92 S10 Blazer TBI Rich

Discussion in 'Domestics' started by Gunnsmith57, Aug 27, 2017.

  1. billr

    billr wrench Staff Member

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    Well, I'm really confused now. The spark plug threads/gasket were leaking that bad? That seems impossible. Likewise, the compression gauge should have its own gasket or O-ring there, not dependent on the plug gasket at all. If the gauge worked in the other cylinders, it should have worked OK in #5.
     
  2. Mobile Dan

    Mobile Dan wrench

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    I'm wondering if a "foreign object" was preventing valve closure on cyl 5. Perhaps it finally broke up and valve is sealing again. I would not tear engine apart unless the cylinder "died again". Was the manifold bolt problem on the cyl 5 head?
     
  3. Gunnsmith57

    Gunnsmith57 Newbie

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    I was thinking the same thing Bill, but the gauge doesn't have any kind of seal at all. I even tried Teflon when I was testing it.

    Dan may be right about something keeping the exhaust valve from closing all the way, but it was driven a couple weeks like that before I ever did anything so I don't know. I figure if it was something, it would have came out before now.

    And the bolt on the manifold was on the other side, so it wouldn't have anything to do with that cylinder.

    I'm inclined to not touch it while it's running better, but at the same time, this weekend is a perfect time to do that gasket again if I had to. I'm thinking this afternoon I'll check compression again on that bank and see what the difference is from the other bank. If there's still a 20psi difference, or if I can still hear the compression hissing out, I'll go ahead and change it.
     
    Last edited: Sep 2, 2017
  4. Mobile Dan

    Mobile Dan wrench

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    My question about manifold bolt location was in regards to "The list of reasons why Gunn should pull that head off again".
     
  5. Gunnsmith57

    Gunnsmith57 Newbie

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    Just to update, the engine is still running like a champ for the most part. She's getting about 20mpg right now, which shocked me, and it'll get even better after I fix the TCC issue that's reared it's ugly head.

    I decided to not take the head back off right now and save my patience for when I change the valve seals later.

    I do have a question though. After driving the truck for around 15+ minutes the SES light comes on with a code 32 and stays on until the ignition is turned off. It seems to be running fine so it can't be running too far rich. Vacuum hose is in good condition and doesn't appear to be leaking. Knowing GM MAP sensors tend to last forever, could a faulty one cause this or should I look elsewhere? And since it's related, the PCV valve rattles like crazy after the engine warms up (new valve).

    And finally, I have a question about the TCC system and one about the 4WAL system. Should I start a new thread for those or just ask them here?
     
  6. kev2

    kev2 wrench

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    I think DTC 32 is a EGR issue, recheck your code descriptions, I will later double check # time permitting...
    A 4.3 with an EGR issue is so normal.

    Ask away we are watching this post,
    TCC?
    4WAL?
     
  7. Gunnsmith57

    Gunnsmith57 Newbie

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    32 can either be an EGR, Barometric, or MAP. The EGR on this one isn't monitored so it has to be the MAP (plus it already had a new EGR installed before I started to mess with this truck).

    The TCC (Torque Converter Clutch) is locking up almost at random and it has even killed the engine a couple times because it didn't unlock on deceleration. The first time it killed it (and the first time I noticed the problem), I was waiting at am intersection and when I started to take off it decided to lock as soon as I hit the gas and it immediately sputtered and died and I very slowly rolled over to the shoulder amidst some very surprised cursing. I stuck it in park, cycled the key, and it started right back up with no hesitation and I continued home, and about 8 miles later when I started to slow down for the next stop sign it started sputtering and died again. I put it in neutral and tried to start it and it didn't fire right up like I expected, tried again and still nothing so I put it in park, cycled the ignition, and it roared back to life. Another 8-10 miles and it started sputtering when I slowed down again but I dropped it down from OD to Drive as soon as it started and it unlocked and straightened back up. It hasn't really stuck locked since that day thankfully (it doesn't unlock as easily as it should when trying to accelerate or go up hills still, and that's when it even decides to lock like it should). Judging by the rest of the truck, I'm betting the transmission fluid has never been changed in the past 200k miles so I'm going to be doing that in a couple weeks. I'm wondering if I should bother getting a new solenoid for the TCC and change it while I have the pan off or if the problem is likely deeper?

