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I'm working on my sister's beat to poo poo '92 S10 Blazer and so far the only thing I've figured out is that this car hates me. Alright, so the engine is a 4.3L Vortec V6 with central port injection, engine VIN W. My sister lives 75 miles away in the middle of horsefuck nowhere, knows nothing about cars, and doesn't have phone or internet right now. She was having problems with it running hot, and sometimes it wouldn't start, while other times it would. This was all I know. I've had it at my house for the last couple of days. I drove it down here myself, and while it didn't run well, it did make it here alright. I even hit 80 on the interstate. One thing I knew was wrong with it was that the fuel injector lines inside the intake manifold were leaking, not majorly but it was causing a rich condition. The bolt holding the injector lines in stripped out and couldn't be removed with a bolt extractor or screw extractor. Because of the way this thing is made you have to take the intake manifold plenum off just to get to the lines and injector, and I eventually had to remove the entire intake manifold and use a welder to remove the stripped bolt. Here are the new lines installed: http://onyxphoto.net/images/pressure-lines.jpg So far on this car I have replaced: TPS, MAP sensor, idle air control valve, fuel injector pressure lines, distributor rotor, distributor cap, spark plugs, spark plug wires, oxygen sensor, intake maifold and plenum gaskets, valve pan gaskets, fuel filter, air filter, and changed the oil and transmission fluid, along with fixing some issues with the exhaust and headlights. Even after all that I'm still having some problems. For one thing, I can't figure out what's going on with the timing. You're supposed to follow the instructions on the VECI label to set the timing, but that's missing. I knew there was a "timing wire" somewhere, a tan w/black stripe wire that is supposed to disable the computer controlled timing advance. According to the internet it's in the passenger side kick panel, or in the engine bay near the distributor, or behind the glovebox... After many fruitless searches I finally found the mythical timing wire under the carpet against the firewall on the passenger side. Now, what's so puzzling is that the engine runs like crap with the timing marks lined up. It doesn't run great no matter how the timing is set, but with the timing marked aligned with the big groove it just chugs and sputters whenever you give it throttle. Here's what the timing is supposed to look like: http://onyxphoto.net/images/crap.jpg And this is what it looks like where it runs best: http://onyxphoto.net/images/good.jpg Am I missing something? I hosed up and didn't label the plug wires when I took the distributor apart. Do I have the plug wires on in the wrong order or something? I know the firing order is supposed to be 6-1-2-3-4-5 and the distributor spins clockwise. According to the service manual, the terminal for #1 is supposed to be labeled as such on the distributor cap, but neither the original one or the one I replaced it with had any numbers on them at all. http://onyxphoto.net/images/wires.jpg When I took it for a test drive it overheated really quickly after about 20 miles, the last three of which were at 70 on the interstate. The coolant was at a rolling boil, even in the reservoir. The temperature gauge was at 240, and when I restarted it and let it run for a minute it went all the way up to around 270. I don't think this is related to the timing issue but I could be wrong. I waited for it to cool down, added some water to replace the coolant that boiled off and drove it back to my house; with the heater on full blast and not going over 55 the engine coolant temp didn't go above 170. Weird. The coolant looked like it had a lot of suspended solids so tomorrow I'm going to clean the radiator with a strong chemical flush and replace the thermostat. I'm also wondering if there's any way to bench test the CPI unit. I'd like to see that all of the ports are working. I built a test rig I can load with carb cleaner or paint thinner and hook up to an air compressor, but I'm afraid to try it because I don't know what voltage the injector in the CPI operates at. I should also mention that this car might have some wiring problems. Even through all these problems the check engine light never came on. Hell, it might be burned out. I have an Inova 3120f that's supposed to be able to read OBD1 codes for vehicles all the way back to 1982, but when try to use it I get a "Communication Error" message. So, that's the sad hosed up story of how I spent my sad hosed up weekend. If any of you goons have any advice I'd be glad to hear it. Since all my cars are Fords I'm not really familiar with this engine. I had an 84 Pontiac Parisienne that I rebuilt about 15 years ago, but this is the first time I've done major work on a 90's or later GM vehicle. Revenna Fox fucked around with this message at 10:03 on Oct 23, 2017 |
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Oct 23, 2017 09:57
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| # ? May 6, 2024 02:28 |
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I owned the exact same truck. The CPI injector was hilariously bad in those engines. The fuel pressure regulator would leak inside the manifold and cause all sorts of issues. For a long time the only way to fix it was to replace the entire injector assembly a 300 dollars a pop. I think HELP started making the fuel pressure regulator by itself as a kit and came with the tools to remove the old one. You could always tell if it was leaking since it would make the lower intake manifold nice and shiny. I remember setting the timing on that required jumping two terminals on the ALDL connector. Let me know if you need to know the pinout, I may have the factory service manual around here somewhere. You were also able to get any codes to flash with the check engine light by jumping another terminal on the ALDL connector. No equipment needed.
