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Discussion Starter #1
I know, just what we all wanted to see!

Actually, I am having some issues with the car's idle after doing some work with the intake plenum off and I thought I would document my troubleshooting here just in case someone else also has this issue. Yes, there are multiple similar threads of varying degrees, but none seem to match my issues exactly.

I will be following Greg Gordon's troubleshooting guide through this process as well after I get through some of the basics.

Vehicle: 1988 Alfa Spider Veloce 104k miles

Symptoms before/after intake removal:
-slightly higher than normal idle
-when starting (hot & cold), it will catch, then almost stall, then recover again.

What was replaced:
-motor mounts
-all vacuum lines with Greg Gordon's silicone hose kit (great stuff!)
-injector seals/short hoses
-all the rubber hoses/seals from the AFM to the TPS

First, I checked my idle o-ring; although it seems to be OK, I ordered a new one just to be on the safe side.

Pulled the AAV and noticed that it does not open very far at all [see photo below when cold]. I stuck it in the freezer for about 20 min, no change. I checked it hot and it does appear to close all the way. I was able to move the flap with a screw driver and it springs back.

I waited until the next morning, then bypassed the AAV completely and the car sprung to life, no stalling, but then the car started idling very erratic, revs going up and down, until i pinched the hose a little bit. I could control the idle by how much I pinched the hose.

Now, I know for a fact that my throttle linkage is a little out of whack, I will need to adjust those, but with them disconnected, the car still has a high idle. I don't believe that the linkage should be putting any tension on the throttle body, but please correct me if I'm wrong! I don't think those cheap little plastic pieces would last very long if that was the case.

I've only had the car for about 6 months and it looks like the PO has messed with the set screw on the TB as the rubber cover is missing, so I will get to that eventually.

[more to come, have to go to work now]
 

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Pulled the AAV and noticed that it does not open very far at all [see photo below when cold]. I stuck it in the freezer for about 20 min, no change. I checked it hot and it does appear to close all the way. I was able to move the flap with a screw driver and it springs back.

Now, I know for a fact that my throttle linkage is a little out of whack, I will need to adjust those, but with them disconnected, the car still has a high idle. I don't believe that the linkage should be putting any tension on the throttle body, but please correct me if I'm wrong!
Hi elite,

First off, thank you for sharing your journey with the group! All evaluations are helpful.

Regarding your freezer experiment with the AAV, are you sure that 20 minutes is an adequate amount of time to achieve complete movement? I guess it might be, but I put mine in the freezer for 3 hours (and I had it in a zip lock bag to prevent any moisture entry).

The first picture below shows how it looked right out of the freezer. I also tried it overnight and the opening was the same size.

For my next test, I connected the electrical contacts on the end to 12V for 30 minutes. The second photo is how it looked after that test. Looks pretty closed, right? Well, athough it "looked" closed, I could still blow a bit of air through the tubes. I also left it connected to 12 volts for 4 hours and it didn't close any further or block all the air from passing through.

Not sure why, but the AAV that was on my 1988 Spider when I got it was a Bosch 0280140166 (not the specified 0280140140) even though it seemed to be functioning. I have since replaced it with a similarly functioning 0280140140.

As far as the throttle linkage goes, you are absolutely correct in that it should not be pulling on the throttle plate at all when no pressure is being applied to the gas pedal. And since there are several places where the linkage can be disconnected, any time you want to be sure that there is no "pull" on the butterfly valve, you should disconnect the socket clip from the ball right at the throttle body (since the bell crank has a spring, and if the short rod between the throttle body and the bell crank is still connected, the bell crank spring could be pulling the butterfly valve open). I'm sure you were aware of this already, but it doesn't hurt to check.

Thanks again for posting the photos and your progress. I'll be interested to hear what you discover.
 

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Is the Throttle Position Switch adjusted correctly? The TPS tells the computer when the throttle is at idle. If misadjusted such the computer will keep trying to adjust the mixture instead of following its pre-programmed fuel map. As it tries to adjust the mixture the idle will become erratic.

Have you cleaned out the Oil Vapor Separator? When the OVS becomes clogged that messes with sump scavanging & mimics an intake air leak. L-jet does not tolerate air leaks.

Remove the OVS, soak it with solvent (brake cleaning spray works well), rinse & repeat. Also make sure its hoses are not clogged. When you're done add a little clean oil to the smaller dia drain hose at the bottom of the OVS to act as a one-way valve.
 

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Discussion Starter #4
Thanks you two for your interest in this thread. I've been feeling under the weather the last couple of days, so I didn't really get to do much except for about an hour today.

Following Greg Gordon's guide, I skipped the flywheel sensor part as I believe the car wouldn't start/run at all if they were not working right, agree? If not, I can still go back and check them.

