, I can raise the engine speed to over 3000 RPM with the handle pulled out all the way. Unless your hand throttle linkage is somehow even more sloppy than mine, something must be seriously out of whack!

A large enough vacuum leak to cause engine stalling will usually be fairly consistent, and it usually means that the engine will run OK-ish at higher RPM, but I am unsure if this latest symptom is the same old thing or something new (hence my initial question about fuel pressure). Based on your latest description, it seems that something is intermittently causing the air/fuel ratio to change massively.

If the fuel pressure and delivery volume situation is now OK, I would begin to focus on the airflow meter. Does the metering plate move freely without dragging? I am normally against parts-swapping, but it might be useful to swap in a known good AFM because it is so quick and easy . . . . .

Chris

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #108 of 302 (permalink) Old 04-02-2017, 06:56 AM Thread Starter
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Fuel pressure remains consistent at a stall. Voltage to the pump is also consistent. It'll restart after a stall first try, although it might not run for more than a few seconds.

The manual AAV is just that. I was having issues with my stock part closing so I swapped in a heater core, per a thread here, that can be opened and closed with a choke cable in the cabin. It has the advantage of opening and closing fully. It is not the hand throttle.

The O2 sensor is disconnected. Earlier in the thread I'd discovered that the lead had been destroyed (I guess something on the road caught the wire and ripped it out of the sensor) so I'd been running without it for who knows how long. I thought it could be contributing so I swapped in my spare. It's plugged in but I'll disconnect it again to see if there's any change.

Before swapping the fuel pump it would stall out with the slightest touch of the throttle. Now it'll still do that but ONLY if it's already starting to stall. As it stalls the vacuum drops to around 5" and I assume there's not enough pressure for the regulator and distributor to function properly.

What's strange about all of this is that the sudden stalling is actually fairly new. The car would stall before, but only after a while on the road. I assume that's because whatever the source of the problem is, is now becoming more and more broken. Whether it's the AFM or a shoring ECU. Although the vacuum situation is something else to chase.

I had problems with the injector seals, after the head removal. My injectors are all missing the hard phenolic caps that are supposed to hold them in the head. I was recommended to "double up" the pintle cap seals instead - fairly common for those hard caps to disintegrate. But after assembling the first time I realized I'd left out the intake tube gaskets so had to pull everything back out. I noticed a couple of the injector seals were badly pinched. I was more careful the second time, but if that happened again is it possible that's the problem? Could that also be the reason I'm seeing low numbers for a couple of cylinders? I thought not, since the reading comes with the valves are closed. But my reading indicates a leaking injector seals manifests as a massive vacuum leak along with poor running. SO at the moment, that's a prime candidate.

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post #109 of 302 (permalink) Old 04-02-2017, 07:54 AM
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I tend to agree with your last statement Mr Chairman... assuming that gauge is correct, there has to be a reason for that low vacuum reading. And a bad AFM or ECU will not directly cause low vacuum. A big enough intake leak somewhere will give you the symptoms you describe. So what about the distributor advance unit and the throttle body hiss you mentioned?
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post #110 of 302 (permalink) Old 04-02-2017, 09:14 AM Thread Starter
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Distributor has two hoses on the diaphragm. The lower hose goes to the upper nipple on the intake, the upper on the diaphragm goes to the lower nipple on the throttle body. No obvious leaks.

So in the past I've used carb cleaner to identify vacuum leaks but found it less than totally reliable, since I don't have a $1,000 smoke machine. I also don't want to shoot highly flammable liquids into a leaking injector well. Seems... like a bad idea. But I wonder if using a mild vacuum on the system, say a shop vac in the intake then sealed, would produce an audible hiss at the leak source? Any ideas are welcome.

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post #111 of 302 (permalink) Old 04-02-2017, 09:20 AM Thread Starter
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post #112 of 302 (permalink) Old 04-02-2017, 10:49 AM Thread Starter
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The smoke test wasn't totally conclusive but it did provide some clues. I wasn't able to get a steady, constant flow into the engine but I did get enough to see and smell I coming from the under the plenum, and nowhere else.

In the pic of the injector well there's a greasy residue that leads me to believe it's leaking. Two of the six were like this. A third one had a broken secondary seal (the upper of the doubles up situation, that squishes on top of the head). The pic of the seal on the injector is indicative of all of the lower seals. None broken or squashed to oblivion.