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Oct 23, 2017 11:49
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Thanks for the info. I probably should have replaced the pressure regulator while I had the plenum off, I drove it some today and the rich condition seems to have cleared up after replacing the pressure lines, so I'm keeping my fingers crossed that the regulator holds up. I really wish it had throttle body injection, we had a 1991 Chevy Cheyenne 1500 back in the 90s and never had this kind of trouble with the fuel system. The injectors for those are only like $15 now at Rock Auto. CPI doesn't make a lot of sense to me since it's even more expensive than sequential multi-port fuel injection and doesn't have any of the advantages of SMFI. I did some more work on it today. I took the thermostat out, and hooked up one of those Prestone flush and fill things. It took about 10 minutes of running clean water through it but I finally got the water coming out of the radiator to run clear, then added some flushing chemicals. I ran it on the highway some at 70 without the thermostat, it was about 65 out today, and the temperature gauge never got above about 120-ish, so it looks like I've solved the overheating problem. Judging by the metallic particles that came out I think somebody overdid it with those stop leak pellets and it clogged some of the radiator tubes. And the thermostat was sticky. I'll replace the thermostat before I fill it with antifreeze. I also found the cause of the mysterious and intermittent "starts easy sometimes, then doesn't start at all for no apparent reason after sitting for more than 20 minutes" condition. It finally happened in my driveway where I could check things out. I measured the fuel pressure and got 0 PSI, tried jumping the fuel pump test connector (against the firewall between the AC evaporator and the distributor) directly to the battery, and still got 0 PSI. I knew I'd have to take the fuel tank off and started messing around back there with an impact wrench taking some of the bolts out, and the fuel pump, which I forgot and left connected to the battery, started running. So, sticky fuel pump. When I was taking it apart I noted the connector inside the tank was burned and corroded (ethanol is why we can't have nice things): http://onyxphoto.net/images/burned.jpg I made a new wiring harness where everything was soldered and shrink tubed: http://onyxphoto.net/images/harness.jpg I had to cut the rubber lines going into the sending unit when I took the gas tank out. I thought I was just going to buy some threaded fittings with hose barbs and hose clamp those suckers back on there, but I couldn't find the right fittings and came up with a more elegant solution. I made a bubble flare on the end of the metal tubes, then connected the rubber tubes directly to the sending unit. The only cost was about $3 for the itty wittle hose clamps. I did have to buy a new section of hose to go between the pump output and the fuel filter, but I was going to do that anyway because some idiot had used a fuel line repair kit with hoses that said "NOT FOR USE IN FUEL INJECTED SYSTEMS" on them in huge yellow letters. As for the check engine light/MIL, I don't think the MIL is working so I'm going to wire up a test light to the "MIL IND CTRL", which is supposed to be a brown and white wire that is pulled low when the MIL comes on. I have the Haynes manual and it shows the pinout for the diagnostic connector (ALDL) like this: _____________ |F|E|D|C|B|A| |G|H| | | |M| A: Ground B: Diagnostic terminal C: AIR (I don't know what that means) D: Check engine light (MIL) E: Serial data F: TCC G: Fuel pump H: Brake sense speed input M: Serial data I know mine doesn't have a few of these, like the fuel pump jumper, which is under the hood, and the manual says the serial data link is only present on the 4 cylinder models, which is probably why my tool doesn't work. If you want to verify that pinout against the factory manual I'd appreciate it. I'll try and see what codes it flashes out, if any, tomorrow. The procedure is turn ignition on, ground pin B, watch MIL for 1 flash, then two quick flashes, right? Is pin B the same one you ground to set the timing? Does it matter if I ground it before or after I start the engine for setting the timing? I wonder if that black and tan "timing wire" has to unplugged while I'm doing this. I'll post updates after I try this out. Revenna Fox fucked around with this message at 08:23 on Oct 24, 2017 |
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Oct 24, 2017 08:13
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OK, I took apart the instrument cluster and found out why the "SERVICE ENGINE SOON" light wasn't coming on even while I was doing all kinds of crazy stuff to the engine: somebody took it out. After putting a new lamp in, I tried to set the timing again, once by starting it up with pins A and B of the ALDL shorted, once by unplugging the fabled "timing wire", and once with both the pins shorted and the timing wire unplugged, and still no difference. The timing mark is right where it is when I haven't done any of the above. I am officially out of ideas.