I had time to test the VVT device. Car off, ignition on, I turned the TB all the way and no click. I started the car, let it warm up, and jumpered pins 3 & 18 on the TPS connector, still nothing. Now to look for this fuse...I couldn't find it for the life of me, so I consulted papajam's wiring diagram and eventually found the wires and sure enough, there was no fuse and they weren't even connected [see below]. I verified they were both black/green wires under the protective cover and then jumpered both. Repeated the above procedure and I did hear the click and see the VVT solenoid engagement through the site-hole. This had zero affect on the car's idle.

Is there a reason why someone would bypass the VVT solenoid?

I'm also curious if anyone has an AAV (verified working/new)that opens up more than mine and Norseman50's. I would like to rule that out ASAP. When I bypassed it completely, I was thrilled that it immediately sprung to life without any hints of almost stalling.

The next steps will be to check the CTS, TTS, and then TPS.

Regarding your freezer experiment with the AAV, are you sure that 20 minutes is an adequate amount of time to achieve complete movement? I guess it might be, but I put mine in the freezer for 3 hours (and I had it in a zip lock bag to prevent any moisture entry).
I guess I could put it in for longer, but it was pretty **** cold when I pulled it out and it should respond to temperature fairly quickly.
 

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Thanks you two for your interest in this thread. I've been feeling under the weather the last couple of days, so I didn't really get to do much except for about an hour today.

Following Greg Gordon's guide, I skipped the flywheel sensor part as I believe the car wouldn't start/run at all if they were not working right, agree? If not, I can still go back and check them.

I had time to test the VVT device. Car off, ignition on, I turned the TB all the way and no click. I started the car, let it warm up, and jumpered pins 3 & 18 on the TPS connector, still nothing. Now to look for this fuse...I couldn't find it for the life of me, so I consulted papajam's wiring diagram and eventually found the wires and sure enough, there was no fuse and they weren't even connected [see below]. I verified they were both black/green wires under the protective cover and then jumpered both. Repeated the above procedure and I did hear the click and see the VVT solenoid engagement through the site-hole. This had zero affect on the car's idle.

Is there a reason why someone would bypass the VVT solenoid?
The VVT if it gets stuck will cause a low idle as if it has a wicked bad vacuum leak. That is just the cam staying advanced and throwing off the idle. That would be the only reason to disable it. I would check to make sure it's adjusted properly. There are a few VVT threads in the FAQ at the top of this forum.

THere are a few threads in the fuel system area that might interest you as well. AFM are getting worn in our old cars and this can contribute to the cold stumble. We are chasing for years a similar issue on my daughters 944 which uses essentially the same system. There's a LOT of moving parts in this system and no single 1 may be the answer.
 

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Discussion Starter #6 (Edited)
Thanks Jon, good information!

Okay, moving forward. Pulled out the handy digital multi-meter and tested the CTS and TTS. Both read values per the specifications listed. I also pulled the Cold Start injector and verified that it was shooting a nice stream of fuel into a container.

I then got to the TPS and that's where things got interesting. So, my initial readings on both open and closed where the resistance should be 0, the actual was 2 ohms. I tried adjusting but didn't make a difference. I took off the rubber hoses between the intake and AFM to have a look inside the TB and found it was filthy in there. I took several shop towels and some TB cleaner and cleaned as much grime out of there as possible. I was then able to adjust it to 0.4 ohms, but I could not get the value down to 0 in either direction. I'm guessing this switch is aging and needs to be replaced. The adjustment screw had zero affect on this. Yeah, since someone had already messed with it, I figured it couldn't hurt to try that theory out. Does the screw do anything other than set a stopping point? If so, then wouldn't most of it be lost motion?

I put everything back together and it actually seemed to idle a little smoother and lower, much less hunting than before. The idle is definitely not high, but it's not as smooth as I would like it to be...or how the smog inspector might want it to be! I need to verify with a digital timing light to be sure.

I was also able to source some new 3/4" ID vapor hose for the OVS to replace my band-aid fix. I did this after obtaining the above results just to rule out any other variables.

I sourced a new fuse holder for the VVT and will splice that in and retest next time. I may also attempt to readjust that as well to ensure proper operation.

The car still does the start --> almost stall --> recover to normal idle when you start it hot or cold. I'd like to think that this has something to do with the AAV because I had bypassed it earlier completely and it did not do it at all. So maybe it's still not opening far enough.

More than likely, there are several contributing factors here, so when the idle o-ring arrives monday, I'll go from there.

S
 

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Discussion Starter #9 (Edited)
I did a test series of 3 "cold starts". It was by no means cold outside, but the car had not been started since yesterday.

The first start was actually not bad, the rev's dip slightly after starting and then it recovers quickly.

The second start was a little worse on recovery and the third was worse than the second.

On all three starts, I did use some throttle after the initial start to get a smooth idle. Also, the car didn't die at all, it was me turning it on and off.

Plugs, cap, and rotor were replaced probably about 3 months ago.


(i'm not sure how to embed the video)
 

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Idle

Just going on a whim here, not sure if it will help. Look for the air hose that is located on the intake plenum, the one that goes to the rear of the car. It connects to a sensor located behind the passenger seat. Its a vacuum sensor. These tend to fail quite easily. Plug the hose at the plenum and see if that changes anything. Its a small vacuum line.
 