    As for the 4WAL (4 Wheel Anti-Lock).. Almost 2 years ago my girlfriend said the ABS pump started to run constantly (even with the ignition off) so her friend unplugged the pump and it's been that way ever since. I figured it just needed a new control module which I planned on doing after I fixed the more important things. I just changed the brake booster, master Cylinder, front calipers, pads, and rotors, all of which it needed. Bled the system like normal except the ABS module since I didn't know this one needed to be bled (going to do that later today when I have a foot for the pedal). Anyway, it's still acting like the master cylinder is bad and losing pressure somewhere (but not fluid). The front brakes don't engage as strong as they should (sometimes not at all) and the rear brakes are engaging stronger than they should. Am I looking at replacing the ABS pump? If so, where's the best place to get this elusive part? I'd hate to know what a dealer would charge for it but after looking up the pump everywhere I can think of, it seems like it might be the only place I can get one (if they can even get one still).
     
  8. kev2

    kev2 wrench

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    FYI: EGR is monitored, when EGR is commanded the PCM observes either a change in o2 sensor or the change in MAP. If there is no swing in readings when EGR commanded the PCM 'ASSUMES' a EGR issue and codes will set.
    As I mentioned 4.3 and EGR are common..... New does not guarantee it working, Any way EGR and MAP are easy tests. I will post later. Do you have a vac gauge?

    TCC I think you are correct fluid and filter..... A bottle of "lube guard RED" as that may help any sludge varnish issues.
    A second thought TCC utilizes brake switch to interrupt TCC, not the part that operates brake lights a separate circuit in brake sw.

    4WAL - sure its not RWAL - this oldie is testing the memory :)
    ABS there is a way to obtain ABS codes thru ALDL - unfortunately I cannot remember it I will look or someone will post the answer.
    On the proportioning/metering valve I THINK there is a valve that can shift during bleeding or system failure that needs resetting - located on front of valve sometimes under a rubber bellows looking cover

    PS vin # Z or W - 8th character will ID system
     
    Last edited: Oct 6, 2017
  9. Gunnsmith57

    Gunnsmith57 Newbie

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    Yep, I went and got my MightyVac after I fixed the dead cylinder.

    For the TCC, I know the brake switch you're talking about. I had to adjust the stoplight switch after changing the booster and wondered what that other one next to it was for. It looked like it just had a vacuum hose connected to it. I'll check it for adjustment later.

    I'm positive it's 4WAL as it has the ABS rings on the hubs and the sensors. I tried reading the ABS code using the ALDL (jump from pin A to H) but the light would just slowly fade on and stay solid, no flashing. But now that I'm thinking about it I didn't plug the pump in when testing so I'll try that while I'm out there to see if it makes a difference reading the code (also, when the pump is plugged up the pedal goes straight to the floor and the brakes are almost nonexistent). I believe I remember seeing the cover you're talking about on the combination valve (either that or I saw it on a picture of one when looking for a solution online) so that's something else I'll check when I'm out there bleeding the ABS unit.

    It's vin Z. I only wish it was W so it would be truly fuel injected instead of the halfway point between fi and carb.

    And I called a dealer to see if they could get a new ABS pump just in case. It has been discontinued and lists for $1300. I think I peed a little bit when he said that.
     
  10. kev2

    kev2 wrench

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    I think your TCC idea fluid filter and ck switch will keep you busy as we get ABS details

    1992 s10 vin z... I would NOT condemn the module or pump
    before testing..... I will look for more info ie a wiring dia - somrthing has commanded the pump to run, Do a code check
    copy and paste below take note terminal A or ground, might help.