For reference - http://www.alfabb.com/bb/forums/alfe...s-o-rings.html

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post #113 of 302 (permalink) Old 04-02-2017, 05:49 PM
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OK, thanks for the clarification on the manual AAV conversion---it seems like there is new information like that added in every post, so it is difficult to keep up!

Anyway, those injector seals are certainly a problem and obviously should be fixed, but I doubt that a few vacuum leaks from bad injector seals are causing the engine to completely stall. Such vacuum leaks usually cause a rough idle and poor running at lower RPM, but based on your YouTube videos, it seems like your engine idles smoothly until something changes, and then it suddenly begins to stumble.

All of the seals for that style of Bosch injector are readily available, so I would suggest proper replacement of all of the the injector seals (I am unclear what would be accomplished by "doubling up" on the pintle cap seals as mentioned in a previous post, but it sounds hokey), and then continue to monitor vitals. Use silicone grease or something similar to lube up the lower injector seals to prevent pinching/rolling. Take a good hard look at the intake manifold sleeves at the same time (have they been replaced?) and make sure that the manifold is fully seated before gradually tightening down all of the clamps.

Good luck,

Chris

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!

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post #114 of 302 (permalink) Old 04-02-2017, 06:26 PM
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OK, I took a closer look at the pictures, and I see that the plastic pintle caps of the injectors are missing.

I might be mistaken, but this appears to be correct (scroll down and look at the "Bosch hose-type MPI injector" parts pics for visualization):

Bosch Denso Pintle Cap

When I first acquired my junkyard GTV6 last fall, one of the first things I did (as with any non-running EFI car that I come across that has sat for a long time) was to send out the injectors to RC engineering for cleaning and flow testing. As part of the job, they automatically replace all seals, including the pintle caps, so the parts are certainly available to injector rebuilders:

https://www.rceng.com/

Again, I don't think that this is THE problem, but you should properly re-seal the injectors to prevent any future issues.

Chris

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!
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post #115 of 302 (permalink) Old 04-02-2017, 06:44 PM Thread Starter
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The reason I'm so concerned is this: L-jetronic Fuel Injection Technical Troubleshooting Article

The worst place to have an air leak is at an injector seal. Fortunately it's also the rarest place for an air leak. Each of the car's six fuel injectors press into a small rubber seal in the intake runner. These seals are often forgotten since they are out of sight below the injectors. However when they get old they can leak. Most people think that a failed lower injector seal will result in an external fuel leak but that's not the case. A failure of a lower injector seal will cause an air leak into the engine not a fuel leak out. There are a few reasons this is the worst air leak to have. Most air leaks are upstream of the intake plenum which means that these air leaks are divided evenly among the cylinders. In those cases the O2 sensor will try to richen the mixture to compensate and during steady driving will do a fairly good job. Your car won't run just right and it will not have full power but at least during normal driving your mixture will be close enough so your engine won't suffer any damage. All of the air leaking in through a bad injector seal will go into just one cylinder. The O2 sensor will try to compensate by richening the mixture in all cylinders which is all it can do. The result will be a mixture that is too rich in five cylinders and too lean in just one. Running the car like this for an extended period of time can result in burned valves, damage to the valve seat area and excessive cylinder and piston ring wear. In short this is the worst air leak to have because not only does it cause the running problems the other air leaks do but over time it can result in ENGINE DAMAGE!

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post #116 of 302 (permalink) Old 04-02-2017, 06:45 PM Thread Starter
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I'll check out the link! My understanding was the cups were NLA. The "doubling up" method actually replaces the hard cups with a rubber seal. No real magic going on, although I don't think anyone agrees it's better than having the original parts!

In the first photo I posted you can see how that works. The first seal goes into the injector well in the head. The second seal slides onto the injector body, where the seal would normally go. When you torque them down (8 ft lbs, I think), the lower seal has the tendency to slide under the upper seal a bit. I think I might've overtightened one, causing it to break, and leak.

But the injectors all have pintle caps... what's missing are the hard cups. Here's another thread on the subject, from the Spider forum (same injectors, just two fewer) - http://www.alfabb.com/bb/forums/spid...available.html

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post #117 of 302 (permalink) Old 04-02-2017, 06:58 PM
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Originally Posted by chairmankaga View Post
The reason I'm so concerned is this: L-jetronic Fuel Injection Technical Troubleshooting Article

