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Hello everybody! I've been here for a while now but haven't posted because I haven't been stumped like this yet. Blanche has been an exceptionally reliable ride since I got her, but a couple weeks ago she had a major malfunction that I can't explain. In the summer she's my DD and gets the heated garage for winter. I fired her up and drove all summer, but when I let the wife (let's call her "Midas Touch" because if it's gonna break, she's the one that's driving) drive her one day and Blanche left her stranded on the highway. From what wifey says, all of a sudden she heard some pinging from the rear of the vehicle and the gas pedal "wouldn't work" but the engine was running. She shut it off and it refused to start again. Initially I thought the pinging could be from the tires picking up rocks on the side of the road and flinging them at the wheel wells. I don't know right now if that's what it was, but underneath is really clean and still in place.
I tried fuses, relays, lock cylinder jiggling-all the stuff that can be done on the side of the road with cars whizzing by at 100kph+ but all I could get was a couple ba-dum ba-dums. I had to get it towed home, and after some short figuring I thought it wasn't getting fuel, so I ordered a new fuel pump thinking that would fix it. Installed the pump and nothing has changed except it holds pressure now. I went through the diagnostic pages on shoebox's f-body website (wow that guy's a surgeon with these things) as well as searched as many forum posts as I could before posting myself.
This is the order of my testing procedures:
1. New QFS-343FT fuel pump via the trap door method. Checked the pressure at the Schrader valve - 45psi prime, 38-40psi pump off and holds for as long as I let it. New fuel filter earlier this summer too.
2. ICM: Checked for system voltage @ A & D-good. 0-0.2 ohms @ C to ground with key off-good I think. I was getting weird readings initially and thought either a bad ground or poor lead connection from the DVM, so I traced the wiring back and cannot manipulate the wires to reproduce a bad ground. I'm thinking I just didn't have a good connection at the beginning. ~2-3 volts AC @ B while cranking-good.
3. Coil: Connected 1 lead to high-tension and tested all 4 pins-8200 ohm-good I think.
4. Optispark connector: Checked A & B for 5V-checked ok. system voltage to C-ok. 0.1 ohms @ D to ground-ok. Also probed for continuity between connector on side of manifold to Optispark plug-checked ok.
5. Hooked up an old spark plug to high-tension from coil and I have spark, but I was doing this all by myself and had to video record as I cranked so I'm not sure if the spark was good enough from the shaky video. I'll go to NAPA and get one of them 25,000V spark testers and see for sure. Haven't done a compression test in a while, but if the car ran perfect and then all of a sudden quit, I don't think I burned out rings or valves that quickly. Coolant level is up and colour is green; oil level is up and colour is clear and...oily...so head gasket I don't think is an issue either.
6. Maybe the cat is plugged. Removed bolts right behind converter and checked-honeycomb is pristine (at least from the rear) and no signs of fouling. Still won't start.
7. Maybe the VATS since the security light has been either on steady or flashing for a while now while driving it. The first owner took it apart and didn't realize there was a resistance value needed so it wouldn't run for him-that's why I got the car for $1200. I had to put the metal tabs back into the clear assembly, then epoxy the cylinder back together. Worked for the last 3 years, but the other day I noticed the tabs were broken and had no resistance value at the connector between the orange-wrapped white wires to the purple/yellow wire connector; I took apart an electronic charger that no longer works, de-soldered some resistors and put them in series to add up to ~9500 ohm (pellet value #14), then soldered it in place of the lock cylinder sensors. Security light now comes on for bulb check and turns off after about 5 seconds. Still no start.
8. Could be the fuel injectors-I had some extra LED's I got from SBL and wired one into the #2 injector harness. It didn't light up at all, but I may have not have the correct voltage range for the LED (???). I'l try again after I get a real noid light set from Partsource or Canadian Tire later today, and I'll check the other injectors as well for pulses and resistance. I checked with a test light and I have +V where its supposed to be on all 8 plugs, so unless something jumps out and slaps me in the face, I figure they're ok. I'll check anyways for peace of mind. *Note* Hooking up a 9V battery makes the injector click and the tailpipe smells like raw fuel when I crank, so I'm thinking delivery may not be a problem.
9. Took a valve cover off to make sure chain wasn't broken; valves open and close as they should, at least on bank 1 so I can assume bank 2 is good as well.
10. Disconnected MAF, IAT, MaP, EGR, IAC and TPS (one at a time, then multiple variations until all were disconnected-just to see) and cranked. No start.
11. Plugs and wires I changed about 2 years ago (less than 10,000km on new set of NGK Iridium's and NGK 8mm wires as of now).
12. Random fixes-new P/S pump and pulley 2 years ago (of course while wifey was driving); AIR delete (I love Alberta) but left the pump hooked up for the SES light; injector grommets and intake manifold gaskets to fix the China wall leak; exhaust manifold gaskets; ~4000km oil and filter changes with dino 10W-30 and good filter; A4 pan gasket and filter; radiator popped a hole (wifey again) and needed a new one; GM heater and rad hoses (wife-see why I call her "Midas Touch"?) with the intake bypass; window motors (went cheap and now paying for it); door lock solenoids; LED's all around but for headlamps and spoiler light so my cruise would work; LED flasher and hazard relays; rear diff drain and fill with GL-5, posi-goo and new cover gasket; front spindles; 4 wheel brakes and rotors; E-brake wires (that's on me from trying to drift-I'm not a teenager anymore I guess); full-meal-deal professional detailing multiple times (those were because of the kids and their need for yogurt/peanut butter/chocolate milk); new rubber because the originals were like 4 bologna rinds and the tires almost cost more than what I paid for the car!