    Trouble code read out may be started using a jumper wire to connect Terminal H on the ALDL/DLC (diagnostic connector located under the instrument panel - refer to self-diagnostics in Section 4 of this manual for more information) to either body ground or to terminal A (internal ground). The terminals must be connected for a few seconds before the code will transmit. Observe the ANTILOCK light on the dash and count the flashes in groups: a group of 4 flashes, a pause and a group of 3 flashes indicates Code 43.
     

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  11. kev2

    kev2 wrench

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    this is your EGR system? A vacuum operated negative feed back.
    Code 32 continues to be EGR in my search
     
  12. Gunnsmith57

    Gunnsmith57 Newbie

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    I just looked up how to test the EGR so I'll be doing that in a little bit also. Haven't been able to do anything just yet, waiting for my girlfriend to get home with the truck, which should be any minute, then I'll have to let it cool off a little bit. I almost miss running it without a thermostat since it would cool off so quickly and let me work on it lol.

    I'll get back with you as soon as I have some more info. Thanks again Kev!
     
  13. kev2

    kev2 wrench

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    dia sorry I have no time to think on this BUT codes are a start
     

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  14. Gunnsmith57

    Gunnsmith57 Newbie

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    EGR was an easy fix. Went to test it and found the vacuum line between it and the solenoid had come off and I didn't notice cuz I was thinking the MAP sensor. It's now on much more securely.

    The brake proportion, I believe, is off because of the combination valve. I found the covers Kev mentioned (one on front and rear of the combination) and the valve is pushed back, blocking off the front brakes. When you step on the brakes you can feel the valve push back even more. I'm betting that when the truck needed a new brake hose on the front a couple years ago the valve blocked off the front like it's supposed to, and no one reset it after changing the hose. I tried to center it but my 9/16 wrench is apparently stretched out and won't break the line nut loose so Monday I'll get a line wrench for it and try to center it again. I also still couldn't pull any ABS codes off even with the pump plugged in. The ABS light just stays solid. Would a faulty ABS control module cause this (and is there a way to test it)? I know it can cause the pump to run constantly, which adds up.

    The brake switch for the TCC is adjusted correctly so I'm still banking on a fluid/filter change (and the lubeguard red, or TransX if the parts stores don't have it) as well as changing the TCC solenoid while the trans pan is off. May as well change the $30 part while the pan is off so I don't have to buy more fluid if the fluid/filter change doesn't fix the TCC.
     
    Last edited: Oct 7, 2017
  15. Gunnsmith57

    Gunnsmith57 Newbie

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    :oops: Scratch what I said about the combination valve. What I read originally about how it works was apparently completely wrong and now I feel like an idjit. What I thought was supposed to be a valve on the front of it is apparently just a vent hole.

    The valve stem on the rear of the combination valve is flush and doesn't stick out at all until the brakes are pressed. Is this normal?

    And after doing more research, I'm thinking the EHCU is leaking pressure into the low pressure dump, leading to the same symptoms as a bad master cylinder. I stuck the bleeder plugs back in the MC earlier to make sure the new MC isn't bad and it's not (I also bled it again while I had the plugs in and had air come out, despite having extensively bled it during install). While I was working on it today I ATTEMPTED to bleed the EHCU but couldn't get any fluid out and now I know why and have to wait a little bit to get those three special depressors to try bleeding it. What I did did have some effect on the ABS though. The pump was super loud (almost like a small air compressor) when running before, and after my attempt it's now quieter.

    Should I bother trying to bleed the EHCU with the depressors or try to find a new unit first then bleed it?

    Right now I'm about to :giveup: and just replace the shoes and hardware and let the truck keep depending on the rears to stop for the next 5 months.

    Also, would it be possible to just bypass the EHCU and hook up the brake lines straight into the combination valve? We already have plans on getting a new vehicle at tax time anyway and just keeping this one for short in-town trips so I'm open to almost anything at this point.
     

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