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Discussion Starter #11 (Edited)
Just going on a whim here, not sure if it will help. Look for the air hose that is located on the intake plenum, the one that goes to the rear of the car. It connects to a sensor located behind the passenger seat. Its a vacuum sensor. These tend to fail quite easily. Plug the hose at the plenum and see if that changes anything. Its a small vacuum line.
Is this hose on the left side of the plenum hooked to a hard plastic line? I have heard some random whistling in the past, but it has not happened in months. Usually, I can make it go away with tapping the brake pedal once or twice. Probably yet another piece slowly failing on this poor car.

So if this device is failing or dead, how does it affect the idle?
 

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Discussion Starter #13 (Edited)
Thats the one. Just plug it.
Didn't seem to make a difference. I suppose it's still kind of working? I pulled the access panel and while I was in there, replaced the soft tube from the hard line to MAP with silicone tube leftover from the silicone hose kit.

One thing I found interesting is that I can actually hear when the AAV is open and allowing more air into the plenum. It sounds like a vacuum leak. I verified that there is no such leak, after a few minutes, it closes and goes away. I still wish someone would take a photo of their newer AAV opening when cold to see if mine is opening far enough.
 

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Discussion Starter #14
So funny enough, the high pitch noise does not come from the MAP device at all! It's actually coming from the brake booster. There must be a vacuum seal that leaks and whistles occasionally. I guess that means a new booster at some point, but that is so far down on the list right now.

Anyways, I finally hooked up my digital timing light to verify the exact RPM and it seems to settle between 890-920, which appears to be a little on the low side. For smog requirements, I will probably have to raise it so that it is within spec. The gauge is not even close.

I still don't quite understand the start, almost stall, then recover process. It does it when cold and hot, regardless of the outside air temperature. I will have to re-check grounds too, but I'm fairly sure they are OK.

I do have to say that my high idle is gone, and probably due to:
-adjusting TPS
-cleaning throttle body/butterfly valve
-properly adjusting the accelerator linkage
-new idle o-ring

I thought I saw the light at the end of the tunnel, but then on my way home this week, the clutch started slipping. I'm not sure if it is from oil contamination or age or both. I'm sure the RMS is leaking a little as there is evidence that small amounts of oil is dripping from that weep hole. So, on to yet another adventure with this 88' spider.
 

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So funny enough, the high pitch noise does not come from the MAP device at all! It's actually coming from the brake booster. There must be a vacuum seal that leaks and whistles occasionally.
This is not the first time I have heard about a vacuum leak at the brake booster. If you are still having start or idle issues, you might want to track down where, at the brake booster, the "whistle" is coming from, and try to seal it.

I think the little plastic elbow (where the vacuum hose connects to the side of the booster) is notorious for vacuum leaks. Just a thought, but that could be the source of your cold start or idle problems.
 

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Discussion Starter #16
This is not the first time I have heard about a vacuum leak at the brake booster. If you are still having start or idle issues, you might want to track down where, at the brake booster, the "whistle" is coming from, and try to seal it.

I think the little plastic elbow (where the vacuum hose connects to the side of the booster) is notorious for vacuum leaks. Just a thought, but that could be the source of your cold start or idle problems.
Thanks for your reply!

It's coming from the brake pedal area [interior]. As soon as I tap the pedal, it goes away. It rarely happens though. It also doesn't appear to affect the idle either, but just for the hell of it, i'll plug the vacuum hose for the booster and see if starting is any different.
 

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Exactly the same as yours, with my 91 Veloce. The idling was awful, sometimes stalled. First at startup, then progressed with driving. Then it got so bad I the engine kept shutting down. Mech finally found the coil wire was worn at the top, the whole unit was worn, not producing enough power for spark. Runs great now. My IAV is still a tiny bit choppy, 100 rpm here and there. Probably from me rapping on it trying to dislodge a perfectly working solenoid gate.
 

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Discussion Starter #20
Well, I yanked the engine and transmission for the clutch job, then essentially tore the motor apart to change all the seals and head gasket. I had no intentions of doing that, but since the clutch had failed prematurely due to oil contamination, I figured it would be best to not have to do it again in a few months.

All I can say is that it's MUCH easier to pull a SPICA motor than a Bosch motor, just many more wires, bolts, and parts to remember what goes where.

Anyway, upon restarting, I noticed that it would not idle. I checked everything and it appears OK, but I ordered a new set of plug wires just to be on the safe side as well as cap and rotor. They are so old that the wires are holding their form and are probably too rigid.

The next thing I noticed is that the AAV was completely shut and when I bypassed it, there was no issue starting, but since there was too much air going in, the idle was very erratic. I pinched the hose and it came down to a reasonable idle.

I ordered a rebuilt AAV off ebay, different part number, so we'll see what happens. I may have to put a restrictor in the line as some report a really high idle with similar Bosch units. The part number for the one I purchased is 0280140173, it's for Volvos and VW's.
 
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