The worst place to have an air leak is at an injector seal. Fortunately it's also the rarest place for an air leak. Each of the car's six fuel injectors press into a small rubber seal in the intake runner. These seals are often forgotten since they are out of sight below the injectors. However when they get old they can leak. Most people think that a failed lower injector seal will result in an external fuel leak but that's not the case. A failure of a lower injector seal will cause an air leak into the engine not a fuel leak out. There are a few reasons this is the worst air leak to have. Most air leaks are upstream of the intake plenum which means that these air leaks are divided evenly among the cylinders. In those cases the O2 sensor will try to richen the mixture to compensate and during steady driving will do a fairly good job. Your car won't run just right and it will not have full power but at least during normal driving your mixture will be close enough so your engine won't suffer any damage. All of the air leaking in through a bad injector seal will go into just one cylinder. The O2 sensor will try to compensate by richening the mixture in all cylinders which is all it can do. The result will be a mixture that is too rich in five cylinders and too lean in just one. Running the car like this for an extended period of time can result in burned valves, damage to the valve seat area and excessive cylinder and piston ring wear. In short this is the worst air leak to have because not only does it cause the running problems the other air leaks do but over time it can result in ENGINE DAMAGE!
This is all true, at least in theory. A vacuum leak at an individual intake manifold gasket/sleeve will cause the same issue. But, such a vacuum leak that is bad enough to cause long-term damage as described would also cause an obvious misfire at idle/lower engine RPM (at least when the engine is cold and before the O2 sensor warms up) that would hopefully clue in the driver to check it out!

You are definitely doing the right thing by addressing the issue, and I wish that it would also solve your stalling issue, but experience suggests otherwise . . . .

Chris A: '81 GTV6 rescued from junkyard, "GT" car/'86 Porsche 944 Turbo track/street car/'73 BMW 2002tii fun street car/'74 Jensen Healey Lemons Rally car!

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post #118 of 302 (permalink) Old 04-02-2017, 07:01 PM Thread Starter
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Well, one thing at a time. Check off one problem (I've already handled two significant issues since this thread started) move to the next. I want to resolve the vacuum issue before tackling AFM or ECU, both of which are still high on the suspects list.


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post #119 of 302 (permalink) Old 04-02-2017, 08:52 PM
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Okay

It's possible that I'm not following this correctly but the last series of posts have me confused.

Spider vs. GTV6

The hard plastic injector seals found in the Alfa Spider, are only found in the Spider. They are not used in the GTV6 / Milano. The injector seal in the Milano is a round soft rubber thing more properly described as a square cut O-ring. I've done dozens of these over the years and I've always used the Airtex or Beck Arnley brand.

Smoke testing

I do have the $1,000 smoke test machine (well I have use of it). I always run a smoke test after doing injector seal replacement, and there should be no smoke coming from the intake runners or manifold.

if the system is really tight smoke should come out of the oil filler cap and the oil dipstick. A little should come out throttle body where the shaft passes through body.
The throttle body can be a big source of leaks.
Once worked on a GTV6 that run super well except for a very high idle (1,400 RPM). Big smoke leak through the throttle body. Just replacing the throttle body made the idle drop 600 RPM.

Pintels

I'm looking at the injectors in the pictures and I don't see any missing pintels.

Alternative measures

Chairman kanga, I admire your perseverance in working on this car. Many a lesser man would have given up and began to read the fire loss provisions of the his home owners policy and the revelant arson laws. However it may be time to seek supernatural assistance.

Don't know how (or if) you roll in spiritual matters, but sacrificing a live chicken in the garage, surrounding the car with a protective line of kosher salt, soldering or brazing St. Christopher's medals to the engine block or other bits, filling the coolant system with holy water are all things I have considered or tried in in the past.

Bye
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post #120 of 302 (permalink) Old 04-03-2017, 04:55 AM Thread Starter
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Are you sure about the injector? I had an older thread on this and the ol' "phenolic cup" came up. The diagram indicates a two-part seal, like you describe - the lower seal AND an o-ring. When you buy a seal kit, even from an Alfacentric shop, you only get one seal per injector. When I brought this up, other GTV6'ers indicated it's because I'm missing the hard plastic seal, and to just use a second rubber one, aka double up the seals. But as you can see in the photo, the result is sort of... let's say I'm not totally certain it's right.

I'm still confused on this issue.

http://www.alfabb.com/bb/forums/alfe...s-o-rings.html

regardless, I had a ripped o-ring (the upper of the lower pair) on the #4 injector, and oily residue in the wells of #2 & 3. That's also the general area where I saw a wisp of smoke. So I'm pursuing that issue full bore. If that doesn't fix the vacuum leak I'll try Santeria. Or Craigslist. "Haunted Alfa for sale or trade for a **** good pizza."
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