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Old 01-06-2013, 08:11 PM
KMPJ-93 KMPJ-93 is offline
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Here's an update on the bogging issue I have. I've been heading in the right dirrection.

First off, for older vehicles like this (not sure maybe even all OBD1) a scan tool is NOT required. All you need to do is jump "terminal B" to the ground terminal (i can go into deatail if anyone would like). With these terminals jumped and the ignition on (vehicle not running) the vehicle goes into diagnostics mode and the "SERVICE ENGINE SOON" light begins flashing in sequences. It flashes once, pauses, then flashes twice consecutively (code 12). It does this three times, then flashes the codes. the way it flashes creates a number. EG: flash pause flash flash flash, means 13.

Anyways all I got was code 14, 15, and possibly 16 (did 5 quick flashes then a small pause before the last) Code 14 and 15 have to do with the temp sensor, and 16 has to do with a speed sensor I believe. None of these have to do with an ignition issue so I went on diagnosing sensors manually.

Basically the only left to be tested was the IAC valve. While the engine was running I disconected the IAC and nothing happened (I believe it should rev up?). So I took out the IAC and cleaned it. The haynes manual said the thing inside should not stick out more then 1-1/8" so i made it a bit less and re-intalled it. According to the Haynes manual, ECM will reset the IAC valve once the engine reaches operating temp. and is shut off. When I fired up the engine it idle reaaaallly high and backfired alot and would still bog when the throttle was bliped. But I waited for it to reach operating temp., shut it off, and fired it up again.
Nothing changed, and it was still idleing high, so to me this means the IAC valve did not reset, and is faulty. I pulled the IAC valve again and did an OHM test...55ohms, is that alright?

I then ran the truck without the IAC valve in it, and the wires disconected. It idled high and rich as hell, but when the throtle was bliped it reved right up with no bog.

So I am thinking the IAC valve is my issue. Or perhaps the ECM is not reading the sensors properly. I find it wired that nothing is throwing codes. But any further input would be great.
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