12. To top it all off, about 2 weeks ago I bought a complete T56 (master/slave cylinders, bellhousing with dust shield, flywheel with used clutch/PP/bearing, TA bracket & insert, shifter, boot, bezel/ashtray and mini starter just in case) with 100,000km from a 94 for $1500-David T's Camaro here in Edmonton wanted $4500 and I'd have to pull and swap it all myself-and I'm just waiting for the pedals, crossmember, new clutch assembly and TunerCat software/cable to show up from various online stores. All useless unless I get the motor running...
If I crank it for about 5-7 seconds, I'll get a ba-dum ba-dum when I let off, but she won't run continuously. I haven't taken the Opti off yet-I was hoping it would be a quick fix since she ran like a dream for the last 4 summers-but I'm about to. I went ahead and ordered the AIP Electronics optical sensor yesterday just in case for $92 CAD delivered to my door (it was about $45 cheaper direct rather than through Amazon.ca) and will do the SuperChevy DIY OptiSpark I venting as long as there's no indication of center bearing issues. If there is, I'll see if i can get a new bearing rather than complete distributor. Cap and rotor will be a no-brainer once I check the condition of the assembly.
Thanks for reading this post and if there's anything you guys can think of that I haven't checked, please respond. I'll update with the results of my tests in the next few days. Any experience would be greatly appreciated.
I also changed out the ICM with 2 other ones I had in the garage from a 1998 Blazer and a 2000 Blazer. They all fit on the various years-I know this because Blanche was using one off a 1999 Blazer for the last 3 years. And the ICM frm Blanche made my 1998 5.0 Vortec Blazer fire right up. So that’s good at least. I love Chevy. Most of the time.
Question: I was checking some more posts and does 8200 ohms sound right for the stock coil resistance? I know shoebox says stock is around 8500 on the tech website, but others say 5k is good and over 7k needs replacing. I just don’t want to keep throwing parts at it and the coils from the Blazers have the wrong connectors...
Noid light test confirms I have injector pulses. All injectors between 12.5 and 12.8 ohms. Tried the clear flood technique. Sounds like it wants to fire, but just won’t catch. Checked wires for continuity and they’re all ok. I’ll update once I get the distributor off.
Have you scanned it for codes (maybe the info is in the first post, but it’s so long by the time I get to the end, I can't remember everything I read)?
I was going to build a cable to hook up to my laptop here soon even just to scan for codes. I have an obd2 reader and no cable for obd1, so I'll figure something out and scan it hopefully tomorrow. I'm also going to check the compression and see where I'm at after that.
Ok. So I removed the opti and found some interesting stuff. At first look, the sides of the rotor were melted and the screws were in the wrong spots. It still had spark, but the timing was way out as you can imagine. I chipped away at the plastic mess and the rotor just fell out. Taking the rest apart, I noticed the splined shaft wasn’t turning that well even with the rotor off, so I took the whole thibg apart to find a huge mess. From what I can figure, the bearing failed and got so hot that it melted the plastic parts and got all over the optical ring. One of the screws holding the bearing retainer plate sheared off and it was loose, and somehow the optical ring got spot welded to the bearing plate so I had to separate it with an Olfa knife.
I was going to try a new cap and rotor, but I see online I can get a whole new optispark from Amazon for cheap and I already have the upgraded AIP optical sensor.
P.S.
There were no DTC’s stored in the computer when I hooked up my laptop.
On an OEM factory non-vented (93/94] Opti, the optical disc was spot welded to the backing plate at the factory. I found that out 18 years ago when I replaced my original factory Opti (bought the car new in 1994) and decided to take it apart to see why it was not running right, why the bearing seemed so stiff, etc.. There was also a site many years ago called “The Optispark Dissection Page”. He disassembled a vented unit, and got a lot of negative feedback from 93/94 owners who pointed out you couldn’t take apart an unvented unit without grinding out the spot weld.
The problem with the non-vented unit was ozone. Everyone assumed GM added the vent system in 1995 to remove moisture. But I have a GM publication that indicates they added the vent system to remove ozone. Ozone results from the high voltage discharge, and is very corrosive. The metal separater plate in the unvented unit rusted badly. On my unit, the rust particles had blinded the optical emitter/receptor, blinding the optical module. The ozone apparently caused the bearing to wear prematurely.
AIP used to be called All Ignition Products. Pretty sure they had to change their name because of the terrible reputation they got from their unreliable products, particularly their Opti’s.
Thanks for the info! So I guess that reluctor ring is garbage, huh? I was planning on saving what parts I could, but if there’s no way its usable again I’ll just hang it on the garage wall as a souvenir. The cap has been changed at least once in its lifetime because it has the vent port and its still in fairly decent shape, but it’ll probably hang with the wheel.
I know cheap isn't always the right way to do things, but I want to get it running and moved into the garage before the snow flies. I was looking at it all apart today and figured I should check/replace the timing chain, but if I’m doing that I may as well change the cam and then fix the oil pan gasket leak and then the rear crank seal and then..... where does it end?
08-23-2018, 02:16 PM