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Oct 25, 2017 06:16
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Revenna Fox posted:OK, I took apart the instrument cluster and found out why the "SERVICE ENGINE SOON" light wasn't coming on even while I was doing all kinds of crazy stuff to the engine: somebody took it out. After putting a new lamp in, I tried to set the timing again, once by starting it up with pins A and B of the ALDL shorted, once by unplugging the fabled "timing wire", and once with both the pins shorted and the timing wire unplugged, and still no difference. The timing mark is right where it is when I haven't done any of the above. I am officially out of ideas. Because it's running exactly the same (verified with a timing light, I assume) when in timing bypass mode and normally, it sounds like it's not able or willing to adjust its timing. Maybe you have a wiring problem between the computer and the distributor, so it's always at zero timing. Maybe you have a bad sensor that's causing the computer to go into a limp mode where it won't adjust the timing. Maybe you have a bad distributor that isn't sending the right signal to the computer.
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Oct 25, 2017 06:32
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How many miles are on it? Is it possible that either the outer ring on the harmonic ballancer has slipped, or the timing chain has jumped? If TDC or 0 deg advance is marked on the ballancer, can you check that against No.1 piston via sparkplug hole? I don't know if you have looked into crankshaft position sensor, should throw a code though.
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Oct 25, 2017 09:21
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What codes are stored in the ECM? I had a 1993 Sierra that blew a couple ECMs due to a faulty ignition switch. When the ECM blew the CEL stayed lit but I couldn’t pull codes, the timing stayed at base, engine seemed to rev high, stalled easy and it shifted like it was at full line pressure. Someone also connected the EGR directly to manifold vacuum rather than its solenoid, but that wont gently caress with timing, just rough running/stalling.
rdb fucked around with this message at 09:34 on Oct 25, 2017 |
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Oct 25, 2017 09:32
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I've seen vapor lock with those motors. Just sayin.
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Oct 25, 2017 15:13
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Agreeing that the harmonic balancer has shifted so the timing mark can't be trusted. If there's a spot where it runs good, use that until you confirm the timing mark accuracy. Also since you were having a hard time wondering if dash lights were burned out - that's exactly the reason why they all light up when you turn the key. So that's how you check to see if it's working before you yank the whole cluster out. If you're not seeing the CEL when you turn the key, then it's either burned out or hosed with. Same with the oil light, amp light, brake warning, whatever the car came with. But check engine is universal. Other than that I don't know this engine so good luck from there.
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Oct 25, 2017 16:24
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| # ? May 6, 2024 02:28 |
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The one advantage CPI has is that gives you one (1) benefit of port injection (fuel spayed in the ports doesn't have time to puddle out while traveling through the runners like it can in carb/TBI engines), while still only requiring GM to pay for one fuel injector per truck. It still has all the other issues of tbi/batch fire port injection. It's a piece of garbage stopgap measure loved by beancounters and hated by everyone else. Does it run any better when you hit the gas, or just runs rough no matter what?
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Oct 25, 2017 16:48
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