quote Originally posted by seq:

quote Originally posted by Patrick: Difficult to tell from listening to a video, but to me there's more of an occasional mechanical "rattling" sound than an ignition miss.

quote Originally posted by Patrick: It was very pronounced when you let off the gas at the 4:00 mark. Whatever it is doesn't sound normal to me, although it may or may not be a serious issue.

I guess it was your timing chain slapping around that was making that weird noise!

quote Originally posted by seq: After some thinking, some discussion, and some argumentative persuasion, my Dad convinced me to check out the timing chain. Looks like a lot of slack. Keep in mind that there is even more slack than it looks, because the chain is actually hanging below the crank gear, not really in firm contact. Oddly enough, it appears it has not skipped a tooth. The chain tensioner is broken in the top-right, and bottom left.

Fast forward after a year of trouble-free driving, and I'm stranded, without warning, on the side of the road at night. Crank crank crank, but no start.



As an interesting side-note, CAA texts a URL to your phone when a driver is dispatched, allowing you to track his drive to your location in real time.



So anyway, back to the issue. I get the car towed home, and can't look at it for a few days. When I do, it starts immediately. Took it for a drive, and it sputtered and died around the corner. Limped it home.

Let it run in the drive way, runs fine. Cold, hot, in gear (on jackstands). WTF. Start troubleshooting:

* Fuel pressure is good

* Timing light shows spark

* Air isn't that hard, and it dies when the throttle body is open as well.

I've got fuel, I've got spark, and I've got air. Fire is not that hard. Furthermore, this is a problem I can reproduce by driving the car, but can't reproduce when parked.

Thinking possibly weak spark, I swapped out the Ignition Coil (though I kept the one I was using to swap back in case this didn't resolve it). Also, the centre pin in the distributor cap (the springy bit that touches the rotor) looked rather ground down, so I changed the cap & rotor while I was at it (They're not expensive for the NAPA ones, anyway).

Car seemed to work for a few minutes, but died on me again. Limped into the driveway.

At this point, I'm thinking it's the ECU, as that's the only thing remaining that controls how fire is created. Either directly (hope not), or indirectly (via bad data from a failed sensor). So I start unplugging sensors one at a time.

When I got to the MAP sensor, the car ran like **** , but ran. I have another Fiero handy, so I'll swap MAP sensors to see if that's the issue. Once I get it off, I find something interesting. The rubber vacuum tee that connects the Intake Manifold to the MAP and Fuel Pressure Regulator (according to the Buddy Craig diagram, anyway) has a tear it in. Also, the two plastic vacuum lines leading to the non-torn ends don't feel snug. I think the rubber is dried out.

Here's some photos:





Now, I can't find a part number for this. The parts store only has plastic connectors and rubber hose (I guess the Fiero was designed in bizarro world). In the mean time, I've wrapped some stretchy pipe sealant tape (don't ask why I have it) around the tear, and put dielectric grease on the lines that insert into this tee. Re-inserted, and everything seems to be better connected.

Wouldn't you know it, but the car runs great. I've taken it on two >1 hour drives this week to test, and it's working wonderfully.

Additionally, my hunting idle has been mostly eliminated (still a very small bouncing, but not the +-100rpm I had previously. I'll probably re-seal the other connectors at some point.

So that's the story of how a 30¢ piece of rubber crippled my car and left me stranded (and caused me to miss the Fleetwood cruise-in with my car, although we had my Wife's 88 there).

The only question I have now is where can we get new rubber connectors? It seems the part stores don't stock them. (only plastic connectors). Furthermore, there's nothing in the computer (and I can't find any part numbers from my googling). I'd prefer to not ebay a used, 30-year old piece of rubber as a replacement.

Anyway, I've got an autocross event this weekend, so we'll see how well she holds up. Maybe I'll borrow the vacuum tee from the known-good car (well, the known-no-vacuum-leaks car, anyway) just in case.

Imgur album of these photos.

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Seq

1987 Fiero GT : Information | Gallery

NOTE: If you re-host any of my images on PIP, send me the Image URL and link to this post, and I'll update it.

I would have thought ICM.
But cool if it was only old leaky rubber vaccum stuff.

The only new one I've been able to find but it's way too small

http://www.dormanproducts.c....aspx?origin=keyword

Just noticed I never updated this thread. The car ran fairly well after the last post (June 2017) through to November 2017 when I was trying to move it to winter storage. That said, I didn't drive it a bunch. I did post that as another thread. As you can see in that thread, the car just wouldn't run. I identified it as an ECU problem, eventually isolating it to the connection from the battery junction terminal. The connector had broken (the fusable link itself was fine).

After fixing that, I got the car off to storage without issues.

This year the car has proven to be absolutely 100% reliable. Pulled it out of storage a few days before opening weekend for Watkins Glen. I told my wife I had 100% trust in the car. She believed me. Drove the six hours it to the wettest and foggiest Watkins Glen opening I've been to in the last five-or-so years, but the car handled the track (and the frickin' ice storm) like a champ.

Only thing I've had to fix was a failed rad fan relay (it physically fell apart).

Since the beginning of this thread in mid-2015 through end-2017, I ended up replacing the entire distributor stack, plugs & wires, timing chain, ignition coil, "fixed" a vacuum leak, and repaired some wiring. I think I had a number of contributing factors, as most of those items were bad and/or out of spec when tested with appropriate tools (multi meter for the pickup coil, finger for the timing chain, and multi meter+eyeballs on the wiring).

Put a few thousand more km on it this year between with trips to the Glen, the 35th, a few gatherings with some car friends up north, and a few day trips with my wife along the shores of the great lakes.

Ultimately, at 329,000km on the engine, it probably would have been smarter and more economical to simply source and install an f-body 3.4. But I learned a lot a long the way so far, which is half the reason I bought the car for anyway.

[This message has been edited by seq (edited 10-13-2018).]