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    TBI timing help…

    I still can't tell how the timing is being set. if you pulled the distributor, put the engine at TDC, then you need to stab the distributor with the rotor pointing as close to cylinder 1 as possible. then start it and let it warm up. then unplug the EST bypass and put the timing light on wire...
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    TBI timing help…

    1. The ICM was probably what was bad, not the entire distributor 2. It isn't clear how you set the timing after you dropped the new distributor in. Timing should be set with a timing light on the #1 wire on a warm engine (if possible) with engine running and EST bypass unplugged.
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    Windshield Wiper Intermittent Function

    that sounds like could be the switch or maybe the park switch in the motor is going bad or maybe a short to ground in the wiring....
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    Windshield Wiper Intermittent Function

    the module is available here - https://www.workhorseparts.com/15598496-Module-Asm-Wiper-Switch-Pulse-Control. I've also had the intermittent wipers behave badly because of internal wiper motor issues.
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    Windshield Wiper Intermittent Function

    .
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    Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

    The front system does seem to be boosted when the rear is on in mine also, and I usually at least use the rear fan on LOW when the front is on even if nobody is sitting in the back. There isn't a lot of ductwork in the back. It is just the blower fan and an air deflector. If your deflector is...
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    Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

    I followed this post - https://www.gmsquarebody.com/threads/r4-to-sanden-whith-stock-ac-lines-for-serpantine.22437/ it was suburban specific. I also added a small pusher fan that helps a little, but the stock clutch fan really moves a lot of air on its own. the rear fan probably has had the...
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    1987 R10 shutoff while driving

    I'd say the ICM in the distributor is a highly likely suspect. If you don't want to do further diagnostic to be sure, this is one time getting out the single shot parts cannon isn't a terrible idea. Plus, if it doesn't resolve the issue, keeping a spare ICM in the glovebox is advisable because...
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    Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

    Search the forums., there is a thread on this forum that I followed when I upgraded to a sanden with my 1990 burb. Let me know if you can't find it. It has part numbers for a compressor with the stock hoses, new serpentine belt, etc.
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    1990 suburban Gage/idle fuse circuit shorted

    update - that fuse sends power to the TCC brake switch also. the purple wire from the brake switch that runs down to the TCC solenoid at the transmission was worn threw at a bracket holding the loom right by the connector. I moved it off the bracket and it didn't blow the fuse when i turned the...
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    1990 suburban Gage/idle fuse circuit shorted

    driving today and all of a sudden had no gauges. ECM was still reporting all the right data - coolant, vss, volts (although volts were lower than normal), etc. also noticed that when I turn the lights on, the buzzer buzzes....bc it thinks the ignition is not on. found the gage/idle fuse blown...
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    Vintage Air Gen V (5) or replace existing compressor, etc., for 1987 R20 Suburban?

    stock rebuild for the win
  13. G

    No power at temp gauge

    infinite resistance means it is open and has no continuity, right? sounds like a bad sending unit?
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    Vince's TBI woes, progressive revelations, and tbi mods.

    the TPS% being off is probably because of the .adx file you are using? i dont think that would affect things at the ECM. the TPS voltages look good. and MAP corresponds with TPS voltage - more throttle, less vacuum. the only thing I can think of is a vacuum leak that only appears at heavy...
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    Vince's TBI woes, progressive revelations, and tbi mods.

    I usually just bend the table to adjust TPS voltage at idle. if the tach is bouncing up high at low RPM it sounds like EMI. I used to have EMI so bad that it would even show up in the slow data stream. on a whim, you may check the ICM low reference to make sure it is grounding back through the...
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    Vince's TBI woes, progressive revelations, and tbi mods.

    I think the ECM uses tps volts at start up as a baseline, and anything less than about 1.0 (maybe even higher) won't mess with the ECM. I think the benefit of being around 0.5-0.6 at idle is the tps has more of its operational range to work with.
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    Vince's TBI woes, progressive revelations, and tbi mods.

    you'd think if the FPR were torn and leaking or somehow getting too much fuel, that the fuel trims would pick it up as they does the voltage change at all when it acts up? might also check the plugs/wires and also make sure no plug wires are touching ECM or ICM wires. did you ever check the...
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    700R4 TCC Lockup Issues

    The service manuals are in the Reference Library of the forum
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    Vince's TBI woes, progressive revelations, and tbi mods.

    The IAC counts seem normal. Some folks like them on the low end to have more air through the throttle blades for better fuel delivery. IAC opens up when you are off idle. Mine are normally in the 90-100 range when cruising, and 120ish range with AC on. So blipping the throttle will open IAC. But...
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    700R4 TCC Lockup Issues

    I had a cracked TCC solenoid on my 1990 and it caused partial locking and unlocking. but on my 1990, I could use a scantool to check if the computer was commanding lockup and check to make sure the brake switch was working properly at the ALDL. guessing that your '86 might not have those options...
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    Vince's TBI woes, progressive revelations, and tbi mods.

    there is some sort of a stall-saver mode that will open the IAC to let in more air to bump idle. I don't know a lot about it, though. it kicks in when RPM drops below a certain target is my guess. the AC also affects IAC position. it opens up more when the compressor kicks on. when the idle...
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    Vince's TBI woes, progressive revelations, and tbi mods.

    you said the fuel pump and filter are new, but have you checked the fuel pressure? ideally with a gauge long enough to watch while you drive? or will it idle bad just in the driveway and you don't need to drive it to act up? or a vacuum leak that is worse under load...something like an intake...
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    1987 TBI fuel pump issue

    also check the fuel pressure on that pump....
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    Fluid Changes

    I am assuming I can clean them with a pipe cleaner or one of those stiff brushes meant to clean out straws if the crud isn't too hard?
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    Fluid Changes

    Nope, but that's on my list of things to check....I suspect I may have a combination of slow drain back holes and bad seals. Maybe worth popping off the driver side cover and investigating. I think it comes off without having to get any accessories out of the way...

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